1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
2511
2512
2513
2514
2515
2516
2517
2518
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
3032
3033
3034
3035
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
8586
8587
8588
8589
8590
8591
8592
8593
8594
8595
8596
8597
8598
8599
8600
8601
8602
8603
8604
8605
8606
8607
8608
8609
8610
8611
8612
8613
8614
8615
8616
8617
8618
8619
8620
8621
8622
8623
8624
8625
8626
8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
8663
8664
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
8699
8700
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
8727
8728
8729
8730
8731
8732
8733
8734
8735
8736
8737
8738
8739
8740
8741
8742
8743
8744
8745
8746
8747
8748
8749
8750
8751
8752
8753
8754
8755
8756
8757
8758
8759
8760
8761
8762
8763
8764
8765
8766
8767
8768
8769
8770
8771
8772
8773
8774
8775
8776
8777
8778
8779
8780
8781
8782
8783
8784
8785
8786
8787
8788
8789
8790
8791
8792
8793
8794
8795
8796
8797
8798
8799
8800
8801
8802
8803
8804
8805
8806
8807
8808
8809
8810
8811
8812
8813
8814
8815
8816
8817
8818
8819
8820
8821
8822
8823
8824
8825
8826
8827
8828
8829
8830
8831
8832
8833
8834
8835
8836
8837
8838
8839
8840
8841
8842
8843
8844
8845
8846
8847
8848
8849
8850
8851
8852
8853
8854
8855
8856
8857
8858
8859
8860
8861
8862
8863
8864
8865
8866
8867
8868
8869
8870
8871
8872
8873
8874
8875
8876
8877
8878
8879
8880
8881
8882
8883
8884
8885
8886
8887
8888
8889
8890
8891
8892
8893
8894
8895
8896
8897
8898
8899
8900
8901
8902
8903
8904
8905
8906
8907
8908
8909
8910
8911
8912
8913
8914
8915
8916
8917
8918
8919
8920
8921
8922
8923
8924
8925
8926
8927
8928
8929
8930
8931
8932
8933
8934
8935
8936
8937
8938
8939
8940
8941
8942
8943
8944
8945
8946
8947
8948
8949
8950
8951
8952
8953
8954
8955
8956
8957
8958
8959
8960
8961
8962
8963
8964
8965
8966
8967
8968
8969
8970
8971
8972
8973
8974
8975
8976
8977
8978
8979
8980
8981
8982
8983
8984
8985
8986
8987
8988
8989
8990
8991
8992
8993
8994
8995
8996
8997
8998
8999
9000
9001
9002
9003
9004
9005
9006
9007
9008
9009
9010
9011
9012
9013
9014
9015
9016
9017
9018
9019
9020
9021
9022
9023
9024
9025
9026
9027
9028
9029
9030
9031
9032
9033
9034
9035
9036
9037
9038
9039
9040
9041
9042
9043
9044
9045
9046
9047
9048
9049
9050
9051
9052
9053
9054
9055
9056
9057
9058
9059
9060
9061
9062
9063
9064
9065
9066
9067
9068
9069
9070
9071
9072
9073
9074
9075
9076
9077
9078
9079
9080
9081
9082
9083
9084
9085
9086
9087
9088
9089
9090
9091
9092
9093
9094
9095
9096
9097
9098
9099
9100
9101
9102
9103
9104
9105
9106
9107
9108
9109
9110
9111
9112
9113
9114
9115
9116
9117
9118
9119
9120
9121
9122
9123
9124
9125
9126
9127
9128
9129
9130
9131
9132
9133
9134
9135
9136
9137
9138
9139
9140
9141
9142
9143
9144
9145
9146
9147
9148
9149
9150
9151
9152
9153
9154
9155
9156
9157
9158
9159
9160
9161
9162
9163
9164
9165
9166
9167
9168
9169
9170
9171
9172
9173
9174
9175
9176
9177
9178
9179
9180
9181
9182
9183
9184
9185
9186
9187
9188
9189
9190
9191
9192
9193
9194
9195
9196
9197
9198
9199
9200
9201
9202
9203
9204
9205
9206
9207
9208
9209
9210
9211
9212
9213
9214
9215
9216
9217
9218
9219
9220
9221
9222
9223
9224
9225
9226
9227
9228
9229
9230
9231
9232
9233
9234
9235
9236
9237
9238
9239
9240
9241
9242
9243
9244
9245
9246
9247
9248
9249
9250
9251
9252
9253
9254
9255
9256
9257
9258
9259
9260
9261
9262
9263
9264
9265
9266
9267
9268
9269
9270
9271
9272
9273
9274
9275
9276
9277
9278
9279
9280
9281
9282
9283
9284
9285
9286
9287
9288
9289
9290
9291
9292
9293
9294
9295
9296
9297
9298
9299
9300
9301
9302
9303
9304
9305
9306
9307
9308
9309
9310
9311
9312
9313
9314
9315
9316
9317
9318
9319
9320
9321
9322
9323
9324
9325
9326
9327
9328
9329
9330
9331
9332
9333
9334
9335
9336
9337
9338
9339
9340
9341
9342
9343
9344
9345
9346
9347
9348
9349
9350
9351
9352
9353
9354
9355
9356
9357
9358
9359
| | @c -*- mode: texinfo; coding: utf-8 -*-
@c This is part of the GNU Emacs Lisp Reference Manual.
@c Copyright (C) 1990--1995, 1998--2024 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@node Display
@chapter Emacs Display
This chapter describes a number of features related to the display
that Emacs presents to the user.
@menu
* Refresh Screen:: Clearing the screen and redrawing everything on it.
* Forcing Redisplay:: Forcing redisplay.
* Truncation:: Folding or wrapping long text lines.
* The Echo Area:: Displaying messages at the bottom of the screen.
* Warnings:: Displaying warning messages for the user.
* Invisible Text:: Hiding part of the buffer text.
* Selective Display:: Hiding part of the buffer text (the old way).
* Temporary Displays:: Displays that go away automatically.
* Overlays:: Use overlays to highlight parts of the buffer.
* Size of Displayed Text:: How large displayed text is.
* Line Height:: Controlling the height of lines.
* Faces:: A face defines a graphics style for text characters:
font, colors, etc.
* Fringes:: Controlling window fringes.
* Scroll Bars:: Controlling scroll bars.
* Window Dividers:: Separating windows visually.
* Display Property:: Images, margins, text size, etc.
* Images:: Displaying images in Emacs buffers.
* Icons:: Displaying icons in Emacs buffers.
* Xwidgets:: Displaying native widgets in Emacs buffers.
* Buttons:: Adding clickable buttons to Emacs buffers.
* Abstract Display:: Emacs's Widget for Object Collections.
* Blinking:: How Emacs shows the matching open parenthesis.
* Character Display:: How Emacs displays individual characters.
* Beeping:: Audible signal to the user.
* Window Systems:: Which window system is being used.
* Tooltips:: Tooltip display in Emacs.
* Bidirectional Display:: Display of bidirectional scripts, such as
Arabic and Farsi.
@end menu
@node Refresh Screen
@section Refreshing the Screen
@cindex refresh the screen
@cindex screen refresh
The function @code{redraw-frame} clears and redisplays the entire
contents of a given frame (@pxref{Frames}). This is useful if the
screen is corrupted.
@defun redraw-frame &optional frame
This function clears and redisplays frame @var{frame}. If @var{frame}
is omitted or @code{nil}, it redraws the selected frame.
@end defun
Even more powerful is @code{redraw-display}:
@deffn Command redraw-display
This function clears and redisplays all visible frames.
@end deffn
In Emacs, processing user input takes priority over redisplay. If
you call these functions when input is available, they don't redisplay
immediately, but the requested redisplay does happen
eventually---after all the input has been processed.
On text terminals, suspending and resuming Emacs normally also
refreshes the screen. Some terminal emulators record separate
contents for display-oriented programs such as Emacs and for ordinary
sequential display. If you are using such a terminal, you might want
to inhibit the redisplay on resumption.
@defopt no-redraw-on-reenter
@cindex suspend (cf. @code{no-redraw-on-reenter})
@cindex resume (cf. @code{no-redraw-on-reenter})
This variable controls whether Emacs redraws the entire screen after it
has been suspended and resumed. Non-@code{nil} means there is no need
to redraw, @code{nil} means redrawing is needed. The default is @code{nil}.
@end defopt
@node Forcing Redisplay
@section Forcing Redisplay
@cindex forcing redisplay
Emacs normally tries to redisplay the screen whenever it waits for
input. With the following function, you can request an immediate
attempt to redisplay, in the middle of Lisp code, without actually
waiting for input.
@defun redisplay &optional force
This function tries immediately to redisplay. The optional argument
@var{force}, if non-@code{nil}, forces the redisplay to be performed,
instead of being preempted if input is pending.
The function returns @code{t} if it actually tried to redisplay, and
@code{nil} otherwise. A value of @code{t} does not mean that
redisplay proceeded to completion; it could have been preempted by
newly arriving input.
@end defun
Although @code{redisplay} tries immediately to redisplay, it does
not change how Emacs decides which parts of its frame(s) to redisplay.
By contrast, the following function adds certain windows to the
pending redisplay work (as if their contents had completely changed),
but does not immediately try to perform redisplay.
@defun force-window-update &optional object
This function forces some or all windows to be updated the next time
Emacs does a redisplay. If @var{object} is a window, that window is
to be updated. If @var{object} is a buffer or buffer name, all
windows displaying that buffer are to be updated. If @var{object} is
@code{nil} (or omitted), all windows are to be updated.
This function does not do a redisplay immediately; Emacs does that as
it waits for input, or when the function @code{redisplay} is called.
@end defun
@defvar pre-redisplay-function
A function run just before redisplay. It is called with one argument,
the set of windows to be redisplayed. The set can be @code{nil},
meaning only the selected window, or @code{t}, meaning all the
windows.
@end defvar
@defvar pre-redisplay-functions
This hook is run just before redisplay. It is called once in each
window that is about to be redisplayed, with @code{current-buffer} set
to the buffer displayed in that window.
@end defvar
@node Truncation
@section Truncation
@cindex line wrapping
@cindex line truncation
@cindex continuation lines
@cindex @samp{$} in display
@cindex @samp{\} in display
When a line of text extends beyond the right edge of a window, Emacs
can @dfn{continue} the line (make it wrap to the next screen
line), or @dfn{truncate} the line (limit it to one screen line). The
additional screen lines used to display a long text line are called
@dfn{continuation} lines. Continuation is not the same as filling;
continuation happens on the screen only, not in the buffer contents,
and it breaks a line precisely at the right margin, not at a word
boundary. @xref{Filling}.
On a graphical display, tiny arrow images in the window fringes
indicate truncated and continued lines (@pxref{Fringes}). On a text
terminal, a @samp{$} in the rightmost column of the window indicates
truncation; a @samp{\} on the rightmost column indicates a line that
wraps. (The display table can specify alternate characters to use
for this; @pxref{Display Tables}).
Since wrapping and truncation of text contradict each other, Emacs
turns off line truncation when wrapping is requested, and vice versa.
@defopt truncate-lines
If this buffer-local variable is non-@code{nil}, lines that extend
beyond the right edge of the window are truncated; otherwise, they are
continued. As a special exception, the variable
@code{truncate-partial-width-windows} takes precedence in
@dfn{partial-width} windows (i.e., windows that do not occupy the
entire frame width).
@end defopt
@defopt truncate-partial-width-windows
@cindex partial-width windows
This variable controls line truncation in @dfn{partial-width} windows.
A partial-width window is one that does not occupy the entire frame
width (@pxref{Splitting Windows}). If the value is @code{nil}, line
truncation is determined by the variable @code{truncate-lines} (see
above). If the value is an integer @var{n}, lines are truncated if
the partial-width window has fewer than @var{n} columns, regardless of
the value of @code{truncate-lines}; if the partial-width window has
@var{n} or more columns, line truncation is determined by
@code{truncate-lines}. For any other non-@code{nil} value, lines are
truncated in every partial-width window, regardless of the value of
@code{truncate-lines}.
@end defopt
When horizontal scrolling (@pxref{Horizontal Scrolling}) is in use in
a window, that forces truncation.
@defvar wrap-prefix
If this buffer-local variable is non-@code{nil}, it defines a
@dfn{wrap prefix} which Emacs displays at the start of every
continuation line. (If lines are truncated, @code{wrap-prefix} is
never used.) Its value may be a string or an image (@pxref{Other
Display Specs}), or a stretch of whitespace such as specified by the
@code{:width} or @code{:align-to} display properties (@pxref{Specified
Space}). The value is interpreted in the same way as a @code{display}
text property. @xref{Display Property}.
A wrap prefix may also be specified for regions of text, using the
@code{wrap-prefix} text or overlay property. This takes precedence
over the @code{wrap-prefix} variable. @xref{Special Properties}.
@end defvar
@defvar line-prefix
If this buffer-local variable is non-@code{nil}, it defines a
@dfn{line prefix} which Emacs displays at the start of every
non-continuation line. Its value may be a string or an image
(@pxref{Other Display Specs}), or a stretch of whitespace such as
specified by the @code{:width} or @code{:align-to} display properties
(@pxref{Specified Space}). The value is interpreted in the same way
as a @code{display} text property. @xref{Display Property}.
A line prefix may also be specified for regions of text using the
@code{line-prefix} text or overlay property. This takes precedence
over the @code{line-prefix} variable. @xref{Special Properties}.
@end defvar
@ignore
If your buffer contains only very short lines, you might find it
advisable to set @code{cache-long-scans} to @code{nil}.
@defvar cache-long-scans
If this variable is non-@code{nil} (the default), various indentation
and motion functions, and Emacs redisplay, cache the results of
scanning the buffer, and consult the cache to avoid rescanning regions
of the buffer unless they are modified.
Turning off the cache speeds up processing of short lines somewhat.
This variable is automatically buffer-local in every buffer.
@end defvar
@end ignore
@node The Echo Area
@section The Echo Area
@cindex error display
@cindex echo area
@c FIXME: Why not use @xref{Minibuffers} directly? --xfq
The @dfn{echo area} is used for displaying error messages
(@pxref{Errors}), for messages made with the @code{message} primitive,
and for echoing keystrokes. It is not the same as the minibuffer,
despite the fact that the minibuffer appears (when active) in the same
place on the screen as the echo area. @xref{Minibuffer,, The
Minibuffer, emacs, The GNU Emacs Manual}.
Apart from the functions documented in this section, you can print
Lisp objects to the echo area by specifying @code{t} as the output
stream. @xref{Output Streams}.
@menu
* Displaying Messages:: Explicitly displaying text in the echo area.
* Progress:: Informing user about progress of a long operation.
* Logging Messages:: Echo area messages are logged for the user.
* Echo Area Customization:: Controlling the echo area.
@end menu
@node Displaying Messages
@subsection Displaying Messages in the Echo Area
@cindex display message in echo area
This section describes the standard functions for displaying
messages in the echo area.
@defun message format-string &rest arguments
This function displays a message in the echo area.
@var{format-string} is a format string, and @var{arguments} are the
objects for its format specifications, like in the @code{format-message}
function (@pxref{Formatting Strings}). The resulting formatted string
is displayed in the echo area; if it contains @code{face} text
properties, it is displayed with the specified faces (@pxref{Faces}).
The string is also added to the @file{*Messages*} buffer, but without
text properties (@pxref{Logging Messages}).
Typically grave accent and apostrophe in the format translate to
matching curved quotes, e.g., @t{"Missing `%s'"} might result in
@t{"Missing ‘foo’"}. @xref{Text Quoting Style}, for how to influence
or inhibit this translation.
In batch mode, the message is printed to the standard error stream,
followed by a newline.
When @code{inhibit-message} is non-@code{nil}, no message will be displayed
in the echo area, it will only be logged to @samp{*Messages*}.
If @var{format-string} is @code{nil} or the empty string,
@code{message} clears the echo area; if the echo area has been
expanded automatically, this brings it back to its normal size. If
the minibuffer is active, this brings the minibuffer contents back
onto the screen immediately.
@example
@group
(message "Reverting `%s'..." (buffer-name))
@print{} Reverting ‘subr.el’...
@result{} "Reverting ‘subr.el’..."
@end group
@group
---------- Echo Area ----------
Reverting ‘subr.el’...
---------- Echo Area ----------
@end group
@end example
To automatically display a message in the echo area or in a pop-buffer,
depending on its size, use @code{display-message-or-buffer} (see below).
@strong{Warning:} If you want to use your own string as a message
verbatim, don't just write @code{(message @var{string})}. If
@var{string} contains @samp{%}, @samp{`}, or @samp{'} it may be
reformatted, with undesirable results. Instead, use @code{(message
"%s" @var{string})}.
@end defun
The following facilities allow users and Lisp programs to control how
echo-area messages are displayed.
@defvar set-message-function
If this variable is non-@code{nil}, it should be a function of one
argument, the text of a message to display in the echo area. That
function will be called by @code{message} and related functions. If
the function returns @code{nil}, the message is displayed in the echo
area as usual. If the function returns a string, that string is
displayed in the echo area @emph{instead} of the original message. If
the function returns any other non-@code{nil} value, that means the
message was already handled, so @code{message} will not display
anything in the echo area.
The default value calls @code{set-minibuffer-message}, described
below.
@end defvar
@defvar clear-message-function
If this variable is non-@code{nil}, it should be a function of no
arguments; @code{message} and related functions call it when their
argument message is @code{nil} or the empty string, to clear the echo
area.
Usually this function is called when the next input event arrives
after displaying an echo-area message. The function is expected to
clear the message displayed by its counterpart function specified by
@code{set-message-function}, but doesn't have to. If the function
wants the echo area to remain uncleared, it should return the symbol
@code{dont-clear-message}; any other value will result in the echo
area being cleared.
The default value is the function that clears the message displayed in
an active minibuffer.
@end defvar
@defopt set-message-functions
The value of this user option is a list of functions to be called for
handling display of echo-area messages. Each function is called with
one argument, the text of the message to display. If the function
returns a string, that string replaces the original message, and the
next function in the list is called with the new message text. If the
function returns @code{nil}, the next function in the list is called
with the same text; if the last function in the list returns
@code{nil}, the message text is displayed in the echo area. If the
function returns a non-@code{nil} value that is not a string, the
message is considered to be handled, and no further functions in the
list are called.
The three useful functions to be put in the list that is the value of
this option are described below.
@end defopt
@defun set-minibuffer-message message
This function displays @var{message} in the echo-area when the
minibuffer is not active, and at the end of the minibuffer when the
minibuffer is active. However, if the text shown in the active
minibuffer has the @code{minibuffer-message} text property
(@pxref{Special Properties}) on some character, the message will be
displayed before the first character having that property.
This function is by default the only member of the list in
@code{set-message-functions}.
@end defun
@vindex inhibit-message-regexps
@defun inhibit-message message
If an echo-area @var{message} matches any regexp in the list that is
the value of the user option @code{inhibit-message-regexps}, this
function suppresses the display of that message and returns a
non-@code{nil} value that is not a string. Thus, if this function is
in the list @code{set-message-functions}, the rest of the functions in
the list will not be called when @var{message} matches the regexps in
@code{inhibit-message-regexps}. To ensure a matching @var{message}
will never be displayed, make this function be the first element of
the list in @code{set-message-functions}.
@end defun
@vindex multi-message-max
@vindex multi-message-timeout
@defun set-multi-message message
This function accumulates several echo-area messages emitted one after
another, and returns them as a single string in which individual
messages are separated by newlines. Up to @code{multi-message-max}
recent messages can be accumulated. The accumulated messages are
discarded when more than @code{multi-message-timeout} seconds have
elapsed since the time the first message was emitted.
@end defun
@defvar inhibit-message
When this variable is non-@code{nil}, @code{message} and related functions
will not display any messages in the Echo Area. Echo-area messages
are still logged in the @file{*Messages*} buffer, though.
@end defvar
@defmac with-temp-message message &rest body
This construct displays a message in the echo area temporarily, during
the execution of @var{body}. It displays @var{message}, executes
@var{body}, then returns the value of the last body form while restoring
the previous echo area contents.
@end defmac
@defun message-or-box format-string &rest arguments
This function displays a message like @code{message}, but may display it
in a dialog box instead of the echo area. If this function is called in
a command that was invoked using the mouse---more precisely, if
@code{last-nonmenu-event} (@pxref{Command Loop Info}) is either
@code{nil} or a list---then it uses a dialog box or pop-up menu to
display the message. Otherwise, it uses the echo area. (This is the
same criterion that @code{y-or-n-p} uses to make a similar decision; see
@ref{Yes-or-No Queries}.)
You can force use of the mouse or of the echo area by binding
@code{last-nonmenu-event} to a suitable value around the call.
@end defun
@defun message-box format-string &rest arguments
@anchor{message-box}
This function displays a message like @code{message}, but uses a dialog
box (or a pop-up menu) whenever that is possible. If it is impossible
to use a dialog box or pop-up menu, because the terminal does not
support them, then @code{message-box} uses the echo area, like
@code{message}.
@end defun
@defun display-message-or-buffer message &optional buffer-name action frame
This function displays the message @var{message}, which may be either a
string or a buffer. If it is shorter than the maximum height of the
echo area, as defined by @code{max-mini-window-height}, it is displayed
in the echo area, using @code{message}. Otherwise,
@code{display-buffer} is used to show it in a pop-up buffer.
Returns either the string shown in the echo area, or when a pop-up
buffer is used, the window used to display it.
If @var{message} is a string, then the optional argument
@var{buffer-name} is the name of the buffer used to display it when a
pop-up buffer is used, defaulting to @file{*Message*}. In the case
where @var{message} is a string and displayed in the echo area, it is
not specified whether the contents are inserted into the buffer anyway.
The optional arguments @var{action} and @var{frame} are as for
@code{display-buffer}, and only used if a buffer is displayed.
@end defun
@defun current-message
This function returns the message currently being displayed in the
echo area, or @code{nil} if there is none.
@end defun
@node Progress
@subsection Reporting Operation Progress
@cindex progress reporting
When an operation can take a while to finish, you should inform the
user about the progress it makes. This way the user can estimate
remaining time and clearly see that Emacs is busy working, not hung.
A convenient way to do this is to use a @dfn{progress reporter}.
Here is a working example that does nothing useful:
@smallexample
(let ((progress-reporter
(make-progress-reporter "Collecting mana for Emacs..."
0 500)))
(dotimes (k 500)
(sit-for 0.01)
(progress-reporter-update progress-reporter k))
(progress-reporter-done progress-reporter))
@end smallexample
@defun make-progress-reporter message &optional min-value max-value current-value min-change min-time
This function creates and returns a progress reporter object, which
you will use as an argument for the other functions listed below. The
idea is to precompute as much data as possible to make progress
reporting very fast.
When this progress reporter is subsequently used, it will display
@var{message} in the echo area, followed by progress percentage.
@var{message} is treated as a simple string. If you need it to depend
on a filename, for instance, use @code{format-message} before calling this
function.
The arguments @var{min-value} and @var{max-value} should be numbers
standing for the starting and final states of the operation. For
instance, an operation that scans a buffer should set these to the
results of @code{point-min} and @code{point-max} correspondingly.
@var{max-value} should be greater than @var{min-value}.
Alternatively, you can set @var{min-value} and @var{max-value} to
@code{nil}. In that case, the progress reporter does not report
process percentages; it instead displays a ``spinner'' that rotates a
notch each time you update the progress reporter.
If @var{min-value} and @var{max-value} are numbers, you can give the
argument @var{current-value} a numerical value specifying the initial
progress; if omitted, this defaults to @var{min-value}.
The remaining arguments control the rate of echo area updates. The
progress reporter will wait for at least @var{min-change} more
percents of the operation to be completed before printing next
message; the default is one percent. @var{min-time} specifies the
minimum time in seconds to pass between successive prints; the default
is 0.2 seconds. (On some operating systems, the progress reporter may
handle fractions of seconds with varying precision).
This function calls @code{progress-reporter-update}, so the first
message is printed immediately.
@end defun
@defun progress-reporter-update reporter &optional value suffix
This function does the main work of reporting progress of your
operation. It displays the message of @var{reporter}, followed by
progress percentage determined by @var{value}. If percentage is zero,
or close enough according to the @var{min-change} and @var{min-time}
arguments, then it is omitted from the output.
@var{reporter} must be the result of a call to
@code{make-progress-reporter}. @var{value} specifies the current
state of your operation and must be between @var{min-value} and
@var{max-value} (inclusive) as passed to
@code{make-progress-reporter}. For instance, if you scan a buffer,
then @var{value} should be the result of a call to @code{point}.
Optional argument @var{suffix} is a string to be displayed after
@var{reporter}'s main message and progress text. If @var{reporter} is
a non-numerical reporter, then @var{value} should be @code{nil}, or a
string to use instead of @var{suffix}.
This function respects @var{min-change} and @var{min-time} as passed
to @code{make-progress-reporter} and so does not output new messages
on every invocation. It is thus very fast and normally you should not
try to reduce the number of calls to it: resulting overhead will most
likely negate your effort.
@end defun
@defun progress-reporter-force-update reporter &optional value new-message suffix
This function is similar to @code{progress-reporter-update} except
that it prints a message in the echo area unconditionally.
@var{reporter}, @var{value}, and @var{suffix} have the same meaning as for
@code{progress-reporter-update}. Optional @var{new-message} allows
you to change the message of the @var{reporter}. Since this function
always updates the echo area, such a change will be immediately
presented to the user.
@end defun
@defun progress-reporter-done reporter
This function should be called when the operation is finished. It
prints the message of @var{reporter} followed by word @samp{done} in the
echo area.
You should always call this function and not hope for
@code{progress-reporter-update} to print @samp{100%}. Firstly, it may
never print it, there are many good reasons for this not to happen.
Secondly, @samp{done} is more explicit.
@end defun
@defmac dotimes-with-progress-reporter (var count [result]) reporter-or-message body@dots{}
This is a convenience macro that works the same way as @code{dotimes}
does, but also reports loop progress using the functions described
above. It allows you to save some typing. The argument
@var{reporter-or-message} can be either a string or a progress
reporter object.
You can rewrite the example in the beginning of this subsection using
this macro as follows:
@example
@group
(dotimes-with-progress-reporter
(k 500)
"Collecting some mana for Emacs..."
(sit-for 0.01))
@end group
@end example
Using a reporter object as the @var{reporter-or-message} argument is
useful if you want to specify the optional arguments in
@var{make-progress-reporter}. For instance, you can write the
previous example as follows:
@example
@group
(dotimes-with-progress-reporter
(k 500)
(make-progress-reporter "Collecting some mana for Emacs..." 0 500 0 1 1.5)
(sit-for 0.01))
@end group
@end example
@end defmac
@defmac dolist-with-progress-reporter (var list [result]) reporter-or-message body@dots{}
This is another convenience macro that works the same way as @code{dolist}
does, but also reports loop progress using the functions described
above. As in @code{dotimes-with-progress-reporter},
@code{reporter-or-message} can be a progress reporter or a string.
You can rewrite the previous example with this macro as follows:
@example
@group
(dolist-with-progress-reporter
(k (number-sequence 0 500))
"Collecting some mana for Emacs..."
(sit-for 0.01))
@end group
@end example
@end defmac
@defmac with-delayed-message (timeout message) body@dots{}
Sometimes it's unclear whether an operation will take a long time to
execute or not, or it can be inconvenient to implement a progress
reporter. This macro can be used in those situations.
@lisp
(with-delayed-message (2 (format "Gathering data for %s" entry))
(setq data (gather-data entry)))
@end lisp
In this example, if the body takes more than two seconds to execute,
the message will be displayed. If it takes a shorter time than that,
the message won't be displayed. In either case, the body is evaluated
as normally, and the return value of the final element in the body is
the return value of the macro.
The @var{message} element is evaluated before @var{body}, and is
always evaluated, whether the message is displayed or not.
@end defmac
@node Logging Messages
@subsection Logging Messages in @file{*Messages*}
@cindex logging echo-area messages
Almost all the messages displayed in the echo area are also recorded
in the @file{*Messages*} buffer so that the user can refer back to
them. This includes all the messages that are output with
@code{message}. By default, this buffer is read-only and uses the major
mode @code{messages-buffer-mode}. Nothing prevents the user from
killing the @file{*Messages*} buffer, but the next display of a message
recreates it. Any Lisp code that needs to access the
@file{*Messages*} buffer directly and wants to ensure that it exists
should use the function @code{messages-buffer}.
@defun messages-buffer
This function returns the @file{*Messages*} buffer. If it does not
exist, it creates it, and switches it to @code{messages-buffer-mode}.
@end defun
@defopt message-log-max
This variable specifies how many lines to keep in the @file{*Messages*}
buffer. The value @code{t} means there is no limit on how many lines to
keep. The value @code{nil} disables message logging entirely. Here's
how to display a message and prevent it from being logged:
@example
(let (message-log-max)
(message @dots{}))
@end example
@end defopt
@defvar messages-buffer-name
This variable has the name of the buffer where messages should be
logged to, and defaults to @file{*Messages*}. Some packages may find
it useful to temporarily redirect the output to a different buffer
(perhaps to write the buffer out to a log file later), and they can
bind this variable to a different buffer name. (Note that this buffer
(if it doesn't exist already), will be created and put into
@code{messages-buffer-mode}.)
@end defvar
To make @file{*Messages*} more convenient for the user, the logging
facility combines successive identical messages. It also combines
successive related messages for the sake of two cases: question
followed by answer, and a series of progress messages.
A question followed by an answer has two messages like the
ones produced by @code{y-or-n-p}: the first is @samp{@var{question}},
and the second is @samp{@var{question}...@var{answer}}. The first
message conveys no additional information beyond what's in the second,
so logging the second message discards the first from the log.
A series of progress messages has successive messages like
those produced by @code{make-progress-reporter}. They have the form
@samp{@var{base}...@var{how-far}}, where @var{base} is the same each
time, while @var{how-far} varies. Logging each message in the series
discards the previous one, provided they are consecutive.
The functions @code{make-progress-reporter} and @code{y-or-n-p}
don't have to do anything special to activate the message log
combination feature. It operates whenever two consecutive messages
are logged that share a common prefix ending in @samp{...}.
@node Echo Area Customization
@subsection Echo Area Customization
@cindex echo area customization
These variables control details of how the echo area works.
@defvar cursor-in-echo-area
This variable controls where the cursor appears when a message is
displayed in the echo area. If it is non-@code{nil}, then the cursor
appears at the end of the message. Otherwise, the cursor appears at
point---not in the echo area at all.
The value is normally @code{nil}; Lisp programs bind it to @code{t}
for brief periods of time.
@end defvar
@defvar echo-area-clear-hook
This normal hook is run whenever the echo area is cleared---either by
@code{(message nil)} or for any other reason.
@end defvar
@defopt echo-keystrokes
This variable determines how much time should elapse before command
characters echo. Its value must be a number, and specifies the
number of seconds to wait before echoing. If the user types a prefix
key (such as @kbd{C-x}) and then delays this many seconds before
continuing, the prefix key is echoed in the echo area. (Once echoing
begins in a key sequence, all subsequent characters in the same key
sequence are echoed immediately.)
If the value is zero, then command input is not echoed.
@end defopt
@defvar message-truncate-lines
Normally, displaying a long message resizes the echo area to display
the entire message, wrapping long line as needed. But if the variable
@code{message-truncate-lines} is non-@code{nil}, long lines of
echo-area message are instead truncated to fit the mini-window width.
@end defvar
The variable @code{max-mini-window-height}, which specifies the
maximum height for resizing minibuffer windows, also applies to the
echo area (which is really a special use of the minibuffer window;
@pxref{Minibuffer Windows}).
@node Warnings
@section Reporting Warnings
@cindex warnings
@dfn{Warnings} are a facility for a program to inform the user of a
possible problem, but continue running (as opposed to signaling an
error, @pxref{Errors}).
@menu
* Warning Basics:: Warnings concepts and functions to report them.
* Warning Variables:: Variables programs bind to customize their warnings.
* Warning Options:: Variables users set to control display of warnings.
* Delayed Warnings:: Deferring a warning until the end of a command.
@end menu
@node Warning Basics
@subsection Warning Basics
@cindex severity level
Every warning is a textual message, which explains the problem for
the user, with the associated @dfn{severity level} which is a symbol.
Here are the supported severity levels, in order of decreasing
severity, and their meanings:
@table @code
@item :emergency
A problem that will seriously impair Emacs operation soon
if the user does not attend to it promptly.
@item :error
A report about data or circumstances that are inherently wrong.
@item :warning
A report about data or circumstances that are not inherently wrong,
but raise suspicion of a possible problem.
@item :debug
A report of information that may be useful if the user is currently
debugging the Lisp program which issues the warning.
@end table
When your program encounters invalid input data, it can either
signal a Lisp error by calling @code{error} or @code{signal}
(@pxref{Signaling Errors}) or report a warning with severity
@code{:error}. Signaling a Lisp error is the easiest thing to do, but
it means the signaling program cannot continue execution. If you want
to take the trouble of implementing a way to continue processing
despite the invalid data, then reporting a warning of severity
@code{:error} is the right way of informing the user of the problem.
For instance, the Emacs Lisp byte compiler can report an error that
way and continue compiling other functions. (If the program signals a
Lisp error and then handles it with @code{condition-case}, the user
won't see the error message; reporting that as a warning instead
avoids that problem.)
@cindex warning type
In addition to severity level, each warning has a @dfn{warning type}
to classify it. The warning type is either a symbol or a list of
symbols. If it is a symbol, it should be the custom group that you
use for the program's user options; if it is a list, the first element
of the list should be that custom group. For example, byte compiler
warnings use the warning type @code{(bytecomp)}. If the warning type
is a list, the elements of the list after the first one, which should
be arbitrary symbols, represent subcategories of the warning: they
will be displayed to the user to better explain the nature of the
warning.
@defun display-warning type message &optional level buffer-name
This function reports a warning, using the string @var{message} as the
warning text and @var{type} as the warning type. @var{level} should
be the severity level, and defaults to @code{:warning} if omitted or
@code{nil}.
@var{buffer-name}, if non-@code{nil}, specifies the name of the buffer
for logging the warning message. By default, it is @file{*Warnings*}.
@end defun
@defun lwarn type level message &rest args
This function reports a warning using the value returned by
@w{@code{(format-message @var{message} @var{args}@dots{})}} as the
message text in the @file{*Warnings*} buffer. In other respects it is
equivalent to @code{display-warning}.
@end defun
@defun warn message &rest args
This function reports a warning using the value returned by
@w{@code{(format-message @var{message} @var{args}@dots{})}} as the
message text, @code{emacs} as the warning type, and @code{:warning} as
the severity level. It exists for compatibility only; we recommend
not using it, because you should specify a specific warning type.
@end defun
@node Warning Variables
@subsection Warning Variables
@cindex warning variables
Programs can customize how their warnings appear by binding
the variables described in this section.
@defvar warning-levels
This list defines the meaning and severity order of the warning
severity levels. Each element defines one severity level,
and they are arranged in order of decreasing severity.
Each element has the form @w{@code{(@var{level} @var{string}
[@var{function}])}}, where @var{level} is the severity level it
defines. @var{string} specifies the textual description of this
level. @var{string} should use @samp{%s} to specify where to put the
warning type information, or it can omit the @samp{%s} so as not to
include that information.
The optional @var{function}, if non-@code{nil}, is a function to call
with no arguments, to get the user's attention. A notable example is
@code{ding} (@pxref{Beeping}).
Normally you should not change the value of this variable.
@end defvar
@defvar warning-prefix-function
If non-@code{nil}, the value is a function to generate prefix text for
warnings. Programs can bind the variable to a suitable function.
@code{display-warning} calls this function with the warnings buffer
the current buffer, and the function can insert text into it. That
text becomes the beginning of the warning message.
The function is called with two arguments, the severity level and its
entry in @code{warning-levels}. It should return a list to use
@emph{instead} of that entry (the value need not be an actual member
of @code{warning-levels}, but it must have the same structure). By
constructing this value, the function can change the severity of the
warning, or specify different handling for a given severity level.
If the variable's value is @code{nil}, there's no prefix text, before
the warning is displayed, starting with the @var{string} part of the
entry in @code{warning-levels} corresponding to the warning's level.
@end defvar
@defvar warning-series
Programs can bind this variable to @code{t} to say that the next
warning should begin a series. When several warnings form a series,
that means to leave point on the first warning of the series, rather
than keep moving it for each warning so that it appears on the last one.
The series ends when the local binding of this variable is unbound and
@code{warning-series} becomes @code{nil} again.
The value can also be a symbol with a function definition. That is
equivalent to @code{t}, except that the next warning will also call
the function with no arguments with the warnings buffer the current
buffer. The function can, for example, insert text which will serve
as a header for the series of warnings.
Once a series has begun, the value of this variable is a marker which
points to the buffer position in the warnings buffer of the start of
the series.
The variable's normal value is @code{nil}, which means to handle
each warning separately.
@end defvar
@defvar warning-fill-prefix
When this variable is non-@code{nil}, it specifies a fill prefix to
use for filling the text of each warning.
@end defvar
@defvar warning-fill-column
The column at which to fill warnings.
@end defvar
@defvar warning-type-format
This variable specifies the format for displaying the warning type
in the warning text. The result of formatting the type this way
gets included in the message under the control of the string in the
entry in @code{warning-levels}. The default value is @code{" (%s)"}.
If you bind it to the empty string @code{""} then the warning type
won't appear at all.
@end defvar
@node Warning Options
@subsection Warning Options
@cindex warning options
These variables are used by users to control what happens
when a Lisp program reports a warning.
@defopt warning-minimum-level
This user option specifies the minimum severity level that should be
shown immediately to the user, by popping the warnings buffer in some
window. The default is @code{:warning}, which means to show the
warning buffer for any warning severity except @code{:debug}. The
warnings of lower severity levels will still be written into the
warnings buffer, but the buffer will not be forced onto display.
@end defopt
@defopt warning-minimum-log-level
This user option specifies the minimum severity level that should be
logged in the warnings buffer. Warnings of lower severity will be
completely ignored: not written to the warnings buffer and not
displayed. The default is @code{:warning}, which means to log
warnings of any severity except @code{:debug}.
@end defopt
@defopt warning-suppress-types
This list specifies which warning types should not be displayed
immediately when they occur. Each element of the list should be a
list of symbols. If an element of this list has the same elements as
the first elements in a warning type, then the warning of that type
will not be shown on display by popping the warnings buffer in some
window (the warning will still be logged in the warnings buffer).
For example, if the value of this variable is a list like this:
@lisp
((foo) (bar subtype))
@end lisp
@noindent
then warnings whose types are @code{foo} or @code{(foo)} or
@w{@code{(foo something)}} or @w{@code{(bar subtype other)}} will not
be shown to the user.
@end defopt
@defopt warning-suppress-log-types
This list specifies which warning types should be ignored: not logged
in the warnings buffer and not shown to the user. The structure and
the matching of warning types are the same as for
@code{warning-suppress-types} above.
@end defopt
@cindex warnings, suppressing during startup
@cindex prevent warnings in init files
During startup, Emacs delays showing any warnings until after it
loads and processes the site-wide and user's init files
(@pxref{Startup Summary}). Let-binding (@pxref{Local Variables}) the
values of these options around some code in your init files which
might emit a warning will therefore not work, because it will not be
in effect by the time the warning is actually processed. Thus, if you
want to suppress some warnings during startup, change the values of
the above options in your init file early enough, or put those
let-binding forms in your @code{after-init-hook} or
@code{emacs-startup-hook} functions. @xref{Init File}.
@node Delayed Warnings
@subsection Delayed Warnings
@cindex delayed warnings
@cindex warnings, delayed
Sometimes, you may wish to avoid showing a warning while a command is
running, and only show it only after the end of the command. You can
use the function @code{delay-warning} for this. Emacs automatically
delays any warnings emitted during the early stages of startup, and
shows them only after the init files are processed.
@defun delay-warning type message &optional level buffer-name
This function is the delayed counterpart to @code{display-warning}
(@pxref{Warning Basics}), and it is called with the same arguments.
The warning message is queued into @code{delayed-warnings-list}.
@end defun
@defvar delayed-warnings-list
The value of this variable is a list of warnings to be displayed after
the current command has finished. Each element must be a list
@smallexample
(@var{type} @var{message} [@var{level} [@var{buffer-name}]])
@end smallexample
@noindent
with the same form, and the same meanings, as the argument list of
@code{display-warning}. Immediately after running
@code{post-command-hook} (@pxref{Command Overview}), the Emacs
command loop displays all the warnings specified by this variable,
then resets the variable to @code{nil}.
@end defvar
Programs which need to further customize the delayed warnings
mechanism can change the variable @code{delayed-warnings-hook}:
@defvar delayed-warnings-hook
This is a normal hook which is run by the Emacs command loop, after
@code{post-command-hook}, in order to process and display delayed
warnings. Emacs also runs this hook during startup, after loading the
site-start and user init files (@pxref{Startup Summary}), because
warnings emitted before that are automatically delayed.
Its default value is a list of two functions:
@smallexample
(collapse-delayed-warnings display-delayed-warnings)
@end smallexample
@findex collapse-delayed-warnings
@findex display-delayed-warnings
@noindent
The function @code{collapse-delayed-warnings} removes repeated entries
from @code{delayed-warnings-list}. The function
@code{display-delayed-warnings} calls @code{display-warning} on each
of the entries in @code{delayed-warnings-list}, in turn, and then sets
@code{delayed-warnings-list} to @code{nil}.
@end defvar
@node Invisible Text
@section Invisible Text
@cindex invisible text
You can make characters @dfn{invisible}, so that they do not appear on
the screen, with the @code{invisible} property. This can be either a
text property (@pxref{Text Properties}) or an overlay property
(@pxref{Overlays}). Cursor motion also partly ignores these
characters; if the command loop finds that point is inside a range of
invisible text after a command, it relocates point to the other side
of the text.
In the simplest case, any non-@code{nil} @code{invisible} property makes
a character invisible. This is the default case---if you don't alter
the default value of @code{buffer-invisibility-spec}, this is how the
@code{invisible} property works. You should normally use @code{t}
as the value of the @code{invisible} property if you don't plan
to set @code{buffer-invisibility-spec} yourself.
More generally, you can use the variable @code{buffer-invisibility-spec}
to control which values of the @code{invisible} property make text
invisible. This permits you to classify the text into different subsets
in advance, by giving them different @code{invisible} values, and
subsequently make various subsets visible or invisible by changing the
value of @code{buffer-invisibility-spec}.
Controlling visibility with @code{buffer-invisibility-spec} is
especially useful in a program to display the list of entries in a
database. It permits the implementation of convenient filtering
commands to view just a part of the entries in the database. Setting
this variable is very fast, much faster than scanning all the text in
the buffer looking for properties to change.
@defvar buffer-invisibility-spec
This variable specifies which kinds of @code{invisible} properties
actually make a character invisible. Setting this variable makes it
buffer-local.
@table @asis
@item @code{t}
A character is invisible if its @code{invisible} property is
non-@code{nil}. This is the default.
@item a list
Each element of the list specifies a criterion for invisibility; if a
character's @code{invisible} property fits any one of these criteria,
the character is invisible. The list can have two kinds of elements:
@table @code
@item @var{atom}
A character is invisible if its @code{invisible} property value is
@var{atom} or if it is a list with @var{atom} as a member; comparison
is done with @code{eq}.
@item (@var{atom} . t)
A character is invisible if its @code{invisible} property value is
@var{atom} or if it is a list with @var{atom} as a member; comparison
is done with @code{eq}. Moreover, a sequence of such characters
displays as an ellipsis.
@end table
@end table
@end defvar
Two functions are specifically provided for adding elements to
@code{buffer-invisibility-spec} and removing elements from it.
@defun add-to-invisibility-spec element
This function adds the element @var{element} to
@code{buffer-invisibility-spec}. If @code{buffer-invisibility-spec}
was @code{t}, it changes to a list, @code{(t)}, so that text whose
@code{invisible} property is @code{t} remains invisible.
@end defun
@defun remove-from-invisibility-spec element
This removes the element @var{element} from
@code{buffer-invisibility-spec}. This does nothing if @var{element}
is not in the list.
@end defun
A convention for use of @code{buffer-invisibility-spec} is that a
major mode should use the mode's own name as an element of
@code{buffer-invisibility-spec} and as the value of the
@code{invisible} property:
@example
;; @r{If you want to display an ellipsis:}
(add-to-invisibility-spec '(my-symbol . t))
;; @r{If you don't want ellipsis:}
(add-to-invisibility-spec 'my-symbol)
(overlay-put (make-overlay beginning end)
'invisible 'my-symbol)
;; @r{When done with the invisibility:}
(remove-from-invisibility-spec '(my-symbol . t))
;; @r{Or respectively:}
(remove-from-invisibility-spec 'my-symbol)
@end example
You can check for invisibility using the following function:
@defun invisible-p pos-or-prop
If @var{pos-or-prop} is a marker or number, this function returns a
non-@code{nil} value if the text at that position is currently
invisible.
If @var{pos-or-prop} is any other kind of Lisp object, that is taken
to mean a possible value of the @code{invisible} text or overlay
property. In that case, this function returns a non-@code{nil} value
if that value would cause text to become invisible, based on the
current value of @code{buffer-invisibility-spec}.
The return value of this function is @code{t} if the text would be
completely hidden on display, or a non-@code{nil}, non-@code{t} value
if the text would be replaced by an ellipsis.
@end defun
@vindex line-move-ignore-invisible
Ordinarily, functions that operate on text or move point do not care
whether the text is invisible, they process invisible characters and
visible characters alike. The user-level line motion commands,
such as @code{next-line}, @code{previous-line}, ignore invisible
newlines if @code{line-move-ignore-invisible} is non-@code{nil} (the
default), i.e., behave like these invisible newlines didn't exist in
the buffer, but only because they are explicitly programmed to do so.
If a command ends with point inside or at the boundary of
invisible text, the main editing loop relocates point to one of the
two ends of the invisible text. Emacs chooses the direction of
relocation so that it is the same as the overall movement direction of
the command; if in doubt, it prefers a position where an inserted char
would not inherit the @code{invisible} property. Additionally, if the
text is not replaced by an ellipsis and the command only moved within
the invisible text, then point is moved one extra character so as to
try and reflect the command's movement by a visible movement of the
cursor.
Thus, if the command moved point back to an invisible range (with the usual
stickiness), Emacs moves point back to the beginning of that range. If the
command moved point forward into an invisible range, Emacs moves point forward
to the first visible character that follows the invisible text and then forward
one more character.
These @dfn{adjustments} of point that ended up in the middle of
invisible text can be disabled by setting @code{disable-point-adjustment}
to a non-@code{nil} value. @xref{Adjusting Point}.
Incremental search can make invisible overlays visible temporarily
and/or permanently when a match includes invisible text. To enable
this, the overlay should have a non-@code{nil}
@code{isearch-open-invisible} property. The property value should be a
function to be called with the overlay as an argument. This function
should make the overlay visible permanently; it is used when the match
overlaps the overlay on exit from the search.
During the search, such overlays are made temporarily visible by
temporarily modifying their invisible and intangible properties. If you
want this to be done differently for a certain overlay, give it an
@code{isearch-open-invisible-temporary} property which is a function.
The function is called with two arguments: the first is the overlay, and
the second is @code{nil} to make the overlay visible, or @code{t} to
make it invisible again.
@node Selective Display
@section Selective Display
@c @cindex selective display Duplicates selective-display
@dfn{Selective display} refers to a pair of related features for
hiding certain lines on the screen.
@cindex explicit selective display
The first variant, explicit selective display, was designed for use in a Lisp
program: it controls which lines are hidden by altering the text. This kind of
hiding is now obsolete and deprecated; instead you should use the
@code{invisible} property (@pxref{Invisible Text}) to get the same effect.
In the second variant, the choice of lines to hide is made
automatically based on indentation. This variant is designed to be a
user-level feature.
The way you control explicit selective display is by replacing a
newline (control-j) with a carriage return (control-m). The text that
was formerly a line following that newline is now hidden. Strictly
speaking, it is temporarily no longer a line at all, since only
newlines can separate lines; it is now part of the previous line.
Selective display does not directly affect editing commands. For
example, @kbd{C-f} (@code{forward-char}) moves point unhesitatingly
into hidden text. However, the replacement of newline characters with
carriage return characters affects some editing commands. For
example, @code{next-line} skips hidden lines, since it searches only
for newlines. Modes that use selective display can also define
commands that take account of the newlines, or that control which
parts of the text are hidden.
When you write a selectively displayed buffer into a file, all the
control-m's are output as newlines. This means that when you next read
in the file, it looks OK, with nothing hidden. The selective display
effect is seen only within Emacs.
@defvar selective-display
This buffer-local variable enables selective display. This means that
lines, or portions of lines, may be made hidden.
@itemize @bullet
@item
If the value of @code{selective-display} is @code{t}, then the character
control-m marks the start of hidden text; the control-m, and the rest
of the line following it, are not displayed. This is explicit selective
display.
@item
If the value of @code{selective-display} is a positive integer, then
lines that start with more than that many columns of indentation are not
displayed.
@end itemize
When some portion of a buffer is hidden, the vertical movement
commands operate as if that portion did not exist, allowing a single
@code{next-line} command to skip any number of hidden lines.
However, character movement commands (such as @code{forward-char}) do
not skip the hidden portion, and it is possible (if tricky) to insert
or delete text in a hidden portion.
In the examples below, we show the @emph{display appearance} of the
buffer @code{foo}, which changes with the value of
@code{selective-display}. The @emph{contents} of the buffer do not
change.
@example
@group
(setq selective-display nil)
@result{} nil
---------- Buffer: foo ----------
1 on this column
2on this column
3n this column
3n this column
2on this column
1 on this column
---------- Buffer: foo ----------
@end group
@group
(setq selective-display 2)
@result{} 2
---------- Buffer: foo ----------
1 on this column
2on this column
2on this column
1 on this column
---------- Buffer: foo ----------
@end group
@end example
@end defvar
@defopt selective-display-ellipses
If this buffer-local variable is non-@code{nil}, then Emacs displays
@samp{@dots{}} at the end of a line that is followed by hidden text.
This example is a continuation of the previous one.
@example
@group
(setq selective-display-ellipses t)
@result{} t
---------- Buffer: foo ----------
1 on this column
2on this column ...
2on this column
1 on this column
---------- Buffer: foo ----------
@end group
@end example
You can use a display table to substitute other text for the ellipsis
(@samp{@dots{}}). @xref{Display Tables}.
@end defopt
@node Temporary Displays
@section Temporary Displays
@cindex temporary display
@cindex temporary buffer display
Temporary displays are used by Lisp programs to put output into a
buffer and then present it to the user for perusal rather than for
editing. Many help commands use this feature.
@defmac with-output-to-temp-buffer buffer-name body@dots{}
This function executes the forms in @var{body} while arranging to insert
any output they print into the buffer named @var{buffer-name}, which is
first created if necessary, and put into Help mode. (See the similar
form @code{with-temp-buffer-window} below.) Finally, the buffer is
displayed in some window, but that window is not selected.
If the forms in @var{body} do not change the major mode in the output
buffer, so that it is still Help mode at the end of their execution,
then @code{with-output-to-temp-buffer} makes this buffer read-only at
the end, and also scans it for function and variable names to make them
into clickable cross-references. @xref{Docstring hyperlinks, , Tips for
Documentation Strings}, in particular the item on hyperlinks in
documentation strings, for more details.
The string @var{buffer-name} specifies the temporary buffer, which need
not already exist. The argument must be a string, not a buffer. The
buffer is erased initially (with no questions asked), and it is marked
as unmodified after @code{with-output-to-temp-buffer} exits.
@code{with-output-to-temp-buffer} binds @code{standard-output} to the
temporary buffer, then it evaluates the forms in @var{body}. Output
using the Lisp output functions within @var{body} goes by default to
that buffer (but screen display and messages in the echo area, although
they are ``output'' in the general sense of the word, are not affected).
@xref{Output Functions}.
Several hooks are available for customizing the behavior
of this construct; they are listed below.
The value of the last form in @var{body} is returned.
@example
@group
---------- Buffer: foo ----------
This is the contents of foo.
---------- Buffer: foo ----------
@end group
@group
(with-output-to-temp-buffer "foo"
(print 20)
(print standard-output))
@result{} #<buffer foo>
---------- Buffer: foo ----------
20
#<buffer foo>
---------- Buffer: foo ----------
@end group
@end example
@end defmac
@defopt temp-buffer-show-function
If this variable is non-@code{nil}, @code{with-output-to-temp-buffer}
calls it as a function to do the job of displaying a help buffer. The
function gets one argument, which is the buffer it should display.
It is a good idea for this function to run @code{temp-buffer-show-hook}
just as @code{with-output-to-temp-buffer} normally would, inside of
@code{save-selected-window} and with the chosen window and buffer
selected.
@end defopt
@defvar temp-buffer-setup-hook
This normal hook is run by @code{with-output-to-temp-buffer} before
evaluating @var{body}. When the hook runs, the temporary buffer is
current. This hook is normally set up with a function to put the
buffer in Help mode.
@end defvar
@defvar temp-buffer-show-hook
This normal hook is run by @code{with-output-to-temp-buffer} after
displaying the temporary buffer. When the hook runs, the temporary buffer
is current, and the window it was displayed in is selected.
@end defvar
@defmac with-temp-buffer-window buffer-or-name action quit-function body@dots{}
This macro is similar to @code{with-output-to-temp-buffer}. Like that
construct, it executes @var{body} while arranging to insert any output
it prints into the buffer named @var{buffer-or-name} and displays that
buffer in some window. Unlike @code{with-output-to-temp-buffer},
however, it does not automatically switch that buffer to Help mode.
The argument @var{buffer-or-name} specifies the temporary buffer. It
can be either a buffer, which must already exist, or a string, in which
case a buffer of that name is created, if necessary. The buffer is
marked as unmodified and read-only when @code{with-temp-buffer-window}
exits.
This macro does not call @code{temp-buffer-show-function}. Rather, it
passes the @var{action} argument to @code{display-buffer}
(@pxref{Choosing Window}) in order to display the buffer.
The value of the last form in @var{body} is returned, unless the
argument @var{quit-function} is specified. In that case, it is called
with two arguments: the window showing the buffer and the result of
@var{body}. The final return value is then whatever @var{quit-function}
returns.
@vindex temp-buffer-window-setup-hook
@vindex temp-buffer-window-show-hook
This macro uses the normal hooks @code{temp-buffer-window-setup-hook}
and @code{temp-buffer-window-show-hook} in place of the analogous hooks
run by @code{with-output-to-temp-buffer}.
@end defmac
The two constructs described next are mostly identical to
@code{with-temp-buffer-window} but differ from it as specified:
@defmac with-current-buffer-window buffer-or-name action quit-function &rest body
This macro is like @code{with-temp-buffer-window} but unlike that makes
the buffer specified by @var{buffer-or-name} current for running
@var{body}.
@end defmac
A window showing a temporary buffer can be fitted to the size of that
buffer using the following mode:
@defopt temp-buffer-resize-mode
When this minor mode is enabled, windows showing a temporary buffer are
automatically resized to fit their buffer's contents.
A window is resized if and only if it has been specially created for the
buffer. In particular, windows that have shown another buffer before
are not resized. By default, this mode uses @code{fit-window-to-buffer}
(@pxref{Resizing Windows}) for resizing. You can specify a different
function by customizing the options @code{temp-buffer-max-height} and
@code{temp-buffer-max-width} below.
The effect of this option can be overridden by providing a suitable
@code{window-height}, @code{window-width} or @code{window-size} action
alist entry for @code{display-buffer} (@pxref{Buffer Display Action
Alists}).
@end defopt
@defopt temp-buffer-max-height
This option specifies the maximum height (in lines) of a window
displaying a temporary buffer when @code{temp-buffer-resize-mode} is
enabled. It can also be a function to be called to choose the height
for such a buffer. It gets one argument, the buffer, and should return
a positive integer. At the time the function is called, the window to
be resized is selected.
@end defopt
@defopt temp-buffer-max-width
This option specifies the maximum width of a window (in columns)
displaying a temporary buffer when @code{temp-buffer-resize-mode} is
enabled. It can also be a function to be called to choose the width for
such a buffer. It gets one argument, the buffer, and should return a
positive integer. At the time the function is called, the window to be
resized is selected.
@end defopt
The following function uses the current buffer for temporary display:
@defun momentary-string-display string position &optional char message
This function momentarily displays @var{string} in the current buffer at
@var{position}. It has no effect on the undo list or on the buffer's
modification status.
The momentary display remains until the next input event. If the next
input event is @var{char}, @code{momentary-string-display} ignores it
and returns. Otherwise, that event remains buffered for subsequent use
as input. Thus, typing @var{char} will simply remove the string from
the display, while typing (say) @kbd{C-f} will remove the string from
the display and later (presumably) move point forward. The argument
@var{char} is a space by default.
The return value of @code{momentary-string-display} is not meaningful.
If the string @var{string} does not contain control characters, you can
do the same job in a more general way by creating (and then subsequently
deleting) an overlay with a @code{before-string} property.
@xref{Overlay Properties}.
If @var{message} is non-@code{nil}, it is displayed in the echo area
while @var{string} is displayed in the buffer. If it is @code{nil}, a
default message says to type @var{char} to continue.
In this example, point is initially located at the beginning of the
second line:
@example
@group
---------- Buffer: foo ----------
This is the contents of foo.
@point{}Second line.
---------- Buffer: foo ----------
@end group
@group
(momentary-string-display
"**** Important Message! ****"
(point) ?\r
"Type RET when done reading")
@result{} t
@end group
@group
---------- Buffer: foo ----------
This is the contents of foo.
**** Important Message! ****Second line.
---------- Buffer: foo ----------
---------- Echo Area ----------
Type RET when done reading
---------- Echo Area ----------
@end group
@end example
@end defun
@node Overlays
@section Overlays
@cindex overlays
@c FIXME: mention intervals in this section?
You can use @dfn{overlays} to alter the appearance of a buffer's text on
the screen, for the sake of presentation features. An overlay is an
object that belongs to a particular buffer, and has a specified
beginning and end. It also has properties that you can examine and set;
these affect the display of the text within the overlaid portion of
the buffer.
Editing the text of the buffer adjusts the beginning and end of each
overlay so that it stays with the text. When you create the overlay,
you can specify whether text inserted at the beginning should be
inside the overlay or outside, and likewise for the end of the overlay.
@menu
* Managing Overlays:: Creating and moving overlays.
* Overlay Properties:: How to read and set properties.
What properties do to the screen display.
* Finding Overlays:: Searching for overlays.
@end menu
@node Managing Overlays
@subsection Managing Overlays
@cindex managing overlays
@cindex overlays, managing
This section describes the functions to create, delete and move
overlays, and to examine their contents. Overlay changes are not
recorded in the buffer's undo list, since the overlays are not
considered part of the buffer's contents.
@defun overlayp object
This function returns @code{t} if @var{object} is an overlay.
@end defun
@defun make-overlay start end &optional buffer front-advance rear-advance
This function creates and returns an overlay that belongs to
@var{buffer} and ranges from @var{start} to @var{end}. Both @var{start}
and @var{end} must specify buffer positions; they may be integers or
markers. If @var{buffer} is omitted, the overlay is created in the
current buffer.
@cindex empty overlay
@cindex overlay, empty
An overlay whose @var{start} and @var{end} specify the same buffer
position is known as @dfn{empty}. A non-empty overlay can become
empty if the text between its @var{start} and @var{end} is deleted.
When that happens, the overlay is by default not deleted, but you can
cause it to be deleted by giving it the @samp{evaporate} property
(@pxref{Overlay Properties, evaporate property}).
The arguments @var{front-advance} and @var{rear-advance} specify what
happens when text is inserted at the beginning (i.e., before
@var{start}) and at the end. If they are both @code{nil}, the
default, then the overlay extends to include any text inserted at the
beginning, but not text inserted at the end. If @var{front-advance}
is non-@code{nil}, text inserted at the beginning of the overlay is
excluded from the overlay. If @var{rear-advance} is non-@code{nil},
text inserted at the end of the overlay is included in the overlay.
@end defun
@defun overlay-start overlay
This function returns the position at which @var{overlay} starts,
as an integer.
@end defun
@defun overlay-end overlay
This function returns the position at which @var{overlay} ends,
as an integer.
@end defun
@defun overlay-buffer overlay
This function returns the buffer that @var{overlay} belongs to. It
returns @code{nil} if @var{overlay} has been deleted.
@end defun
@defun delete-overlay overlay
This function deletes the specified @var{overlay}. The overlay
continues to exist as a Lisp object, and its property list is
unchanged, but it ceases to be attached to the buffer it belonged to,
and ceases to have any effect on display.
A deleted overlay is not permanently disconnected. You can give it a
position in a buffer again by calling @code{move-overlay}.
@end defun
@defun move-overlay overlay start end &optional buffer
This function moves @var{overlay} to @var{buffer}, and places its
bounds at @var{start} and @var{end} in that buffer. Both arguments
@var{start} and @var{end} must specify buffer positions; they may be
integers or markers.
If @var{buffer} is omitted, @var{overlay} stays in the same buffer it
was already associated with; if @var{overlay} was previously deleted
(and thus isn't associated with any buffer), it goes into the current
buffer.
The return value is @var{overlay}.
This function is the only valid way to change the endpoints of an
overlay.
@end defun
@defun remove-overlays &optional start end name value
This function removes all the overlays between @var{start} and
@var{end} whose property @var{name} has the specified @var{value}. It
can move the endpoints of the overlays in the region, or split them.
If @var{name} is omitted or @code{nil}, it means to delete all overlays in
the specified region. If @var{start} and/or @var{end} are omitted or
@code{nil}, that means the beginning and end of the buffer respectively.
Therefore, @code{(remove-overlays)} removes all the overlays in the
current buffer.
@end defun
@defun copy-overlay overlay
This function returns a copy of @var{overlay}. The copy has the same
endpoints and properties as @var{overlay}. However, the text
insertion type for the start of the overlay and for the end of the
overlay are set to their default values.
@end defun
Here are some examples:
@example
@group
;; @r{Create an overlay.}
(setq foo (make-overlay 1 10))
@result{} #<overlay from 1 to 10 in display.texi>
@end group
@group
(overlay-start foo)
@result{} 1
@end group
@group
(overlay-end foo)
@result{} 10
(overlay-buffer foo)
@result{} #<buffer display.texi>
;; @r{Give it a property we can check later.}
(overlay-put foo 'happy t)
@result{} t
;; @r{Verify the property is present.}
(overlay-get foo 'happy)
@result{} t
@end group
@group
;; @r{Move the overlay.}
(move-overlay foo 5 20)
@result{} #<overlay from 5 to 20 in display.texi>
(overlay-start foo)
@result{} 5
(overlay-end foo)
@result{} 20
@end group
@group
;; @r{Delete the overlay.}
(delete-overlay foo)
@result{} nil
;; @r{Verify it is deleted.}
foo
@result{} #<overlay in no buffer>
;; @r{A deleted overlay has no position.}
(overlay-start foo)
@result{} nil
(overlay-end foo)
@result{} nil
(overlay-buffer foo)
@result{} nil
@end group
@group
;; @r{Undelete the overlay.}
(move-overlay foo 1 20)
@result{} #<overlay from 1 to 20 in display.texi>
;; @r{Verify the results.}
(overlay-start foo)
@result{} 1
(overlay-end foo)
@result{} 20
(overlay-buffer foo)
@result{} #<buffer display.texi>
@end group
@group
;; @r{Moving and deleting the overlay does not change its properties.}
(overlay-get foo 'happy)
@result{} t
@end group
@end example
@node Overlay Properties
@subsection Overlay Properties
@cindex overlay properties
Overlay properties are like text properties in that the properties that
alter how a character is displayed can come from either source. But in
most respects they are different. @xref{Text Properties}, for comparison.
Text properties are considered a part of the text; overlays and
their properties are specifically considered not to be part of the
text. Thus, copying text between various buffers and strings
preserves text properties, but does not try to preserve overlays.
Changing a buffer's text properties marks the buffer as modified,
while moving an overlay or changing its properties does not. Unlike
text property changes, overlay property changes are not recorded in
the buffer's undo list.
Since more than one overlay can specify a property value for the
same character, Emacs lets you specify a priority value of each
overlay. The priority value is used to decide which of the
overlapping overlays will ``win''.
These functions read and set the properties of an overlay:
@defun overlay-get overlay prop
This function returns the value of property @var{prop} recorded in
@var{overlay}, if any. If @var{overlay} does not record any value for
that property, but it does have a @code{category} property which is a
symbol, that symbol's @var{prop} property is used. Otherwise, the value
is @code{nil}.
@end defun
@defun overlay-put overlay prop value
This function sets the value of property @var{prop} recorded in
@var{overlay} to @var{value}. It returns @var{value}.
@end defun
@defun overlay-properties overlay
This returns a copy of the property list of @var{overlay}.
@end defun
See also the function @code{get-char-property} which checks both
overlay properties and text properties for a given character.
@xref{Examining Properties}.
Many overlay properties have special meanings; here is a table
of them:
@table @code
@item priority
@kindex priority @r{(overlay property)}
This property's value determines the priority of the overlay. If you
want to specify a priority value, use either @code{nil} (or zero), or
a positive integer, or a cons of two values. Any other value triggers
undefined behavior.
The priority matters when two or more overlays cover the same
character and both specify the same property with different values;
the one whose @code{priority} value is higher overrides the other.
(For the @code{face} property, the higher priority overlay's value
does not completely override the other value; instead, its individual
face attributes override the corresponding face attributes of the
@code{face} property whose priority is lower.) If two overlays have
the same priority value, and one is ``nested'' in the other (i.e.,
covers fewer buffer or string positions), then the inner one will
prevail over the outer one. If neither is nested in the other then
you should not make assumptions about which overlay will prevail.
When a Lisp program puts overlays with defined priorities on text that
might have overlays without priorities, this could cause undesirable
results, because any overlay with a positive priority value will
override all the overlays without a priority. Since most Emacs
features that use overlays don't specify priorities for their
overlays, integer priorities should be used with care. Instead of
using integer priorities and risk overriding other overlays, you can
use priority values of the form @w{@code{(@var{primary} . @var{secondary})}},
where the @var{primary} value is used as described above, and
@var{secondary} is the fallback value used when @var{primary} and the
nesting considerations fail to resolve the precedence between
overlays. In particular, priority value @w{@code{(nil . @var{n})}},
with @var{n} a positive integer, enables you to have the overlays
ordered by priority when necessary without completely overriding other
overlays.
Currently, all overlays take priority over text properties.
If you need to put overlays in priority order, use the @var{sorted}
argument of @code{overlays-at}. @xref{Finding Overlays}.
@item window
@kindex window @r{(overlay property)}
If the @code{window} property is non-@code{nil}, then the overlay
applies only on that window.
@item category
@kindex category @r{(overlay property)}
If an overlay has a @code{category} property, we call it the
@dfn{category} of the overlay. It should be a symbol. The properties
of the symbol serve as defaults for the properties of the overlay.
@item face
@kindex face @r{(overlay property)}
This property controls the appearance of the text (@pxref{Faces}).
The value of the property can be the following:
@itemize @bullet
@item
A face name (a symbol or string).
@item
An anonymous face: a property list of the form @code{(@var{keyword}
@var{value} @dots{})}, where each @var{keyword} is a face attribute
name and @var{value} is a value for that attribute.
@item
A list of faces. Each list element should be either a face name or an
anonymous face. This specifies a face which is an aggregate of the
attributes of each of the listed faces. Faces occurring earlier in
the list have higher priority.
@item
A cons cell of the form @code{(foreground-color . @var{color-name})}
or @code{(background-color . @var{color-name})}. This specifies the
foreground or background color, similar to @code{(:foreground
@var{color-name})} or @code{(:background @var{color-name})}. This
form is supported for backward compatibility only, and should be
avoided.
@end itemize
@item mouse-face
@kindex mouse-face @r{(overlay property)}
This property is used instead of @code{face} when the mouse is within
the range of the overlay. However, Emacs ignores all face attributes
from this property that alter the text size (e.g., @code{:height},
@code{:weight}, and @code{:slant}); those attributes are always the
same as in the unhighlighted text.
@item display
@kindex display @r{(overlay property)}
This property activates various features that change the
way text is displayed. For example, it can make text appear taller
or shorter, higher or lower, wider or narrower, or replaced with an image.
@xref{Display Property}.
@item help-echo
@kindex help-echo @r{(overlay property)}
If an overlay has a @code{help-echo} property, then when you move the
mouse onto the text in the overlay, Emacs displays a help string in
the echo area, or as a tooltip. For details see @ref{Text help-echo}.
@item field
@kindex field @r{(overlay property)}
@c Copied from Special Properties.
Consecutive characters with the same @code{field} property constitute a
@emph{field}. Some motion functions including @code{forward-word} and
@code{beginning-of-line} stop moving at a field boundary.
@xref{Fields}.
@item modification-hooks
@kindex modification-hooks @r{(overlay property)}
This property's value is a list of functions to be called if any
character within the overlay is changed or if text is inserted strictly
within the overlay.
The hook functions are called both before and after each change.
If the functions save the information they receive, and compare notes
between calls, they can determine exactly what change has been made
in the buffer text.
When called before a change, each function receives four arguments: the
overlay, @code{nil}, and the beginning and end of the text range to be
modified.
When called after a change, each function receives five arguments: the
overlay, @code{t}, the beginning and end of the text range just
modified, and the length of the pre-change text replaced by that range.
(For an insertion, the pre-change length is zero; for a deletion, that
length is the number of characters deleted, and the post-change
beginning and end are equal.)
When these functions are called, @code{inhibit-modification-hooks} is
bound to non-@code{nil}. If the functions modify the buffer, you
might want to bind @code{inhibit-modification-hooks} to @code{nil}, so
as to cause the change hooks to run for these modifications. However,
doing this may call your own change hook recursively, so be sure to
prepare for that. @xref{Change Hooks}.
Text properties also support the @code{modification-hooks} property,
but the details are somewhat different (@pxref{Special Properties}).
@item insert-in-front-hooks
@kindex insert-in-front-hooks @r{(overlay property)}
This property's value is a list of functions to be called before and
after inserting text right at the beginning of the overlay. The calling
conventions are the same as for the @code{modification-hooks} functions.
@item insert-behind-hooks
@kindex insert-behind-hooks @r{(overlay property)}
This property's value is a list of functions to be called before and
after inserting text right at the end of the overlay. The calling
conventions are the same as for the @code{modification-hooks} functions.
@item invisible
@kindex invisible @r{(overlay property)}
The @code{invisible} property can make the text in the overlay
invisible, which means that it does not appear on the screen.
@xref{Invisible Text}, for details.
@item intangible
@kindex intangible @r{(overlay property)}
The @code{intangible} property on an overlay works just like the
@code{intangible} text property. It is obsolete. @xref{Special
Properties}, for details.
@item isearch-open-invisible
This property tells incremental search (@pxref{Incremental Search,,,
emacs, The GNU Emacs Manual}) how to make an invisible overlay
visible, permanently, if the final match overlaps it. @xref{Invisible
Text}.
@item isearch-open-invisible-temporary
This property tells incremental search how to make an invisible overlay
visible, temporarily, during the search. @xref{Invisible Text}.
@item before-string
@kindex before-string @r{(overlay property)}
This property's value is a string to add to the display at the beginning
of the overlay. The string does not appear in the buffer in any
sense---only on the screen. Note that if the text at the beginning of
the overlay is made invisible, the string will not be displayed.
@item after-string
@kindex after-string @r{(overlay property)}
This property's value is a string to add to the display at the end of
the overlay. The string does not appear in the buffer in any
sense---only on the screen. Note that if the text at the end of the
overlay is made invisible, the string will not be displayed.
@item line-prefix
This property specifies a display spec to prepend to each
non-continuation line at display-time. @xref{Truncation}.
@item wrap-prefix
This property specifies a display spec to prepend to each continuation
line at display-time. @xref{Truncation}.
@item evaporate
@kindex evaporate @r{(overlay property)}
If this property is non-@code{nil}, the overlay is deleted automatically
if it becomes empty (i.e., if its length becomes zero). If you give
an empty overlay (@pxref{Managing Overlays, empty overlay}) a
non-@code{nil} @code{evaporate} property, that deletes it immediately.
Note that, unless an overlay has this property, it will not be deleted
when the text between its starting and ending positions is deleted
from the buffer.
@item keymap
@cindex keymap of character (and overlays)
@kindex keymap @r{(overlay property)}
If this property is non-@code{nil}, it specifies a keymap for a
portion of the text. This keymap takes precedence over most other
keymaps (@pxref{Active Keymaps}), and it is used when point is within
the overlay, where the front-
and rear-advance properties define whether the boundaries are
considered as being @emph{within} or not.
@item local-map
@kindex local-map @r{(overlay property)}
The @code{local-map} property is similar to @code{keymap} but replaces the
buffer's local map rather than augmenting existing keymaps. This also means it
has lower precedence than minor mode keymaps.
@end table
The @code{keymap} and @code{local-map} properties do not affect a
string displayed by the @code{before-string}, @code{after-string}, or
@code{display} properties. This is only relevant for mouse clicks and
other mouse events that fall on the string, since point is never on
the string. To bind special mouse events for the string, assign it a
@code{keymap} or @code{local-map} text property. @xref{Special
Properties}.
@node Finding Overlays
@subsection Searching for Overlays
@cindex searching for overlays
@cindex overlays, searching for
@defun overlays-at pos &optional sorted
This function returns a list of all the overlays that cover the character at
position @var{pos} in the current buffer. If @var{sorted} is non-@code{nil},
the list is in decreasing order of priority, otherwise it is in no particular
order. An overlay contains position @var{pos} if it begins at or before
@var{pos}, and ends after @var{pos}.
To illustrate usage, here is a Lisp function that returns a list of the
overlays that specify property @var{prop} for the character at point:
@smallexample
(defun find-overlays-specifying (prop)
(let ((overlays (overlays-at (point)))
found)
(while overlays
(let ((overlay (car overlays)))
(if (overlay-get overlay prop)
(setq found (cons overlay found))))
(setq overlays (cdr overlays)))
found))
@end smallexample
@end defun
@defun overlays-in beg end
This function returns a list of the overlays that overlap the region
@var{beg} through @var{end}. An overlay overlaps with a region if it
contains one or more characters in the region; empty overlays
(@pxref{Managing Overlays, empty overlay}) overlap if they are at
@var{beg}, strictly between @var{beg} and @var{end}, or at @var{end}
when @var{end} denotes the position at the end of the accessible part
of the buffer.
@end defun
@defun next-overlay-change pos
This function returns the buffer position of the next beginning or end
of an overlay, after @var{pos}. If there is none, it returns
@code{(point-max)}.
@end defun
@defun previous-overlay-change pos
This function returns the buffer position of the previous beginning or
end of an overlay, before @var{pos}. If there is none, it returns
@code{(point-min)}.
@end defun
As an example, here's a simplified (and inefficient) version of the
primitive function @code{next-single-char-property-change}
(@pxref{Property Search}). It searches forward from position
@var{pos} for the next position where the value of a given property
@code{prop}, as obtained from either overlays or text properties,
changes.
@smallexample
(defun next-single-char-property-change (position prop)
(save-excursion
(goto-char position)
(let ((propval (get-char-property (point) prop)))
(while (and (not (eobp))
(eq (get-char-property (point) prop) propval))
(goto-char (min (next-overlay-change (point))
(next-single-property-change (point) prop)))))
(point)))
@end smallexample
@node Size of Displayed Text
@section Size of Displayed Text
@cindex size of text on display
@cindex character width on display
Since not all characters have the same width, these functions let you
check the width of a character. @xref{Primitive Indent}, and
@ref{Screen Lines}, for related functions.
@defun char-width char
This function returns the width in columns of the character
@var{char}, if it were displayed in the current buffer (i.e., taking
into account the buffer's display table, if any; @pxref{Display
Tables}). The width of a tab character is usually @code{tab-width}
(@pxref{Usual Display}).
@end defun
@defun char-uppercase-p char
Return non-@code{nil} if @var{char} is an uppercase character
according to Unicode.
@end defun
@defun string-width string &optional from to
This function returns the width in columns of the string @var{string},
if it were displayed in the current buffer and the selected window.
Optional arguments @var{from} and @var{to} specify the substring of
@var{string} to consider, and are interpreted as in @code{substring}
(@pxref{Creating Strings}).
The return value is an approximation: it only considers the values
returned by @code{char-width} for the constituent characters, always
takes a tab character as taking @code{tab-width} columns, ignores
display properties and fonts, etc. For these reasons, we recommend
using @code{window-text-pixel-size} or @code{string-pixel-width},
described below, instead.
@end defun
@defun truncate-string-to-width string width &optional start-column padding ellipsis ellipsis-text-property
This function returns a new string that is a truncation of @var{string}
which fits within @var{width} columns on display.
If @var{string} is narrower than @var{width}, the result is equal to
@var{string}; otherwise excess characters are omitted from the result.
If a multi-column character in @var{string} exceeds the goal
@var{width}, that character is omitted from the result. Thus, the
result can sometimes fall short of @var{width}, but cannot go beyond
it.
The optional argument @var{start-column} specifies the starting
column; it defaults to zero. If this is non-@code{nil}, then the
first @var{start-column} columns of the string are omitted from the
result. If one multi-column character in @var{string} extends across
the column @var{start-column}, that character is omitted.
The optional argument @var{padding}, if non-@code{nil}, is a padding
character added at the beginning and end of the result string, to
extend it to exactly @var{width} columns. The padding character is
appended at the end of the result if it falls short of @var{width}, as
many times as needed to reach @var{width}. It is also prepended at
the beginning of the result if a multi-column character in
@var{string} extends across the column @var{start-column}.
If @var{ellipsis} is non-@code{nil}, it should be a string which will
replace the end of @var{string} when it is truncated. In this case,
more characters will be removed from @var{string} to free enough space
for @var{ellipsis} to fit within @var{width} columns. However, if
the display width of @var{string} is less than the display width of
@var{ellipsis}, @var{ellipsis} will not be appended to the result. If
@var{ellipsis} is non-@code{nil} and not a string, it stands for the
value returned by the function @code{truncate-string-ellipsis},
described below.
The optional argument @var{ellipsis-text-property}, if non-@code{nil},
means hide the excess parts of @var{string} with a @code{display} text
property (@pxref{Display Property}) showing the ellipsis, instead of
actually truncating the string.
@example
@group
(truncate-string-to-width "\tab\t" 12 4)
@result{} "ab"
(truncate-string-to-width "\tab\t" 12 4 ?\s)
@result{} " ab "
@end group
@end example
This function uses @code{string-width} and @code{char-width} to find
the suitable truncation point when @var{string} is too wide, so it
suffers from the same basic issues as @code{string-width} does. In
particular, when character composition happens within @var{string},
the display width of a string could be smaller than the sum of widths
of the constituent characters, and this function might return
inaccurate results.
@end defun
@defun truncate-string-ellipsis
This function returns the string to be used as an ellipses in
@code{truncate-string-to-width} and other similar contexts. The value
is that of the variable @code{truncate-string-ellipsis}, if it's
non-@code{nil}, the string with the single character @sc{U+2026
HORIZONTAL ELLIPSIS} if that character can be displayed on the
selected frame, and the string @samp{...} otherwise.
@end defun
The following function returns the size in pixels of text as if it were
displayed in a given window. This function is used by
@code{fit-window-to-buffer} and @code{fit-frame-to-buffer}
(@pxref{Resizing Windows}) to make a window exactly as large as the text
it contains.
@defun window-text-pixel-size &optional window from to x-limit y-limit mode-lines ignore-line-at-end
This function returns the size of the text of @var{window}'s buffer in
pixels. @var{window} must be a live window and defaults to the
selected one. The return value is a cons of the maximum pixel-width
of any text line and the maximum pixel-height of all text lines. This
function exists to allow Lisp programs to adjust the dimensions of
@var{window} to the buffer text it needs to display, and for other
similar situations.
The return value can also optionally (see below) include the buffer
position of the first line whose dimensions were measured.
The optional argument @var{from}, if non-@code{nil}, specifies the
first text position to consider, and defaults to the minimum
accessible position of the buffer. If @var{from} is @code{t}, it
stands for the minimum accessible position that is not a newline
character. If @var{from} is a cons, its @code{car} specifies a buffer
position, and its @code{cdr} specifies the vertical offset in pixels
from that position to the first screen line whose text is to be
measured. (The measurement will start from the visual beginning of
that screen line.) In that case, the return value will instead be a
list of the pixel-width, pixel-height, and the buffer position of the
first line that was measured. The optional argument @var{to}, if
non-@code{nil}, specifies the last text position to consider, and
defaults to the maximum accessible position of the buffer. If
@var{to} is @code{t}, it stands for the maximum accessible position
that is not a newline character.
The optional argument @var{x-limit}, if non-@code{nil}, specifies the
maximum X coordinate beyond which text should be ignored; it is
therefore also the largest value of pixel-width that the function can
return. If @var{x-limit} @code{nil} or omitted, it means to use the
pixel-width of @var{window}'s body (@pxref{Window Sizes}); this
default means that text of truncated lines wider than the window will
be ignored. This default is useful when the caller does not intend to
change the width of @var{window}. Otherwise, the caller should
specify here the maximum width @var{window}'s body may assume; in
particular, if truncated lines are expected and their text needs to be
accounted for, @var{x-limit} should be set to a large value. Since
calculating the width of long lines can take some time, it's always a
good idea to make this argument as small as needed; in particular, if
the buffer might contain long lines that will be truncated anyway.
The optional argument @var{y-limit}, if non-@code{nil}, specifies the
maximum Y coordinate beyond which text is to be ignored; it is
therefore also the maximum pixel-height that the function can return.
If @var{y-limit} is @code{nil} or omitted, it means to consider all the
lines of text till the buffer position specified by @var{to}. Since
calculating the pixel-height of a large buffer can take some time, it
makes sense to specify this argument; in particular, if the caller
does not know the size of the buffer.
The optional argument @var{mode-lines} @code{nil} or omitted means to
not include the height of the mode-, tab- or header-line of @var{window}
in the return value. If it is either the symbol @code{mode-line},
@code{tab-line} or @code{header-line}, include only the height of that
line, if present, in the return value. If it is @code{t}, include the
height of all of these lines, if present, in the return value.
@end defun
The optional argument @var{ignore-line-at-end} controls whether or
not to count the height of text in @var{to}'s screen line as part of
the returned pixel-height. This is useful if your Lisp program is
only interested in the dimensions of text up to and excluding the
visual beginning of @var{to}'s screen line.
@code{window-text-pixel-size} treats the text displayed in a window as a
whole and does not care about the size of individual lines. The
following function does.
@defun window-lines-pixel-dimensions &optional window first last body inverse left
This function calculates the pixel dimensions of each line displayed in
the specified @var{window}. It does so by walking @var{window}'s
current glyph matrix---a matrix storing the glyph (@pxref{Glyphs}) of
each buffer character currently displayed in @var{window}. If
successful, it returns a list of cons pairs representing the x- and
y-coordinates of the lower right corner of the last character of each
line. Coordinates are measured in pixels from an origin (0, 0) at the
top-left corner of @var{window}. @var{window} must be a live window and
defaults to the selected one.
If the optional argument @var{first} is an integer, it denotes the index
(starting with 0) of the first line of @var{window}'s glyph matrix to be
returned. Note that if @var{window} has a header line, the line with
index 0 is that header line. If @var{first} is @code{nil}, the first line to
be considered is determined by the value of the optional argument
@var{body}: If @var{body} is non-@code{nil}, this means to start with
the first line of @var{window}'s body, skipping any header line, if
present. Otherwise, this function will start with the first line of
@var{window}'s glyph matrix, possibly the header line.
If the optional argument @var{last} is an integer, it denotes the index
of the last line of @var{window}'s glyph matrix that shall be returned.
If @var{last} is @code{nil}, the last line to be considered is determined by
the value of @var{body}: If @var{body} is non-@code{nil}, this means to
use the last line of @var{window}'s body, omitting @var{window}'s mode
line, if present. Otherwise, this means to use the last line of
@var{window} which may be the mode line.
The optional argument @var{inverse}, if @code{nil}, means that the
y-pixel value returned for any line specifies the distance in pixels
from the left edge (body edge if @var{body} is non-@code{nil}) of
@var{window} to the right edge of the last glyph of that line.
@var{inverse} non-@code{nil} means that the y-pixel value returned for
any line specifies the distance in pixels from the right edge of the
last glyph of that line to the right edge (body edge if @var{body} is
non-@code{nil}) of @var{window}. This is useful for determining the
amount of slack space at the end of each line.
The optional argument @var{left}, if non-@code{nil} means to return the
x- and y-coordinates of the lower left corner of the leftmost character
on each line. This is the value that should be used for windows that
mostly display text from right to left.
If @var{left} is non-@code{nil} and @var{inverse} is @code{nil}, this
means that the y-pixel value returned for any line specifies the
distance in pixels from the left edge of the last (leftmost) glyph of
that line to the right edge (body edge if @var{body} is non-@code{nil})
of @var{window}. If @var{left} and @var{inverse} are both
non-@code{nil}, the y-pixel value returned for any line specifies the
distance in pixels from the left edge (body edge if @var{body} is
non-@code{nil}) of @var{window} to the left edge of the last (leftmost)
glyph of that line.
This function returns @code{nil} if the current glyph matrix of
@var{window} is not up-to-date which usually happens when Emacs is busy,
for example, when processing a command. The value should be retrievable
though when this function is run from an idle timer with a delay of zero
seconds.
@end defun
@defun buffer-text-pixel-size &optional buffer-or-name window from to x-limit y-limit
This is much like @code{window-text-pixel-size}, but can be used when
the buffer isn't shown in a window. (@code{window-text-pixel-size} is
faster when it is, so this function shouldn't be used in that case.)
@var{buffer-or-name} must specify a live buffer or the name of a live
buffer and defaults to the current buffer. @var{window} must be a
live window and defaults to the selected one; the function will
compute the text dimensions as if @var{buffer} is displayed in
@var{window}. The return value is a cons of the maximum pixel-width
of any text line and the pixel-height of all the text lines of the
buffer specified by @var{buffer-or-name}.
The optional arguments @var{x-limit} and @var{y-limit} have the same
meaning as with @code{window-text-pixel-size}.
@end defun
@defun string-pixel-width string
This is a convenience function that uses @code{window-text-pixel-size}
to compute the width of @var{string} (in pixels).
@end defun
@defun line-pixel-height
This function returns the height in pixels of the line at point in the
selected window. The value includes the line spacing of the line
(@pxref{Line Height}).
@end defun
@cindex grapheme cluster
@defun string-glyph-split string
When character compositions are in effect, sequence of characters can
be composed for display to form @dfn{grapheme clusters}, for example
to display accented characters, or ligatures, or Emoji, or when
complex text shaping requires that for some scripts. When that
happens, characters no longer map in a simple way to display columns,
and display layout decisions with such strings, such as truncating too
wide strings, can be a complex job. This function helps in performing
such jobs: it splits up its argument @var{string} into a list of
substrings, where each substring produces a single grapheme cluster
that should be displayed as a unit. Lisp programs can then use this
list to construct visually-valid substrings of @var{string} which will
look correctly on display, or compute the width of any substring of
@var{string} by adding the width of its constituents in the returned
list, etc.
For instance, if you want to display a string without the first glyph,
you can say:
@example
(apply #'insert (cdr (string-glyph-split string))))
@end example
@end defun
When a buffer is displayed with line numbers (@pxref{Display Custom,,,
emacs, The GNU Emacs Manual}), it is sometimes useful to know the
width taken for displaying the line numbers. The following function
is for Lisp programs which need this information for layout
calculations.
@defun line-number-display-width &optional pixelwise
This function returns the width used for displaying the line numbers
in the selected window. If the optional argument @var{pixelwise} is
the symbol @code{columns}, the return value is a float number of the
frame's canonical columns; if @var{pixelwise} is @code{t} or any other
non-@code{nil} value, the value is an integer and is measured in
pixels. If @var{pixelwise} is omitted or @code{nil}, the value is the
integer number of columns of the font defined for the
@code{line-number} face, and doesn't include the 2 columns used to pad
the numbers on display. If line numbers are not displayed in the
selected window, the value is zero regardless of the value of
@var{pixelwise}. Use @code{with-selected-window} (@pxref{Selecting
Windows}) if you need this information about another window.
@end defun
@node Line Height
@section Line Height
@cindex line height
@cindex height of a line
The total height of each display line consists of the height of the
contents of the line, plus optional additional vertical line spacing
above or below the display line.
The height of the line contents is the maximum height of any character
or image on that display line, including the final newline if there is
one. (A display line that is continued doesn't include a final
newline.) That is the default line height, if you do nothing to specify
a greater height. (In the most common case, this equals the height of
the corresponding frame's default font, see @ref{Frame Font}.)
There are several ways to explicitly specify a larger line height,
either by specifying an absolute height for the display line, or by
specifying vertical space. However, no matter what you specify, the
actual line height can never be less than the default.
@kindex line-height @r{(text property)}
A newline can have a @code{line-height} text or overlay property
that controls the total height of the display line ending in that
newline. The property value can be one of several forms:
@table @code
@item t
If the property value is @code{t}, the newline character has no
effect on the displayed height of the line---the visible contents
alone determine the height. The @code{line-spacing} property of the
newline, described below, is also ignored in this case. This is
useful for tiling small images (or image slices) without adding blank
areas between the images.
@item (@var{height} @var{total})
If the property value is a list of the form shown, that adds extra
space @emph{below} the display line. First Emacs uses @var{height} as
a height spec to control extra space @emph{above} the line; then it
adds enough space @emph{below} the line to bring the total line height
up to @var{total}. In this case, any value of @code{line-spacing}
property for the newline is ignored.
@end table
@cindex height spec
Any other kind of property value is a height spec, which translates
into a number---the specified line height. There are several ways to
write a height spec; here's how each of them translates into a number:
@table @code
@item @var{integer}
If the height spec is a positive integer, the height value is that integer.
@item @var{float}
If the height spec is a float, @var{float}, the numeric height value
is @var{float} times the frame's default line height.
@item (@var{face} . @var{ratio})
If the height spec is a cons of the format shown, the numeric height
is @var{ratio} times the height of face @var{face}. @var{ratio} can
be any type of number, or @code{nil} which means a ratio of 1.
If @var{face} is @code{t}, it refers to the current face.
@item (nil . @var{ratio})
If the height spec is a cons of the format shown, the numeric height
is @var{ratio} times the height of the contents of the line.
@end table
Thus, any valid height spec determines the height in pixels, one way
or another. If the line contents' height is less than that, Emacs
adds extra vertical space above the line to achieve the specified
total height.
If you don't specify the @code{line-height} property, the line's
height consists of the contents' height plus the line spacing.
There are several ways to specify the line spacing for different
parts of Emacs text.
On graphical terminals, you can specify the line spacing for all
lines in a frame, using the @code{line-spacing} frame parameter
(@pxref{Layout Parameters}). However, if the default value of
@code{line-spacing} is non-@code{nil}, it overrides the
frame's @code{line-spacing} parameter. An integer specifies the
number of pixels put below lines. A floating-point number specifies
the spacing relative to the frame's default line height.
@vindex line-spacing
You can specify the line spacing for all lines in a buffer via the
buffer-local @code{line-spacing} variable. An integer specifies
the number of pixels put below lines. A floating-point number
specifies the spacing relative to the default frame line height. This
overrides line spacings specified for the frame.
@kindex line-spacing @r{(text property)}
Finally, a newline can have a @code{line-spacing} text or overlay
property that can enlarge the default frame line spacing and the
buffer local @code{line-spacing} variable: if its value is larger than
the buffer or frame defaults, that larger value is used instead, for
the display line ending in that newline (unless the newline also has
the @code{line-height} property whose value is one of the special
values which cause @code{line-spacing} to be ignored, see above).
One way or another, these mechanisms specify a Lisp value for the
spacing of each line. The value is a height spec, and it translates
into a Lisp value as described above. However, in this case the
numeric height value specifies the line spacing, rather than the line
height.
On text terminals, the line spacing cannot be altered.
@node Faces
@section Faces
@cindex faces
A @dfn{face} is a collection of graphical attributes for displaying
text: font, foreground color, background color, optional underlining,
etc. Faces control how Emacs displays text in buffers, as well as
other parts of the frame such as the mode line.
@cindex anonymous face
One way to represent a face is as a property list of attributes,
like @code{(:foreground "red" :weight bold)}. Such a list is called
an @dfn{anonymous face}. For example, you can assign an anonymous
face as the value of the @code{face} text property, and Emacs will
display the underlying text with the specified attributes.
@xref{Special Properties}.
@cindex face name
More commonly, a face is referred to via a @dfn{face name}: a Lisp
symbol associated with a set of face attributes@footnote{For backward
compatibility, you can also use a string to specify a face name; that
is equivalent to a Lisp symbol with the same name.}. Named faces are
defined using the @code{defface} macro (@pxref{Defining Faces}).
Emacs comes with several standard named faces (@pxref{Basic Faces}).
Some parts of Emacs require named faces (e.g., the functions
documented in @ref{Attribute Functions}). Unless otherwise stated, we
will use the term @dfn{face} to refer only to named faces.
@defun facep object
This function returns a non-@code{nil} value if @var{object} is a
named face: a Lisp symbol or string which serves as a face name.
Otherwise, it returns @code{nil}.
@end defun
@menu
* Face Attributes:: What is in a face?
* Defining Faces:: How to define a face.
* Attribute Functions:: Functions to examine and set face attributes.
* Displaying Faces:: How Emacs combines the faces specified for a character.
* Face Remapping:: Remapping faces to alternative definitions.
* Face Functions:: How to define and examine faces.
* Auto Faces:: Hook for automatic face assignment.
* Basic Faces:: Faces that are defined by default.
* Font Selection:: Finding the best available font for a face.
* Font Lookup:: Looking up the names of available fonts
and information about them.
* Fontsets:: A fontset is a collection of fonts
that handle a range of character sets.
* Low-Level Font:: Lisp representation for character display fonts.
@end menu
@node Face Attributes
@subsection Face Attributes
@cindex face attributes
@dfn{Face attributes} determine the visual appearance of a face.
The following table lists all the face attributes, their possible
values, and their effects.
@cindex unspecified, face attribute value
Apart from the values given below, each face attribute can have the
value @code{unspecified}. This special value means that the face
doesn't specify that attribute directly. An @code{unspecified}
attribute tells Emacs to refer instead to a parent face (see the
description @code{:inherit} attribute below); or, failing that, to an
underlying face (@pxref{Displaying Faces}). (However,
@code{unspecified} is not a valid value in @code{defface}.)
@cindex reset, face attribute value
A face attribute can also have the value @code{reset}. This special
value stands for the value of the corresponding attribute of the
@code{default} face.
The @code{default} face must explicitly specify all attributes, and
cannot use the special value @code{reset}.
Some of these attributes are meaningful only on certain kinds of
displays. If your display cannot handle a certain attribute, the
attribute is ignored.
@table @code
@item :family
Font family name (a string). @xref{Fonts,,, emacs, The GNU
Emacs Manual}, for more information about font families. The function
@code{font-family-list} (see below) returns a list of available family
names.
@item :foundry
The name of the @dfn{font foundry} for the font family specified by
the @code{:family} attribute (a string). @xref{Fonts,,, emacs, The
GNU Emacs Manual}.
@item :width
Relative character width. This should be one of the symbols
@code{ultra-condensed}, @code{extra-condensed}, @code{condensed},
@code{semi-condensed}, @code{normal}, @code{regular}, @code{medium},
@code{semi-expanded}, @code{expanded}, @code{extra-expanded}, or
@code{ultra-expanded}.
@item :height
The height of the font. In the simplest case, this is an integer in
units of 1/10 point.
The value can also be floating point or a function, which
specifies the height relative to an @dfn{underlying face}
(@pxref{Displaying Faces}). A floating-point value
specifies the amount by which to scale the height of the
underlying face. A function value is called
with one argument, the height of the underlying face, and returns the
height of the new face. If the function is passed an integer
argument, it must return an integer.
The height of the default face must be specified using an integer;
floating point and function values are not allowed.
@item :weight
Font weight---one of the symbols (from densest to faintest)
@code{ultra-bold}, @code{extra-bold}, @code{bold}, @code{semi-bold},
@code{normal}, @code{semi-light}, @code{light}, @code{extra-light}, or
@code{ultra-light}. On text terminals which support
variable-brightness text, any weight greater than normal is displayed
as extra bright, and any weight less than normal is displayed as
half-bright.
@cindex italic text
@item :slant
Font slant---one of the symbols @code{italic}, @code{oblique},
@code{normal}, @code{reverse-italic}, or @code{reverse-oblique}. On
text terminals that support variable-brightness text, slanted text is
displayed as half-bright.
@item :foreground
Foreground color, a string. The value can be a system-defined color
name, or a hexadecimal color specification. @xref{Color Names}. On
black-and-white displays, certain shades of gray are implemented by
stipple patterns.
@item :distant-foreground
Alternative foreground color, a string. This is like @code{:foreground}
but the color is only used as a foreground when the background color is
near to the foreground that would have been used. This is useful for
example when marking text (i.e., the region face). If the text has a foreground
that is visible with the region face, that foreground is used.
If the foreground is near the region face background,
@code{:distant-foreground} is used instead so the text is readable.
@item :background
Background color, a string. The value can be a system-defined color
name, or a hexadecimal color specification. @xref{Color Names}.
@cindex underlined text
@item :underline
Whether or not characters should be underlined, and in what
way. The possible values of the @code{:underline} attribute are:
@table @asis
@item @code{nil}
Don't underline.
@item @code{t}
Underline with the foreground color of the face.
@item @var{color}
Underline in color @var{color}, a string specifying a color.
@item @code{(:color @var{color} :style @var{style} :position @var{position})}
@var{color} is either a string, or the symbol @code{foreground-color},
meaning the foreground color of the face. Omitting the attribute
@code{:color} means to use the foreground color of the face.
@var{style} should be a symbol @code{line} or @code{wave}, meaning to
use a straight or wavy line. Omitting the attribute @code{:style}
means to use a straight line. @var{position}, if non-@code{nil}, means to
display the underline at the descent of the text, instead of at the
baseline level. If it is a number, then it specifies the amount of
pixels above the descent to display the underline.
@end table
@cindex overlined text
@item :overline
Whether or not characters should be overlined, and in what color.
If the value is @code{t}, overlining uses the foreground color of the
face. If the value is a string, overlining uses that color. The
value @code{nil} means do not overline.
@cindex strike-through text
@item :strike-through
Whether or not characters should be strike-through, and in what
color. The value is used like that of @code{:overline}.
@cindex 2D box
@cindex 3D box
@item :box
Whether or not a box should be drawn around characters, its color, the
width of the box lines, and 3D appearance. Here are the possible
values of the @code{:box} attribute, and what they mean:
@table @asis
@item @code{nil}
Don't draw a box.
@item @code{t}
Draw a box with lines of width 1, in the foreground color.
@item @var{color}
Draw a box with lines of width 1, in color @var{color}.
@item @code{(:line-width (@var{vwidth} . @var{hwidth}) :color @var{color} :style @var{style})}
You can explicitly specify all aspects of the box with a plist on this
form. Any element in this plist can be omitted.
The values of @var{vwidth} and @var{hwidth} specify respectively the
width of the vertical and horizontal lines to draw; they default to (1
. 1). A negative horizontal or vertical width @minus{}@var{n} means
to draw a line of width @var{n} that occupies the space of the
underlying text, thus avoiding any increase in the character height or
width. For simplification the width could be specified with only a
single number @var{n} instead of a list, such case is equivalent to
@code{((abs @var{n}) . @var{n})}.
The value of @var{color} specifies the color to draw with. The default
is the background color of the face for 3D boxes and
@code{flat-button}, and the foreground color of the face for other
boxes.
The value of @var{style} specifies whether to draw a 3D box. If it is
@code{released-button}, the box looks like a 3D button that is not
being pressed. If it is @code{pressed-button}, the box looks like a
3D button that is being pressed. If it is @code{nil},
@code{flat-button} or omitted, a plain 2D box is used.
@end table
@item :inverse-video
Whether or not characters should be displayed in inverse video. The
value should be @code{t} (yes) or @code{nil} (no).
@item :stipple
The background stipple, a bitmap.
The value can be a string; that should be the name of a file containing
external-format X bitmap data. The file is found in the directories
listed in the variable @code{x-bitmap-file-path}.
Alternatively, the value can specify the bitmap directly, with a list
of the form @code{(@var{width} @var{height} @var{data})}. Here,
@var{width} and @var{height} specify the size in pixels, and
@var{data} is a string containing the raw bits of the bitmap, row by
row. Each row occupies @math{(@var{width} + 7) / 8} consecutive bytes
in the string (which should be a unibyte string for best results).
This means that each row always occupies at least one whole byte.
If the value is @code{nil}, that means use no stipple pattern.
Normally you do not need to set the stipple attribute, because it is
used automatically to handle certain shades of gray.
@item :font
The font used to display the face. Its value should be a font object
or a fontset. If it is a font object, it specifies the font to be
used by the face for displaying ASCII characters. @xref{Low-Level
Font}, for information about font objects, font specs, and font
entities. @xref{Fontsets}, for information about fontsets.
@anchor{face-font-attribute}
When specifying this attribute using @code{set-face-attribute} or
@code{set-face-font} (@pxref{Attribute Functions}), you may also
supply a font spec, a font entity, or a string. Emacs converts such
values to an appropriate font object, and stores that font object as
the actual attribute value. If you specify a string, the contents of
the string should be a font name (@pxref{Fonts,,, emacs, The GNU Emacs
Manual}); if the font name is an XLFD containing wildcards, Emacs
chooses the first font matching those wildcards. Specifying this
attribute also changes the values of the @code{:family},
@code{:foundry}, @code{:width}, @code{:height}, @code{:weight}, and
@code{:slant} attributes.
@cindex inheritance, for faces
@item :inherit
The name of a face from which to inherit attributes, or a list of face
names. Attributes from inherited faces are merged into the face like
an underlying face would be, with higher priority than underlying
faces (@pxref{Displaying Faces}). If the face to inherit from is
@code{unspecified}, it is treated the same as @code{nil}, since Emacs
never merges @code{:inherit} attributes. If a list of faces is used,
attributes from faces earlier in the list override those from later
faces.
@item :extend
Whether or not this face will be extended beyond end of line and will
affect the display of the empty space between the end of line and the
edge of the window. The value should be @code{t} to display the empty
space between end of line and edge of the window using this face, or
@code{nil} to not use this face for the space between the end of the
line and the edge of the window. When Emacs merges several faces for
displaying the empty space beyond end of line, only those faces with
@code{:extend} non-@code{nil} will be merged. By default, only a
small number of faces, notably, @code{region}, have this attribute
set. This attribute is different from the others in that when a theme
doesn't specify an explicit value for a face, the value from the
original face definition by @code{defface} is inherited
(@pxref{Defining Faces}).
Some modes, like @code{hl-line-mode}, use a face with an
@code{:extend} property to mark the entire current line. Note,
however, that Emacs will always allow you to move point after the
final character in a buffer, and if the buffer ends with a newline
character, point can be placed on what is seemingly a line at the end
of the buffer---but Emacs can't highlight that ``line'', because it
doesn't really exist.
@end table
@defun font-family-list &optional frame
This function returns a list of available font family names. The
optional argument @var{frame} specifies the frame on which the text is
to be displayed; if it is @code{nil}, the selected frame is used.
@end defun
@defopt underline-minimum-offset
This variable specifies the minimum distance between the baseline and
the underline, in pixels, when displaying underlined text.
@end defopt
@defopt x-bitmap-file-path
This variable specifies a list of directories for searching
for bitmap files, for the @code{:stipple} attribute.
@end defopt
@defun bitmap-spec-p object
This returns @code{t} if @var{object} is a valid bitmap specification,
suitable for use with @code{:stipple} (see above). It returns
@code{nil} otherwise.
@end defun
@node Defining Faces
@subsection Defining Faces
@cindex defining faces
@cindex face spec
The usual way to define a face is through the @code{defface} macro.
This macro associates a face name (a symbol) with a default @dfn{face
spec}. A face spec is a construct which specifies what attributes a
face should have on any given terminal; for example, a face spec might
specify one foreground color on high-color terminals, and a different
foreground color on low-color terminals.
People are sometimes tempted to create a variable whose value is a
face name. In the vast majority of cases, this is not necessary; the
usual procedure is to define a face with @code{defface}, and then use
its name directly.
@cindex face (non-removability of)
Note that once you have defined a face (usually with @code{defface}),
you cannot later undefine this face safely, except by restarting
Emacs.
@defmac defface face spec doc [keyword value]@dots{}
This macro declares @var{face} as a named face whose default face spec
is given by @var{spec}. You should not quote the symbol @var{face},
and it should not end in @samp{-face} (that would be redundant). The
argument @var{doc} is a documentation string for the face. The
additional @var{keyword} arguments have the same meanings as in
@code{defgroup} and @code{defcustom} (@pxref{Common Keywords}).
If @var{face} already has a default face spec, this macro does
nothing.
The default face spec determines @var{face}'s appearance when no
customizations are in effect (@pxref{Customization}). If @var{face}
has already been customized (via Custom themes or via customizations
read from the init file), its appearance is determined by the custom
face spec(s), which override the default face spec @var{spec}.
However, if the customizations are subsequently removed, the
appearance of @var{face} will again be determined by its default face
spec.
@cindex @code{eval-defun}, and @code{defface} forms
@cindex @code{eval-last-sexp}, and @code{defface} forms
As an exception, if you evaluate a @code{defface} form with
@kbd{C-M-x} (@code{eval-defun}) or with @kbd{C-x C-e}
(@code{eval-last-sexp}) in Emacs Lisp mode, a special feature of these
commands overrides any custom face specs on the face, causing the face
to reflect exactly what the @code{defface} says.
The @var{spec} argument is a @dfn{face spec}, which states how the
face should appear on different kinds of terminals. It should be an
alist whose elements each have the form
@example
(@var{display} . @var{plist})
@end example
@noindent
@var{display} specifies a class of terminals (see below). @var{plist}
is a property list of face attributes and their values, specifying how
the face appears on such terminals. For backward compatibility, you
can also write an element as @code{(@var{display} @var{plist})}.
The @var{display} part of an element of @var{spec} determines which
terminals the element matches. If more than one element of @var{spec}
matches a given terminal, the first element that matches is the one
used for that terminal. There are three possibilities for
@var{display}:
@table @asis
@item @code{default}
This element of @var{spec} doesn't match any terminal; instead, it
specifies defaults that apply to all terminals. This element, if
used, must be the first element of @var{spec}. Each of the following
elements can override any or all of these defaults.
@item @code{t}
This element of @var{spec} matches all terminals. Therefore, any
subsequent elements of @var{spec} are never used. Normally @code{t}
is used in the last (or only) element of @var{spec}.
@item a list
If @var{display} is a list, each element should have the form
@code{(@var{characteristic} @var{value}@dots{})}. Here
@var{characteristic} specifies a way of classifying terminals, and the
@var{value}s are possible classifications which @var{display} should
apply to. Here are the possible values of @var{characteristic}:
@table @code
@item type
The kind of window system the terminal uses---either @code{graphic}
(any graphics-capable display), @code{x}, @code{pc} (for the MS-DOS
console), @code{w32} (for MS Windows 9X/NT/2K/XP), @code{haiku} (for
Haiku), @code{pgtk} (for pure GTK), @code{android} (for Android), or
@code{tty} (a non-graphics-capable display). @xref{Window Systems,
window-system}.
@item class
What kinds of colors the terminal supports---either @code{color},
@code{grayscale}, or @code{mono}.
@item background
The kind of background---either @code{light} or @code{dark}.
@item min-colors
An integer that represents the minimum number of colors the terminal
should support. This matches a terminal if its
@code{display-color-cells} value is at least the specified integer.
@item supports
Whether or not the terminal can display the face attributes given in
@var{value}@dots{} (@pxref{Face Attributes}). @xref{Display Face
Attribute Testing}, for more information on exactly how this testing
is done.
@end table
If an element of @var{display} specifies more than one @var{value} for
a given @var{characteristic}, any of those values is acceptable. If
@var{display} has more than one element, each element should specify a
different @var{characteristic}; then @emph{each} characteristic of the
terminal must match one of the @var{value}s specified for it in
@var{display}.
@end table
@end defmac
For example, here's the definition of the standard face
@code{highlight}:
@example
(defface highlight
'((((class color) (min-colors 88) (background light))
:background "darkseagreen2")
(((class color) (min-colors 88) (background dark))
:background "darkolivegreen")
(((class color) (min-colors 16) (background light))
:background "darkseagreen2")
(((class color) (min-colors 16) (background dark))
:background "darkolivegreen")
(((class color) (min-colors 8))
:background "green" :foreground "black")
(t :inverse-video t))
"Basic face for highlighting."
:group 'basic-faces)
@end example
@kindex face-defface-spec @r{(face symbol property)}
@kindex saved-face @r{(face symbol property)}
@kindex customized-face @r{(face symbol property)}
@kindex theme-face @r{(face symbol property)}
@kindex face-documentation @r{(face symbol property)}
Internally, Emacs stores each face's default spec in its
@code{face-defface-spec} symbol property (@pxref{Symbol Properties}).
The @code{saved-face} property stores any face spec saved by the user
using the customization buffer; the @code{customized-face} property
stores the face spec customized for the current session, but not
saved; and the @code{theme-face} property stores an alist associating
the active customization settings and Custom themes with the face
specs for that face. The face's documentation string is stored in the
@code{face-documentation} property.
Normally, a face is declared just once, using @code{defface}, and
any further changes to its appearance are applied using the Customize
framework (e.g., via the Customize user interface or via the
@code{custom-set-faces} function; @pxref{Applying Customizations}), or
by face remapping (@pxref{Face Remapping}). In the rare event that
you need to change a face spec directly from Lisp, you can use the
@code{face-spec-set} function.
@defun face-spec-set face spec &optional spec-type
This function applies @var{spec} as a face spec for @code{face}.
@var{spec} should be a face spec, as described in the above
documentation for @code{defface}.
This function also defines @var{face} as a valid face name if it is
not already one, and (re)calculates its attributes on existing frames.
@cindex override spec @r{(for a face)}
The optional argument @var{spec-type} determines which spec to set.
If it is omitted or @code{nil} or @code{face-override-spec}, this
function sets the @dfn{override spec}, which overrides face specs on
@var{face} of all the other types mentioned below. This is useful
when calling this function outside of Custom code. If @var{spec-type}
is @code{customized-face} or @code{saved-face}, this function sets the
customized spec or the saved custom spec, respectively. If it is
@code{face-defface-spec}, this function sets the default face spec
(the same one set by @code{defface}). If it is @code{reset}, this
function clears out all customization specs and override specs from
@var{face} (in this case, the value of @var{spec} is ignored). The
effect of any other value of @var{spec-type} on the face specs is
reserved for internal use, but the function will still define
@var{face} itself and recalculate its attributes, as described above.
@end defun
@node Attribute Functions
@subsection Face Attribute Functions
@cindex face attributes, access and modification
This section describes functions for directly accessing and
modifying the attributes of a named face.
@defun face-attribute face attribute &optional frame inherit
This function returns the value of the @var{attribute} attribute for
@var{face} on @var{frame}. @xref{Face Attributes}, for the supported
attributes.
If @var{frame} is omitted or @code{nil}, that means the selected frame
(@pxref{Input Focus}). If @var{frame} is @code{t}, this function
returns the value of the specified attribute for newly-created frames,
i.e.@: the value of the attribute before applying the face spec in the
face's @code{defface} definition (@pxref{Defining Faces}) or the spec
set by @code{face-spec-set}. This default value of @var{attribute} is
normally @code{unspecified}, unless you have specified some other
value using @code{set-face-attribute}; see below.
If @var{inherit} is @code{nil}, only attributes directly defined by
@var{face} are considered, so the return value may be
@code{unspecified}, or a relative value. If @var{inherit} is
non-@code{nil}, @var{face}'s definition of @var{attribute} is merged
with the faces specified by its @code{:inherit} attribute; however the
return value may still be @code{unspecified} or relative. If
@var{inherit} is a face or a list of faces, then the result is further
merged with that face (or faces), until it becomes specified and
absolute.
To ensure that the return value is always specified and absolute, use
a value of @code{default} for @var{inherit}; this will resolve any
unspecified or relative values by merging with the @code{default} face
(which is always completely specified).
For example,
@example
(face-attribute 'bold :weight)
@result{} bold
@end example
@end defun
@c FIXME: Add an index for "relative face attribute", maybe here? --xfq
@defun face-attribute-relative-p attribute value
This function returns non-@code{nil} if @var{value}, when used as the
value of the face attribute @var{attribute}, is relative. This means
it would modify, rather than completely override, any value that comes
from a subsequent face in the face list or that is inherited from
another face.
@code{unspecified} is a relative value for all attributes. For
@code{:height}, floating point and function values are also relative.
For example:
@example
(face-attribute-relative-p :height 2.0)
@result{} t
@end example
@end defun
@defun face-all-attributes face &optional frame
This function returns an alist of attributes of @var{face}. The
elements of the result are name-value pairs of the form
@w{@code{(@var{attr-name} . @var{attr-value})}}. Optional argument
@var{frame} specifies the frame whose definition of @var{face} to
return; if omitted or @code{nil}, the returned value describes the
default attributes of @var{face} for newly created frames, i.e.@: the
values these attributes have before applying the face spec in the
face's @code{defface} definition or the spec set by
@code{face-spec-set}. These default values of the attributes are
normally @code{unspecified}, unless you have specified some other
value using @code{set-face-attribute}; see below.
@end defun
@defun merge-face-attribute attribute value1 value2
If @var{value1} is a relative value for the face attribute
@var{attribute}, returns it merged with the underlying value
@var{value2}; otherwise, if @var{value1} is an absolute value for the
face attribute @var{attribute}, returns @var{value1} unchanged.
@end defun
Normally, Emacs uses the face specs of each face to automatically
calculate its attributes on each frame (@pxref{Defining Faces}). The
function @code{set-face-attribute} can override this calculation by
directly assigning attributes to a face, either on a specific frame or
for all frames. This function is mostly intended for internal usage.
@defun set-face-attribute face frame &rest arguments
This function sets one or more attributes of @var{face} for
@var{frame}. The attributes specified in this way override the face
spec(s) belonging to @var{face}. @xref{Face Attributes}, for the
supported attributes.
The extra arguments @var{arguments} specify the attributes to set, and
the values for them. They should consist of alternating attribute
names (such as @code{:family} or @code{:underline}) and values. Thus,
@example
(set-face-attribute 'foo nil :weight 'bold :slant 'italic)
@end example
@noindent
sets the attribute @code{:weight} to @code{bold} and the attribute
@code{:slant} to @code{italic}.
If @var{frame} is @code{t}, this function sets the default attributes
for newly created frames; they will effectively override the attribute
values specified by @code{defface}. If @var{frame} is @code{nil},
this function sets the attributes for all existing frames, as well as
for newly created frames.
To @emph{reset} the value of an attribute, that is, to indicate that
the face doesn't by itself specify a value for the attribute, use the
special value @code{unspecified} (@emph{not} @code{nil}!@:) for the
attribute, and set the @var{frame} argument to @code{t}, in addition
to the call with @var{frame} set to @code{nil}. This is because the
default attributes for newly created frames are merged with the face's
spec in @code{defface} when a new frame is created, and so having
@code{unspecified} in the default attributes for new frames will be
unable to override @code{defface}; the special call to this function
as described above will arrange for @code{defface} to be overridden.
Note that the attribute-value pairs are evaluated in the order they
are specified, with the exception of the @code{:family} and
@code{:foundry} attributes, which are evaluated first. This means
that if a certain attribute is specified more than once, only the last
value will be used. It also means that in some cases a different
order of attributes will produce different results. For example, when
@code{:weight} is placed before @code{:font}, the weight value is
applied to the current font of the face, and might be rounded to the
closest available weight of that font, whereas when @code{:font} is
placed before @code{:weight} the weight value is applied to the
specified font.
@end defun
The following commands and functions mostly provide compatibility
with old versions of Emacs. They work by calling
@code{set-face-attribute}. Values of @code{t} and @code{nil} (or
omitted) for their @var{frame} argument are handled just like
@code{set-face-attribute} and @code{face-attribute}. The commands
read their arguments using the minibuffer, if called interactively.
@deffn Command set-face-foreground face color &optional frame
@deffnx Command set-face-background face color &optional frame
These set the @code{:foreground} attribute (or @code{:background}
attribute, respectively) of @var{face} to @var{color}.
@end deffn
@deffn Command set-face-stipple face pattern &optional frame
This sets the @code{:stipple} attribute of @var{face} to
@var{pattern}.
@end deffn
@deffn Command set-face-font face font &optional frame
Change the font-related attributes of @var{face} to those of
@var{font} (a string or a font object). @xref{face-font-attribute},
for the supported formats of the @var{font} argument. This function
sets the attribute @code{:font} of the face, and indirectly also the
@code{:family}, @code{:foundry}, @code{:width}, @code{:height},
@code{:weight}, and @code{:slant} attributes, as defined by the font.
If @var{frame} is non-@code{nil}, only change the attributes on the
specified frame.
@end deffn
@defun set-face-bold face bold-p &optional frame
This sets the @code{:weight} attribute of @var{face} to @var{normal}
if @var{bold-p} is @code{nil}, and to @var{bold} otherwise.
@end defun
@defun set-face-italic face italic-p &optional frame
This sets the @code{:slant} attribute of @var{face} to @var{normal} if
@var{italic-p} is @code{nil}, and to @var{italic} otherwise.
@end defun
@deffn Command set-face-underline face underline &optional frame
This sets the @code{:underline} attribute of @var{face} to
@var{underline}.
@end deffn
@deffn Command set-face-inverse-video face inverse-video-p &optional frame
This sets the @code{:inverse-video} attribute of @var{face} to
@var{inverse-video-p}.
@end deffn
@deffn Command invert-face face &optional frame
This swaps the foreground and background colors of face @var{face}.
@end deffn
@deffn Command set-face-extend face extend &optional frame
This sets the @code{:extend} attribute of @var{face} to
@var{extend}.
@end deffn
The following functions examine the attributes of a face. They
mostly provide compatibility with old versions of Emacs. If you don't
specify @var{frame}, they refer to the selected frame; @code{t} refers
to the default data for new frames. They return @code{unspecified} if
the face doesn't define any value for that attribute. If
@var{inherit} is @code{nil}, only an attribute directly defined by the
face is returned. If @var{inherit} is non-@code{nil}, any faces
specified by its @code{:inherit} attribute are considered as well, and
if @var{inherit} is a face or a list of faces, then they are also
considered, until a specified attribute is found. To ensure that the
return value is always specified, use a value of @code{default} for
@var{inherit}.
@defun face-font face &optional frame character
This function returns the name of the font used by the specified
@var{face}.
If the optional argument @var{frame} is specified, it returns the name
of the font of @var{face} for that frame; @var{frame} defaults to the
selected frame if it is @code{nil} or omitted. If @var{frame} is
@code{t}, the function reports on the font defaults for @var{face} to
be used for new frames.
By default, the returned font is for displaying ASCII characters, but
if @var{frame} is anything but @code{t}, and the optional third
argument @var{character} is supplied, the function returns the font
name used by @var{face} for that character.
@end defun
@defun face-foreground face &optional frame inherit
@defunx face-background face &optional frame inherit
These functions return the foreground color (or background color,
respectively) of face @var{face}, as a string. If the color is
unspecified, they return @code{nil}.
@end defun
@defun face-stipple face &optional frame inherit
This function returns the name of the background stipple pattern of face
@var{face}, or @code{nil} if it doesn't have one.
@end defun
@defun face-bold-p face &optional frame inherit
This function returns a non-@code{nil} value if the @code{:weight}
attribute of @var{face} is bolder than normal (i.e., one of
@code{semi-bold}, @code{bold}, @code{extra-bold}, or
@code{ultra-bold}). Otherwise, it returns @code{nil}.
@end defun
@defun face-italic-p face &optional frame inherit
This function returns a non-@code{nil} value if the @code{:slant}
attribute of @var{face} is @code{italic} or @code{oblique}, and
@code{nil} otherwise.
@end defun
@defun face-underline-p face &optional frame inherit
This function returns non-@code{nil} if face @var{face} specifies
a non-@code{nil} @code{:underline} attribute.
@end defun
@defun face-inverse-video-p face &optional frame inherit
This function returns non-@code{nil} if face @var{face} specifies
a non-@code{nil} @code{:inverse-video} attribute.
@end defun
@defun face-extend-p face &optional frame inherit
This function returns non-@code{nil} if face @var{face} specifies
a non-@code{nil} @code{:extend} attribute. The @var{inherit} argument
is passed to @code{face-attribute}.
@end defun
@node Displaying Faces
@subsection Displaying Faces
@cindex displaying faces
@cindex face merging
When Emacs displays a given piece of text, the visual appearance of
the text may be determined by faces drawn from different sources. If
these various sources together specify more than one face for a
particular character, Emacs merges the attributes of the various
faces. Here is the order in which Emacs merges the faces, from
highest to lowest priority:
@itemize @bullet
@item
If the text consists of a special glyph, the glyph can specify a
particular face. @xref{Glyphs}.
@item
If the text lies within an active region, Emacs highlights it using
the @code{region} face. @xref{Standard Faces,,, emacs, The GNU Emacs
Manual}.
@item
If the text lies within an overlay with a non-@code{nil} @code{face}
property, Emacs applies the face(s) specified by that property. If
the overlay has a @code{mouse-face} property and the mouse is near
enough to the overlay, Emacs applies the face or face attributes
specified by the @code{mouse-face} property instead. @xref{Overlay
Properties}.
When multiple overlays cover the same character, an overlay with
higher priority overrides those with lower priority. @xref{Overlays}.
@item
If the text contains a @code{face} or @code{mouse-face} property,
Emacs applies the specified faces and face attributes. @xref{Special
Properties}. (This is how Font Lock mode faces are applied.
@xref{Font Lock Mode}.)
@item
If the text lies within the mode line of the selected window, Emacs
applies the @code{mode-line} face. For the mode line of a
non-selected window, Emacs applies the @code{mode-line-inactive} face.
For a header line, Emacs applies the @code{header-line} face.
For a tab line, Emacs applies the @code{tab-line} face.
@item
If the text comes from an overlay string via @code{before-string} or
@code{after-string} properties (@pxref{Overlay Properties}), or from a
display string (@pxref{Other Display Specs}), and the string doesn't
contain a @code{face} or @code{mouse-face} property, or these
properties leave some face attributes undefined, but the buffer text
affected by the overlay/display property does define a face or those
attributes, Emacs applies the face attributes of the ``underlying''
buffer text. Note that this is so even if the overlay or display
string is displayed in the display margins (@pxref{Display Margins}).
@item
If any given attribute has not been specified during the preceding
steps, Emacs applies the attribute of the @code{default} face.
@end itemize
At each stage, if a face has a valid @code{:inherit} attribute,
Emacs treats any attribute with an @code{unspecified} value as having
the corresponding value drawn from the parent face(s). @pxref{Face
Attributes}. Note that the parent face(s) may also leave the
attribute unspecified; in that case, the attribute remains unspecified
at the next level of face merging.
@node Face Remapping
@subsection Face Remapping
@cindex face remapping
The variable @code{face-remapping-alist} is used for buffer-local or
global changes in the appearance of a face. For instance, it is used
to implement the @code{text-scale-adjust} command (@pxref{Text
Scale,,, emacs, The GNU Emacs Manual}).
@defvar face-remapping-alist
The value of this variable is an alist whose elements have the form
@code{(@var{face} . @var{remapping})}. This causes Emacs to display
any text having the face @var{face} with @var{remapping}, rather than
the ordinary definition of @var{face}.
@var{remapping} may be any face spec suitable for a @code{face} text
property: either a face (i.e., a face name or a property list of
attribute/value pairs), or a list of faces. For details, see the
description of the @code{face} text property in @ref{Special
Properties}. @var{remapping} serves as the complete specification for
the remapped face---it replaces the normal definition of @var{face},
instead of modifying it.
If @code{face-remapping-alist} is buffer-local, its local value takes
effect only within that buffer. If @code{face-remapping-alist}
includes faces applicable only to certain windows, by using the
@w{@code{(:filtered (:window @var{param} @var{val}) @var{spec})}},
that face takes effect only in windows that match the filter
conditions (@pxref{Special Properties}). To turn off face filtering
temporarily, bind @code{face-filters-always-match} to a non-@code{nil}
value, then all face filters will match any window.
Note: face remapping is non-recursive. If @var{remapping} references
the same face name @var{face}, either directly or via the
@code{:inherit} attribute of some other face in @var{remapping}, that
reference uses the normal definition of @var{face}. For instance, if
the @code{mode-line} face is remapped using this entry in
@code{face-remapping-alist}:
@example
(mode-line italic mode-line)
@end example
@noindent
then the new definition of the @code{mode-line} face inherits from the
@code{italic} face, and the @emph{normal} (non-remapped) definition of
@code{mode-line} face.
@end defvar
@cindex relative remapping, faces
@cindex base remapping, faces
The following functions implement a higher-level interface to
@code{face-remapping-alist}. Most Lisp code should use these
functions instead of setting @code{face-remapping-alist} directly, to
avoid trampling on remappings applied elsewhere. These functions are
intended for buffer-local remappings, so they all make
@code{face-remapping-alist} buffer-local as a side-effect. They manage
@code{face-remapping-alist} entries of the form
@example
(@var{face} @var{relative-spec-1} @var{relative-spec-2} @var{...} @var{base-spec})
@end example
@noindent
where, as explained above, each of the @var{relative-spec-N} and
@var{base-spec} is either a face name, or a property list of
attribute/value pairs. Each of the @dfn{relative remapping} entries,
@var{relative-spec-N}, is managed by the
@code{face-remap-add-relative} and @code{face-remap-remove-relative}
functions; these are intended for simple modifications like changing
the text size. The @dfn{base remapping} entry, @var{base-spec}, has
the lowest priority and is managed by the @code{face-remap-set-base}
and @code{face-remap-reset-base} functions; it is intended for major
modes to remap faces in the buffers they control.
@defun face-remap-add-relative face &rest specs
This function adds @var{specs} as relative remappings for face
@var{face} in the current buffer. @var{specs} should be a list where
each element is either a face name, or a property list of
attribute/value pairs.
The return value is a Lisp object that serves as a cookie; you can
pass this object as an argument to @code{face-remap-remove-relative}
if you need to remove the remapping later.
@example
;; Remap the 'escape-glyph' face into a combination
;; of the 'highlight' and 'italic' faces:
(face-remap-add-relative 'escape-glyph 'highlight 'italic)
;; Increase the size of the 'default' face by 50%:
(face-remap-add-relative 'default :height 1.5)
@end example
Note that buffer-local face remapping does not work reliably for
parent faces of basic faces (@pxref{Basic Faces}). (These are the
faces that are used in mode lines, header lines, and other basic
decorations of windows and frames.) For instance,
@code{mode-line-inactive} inherits from @code{mode-line}, but
remapping @code{mode-line} won't normally have the desired effect on
@code{mode-line-inactive}, especially if done locally for some
buffers. Instead you have to remap @code{mode-line-inactive}
directly.
@end defun
@defun face-remap-remove-relative cookie
This function removes a relative remapping previously added by
@code{face-remap-add-relative}. @var{cookie} should be the Lisp
object returned by @code{face-remap-add-relative} when the remapping
was added.
@end defun
@defun face-remap-set-base face &rest specs
This function sets the base remapping of @var{face} in the current
buffer to @var{specs}. If @var{specs} is empty, the default base
remapping is restored, similar to calling @code{face-remap-reset-base}
(see below); note that this is different from @var{specs} containing a
single value @code{nil}, which has the opposite result (the global
definition of @var{face} is ignored).
This overwrites the default @var{base-spec}, which inherits the global
face definition, so it is up to the caller to add such inheritance if
so desired.
@end defun
@defun face-remap-reset-base face
This function sets the base remapping of @var{face} to its default
value, which inherits from @var{face}'s global definition.
@end defun
@node Face Functions
@subsection Functions for Working with Faces
Here are additional functions for creating and working with faces.
@defun face-list
This function returns a list of all defined face names.
@end defun
@cindex face number
@cindex face property of face symbols
@defun face-id face
This function returns the @dfn{face number} of face @var{face}. This
is a number that uniquely identifies a face at low levels within
Emacs. It is seldom necessary to refer to a face by its face number.
However, functions that manipulate glyphs, such as
@code{make-glyph-code} and @code{glyph-face} (@pxref{Glyphs}) access
the face numbers internally. Note that the face number is stored as
the value of the @code{face} property of the face symbol, so we
recommend not to set that property of a face to any value of your own.
@end defun
@defun face-documentation face
This function returns the documentation string of face @var{face}, or
@code{nil} if none was specified for it.
@end defun
@defun face-equal face1 face2 &optional frame
This returns @code{t} if the faces @var{face1} and @var{face2} have the
same attributes for display.
@end defun
@defun face-differs-from-default-p face &optional frame
This returns non-@code{nil} if the face @var{face} displays
differently from the default face.
@end defun
@cindex face alias
@cindex alias, for faces
A @dfn{face alias} provides an equivalent name for a face. You can
define a face alias by giving the alias symbol the @code{face-alias}
property, with a value of the target face name. The following example
makes @code{modeline} an alias for the @code{mode-line} face.
@example
(put 'modeline 'face-alias 'mode-line)
@end example
@defmac define-obsolete-face-alias obsolete-face current-face when
This macro defines @code{obsolete-face} as an alias for
@var{current-face}, and also marks it as obsolete, indicating that it
may be removed in future. @var{when} should be a string indicating
when @code{obsolete-face} was made obsolete (usually a version number
string).
@end defmac
@node Auto Faces
@subsection Automatic Face Assignment
@cindex automatic face assignment
@cindex faces, automatic choice
This hook is used for automatically assigning faces to text in the
buffer. It is part of the implementation of Jit-Lock mode, used by
Font-Lock.
@defvar fontification-functions
This variable holds a list of functions that are called by Emacs
redisplay as needed, just before doing redisplay. They are called even
when Font Lock Mode isn't enabled. When Font Lock Mode is enabled, this
variable usually holds just one function, @code{jit-lock-function}.
The functions are called in the order listed, with one argument, a
buffer position @var{pos}. Collectively they should attempt to assign
faces to the text in the current buffer starting at @var{pos}.
The functions should record the faces they assign by setting the
@code{face} property. They should also add a non-@code{nil}
@code{fontified} property to all the text they have assigned faces to.
That property tells redisplay that faces have been assigned to that text
already.
It is probably a good idea for the functions to do nothing if the
character after @var{pos} already has a non-@code{nil} @code{fontified}
property, but this is not required. If one function overrides the
assignments made by a previous one, the properties after the last
function finishes are the ones that really matter.
For efficiency, we recommend writing these functions so that they
usually assign faces to around 400 to 600 characters at each call.
Note that, when the buffer text includes very long lines, these
functions are called as if they were in a @code{with-restriction} form
(@pxref{Narrowing}), with a
@code{long-line-optimizations-in-fontification-functions} label and
with the buffer narrowed to a portion around @var{pos}.
@end defvar
@node Basic Faces
@subsection Basic Faces
@cindex basic faces
If your Emacs Lisp program needs to assign some faces to text, it is
often a good idea to use certain existing faces or inherit from them,
rather than defining entirely new faces. This way, if other users
have customized those existing faces to give Emacs a certain look,
your program will fit in without additional customization.
Some of the @dfn{basic faces} defined in Emacs are listed below. In
addition to these, you might want to make use of the Font Lock faces
for syntactic highlighting, if highlighting is not already handled by
Font Lock mode, or if some Font Lock faces are not in use.
@xref{Faces for Font Lock}.
@table @code
@item default
The default face, whose attributes are all specified. All other faces
implicitly inherit from it: any unspecified attribute defaults to the
attribute on this face (@pxref{Face Attributes}).
@item mode-line-active
@itemx mode-line-inactive
@itemx header-line
@itemx tab-line
Basic faces used for the mode line, header line, and tab line.
@item tool-bar
@itemx tab-bar
@itemx fringe
@itemx scroll-bar
@itemx window-divider
@itemx border
@itemx child-frame-border
Basic faces used for the corresponding decorations of GUI frames.
@item cursor
The basic face used for the text cursor.
@item mouse
The basic face used for displaying mouse-sensitive text when the mouse
pointer is on that text.
@item bold
@itemx italic
@itemx bold-italic
@itemx underline
@itemx fixed-pitch
@itemx fixed-pitch-serif
@itemx variable-pitch
These have the attributes indicated by their names (e.g., @code{bold}
has a bold @code{:weight} attribute), with all other attributes
unspecified (and so given by @code{default}).
@item shadow
For dimmed-out text. For example, it is used for the ignored
part of a filename in the minibuffer (@pxref{Minibuffer File,,
Minibuffers for File Names, emacs, The GNU Emacs Manual}).
@item link
@itemx link-visited
For clickable text buttons that send the user to a different
buffer or location.
@item highlight
For stretches of text that should temporarily stand out. For example,
it is commonly assigned to the @code{mouse-face} property for cursor
highlighting (@pxref{Special Properties}).
@item match
@itemx isearch
@itemx lazy-highlight
For text matching (respectively) permanent search matches, interactive
search matches, and lazy highlighting other matches than the current
interactive one.
@item error
@itemx warning
@itemx success
For text concerning errors, warnings, or successes. For example,
these are used for messages in @file{*Compilation*} buffers.
@end table
@node Font Selection
@subsection Font Selection
@cindex font selection
@cindex selecting a font
Before Emacs can draw a character on a graphical display, it must
select a @dfn{font} for that character@footnote{In this context, the
term @dfn{font} has nothing to do with Font Lock (@pxref{Font Lock
Mode}).}. @xref{Fonts,,, emacs, The GNU Emacs Manual}. Normally,
Emacs automatically chooses a font based on the faces assigned to that
character---specifically, the face attributes @code{:family},
@code{:weight}, @code{:slant}, and @code{:width} (@pxref{Face
Attributes}). The choice of font also depends on the character to be
displayed; some fonts can only display a limited set of characters.
If no available font exactly fits the requirements, Emacs looks for
the @dfn{closest matching font}. The variables in this section
control how Emacs makes this selection.
@defopt face-font-family-alternatives
If a given family is specified but does not exist, this variable
specifies alternative font families to try. Each element should have
this form:
@example
(@var{family} @var{alternate-families}@dots{})
@end example
If @var{family} is specified but not available, Emacs will try the other
families given in @var{alternate-families}, one by one, until it finds a
family that does exist.
@end defopt
@defopt face-font-selection-order
If there is no font that exactly matches all desired face attributes
(@code{:width}, @code{:height}, @code{:weight}, and @code{:slant}),
this variable specifies the order in which these attributes should be
considered when selecting the closest matching font. The value should
be a list containing those four attribute symbols, in order of
decreasing importance. The default is @code{(:width :height :weight
:slant)}.
Font selection first finds the best available matches for the first
attribute in the list; then, among the fonts which are best in that
way, it searches for the best matches in the second attribute, and so
on.
The attributes @code{:weight} and @code{:width} have symbolic values in
a range centered around @code{normal}. Matches that are more extreme
(farther from @code{normal}) are somewhat preferred to matches that are
less extreme (closer to @code{normal}); this is designed to ensure that
non-normal faces contrast with normal ones, whenever possible.
One example of a case where this variable makes a difference is when the
default font has no italic equivalent. With the default ordering, the
@code{italic} face will use a non-italic font that is similar to the
default one. But if you put @code{:slant} before @code{:height}, the
@code{italic} face will use an italic font, even if its height is not
quite right.
@end defopt
@defopt face-font-registry-alternatives
This variable lets you specify alternative font registries to try, if a
given registry is specified and doesn't exist. Each element should have
this form:
@example
(@var{registry} @var{alternate-registries}@dots{})
@end example
If @var{registry} is specified but not available, Emacs will try the
other registries given in @var{alternate-registries}, one by one,
until it finds a registry that does exist.
@end defopt
@cindex scalable fonts
Emacs can make use of scalable fonts, but by default it does not use
them.
@defopt scalable-fonts-allowed
This variable controls which scalable fonts to use. A value of
@code{nil}, the default, means do not use scalable fonts. @code{t}
means to use any scalable font that seems appropriate for the text.
Otherwise, the value must be a list of regular expressions. Then a
scalable font is enabled for use if its name matches any regular
expression in the list. For example,
@example
(setq scalable-fonts-allowed '("iso10646-1$"))
@end example
@noindent
allows the use of scalable fonts with registry @code{iso10646-1}.
@end defopt
@defvar face-font-rescale-alist
This variable specifies scaling for certain faces. Its value should
be a list of elements of the form
@example
(@var{fontname-regexp} . @var{scale-factor})
@end example
If @var{fontname-regexp} matches the font name that is about to be
used, this says to choose a larger similar font according to the
factor @var{scale-factor}. You would use this feature to normalize
the font size if certain fonts are bigger or smaller than their
nominal heights and widths would suggest.
@end defvar
@node Font Lookup
@subsection Looking Up Fonts
@cindex font lookup
@cindex looking up fonts
@defun x-list-fonts name &optional reference-face frame maximum width
This function returns a list of available font names that match
@var{name}. @var{name} should be a string containing a font name in
either the Fontconfig, GTK+, or XLFD format (@pxref{Fonts,,, emacs, The
GNU Emacs Manual}). Within an XLFD string, wildcard characters may be
used: the @samp{*} character matches any substring, and the @samp{?}
character matches any single character. Case is ignored when matching
font names.
If the optional arguments @var{reference-face} and @var{frame} are
specified, the returned list includes only fonts that are the same
size as @var{reference-face} (a face name) currently is on the frame
@var{frame}.
The optional argument @var{maximum} sets a limit on how many fonts to
return. If it is non-@code{nil}, then the return value is truncated
after the first @var{maximum} matching fonts. Specifying a small
value for @var{maximum} can make this function much faster, in cases
where many fonts match the pattern.
The optional argument @var{width} specifies a desired font width. If
it is non-@code{nil}, the function only returns those fonts whose
characters are (on average) @var{width} times as wide as
@var{reference-face}.
@end defun
@defun x-family-fonts &optional family frame
This function returns a list describing the available fonts for family
@var{family} on @var{frame}. If @var{family} is omitted or @code{nil},
this list applies to all families, and therefore, it contains all
available fonts. Otherwise, @var{family} must be a string; it may
contain the wildcards @samp{?} and @samp{*}.
The list describes the display that @var{frame} is on; if @var{frame} is
omitted or @code{nil}, it applies to the selected frame's display
(@pxref{Input Focus}).
Each element in the list is a vector of the following form:
@example
[@var{family} @var{width} @var{point-size} @var{weight} @var{slant}
@var{fixed-p} @var{full} @var{registry-and-encoding}]
@end example
The first five elements correspond to face attributes; if you
specify these attributes for a face, it will use this font.
The last three elements give additional information about the font.
@var{fixed-p} is non-@code{nil} if the font is fixed-pitch.
@var{full} is the full name of the font, and
@var{registry-and-encoding} is a string giving the registry and
encoding of the font.
@end defun
@node Fontsets
@subsection Fontsets
@cindex fontset
A @dfn{fontset} is a list of fonts, each assigned to a range of
character codes. An individual font cannot display the whole range of
characters that Emacs supports, but a fontset can. Fontsets have names,
just as fonts do, and you can use a fontset name in place of a font name
when you specify the font for a frame or a face. Here is
information about defining a fontset under Lisp program control.
@defun create-fontset-from-fontset-spec fontset-spec &optional style-variant-p noerror
This function defines a new fontset according to the specification
string @var{fontset-spec}. The string should have this format:
@smallexample
@var{fontpattern}, @r{[}@var{charset}:@var{font}@r{]@dots{}}
@end smallexample
@noindent
Whitespace characters before and after the commas are ignored.
The first part of the string, @var{fontpattern}, should have the form of
a standard X font name, except that the last two fields should be
@samp{fontset-@var{alias}}.
The new fontset has two names, one long and one short. The long name is
@var{fontpattern} in its entirety. The short name is
@samp{fontset-@var{alias}}. You can refer to the fontset by either
name. If a fontset with the same name already exists, an error is
signaled, unless @var{noerror} is non-@code{nil}, in which case this
function does nothing.
If optional argument @var{style-variant-p} is non-@code{nil}, that says
to create bold, italic and bold-italic variants of the fontset as well.
These variant fontsets do not have a short name, only a long one, which
is made by altering @var{fontpattern} to indicate the bold and/or italic
status.
The specification string also says which fonts to use in the fontset.
See below for the details.
@end defun
The construct @samp{@var{charset}:@var{font}} specifies which font to
use (in this fontset) for one particular character set. Here,
@var{charset} is the name of a character set, and @var{font} is the font
to use for that character set. You can use this construct any number of
times in the specification string.
For the remaining character sets, those that you don't specify
explicitly, Emacs chooses a font based on @var{fontpattern}: it replaces
@samp{fontset-@var{alias}} with a value that names one character set.
For the @acronym{ASCII} character set, @samp{fontset-@var{alias}} is replaced
with @samp{ISO8859-1}.
In addition, when several consecutive fields are wildcards, Emacs
collapses them into a single wildcard. This is to prevent use of
auto-scaled fonts. Fonts made by scaling larger fonts are not usable
for editing, and scaling a smaller font is not useful because it is
better to use the smaller font in its own size, which Emacs does.
Thus if @var{fontpattern} is this,
@example
-*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24
@end example
@noindent
the font specification for @acronym{ASCII} characters would be this:
@example
-*-fixed-medium-r-normal-*-24-*-ISO8859-1
@end example
@noindent
and the font specification for Chinese GB2312 characters would be this:
@example
-*-fixed-medium-r-normal-*-24-*-gb2312*-*
@end example
You may not have any Chinese font matching the above font
specification. Most X distributions include only Chinese fonts that
have @samp{song ti} or @samp{fangsong ti} in the @var{family} field. In
such a case, @samp{Fontset-@var{n}} can be specified as below:
@smallexample
Emacs.Fontset-0: -*-fixed-medium-r-normal-*-24-*-*-*-*-*-fontset-24,\
chinese-gb2312:-*-*-medium-r-normal-*-24-*-gb2312*-*
@end smallexample
@noindent
Then, the font specifications for all but Chinese GB2312 characters have
@samp{fixed} in the @var{family} field, and the font specification for
Chinese GB2312 characters has a wild card @samp{*} in the @var{family}
field.
@defun set-fontset-font fontset characters font-spec &optional frame add
This function modifies the existing @var{fontset} to use the font
specified by @var{font-spec} for displaying the specified
@var{characters}.
If @var{fontset} is @code{nil}, this function modifies the fontset of
the selected frame or that of @var{frame} if @var{frame} is not
@code{nil}.
If @var{fontset} is @code{t}, this function modifies the default
fontset, whose short name as a string is @samp{fontset-default}.
The @var{characters} argument can be a single character which should
be displayed using @var{font-spec}. It can also be a cons cell
@w{@code{(@var{from} . @var{to})}}, where @var{from} and @var{to} are
characters. In that case, use @var{font-spec} for all the characters
in the range @var{from} and @var{to} (inclusive).
@var{characters} may be a charset symbol (@pxref{Character Sets}). In
that case, use @var{font-spec} for all the characters in the charset.
@var{characters} may be a script symbol (@pxref{Character Properties,
char-script-table}). In that case, use @var{font-spec} for all the
characters belonging to the script.
@var{characters} may be @code{nil}, which means to use @var{font-spec}
for any character in @var{fontset} for which no font-spec is
specified.
@var{font-spec} may be a font-spec object created by the function
@code{font-spec} (@pxref{Low-Level Font}).
@var{font-spec} may be a cons cell @w{@code{(@var{family}
. @var{registry})}}, where @var{family} is a family name of a font
(possibly including a foundry name at the head), and @var{registry} is
a registry name of a font (possibly including an encoding name at the
tail).
@var{font-spec} may be a font name, a string.
@var{font-spec} may be @code{nil}, which explicitly specifies that
there's no font for the specified @var{characters}. This is useful,
for example, to avoid expensive system-wide search for fonts for
characters that have no glyphs, like those from the Unicode Private
Use Area (PUA).
The optional argument @var{add}, if non-@code{nil}, specifies how to
add @var{font-spec} to the font specifications previously set for
@var{characters}. If it is @code{prepend}, @var{font-spec} is
prepended to the existing specs. If it is @code{append},
@var{font-spec} is appended. By default, @var{font-spec} overwrites
the previously set font specs.
For instance, this changes the default fontset to use a font whose
family name is @samp{Kochi Gothic} for all characters belonging to
the charset @code{japanese-jisx0208}:
@smallexample
(set-fontset-font t 'japanese-jisx0208
(font-spec :family "Kochi Gothic"))
@end smallexample
@end defun
@defun char-displayable-p char
This function returns non-@code{nil} if Emacs ought to be able to
display @var{char}. Or more precisely, if the selected frame's fontset
has a font to display the character set that @var{char} belongs to.
Fontsets can specify a font on a per-character basis; when the fontset
does that, this function's value may not be accurate.
This function may return non-@code{nil} even when there is no font
available, since it also checks whether the coding system for the text
terminal can encode the character (@pxref{Terminal I/O Encoding}).
@end defun
@node Low-Level Font
@subsection Low-Level Font Representation
@cindex font property
Normally, it is not necessary to manipulate fonts directly. In case
you need to do so, this section explains how.
In Emacs Lisp, fonts are represented using three different Lisp
object types: @dfn{font objects}, @dfn{font specs}, and @dfn{font
entities}.
@defun fontp object &optional type
Return @code{t} if @var{object} is a font object, font spec, or font
entity. Otherwise, return @code{nil}.
The optional argument @var{type}, if non-@code{nil}, determines the
exact type of Lisp object to check for. In that case, @var{type}
should be one of @code{font-object}, @code{font-spec}, or
@code{font-entity}.
@end defun
@cindex font object
A font object is a Lisp object that represents a font that Emacs has
@dfn{opened}. Font objects cannot be modified in Lisp, but they can
be inspected.
@defun font-at position &optional window string
Return the font object that is being used to display the character at
position @var{position} in the window @var{window}. If @var{window}
is @code{nil}, it defaults to the selected window. If @var{string} is
@code{nil}, @var{position} specifies a position in the current buffer;
otherwise, @var{string} should be a string, and @var{position}
specifies a position in that string.
@end defun
@cindex font spec
A font spec is a Lisp object that contains a set of specifications
that can be used to find a font. More than one font may match the
specifications in a font spec.
@defun font-spec &rest arguments
Return a new font spec using the specifications in @var{arguments},
which should come in @code{property}-@code{value} pairs. The possible
specifications are as follows:
@table @code
@item :name
The font name (a string), in either XLFD, Fontconfig, or GTK+ format.
@xref{Fonts,,, emacs, The GNU Emacs Manual}.
@item :family
@itemx :foundry
@itemx :weight
@itemx :slant
@itemx :width
These have the same meanings as the face attributes of the same name.
@xref{Face Attributes}. @code{:family} and @code{:foundry} are
strings, while the other three are symbols. As example values,
@code{:slant} may be @code{italic}, @code{:weight} may be @code{bold}
and @code{:width} may be @code{normal}.
@item :size
The font size---either a non-negative integer that specifies the pixel
size, or a floating-point number that specifies the point size.
@item :adstyle
Additional typographic style information for the font, such as
@samp{sans}. The value should be a string or a symbol.
@cindex font registry
@item :registry
The charset registry and encoding of the font, such as
@samp{iso8859-1}. The value should be a string or a symbol.
@item :dpi
The resolution in dots per inch for which the font is designed. The
value must be a non-negative number.
@item :spacing
The spacing of the font: proportional, dual, mono, or charcell. The
value should be either an integer (0 for proportional, 90 for dual,
100 for mono, 110 for charcell) or a one-letter symbol (one of
@code{P}, @code{D}, @code{M}, or @code{C}).
@item :avgwidth
The average width of the font in 1/10 pixel units. The value should
be a non-negative number.
@item :script
The script that the font must support (a symbol).
@item :lang
The language that the font should support. The value should be a
symbol whose name is a two-letter ISO-639 language name. On X, the
value is matched against the ``Additional Style'' field of the XLFD
name of a font, if it is non-empty. On MS-Windows, fonts matching the
spec are required to support codepages needed for the language.
Currently, only a small set of CJK languages is supported with this
property: @samp{ja}, @samp{ko}, and @samp{zh}.
@item :otf
@cindex OpenType font
The font must be an OpenType font that supports these OpenType
features, provided Emacs is compiled with a library, such as
@samp{libotf} on GNU/Linux, that supports complex text layout for
scripts which need that. The value must be a list of the form
@smallexample
@code{(@var{script-tag} @var{langsys-tag} @var{gsub} @var{gpos})}
@end smallexample
where @var{script-tag} is the OpenType script tag symbol;
@var{langsys-tag} is the OpenType language system tag symbol, or
@code{nil} to use the default language system; @code{gsub} is a list
of OpenType GSUB feature tag symbols, or @code{nil} if none is
required; and @code{gpos} is a list of OpenType GPOS feature tag
symbols, or @code{nil} if none is required. If @code{gsub} or
@code{gpos} is a list, a @code{nil} element in that list means that
the font must not match any of the remaining tag symbols. The
@code{gpos} element may be omitted. For the list of OpenType script,
language, and feature tags, see
@uref{https://docs.microsoft.com/en-us/typography/opentype/spec/ttoreg,
the list of registered OTF tags}.
@item :type
@cindex font backend
The symbol that specifies the @dfn{font backend} used to draw the
characters. The possible values depend on the platform and on how
Emacs was configured at build time. Typical values include
@code{ftcrhb} and @code{xfthb} on X, @code{harfbuzz} on MS-Windows,
@code{ns} on GNUstep, etc. It can also be @code{nil} if left
unspecified, typically in a font-spec.
@end table
@end defun
@defun font-put font-spec property value
Set the font property @var{property} in the font-spec @var{font-spec}
to @var{value}. The @var{property} can any of the ones described
above.
@end defun
@cindex font entity
A font entity is a reference to a font that need not be open. Its
properties are intermediate between a font object and a font spec:
like a font object, and unlike a font spec, it refers to a single,
specific font. Unlike a font object, creating a font entity does not
load the contents of that font into computer memory. Emacs may open
multiple font objects of different sizes from a single font entity
referring to a scalable font.
@defun find-font font-spec &optional frame
This function returns a font entity that best matches the font spec
@var{font-spec} on frame @var{frame}. If @var{frame} is @code{nil},
it defaults to the selected frame.
@end defun
@defun list-fonts font-spec &optional frame num prefer
This function returns a list of all font entities that match the font
spec @var{font-spec}.
The optional argument @var{frame}, if non-@code{nil}, specifies the
frame on which the fonts are to be displayed. The optional argument
@var{num}, if non-@code{nil}, should be an integer that specifies the
maximum length of the returned list. The optional argument
@var{prefer}, if non-@code{nil}, should be another font spec, which is
used to control the order of the returned list; the returned font
entities are sorted in order of decreasing closeness to that font
spec.
@end defun
If you call @code{set-face-attribute} and pass a font spec, font
entity, or font name string as the value of the @code{:font}
attribute, Emacs opens the best matching font that is available
for display. It then stores the corresponding font object as the
actual value of the @code{:font} attribute for that face.
The following functions can be used to obtain information about a
font. For these functions, the @var{font} argument can be a font
object, a font entity, or a font spec.
@defun font-get font property
This function returns the value of the font property @var{property}
for @var{font}. The @var{property} can any of the ones that
@code{font-spec} supports.
If @var{font} is a font spec and the font spec does not specify
@var{property}, the return value is @code{nil}. If @var{font} is a
font object or font entity, the value for the @var{:script} property
may be a list of scripts supported by the font, and the value of the
@code{:otf} property is a cons of the form @w{@code{(@var{gsub}
. @var{gpos})}}, where @var{gsub} and @var{gpos} are lists
representing OpenType features supported by the font, of the form
@smallexample
((@var{script-tag} (@var{langsys-tag} @var{feature}@dots{}) @dots{}) @dots{})
@end smallexample
@noindent where @var{script-tag}, @var{langsys-tag}, and @var{feature}
are symbols representing OpenType layout tags.
If @var{font} is a font object, the special property
@code{:combining-capability} is non-@code{nil} if the font backend of
@var{font} supports rendering of combining characters for non-OpenType
fonts.
@end defun
@defun font-face-attributes font &optional frame
This function returns a list of face attributes corresponding to
@var{font}. The optional argument @var{frame} specifies the frame on
which the font is to be displayed. If it is @code{nil}, the selected
frame is used. The return value has the form
@smallexample
(:family @var{family} :height @var{height} :weight @var{weight}
:slant @var{slant} :width @var{width})
@end smallexample
where the values of @var{family}, @var{height}, @var{weight},
@var{slant}, and @var{width} are face attribute values. Some of these
key-attribute pairs may be omitted from the list if they are not
specified by @var{font}.
@end defun
@defun font-xlfd-name font &optional fold-wildcards long-xlfds
This function returns the XLFD (X Logical Font Descriptor), a string,
matching @var{font}. @xref{Fonts,,, emacs, The GNU Emacs Manual}, for
information about XLFDs.
If the optional argument @var{fold-wildcards} is non-@code{nil},
consecutive wildcards in the XLFD are folded into one.
If the optional argument @var{long-xlfds} is omitted or @code{nil},
then the function returns @code{nil} if the XLFD would exceed 255
characters in length; this is for compatibility with the X protocol,
which mandates that XLFDs are restricted to that length. If
@var{long-xlfds} is non-@code{nil}, this restriction is lifted, and
the function can return XLFDs of any length.
@end defun
The following two functions return important information about a font.
@defun font-info name &optional frame
This function returns information about a font specified by its
@var{name}, a string, as it is used on @var{frame}. If @var{frame} is
omitted or @code{nil}, it defaults to the selected frame.
The value returned by the function is a vector of the form
@code{[@var{opened-name} @var{full-name} @var{size} @var{height}
@var{baseline-offset} @var{relative-compose} @var{default-ascent}
@var{max-width} @var{ascent} @var{descent} @var{space-width}
@var{average-width} @var{filename} @var{capability}]}. Here's the
description of each components of this vector:
@table @var
@item opened-name
The name used to open the font, a string.
@item full-name
The full name of the font, a string.
@item size
The pixel size of the font.
@item height
The height of the font in pixels.
@item baseline-offset
The offset in pixels from the @acronym{ASCII} baseline, positive
upward.
@item relative-compose
@itemx default-ascent
Numbers controlling how to compose characters.
@item max-width
The maximum advance width of the font.
@item ascent
@itemx descent
The ascent and descent of this font. The sum of these two numbers
should be equal to the value of @var{height} above.
@item space-width
The width, in pixels, of the font's space character.
@item average-width
The average width of the font characters. If this is zero, Emacs uses
the value of @var{space-width} instead, when it calculates text layout
on display.
@item filename
The file name of the font as a string. This can be @code{nil} if the
font back-end does not provide a way to find out the font's file name.
@item capability
A list whose first element is a symbol representing the font type, one
of @code{x}, @code{opentype}, @code{truetype}, @code{type1},
@code{pcf}, or @code{bdf}. For OpenType fonts, the list includes 2
additional elements describing the @sc{gsub} and @sc{gpos} features
supported by the font. Each of these elements is a list of the form
@code{((@var{script} (@var{langsys} @var{feature} @dots{}) @dots{})
@dots{})}, where @var{script} is a symbol representing an OpenType
script tag, @var{langsys} is a symbol representing an OpenType langsys
tag (or @code{nil}, which stands for the default langsys), and each
@var{feature} is a symbol representing an OpenType feature tag.
@end table
@end defun
@defun query-font font-object
This function returns information about a @var{font-object}. (This is
in contrast to @code{font-info}, which takes the font name, a string,
as its argument.)
The value returned by the function is a vector of the form
@code{[@var{name} @var{filename} @var{pixel-size} @var{max-width}
@var{ascent} @var{descent} @var{space-width} @var{average-width}
@var{capability}]}. Here's the description of each components of this
vector:
@table @var
@item name
The font name, a string.
@item filename
The file name of the font as a string. This can be @code{nil} if the
font back-end does not provide a way to find out the font's file name.
@item pixel-size
The pixel size of the font used to open the font.
@item max-width
The maximum advance width of the font.
@item ascent
@itemx descent
The ascent and descent of this font. The sum of these two numbers
gives the font height.
@item space-width
The width, in pixels, of the font's space character.
@item average-width
The average width of the font characters. If this is zero, Emacs uses
the value of @var{space-width} instead, when it calculates text layout
on display.
@item capability
A list whose first element is a symbol representing the font type, one
of @code{x}, @code{opentype}, @code{truetype}, @code{type1},
@code{pcf}, or @code{bdf}. For OpenType fonts, the list includes 2
additional elements describing the @sc{gsub} and @sc{gpos} features
supported by the font. Each of these elements is a list of the form
@code{((@var{script} (@var{langsys} @var{feature} @dots{}) @dots{})
@dots{})}, where @var{script} is a symbol representing an OpenType
script tag, @var{langsys} is a symbol representing an OpenType langsys
tag (or @code{nil}, which stands for the default langsys), and each
@var{feature} is a symbol representing an OpenType feature tag.
@end table
@end defun
@cindex font information for layout
The following four functions return size information about fonts used
by various faces, allowing various layout considerations in Lisp
programs. These functions take face remapping into consideration,
returning information about the remapped face, if the face in question
was remapped. @xref{Face Remapping}.
@defun default-font-width
This function returns the average width in pixels of the font used by
the current buffer's default face, as that face is defined for the
selected frame.
@end defun
@defun default-font-height
This function returns the height in pixels of the font used by the
current buffer's default face, as that face is defined for the
selected frame.
@end defun
@defun window-font-width &optional window face
This function returns the average width in pixels for the font used by
@var{face} in @var{window}. The specified @var{window} must be a live
window. If @code{nil} or omitted, @var{window} defaults to the
selected window, and @var{face} defaults to the default face in
@var{window}.
@end defun
@defun window-font-height &optional window face
This function returns the height in pixels for the font used by
@var{face} in @var{window}. The specified @var{window} must be a live
window. If @code{nil} or omitted, @var{window} defaults to the
selected window, and @var{face} defaults to the default face in
@var{window}.
@end defun
@node Fringes
@section Fringes
@cindex fringes
On graphical displays, Emacs draws @dfn{fringes} next to each
window: thin vertical strips down the sides which can display bitmaps
indicating truncation, continuation, horizontal scrolling, and so on.
@menu
* Fringe Size/Pos:: Specifying where to put the window fringes.
* Fringe Indicators:: Displaying indicator icons in the window fringes.
* Fringe Cursors:: Displaying cursors in the right fringe.
* Fringe Bitmaps:: Specifying bitmaps for fringe indicators.
* Customizing Bitmaps:: Specifying your own bitmaps to use in the fringes.
* Overlay Arrow:: Display of an arrow to indicate position.
@end menu
@node Fringe Size/Pos
@subsection Fringe Size and Position
The following buffer-local variables control the position and width
of fringes in windows showing that buffer.
@defvar fringes-outside-margins
The fringes normally appear between the display margins and the window
text. If the value is non-@code{nil}, they appear outside the display
margins. @xref{Display Margins}.
@end defvar
@defvar left-fringe-width
This variable, if non-@code{nil}, specifies the width of the left
fringe in pixels. A value of @code{nil} means to use the left fringe
width from the window's frame.
@end defvar
@defvar right-fringe-width
This variable, if non-@code{nil}, specifies the width of the right
fringe in pixels. A value of @code{nil} means to use the right fringe
width from the window's frame.
@end defvar
Any buffer which does not specify values for these variables uses
the values specified by the @code{left-fringe} and @code{right-fringe}
frame parameters (@pxref{Layout Parameters}).
The above variables actually take effect via the function
@code{set-window-buffer} (@pxref{Buffers and Windows}), which calls
@code{set-window-fringes} as a subroutine. If you change one of these
variables, the fringe display is not updated in existing windows
showing the buffer, unless you call @code{set-window-buffer} again in
each affected window. You can also use @code{set-window-fringes} to
control the fringe display in individual windows.
@defun set-window-fringes window left &optional right outside-margins persistent
This function sets the fringe widths of window @var{window}.
If @var{window} is @code{nil}, the selected window is used.
The argument @var{left} specifies the width in pixels of the left
fringe, and likewise @var{right} for the right fringe. A value of
@code{nil} for either one stands for the default width. If
@var{outside-margins} is non-@code{nil}, that specifies that fringes
should appear outside of the display margins.
If @var{window} is not large enough to accommodate fringes of the
desired width, this leaves the fringes of @var{window} unchanged.
The values specified here may be later overridden by invoking
@code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
with its @var{keep-margins} argument @code{nil} or omitted. However,
if the optional fifth argument @var{persistent} is non-@code{nil} and
the other arguments are processed successfully, the values specified
here unconditionally survive subsequent invocations of
@code{set-window-buffer}. This can be used to permanently turn off
fringes in the minibuffer window, consult the description of
@code{set-window-scroll-bars} for an example (@pxref{Scroll Bars}).
@end defun
@defun window-fringes &optional window
This function returns information about the fringes of a window
@var{window}. If @var{window} is omitted or @code{nil}, the selected
window is used. The value has the form @code{(@var{left-width}
@var{right-width} @var{outside-margins} @var{persistent})}.
@end defun
@node Fringe Indicators
@subsection Fringe Indicators
@cindex fringe indicators
@cindex indicators, fringe
@dfn{Fringe indicators} are tiny icons displayed in the window
fringe to indicate truncated or continued lines, buffer boundaries,
etc.
@defopt indicate-empty-lines
@cindex fringes, and empty line indication
@cindex empty lines, indicating
When this is non-@code{nil}, Emacs displays a special glyph in the
fringe of each empty line at the end of the buffer, on graphical
displays. @xref{Fringes}. This variable is automatically
buffer-local in every buffer.
@end defopt
@defopt indicate-buffer-boundaries
@cindex buffer boundaries, indicating
This buffer-local variable controls how the buffer boundaries and
window scrolling are indicated in the window fringes.
Emacs can indicate the buffer boundaries---that is, the first and last
line in the buffer---with angle icons when they appear on the screen.
In addition, Emacs can display an up-arrow in the fringe to show
that there is text above the screen, and a down-arrow to show
there is text below the screen.
There are three kinds of basic values:
@table @asis
@item @code{nil}
Don't display any of these fringe icons.
@item @code{left}
Display the angle icons and arrows in the left fringe.
@item @code{right}
Display the angle icons and arrows in the right fringe.
@item any non-alist
Display the angle icons in the left fringe
and don't display the arrows.
@end table
Otherwise the value should be an alist that specifies which fringe
indicators to display and where. Each element of the alist should
have the form @code{(@var{indicator} . @var{position})}. Here,
@var{indicator} is one of @code{top}, @code{bottom}, @code{up},
@code{down}, and @code{t} (which covers all the icons not yet
specified), while @var{position} is one of @code{left}, @code{right}
and @code{nil}.
For example, @code{((top . left) (t . right))} places the top angle
bitmap in left fringe, and the bottom angle bitmap as well as both
arrow bitmaps in right fringe. To show the angle bitmaps in the left
fringe, and no arrow bitmaps, use @code{((top . left) (bottom . left))}.
@end defopt
@defvar fringe-indicator-alist
This buffer-local variable specifies the mapping from logical fringe
indicators to the actual bitmaps displayed in the window fringes. The
value is an alist of elements @code{(@var{indicator}
. @var{bitmaps})}, where @var{indicator} specifies a logical indicator
type and @var{bitmaps} specifies the fringe bitmaps to use for that
indicator.
Each @var{indicator} should be one of the following symbols:
@table @asis
@item @code{truncation}, @code{continuation}.
Used for truncation and continuation lines.
@item @code{up}, @code{down}, @code{top}, @code{bottom}, @code{top-bottom}
Used when @code{indicate-buffer-boundaries} is non-@code{nil}:
@code{up} and @code{down} indicate a buffer boundary lying above or
below the window edge; @code{top} and @code{bottom} indicate the
topmost and bottommost buffer text line; and @code{top-bottom}
indicates where there is just one line of text in the buffer.
@item @code{empty-line}
Used to indicate empty lines after the buffer end when
@code{indicate-empty-lines} is non-@code{nil}.
@item @code{overlay-arrow}
Used for overlay arrows (@pxref{Overlay Arrow}).
@c Is this used anywhere?
@c @item Unknown bitmap indicator:
@c @code{unknown}.
@end table
Each @var{bitmaps} value may be a list of symbols @code{(@var{left}
@var{right} [@var{left1} @var{right1}])}. The @var{left} and
@var{right} symbols specify the bitmaps shown in the left and/or right
fringe, for the specific indicator. @var{left1} and @var{right1} are
specific to the @code{bottom} and @code{top-bottom} indicators, and
are used to indicate that the last text line has no final newline.
Alternatively, @var{bitmaps} may be a single symbol which is used in
both left and right fringes.
@xref{Fringe Bitmaps}, for a list of standard bitmap symbols and how
to define your own. In addition, @code{nil} represents the empty
bitmap (i.e., an indicator that is not shown).
When @code{fringe-indicator-alist} has a buffer-local value, and
there is no bitmap defined for a logical indicator, or the bitmap is
@code{t}, the corresponding value from the default value of
@code{fringe-indicator-alist} is used.
@end defvar
@node Fringe Cursors
@subsection Fringe Cursors
@cindex fringe cursors
@cindex cursor, fringe
When a line is exactly as wide as the window, Emacs displays the
cursor in the right fringe instead of using two lines. Different
bitmaps are used to represent the cursor in the fringe depending on
the current buffer's cursor type.
@defopt overflow-newline-into-fringe
If this is non-@code{nil}, lines exactly as wide as the window (not
counting the final newline character) are not continued. Instead,
when point is at the end of the line, the cursor appears in the right
fringe.
@end defopt
@defvar fringe-cursor-alist
This variable specifies the mapping from logical cursor type to the
actual fringe bitmaps displayed in the right fringe. The value is an
alist where each element has the form @code{(@var{cursor-type}
. @var{bitmap})}, which means to use the fringe bitmap @var{bitmap} to
display cursors of type @var{cursor-type}.
Each @var{cursor-type} should be one of @code{box}, @code{hollow},
@code{bar}, @code{hbar}, or @code{hollow-small}. The first four have
the same meanings as in the @code{cursor-type} frame parameter
(@pxref{Cursor Parameters}). The @code{hollow-small} type is used
instead of @code{hollow} when the normal @code{hollow-rectangle}
bitmap is too tall to fit on a specific display line.
Each @var{bitmap} should be a symbol specifying the fringe bitmap to
be displayed for that logical cursor type.
@iftex
See the next subsection for details.
@end iftex
@ifnottex
@xref{Fringe Bitmaps}.
@end ifnottex
@c FIXME: I can't find the fringes-indicator-alist variable. Maybe
@c it should be fringe-indicator-alist or fringe-cursor-alist? --xfq
When @code{fringe-cursor-alist} has a buffer-local value, and there is
no bitmap defined for a cursor type, the corresponding value from the
default value of @code{fringes-indicator-alist} is used.
@end defvar
@node Fringe Bitmaps
@subsection Fringe Bitmaps
@cindex fringe bitmaps
@cindex bitmaps, fringe
The @dfn{fringe bitmaps} are the actual bitmaps which represent the
logical fringe indicators for truncated or continued lines, buffer
boundaries, overlay arrows, etc. Each bitmap is represented by a
symbol.
@iftex
These symbols are referred to by the variables
@code{fringe-indicator-alist} and @code{fringe-cursor-alist},
described in the previous subsections.
@end iftex
@ifnottex
These symbols are referred to by the variable
@code{fringe-indicator-alist}, which maps fringe indicators to bitmaps
(@pxref{Fringe Indicators}), and the variable
@code{fringe-cursor-alist}, which maps fringe cursors to bitmaps
(@pxref{Fringe Cursors}).
@end ifnottex
Lisp programs can also directly display a bitmap in the left or
right fringe, by using a @code{display} property for one of the
characters appearing in the line (@pxref{Other Display Specs}). Such
a display specification has the form
@example
(@var{fringe} @var{bitmap} [@var{face}])
@end example
@noindent
@var{fringe} is either the symbol @code{left-fringe} or
@code{right-fringe}. @var{bitmap} is a symbol identifying the bitmap
to display. The optional @var{face} names a face whose foreground and
background colors are to be used to display the bitmap, using the
attributes of the @code{fringe} face for colors that @var{face} didn't
specify. If @var{face} is omitted, that means to use the attributes
of the @code{default} face for the colors which the @code{fringe} face
didn't specify. For predictable results that don't depend on the
attributes of the @code{default} and @code{fringe} faces, we recommend
you never omit @var{face}, but always provide a specific face. In
particular, if you want the bitmap to be always displayed in the
@code{fringe} face, use @code{fringe} as @var{face}.
For instance, to display an arrow in the left fringe, using the
@code{warning} face, you could say something like:
@lisp
(overlay-put
(make-overlay (point) (point))
'before-string (propertize
"x" 'display
`(left-fringe right-arrow warning)))
@end lisp
Here is a list of the standard fringe bitmaps defined in Emacs, and
how they are currently used in Emacs (via
@code{fringe-indicator-alist} and @code{fringe-cursor-alist}):
@table @asis
@item @code{left-arrow}, @code{right-arrow}
Used to indicate truncated lines.
@item @code{left-curly-arrow}, @code{right-curly-arrow}
Used to indicate continued lines.
@item @code{right-triangle}, @code{left-triangle}
The former is used by overlay arrows. The latter is unused.
@item @code{up-arrow}, @code{down-arrow}
@itemx @code{bottom-left-angle}, @code{bottom-right-angle}
@itemx @code{top-left-angle}, @code{top-right-angle}
@itemx @code{left-bracket}, @code{right-bracket}
@itemx @code{empty-line}
Used to indicate buffer boundaries.
@item @code{filled-rectangle}, @code{hollow-rectangle}
@itemx @code{filled-square}, @code{hollow-square}
@itemx @code{vertical-bar}, @code{horizontal-bar}
Used for different types of fringe cursors.
@item @code{exclamation-mark}, @code{question-mark}
@itemx @code{large-circle}
Not used by core Emacs features.
@end table
@noindent
The next subsection describes how to define your own fringe bitmaps.
@defun fringe-bitmaps-at-pos &optional pos window
This function returns the fringe bitmaps of the display line
containing position @var{pos} in window @var{window}. The return
value has the form @code{(@var{left} @var{right} @var{ov})}, where @var{left}
is the symbol for the fringe bitmap in the left fringe (or @code{nil}
if no bitmap), @var{right} is similar for the right fringe, and @var{ov}
is non-@code{nil} if there is an overlay arrow in the left fringe.
The value is @code{nil} if @var{pos} is not visible in @var{window}.
If @var{window} is @code{nil}, that stands for the selected window.
If @var{pos} is @code{nil}, that stands for the value of point in
@var{window}.
@end defun
@node Customizing Bitmaps
@subsection Customizing Fringe Bitmaps
@cindex fringe bitmaps, customizing
@defun define-fringe-bitmap bitmap bits &optional height width align
This function defines the symbol @var{bitmap} as a new fringe bitmap,
or replaces an existing bitmap with that name.
The argument @var{bits} specifies the image to use. It should be
either a string or a vector of integers, where each element (an
integer) corresponds to one row of the bitmap. Each bit of an integer
corresponds to one pixel of the bitmap, where the low bit corresponds
to the rightmost pixel of the bitmap. (Note that this order of bits
is opposite of the order in XBM images; @pxref{XBM Images}.)
The height is normally the length of @var{bits}. However, you
can specify a different height with non-@code{nil} @var{height}. The width
is normally 8, but you can specify a different width with non-@code{nil}
@var{width}. The width must be an integer between 1 and 16.
The argument @var{align} specifies the positioning of the bitmap
relative to the range of rows where it is used; the default is to
center the bitmap. The allowed values are @code{top}, @code{center},
or @code{bottom}.
The @var{align} argument may also be a list @code{(@var{align}
@var{periodic})} where @var{align} is interpreted as described above.
If @var{periodic} is non-@code{nil}, it specifies that the rows in
@code{bits} should be repeated enough times to reach the specified
height.
@end defun
@defun destroy-fringe-bitmap bitmap
This function destroys the fringe bitmap identified by @var{bitmap}.
If @var{bitmap} identifies a standard fringe bitmap, it actually
restores the standard definition of that bitmap, instead of
eliminating it entirely.
@end defun
@defun set-fringe-bitmap-face bitmap &optional face
This sets the face for the fringe bitmap @var{bitmap} to @var{face}.
If @var{face} is @code{nil}, it selects the @code{fringe} face. The
bitmap's face controls the color to draw it in.
@var{face} is merged with the @code{fringe} face, so normally
@var{face} should specify only the foreground color.
@end defun
@node Overlay Arrow
@subsection The Overlay Arrow
@c @cindex overlay arrow Duplicates variable names
The @dfn{overlay arrow} is useful for directing the user's attention
to a particular line in a buffer. For example, in the modes used for
interface to debuggers, the overlay arrow indicates the line of code
about to be executed. This feature has nothing to do with
@dfn{overlays} (@pxref{Overlays}).
@defvar overlay-arrow-string
This variable holds the string to display to call attention to a
particular line, or @code{nil} if the arrow feature is not in use.
On a graphical display the contents of the string are ignored if the
left fringe is shown; instead a glyph is displayed in the fringe area
to the left of the display area.
@end defvar
@defvar overlay-arrow-position
This variable holds a marker that indicates where to display the overlay
arrow. It should point at the beginning of a line. On a non-graphical
display, or when the left fringe is not shown, the arrow text
appears at the beginning of that line, overlaying any text that would
otherwise appear. Since the arrow is usually short, and the line
usually begins with indentation, normally nothing significant is
overwritten.
The overlay-arrow string is displayed in any given buffer if the value
of @code{overlay-arrow-position} in that buffer points into that
buffer. Thus, it is possible to display multiple overlay arrow strings
by creating buffer-local bindings of @code{overlay-arrow-position}.
However, it is usually cleaner to use
@code{overlay-arrow-variable-list} to achieve this result.
@c !!! overlay-arrow-position: but the overlay string may remain in the display
@c of some other buffer until an update is required. This should be fixed
@c now. Is it?
@end defvar
You can do a similar job by creating an overlay with a
@code{before-string} property. @xref{Overlay Properties}.
You can define multiple overlay arrows via the variable
@code{overlay-arrow-variable-list}.
@defvar overlay-arrow-variable-list
This variable's value is a list of variables, each of which specifies
the position of an overlay arrow. The variable
@code{overlay-arrow-position} has its normal meaning because it is on
this list.
@end defvar
Each variable on this list can have properties
@code{overlay-arrow-string} and @code{overlay-arrow-bitmap} that
specify an overlay arrow string (for text terminals or graphical
terminals without the left fringe shown) or fringe bitmap
(for graphical terminals with a left fringe) to display at the
corresponding overlay arrow position. If either property is not set,
the default @code{overlay-arrow-string} or @code{overlay-arrow} fringe
indicator is used.
@node Scroll Bars
@section Scroll Bars
@cindex scroll bars
Normally the frame parameter @code{vertical-scroll-bars} controls
whether the windows in the frame have vertical scroll bars, and whether
they are on the left or right. The frame parameter
@code{scroll-bar-width} specifies how wide they are (@code{nil} meaning
the default).
The frame parameter @code{horizontal-scroll-bars} controls whether
the windows in the frame have horizontal scroll bars. The frame
parameter @code{scroll-bar-height} specifies how high they are
(@code{nil} meaning the default). @xref{Layout Parameters}.
@vindex horizontal-scroll-bars-available-p
Horizontal scroll bars are not available on all platforms. The
function @code{horizontal-scroll-bars-available-p} which takes no
argument returns non-@code{nil} if they are available on your system.
The following three functions take as argument a live frame which
defaults to the selected one.
@defun frame-current-scroll-bars &optional frame
This function reports the scroll bar types for frame @var{frame}. The
value is a cons cell @code{(@var{vertical-type} .@:
@var{horizontal-type})}, where @var{vertical-type} is either
@code{left}, @code{right}, or @code{nil} (which means no vertical scroll
bar.) @var{horizontal-type} is either @code{bottom} or @code{nil}
(which means no horizontal scroll bar).
@end defun
@defun frame-scroll-bar-width &optional frame
This function returns the width of vertical scroll bars of @var{frame}
in pixels.
@end defun
@defun frame-scroll-bar-height &optional frame
This function returns the height of horizontal scroll bars of
@var{frame} in pixels.
@end defun
You can override the frame specific settings for individual windows by
using the following function:
@defun set-window-scroll-bars window &optional width vertical-type height horizontal-type persistent
This function sets the width and/or height and the types of scroll bars
for window @var{window}. If @var{window} is @code{nil}, the selected
window is used.
@var{width} specifies the width of the vertical scroll bar in pixels
(@code{nil} means use the width specified for the frame).
@var{vertical-type} specifies whether to have a vertical scroll bar and,
if so, where. The possible values are @code{left}, @code{right},
@code{t}, which means to use the frame's default, and @code{nil} for no
vertical scroll bar.
@var{height} specifies the height of the horizontal scroll bar in
pixels (@code{nil} means use the height specified for the frame).
@var{horizontal-type} specifies whether to have a horizontal scroll
bar. The possible values are @code{bottom}, @code{t}, which means to
use the frame's default, and @code{nil} for no horizontal scroll bar.
Note that for a mini window the value @code{t} has the same meaning as
@code{nil}, namely to not show a horizontal scroll bar. You have to
explicitly specify @code{bottom} in order to show a horizontal scroll
bar in a mini window.
If @var{window} is not large enough to accommodate a scroll bar of the
desired dimension, this leaves the corresponding scroll bar unchanged.
The values specified here may be later overridden by invoking
@code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
with its @var{keep-margins} argument @code{nil} or omitted. However,
if the optional fifth argument @var{persistent} is non-@code{nil} and
the other arguments are processed successfully, the values specified
here unconditionally survive subsequent invocations of
@code{set-window-buffer}.
@end defun
Using the @var{persistent} argument of @code{set-window-scroll-bars}
and @code{set-window-fringes} (@pxref{Fringe Size/Pos}) you can
reliably and permanently turn off scroll bars and/or fringes in any
minibuffer window by adding the following snippet to your early init
file (@pxref{Init File}).
@smallexample
@group
(add-hook 'after-make-frame-functions
(lambda (frame)
(set-window-scroll-bars
(minibuffer-window frame) 0 nil 0 nil t)
(set-window-fringes
(minibuffer-window frame) 0 0 nil t)))
@end group
@end smallexample
The following four functions take as argument a live window which
defaults to the selected one.
@defun window-scroll-bars &optional window
This function returns a list of the form @code{(@var{width}
@var{columns} @var{vertical-type} @var{height} @var{lines}
@var{horizontal-type} @var{persistent})}.
The value @var{width} is the value that was specified for the width of
the vertical scroll bar (which may be @code{nil}); @var{columns} is the
(possibly rounded) number of columns that the vertical scroll bar
actually occupies.
The value @var{height} is the value that was specified for the height of
the horizontal scroll bar (which may be @code{nil}); @var{lines} is the
(possibly rounded) number of lines that the horizontally scroll bar
actually occupies.
The value of @var{persistent} is the value specified for @var{window}
with the last successful invocation of @code{set-window-scroll-bars},
@code{nil} if there never was one.
@end defun
@defun window-current-scroll-bars &optional window
This function reports the scroll bar type for window @var{window}. The
value is a cons cell @code{(@var{vertical-type} .@:
@var{horizontal-type})}. Unlike @code{window-scroll-bars}, this reports
the scroll bar type actually used, once frame defaults and
@code{scroll-bar-mode} are taken into account.
@end defun
@defun window-scroll-bar-width &optional window
This function returns the width in pixels of @var{window}'s vertical
scrollbar.
@end defun
@defun window-scroll-bar-height &optional window
This function returns the height in pixels of @var{window}'s horizontal
scrollbar.
@end defun
If you do not specify a window's scroll bar settings via
@code{set-window-scroll-bars}, the buffer-local variables
@code{vertical-scroll-bar}, @code{horizontal-scroll-bar},
@code{scroll-bar-width} and @code{scroll-bar-height} in the buffer being
displayed control the window's scroll bars. The function
@code{set-window-buffer} examines these variables. If you change them
in a buffer that is already visible in a window, you can make the window
take note of the new values by calling @code{set-window-buffer}
specifying the same buffer that is already displayed.
You can control the appearance of scroll bars for a particular buffer by
setting the following variables which automatically become buffer-local
when set.
@defvar vertical-scroll-bar
This variable specifies the location of the vertical scroll bar. The
possible values are @code{left}, @code{right}, @code{t}, which means to
use the frame's default, and @code{nil} for no scroll bar.
@end defvar
@defvar horizontal-scroll-bar
This variable specifies the location of the horizontal scroll bar. The
possible values are @code{bottom}, @code{t}, which means to use the
frame's default, and @code{nil} for no scroll bar.
@end defvar
@defvar scroll-bar-width
This variable specifies the width of the buffer's vertical scroll bars,
measured in pixels. A value of @code{nil} means to use the value
specified by the frame.
@end defvar
@defvar scroll-bar-height
This variable specifies the height of the buffer's horizontal scroll
bar, measured in pixels. A value of @code{nil} means to use the value
specified by the frame.
@end defvar
Finally you can toggle the display of scroll bars on all frames by
customizing the variables @code{scroll-bar-mode} and
@code{horizontal-scroll-bar-mode}.
@defopt scroll-bar-mode
This variable controls whether and where to put vertical scroll bars in
all frames. The possible values are @code{nil} for no scroll bars,
@code{left} to put scroll bars on the left and @code{right} to put
scroll bars on the right.
@end defopt
@defopt horizontal-scroll-bar-mode
This variable controls whether to display horizontal scroll bars on all
frames.
@end defopt
@node Window Dividers
@section Window Dividers
@cindex window dividers
@cindex right dividers
@cindex bottom dividers
Window dividers are bars drawn between a frame's windows. A right
divider is drawn between a window and any adjacent windows on the right.
Its width (thickness) is specified by the frame parameter
@code{right-divider-width}. A bottom divider is drawn between a
window and adjacent windows on the bottom or the echo area. Its width
is specified by the frame parameter @code{bottom-divider-width}. In
either case, specifying a width of zero means to not draw such dividers.
@xref{Layout Parameters}.
Technically, a right divider belongs to the window on its left,
which means that its width contributes to the total width of that
window. A bottom divider belongs to the window above it, which
means that its width contributes to the total height of that window.
@xref{Window Sizes}. When a window has both, a right and a bottom
divider, the bottom divider prevails. This means that a bottom
divider is drawn over the full total width of its window while the right
divider ends above the bottom divider.
Dividers can be dragged with the mouse and are therefore useful for
adjusting the sizes of adjacent windows with the mouse. They also serve
to visually set apart adjacent windows when no scroll bars or mode lines
are present. The following three faces allow the customization of the
appearance of dividers:
@table @code
@item window-divider
When a divider is less than three pixels wide, it is drawn solidly with
the foreground of this face. For larger dividers this face is used for
the inner part only, excluding the first and last pixel.
@item window-divider-first-pixel
This is the face used for drawing the first pixel of a divider that is
at least three pixels wide. To obtain a solid appearance, set this to
the same value used for the @code{window-divider} face.
@item window-divider-last-pixel
This is the face used for drawing the last pixel of a divider that is at
least three pixels wide. To obtain a solid appearance, set this to the
same value used for the @code{window-divider} face.
@end table
You can get the sizes of the dividers of a specific window with the
following two functions.
@defun window-right-divider-width &optional window
Return the width (thickness) in pixels of @var{window}'s right divider.
@var{window} must be a live window and defaults to the selected one.
The return value is always zero for a rightmost window.
@end defun
@defun window-bottom-divider-width &optional window
Return the width (thickness) in pixels of @var{window}'s bottom divider.
@var{window} must be a live window and defaults to the selected one.
The return value is zero for the minibuffer window or a bottommost
window on a minibuffer-less frame.
@end defun
@node Display Property
@section The @code{display} Property
@cindex display specification
@cindex display property
@kindex display @r{(text property)}
The @code{display} text property (or overlay property) is used to
insert images into text, and to control other aspects of how text
displays. Display specifications in the same @code{display}
property value generally apply in parallel to the text they cover.
If several sources (overlays and/or a text property) specify values
for the @code{display} property, only one of the values takes effect,
following the rules of @code{get-char-property}. @xref{Examining
Properties}.
The value of the @code{display} property should be a display
specification, or a list or vector containing several display
specifications.
@defun get-display-property position prop &optional object properties
This convenience function can be used to get a specific display
property, no matter whether the @code{display} property is a vector, a
list or a simple property. This is like @code{get-text-property}
(@pxref{Examining Properties}), but works on the @code{display}
property only.
@var{position} is the position in the buffer or string to examine, and
@var{prop} is the @code{display} property to return. The optional
@var{object} argument should be either a string or a buffer, and
defaults to the current buffer. If the optional @var{properties}
argument is non-@code{nil}, it should be a @code{display} property,
and in that case, @var{position} and @var{object} are ignored. (This
can be useful if you've already gotten the @code{display} property
with @code{get-char-property}, for instance (@pxref{Examining
Properties}).
@end defun
@defun add-display-text-property start end prop value &optional object
Add @code{display} property @var{prop} of @var{value} to the text from
@var{start} to @var{end}.
If any text in the region has a non-@code{nil} @code{display}
property, those properties are retained. For instance:
@lisp
(add-display-text-property 4 8 'height 2.0)
(add-display-text-property 2 12 'raise 0.5)
@end lisp
After doing this, the region from 2 to 4 will have the @code{raise}
@code{display} property, the region from 4 to 8 will have both the
@code{raise} and @code{height} @code{display} properties, and finally
the region from 8 to 12 will only have the @code{raise} @code{display}
property.
If @var{object} is non-@code{nil}, it should be a string or a buffer.
If @code{nil}, this defaults to the current buffer.
@end defun
@cindex display property, unsafe evaluation
@cindex security, and display specifications
Some of the display specifications allow inclusion of Lisp forms,
which are evaluated at display time. This could be unsafe in certain
situations, e.g., when the display specification was generated by some
external program/agent. Wrapping a display specification in a list
that begins with the special symbol @code{disable-eval}, as in
@w{@code{(disable-eval @var{spec})}}, will disable evaluation of any
Lisp in @var{spec}, while still supporting all the other display
property features.
The rest of this section describes several kinds of
display specifications and what they mean.
@menu
* Replacing Specs:: Display specs that replace the text.
* Specified Space:: Displaying one space with a specified width.
* Pixel Specification:: Specifying space width or height in pixels.
* Other Display Specs:: Displaying an image; adjusting the height,
spacing, and other properties of text.
* Display Margins:: Displaying text or images to the side of the main text.
@end menu
@node Replacing Specs
@subsection Display Specs That Replace The Text
@cindex replacing display specs
Some kinds of display specifications specify something to display
instead of the text that has the property. These are called
@dfn{replacing} display specifications. Emacs does not allow the user
to interactively move point into the middle of buffer text that is
replaced in this way.
If a list of display specifications includes more than one replacing
display specification, the first overrides the rest. Replacing
display specifications make most other display specifications
irrelevant, since those don't apply to the replacement.
For replacing display specifications, @dfn{the text that has the
property} means all the consecutive characters that have the same
Lisp object as their @code{display} property; these characters are
replaced as a single unit. If two characters have different Lisp
objects as their @code{display} properties (i.e., objects which are
not @code{eq}), they are handled separately.
Here is an example which illustrates this point. A string serves as
a replacing display specification, which replaces the text that has
the property with the specified string (@pxref{Other Display Specs}).
Consider the following function:
@smallexample
(defun foo ()
(dotimes (i 5)
(let ((string (concat "A"))
(start (+ i i (point-min))))
(put-text-property start (1+ start) 'display string)
(put-text-property start (+ 2 start) 'display string))))
@end smallexample
@noindent
This function gives each of the first ten characters in the buffer a
@code{display} property which is a string @code{"A"}, but they don't
all get the same string object. The first two characters get the same
string object, so they are replaced with one @samp{A}; the fact that
the display property was assigned in two separate calls to
@code{put-text-property} is irrelevant. Similarly, the next two
characters get a second string (@code{concat} creates a new string
object), so they are replaced with one @samp{A}; and so on. Thus, the
ten characters appear as five A's.
@node Specified Space
@subsection Specified Spaces
@cindex spaces, specified height or width
@cindex variable-width spaces
To display a space of specified width and/or height, use a display
specification of the form @code{(space . @var{props})}, where
@var{props} is a property list (a list of alternating properties and
values). You can put this property on one or more consecutive
characters; a space of the specified height and width is displayed in
place of @emph{all} of those characters. These are the properties you
can use in @var{props} to specify the weight of the space:
@table @code
@item :width @var{width}
If @var{width} is a number, it specifies
that the space width should be @var{width} times the normal character
width. @var{width} can also be a @dfn{pixel width} specification
(@pxref{Pixel Specification}).
@item :relative-width @var{factor}
Specifies that the width of the stretch should be computed from the
first character in the group of consecutive characters that have the
same @code{display} property. The space width is the pixel width of
that character, multiplied by @var{factor}. (On text-mode terminals,
the ``pixel width'' of a character is usually 1, but it could be more
for TABs and double-width CJK characters.)
@item :align-to @var{hpos}
Specifies that the space should be wide enough to reach the column
@var{hpos}. If @var{hpos} is a number, it is a column number, and is
measured in units of the canonical character width (@pxref{Frame
Font}). @var{hpos} can also be a @dfn{pixel width} specification
(@pxref{Pixel Specification}). When the current line is wider than
the window, and is either displayed by one or more continuation lines,
or is truncated and possibly scrolled horizontally (@pxref{Horizontal
Scrolling}), @var{hpos} is measured from the beginning of the logical
line, not from the visual beginning of the screen line. This way,
alignment produced by @code{:align-to} is consistent with functions
that count columns, such as @code{current-column} and
@code{move-to-column} (@pxref{Columns}).
@end table
You should use one and only one of the above properties. You can
also specify the height of the space, with these properties:
@table @code
@item :height @var{height}
Specifies the height of the space.
If @var{height} is a number, it specifies
that the space height should be @var{height} times the normal character
height. The @var{height} may also be a @dfn{pixel height} specification
(@pxref{Pixel Specification}).
@item :relative-height @var{factor}
Specifies the height of the space, multiplying the ordinary height
of the text having this display specification by @var{factor}.
@item :ascent @var{ascent}
If the value of @var{ascent} is a non-negative number no greater than
100, it specifies that @var{ascent} percent of the height of the space
should be considered as the ascent of the space---that is, the part
above the baseline. The ascent may also be specified in pixel units
with a @dfn{pixel ascent} specification (@pxref{Pixel Specification}).
@end table
Don't use both @code{:height} and @code{:relative-height} together.
The @code{:width} and @code{:align-to} properties are supported on
non-graphic terminals, but the other space properties in this section
are not.
Note that space properties are treated as paragraph separators for
the purposes of reordering bidirectional text for display.
@xref{Bidirectional Display}, for the details.
@node Pixel Specification
@subsection Pixel Specification for Spaces
@cindex spaces, pixel specification
The value of the @code{:width}, @code{:align-to}, @code{:height},
and @code{:ascent} properties can be a special kind of expression that
is evaluated during redisplay. The result of the evaluation is used
as an absolute number of pixels.
The following expressions are supported:
@smallexample
@group
@var{expr} ::= @var{num} | (@var{num}) | @var{unit} | @var{elem} | @var{pos} | @var{image} | @var{xwidget} | @var{form}
@var{num} ::= @var{integer} | @var{float} | @var{symbol}
@var{unit} ::= in | mm | cm | width | height
@end group
@group
@var{elem} ::= left-fringe | right-fringe | left-margin | right-margin
| scroll-bar | text
@var{pos} ::= left | center | right
@var{form} ::= (@var{num} . @var{expr}) | (@var{op} @var{expr} ...)
@var{op} ::= + | -
@end group
@end smallexample
The form @var{num} specifies a fraction of the default frame font
height or width. The form @code{(@var{num})} specifies an absolute
number of pixels. If @var{num} is a symbol, @var{symbol}, its
buffer-local variable binding is used; that binding can be either a
number or a cons cell of the forms shown above (including yet another
cons cell whose @code{car} is a symbol that has a buffer-local
binding).
The @code{in}, @code{mm}, and @code{cm} units specify the number of
pixels per inch, millimeter, and centimeter, respectively. The
@code{width} and @code{height} units correspond to the default width
and height of the current face. An image specification of the form
@w{@code{(image . @var{props})}} (@pxref{Image Descriptors})
corresponds to the width or height of the specified image. Similarly,
an xwidget specification of the form @w{@code{(xwidget . @var{props})}}
stands for the width or height of the specified xwidget.
@xref{Xwidgets}.
The elements @code{left-fringe}, @code{right-fringe},
@code{left-margin}, @code{right-margin}, @code{scroll-bar}, and
@code{text} specify the width of the corresponding area of the window.
When the window displays line numbers (@pxref{Size of Displayed
Text}), the width of the @code{text} area is decreased by the screen
space taken by the line-number display.
The @code{left}, @code{center}, and @code{right} positions can be
used with @code{:align-to} to specify a position relative to the left
edge, center, or right edge of the text area. When the window
displays line numbers, and @code{:align-to} is used in display
properties of buffer text (as opposed to header line, see below), the
@code{left} and the @code{center} positions are offset to account for
the screen space taken by the line-number display.
Any of the above window elements (except @code{text}) can also be
used with @code{:align-to} to specify that the position is relative to
the left edge of the given area. Once the base offset for a relative
position has been set (by the first occurrence of one of these
symbols), further occurrences of these symbols are interpreted as the
width of the specified area. For example, to align to the center of
the left-margin, use
@example
:align-to (+ left-margin (0.5 . left-margin))
@end example
If no specific base offset is set for alignment, it is always
relative to the left edge of the text area. For example,
@samp{:align-to 0} aligns with the first text column in the text area.
When the window displays line numbers, the text is considered to start
where the space used for line-number display ends.
A value of the form @code{(@var{num} . @var{expr})} stands for the
product of the values of @var{num} and @var{expr}. For example,
@code{(2 . in)} specifies a width of 2 inches, while @code{(0.5 .
@var{image})} specifies half the width (or height) of the specified
@var{image} (which should be given by its image spec).
The form @code{(+ @var{expr} ...)} adds up the value of the
expressions. The form @code{(- @var{expr} ...)} negates or subtracts
the value of the expressions.
@vindex header-line-format@r{, and } :align-to
@cindex aligning header line, when line numbers are displayed
@cindex header line alignment when line numbers are displayed
Text shown in the header line that uses @code{:align-to} display
specifications is not automatically realigned when
@code{display-line-numbers-mode} is turned on and off, or when the
width of line numbers on display changes. To arrange for the
header-line text alignment to be updated, thus keeping the header-line
text aligned with the buffer text, turn on the
@code{header-line-indent-mode} in the buffer and use its two
variables, @code{header-line-indent} and
@code{header-line-indent-width}, in the display specification.
@xref{Header Lines}. Here's a simple example:
@lisp
(setq header-line-format
(concat (propertize " "
'display
'(space :align-to
(+ header-line-indent-width 10)))
"Column"))
@end lisp
@noindent
This will keep the text @samp{Column} on the header line aligned with
column 10 of buffer text, regardless of whether
@code{display-line-numbers-mode} is on or off, and also when
line-number display changes its width.
@node Other Display Specs
@subsection Other Display Specifications
Here are the other sorts of display specifications that you can use
in the @code{display} text property.
@table @code
@item @var{string}
Display @var{string} instead of the text that has this property.
Recursive display specifications are not supported---@var{string}'s
@code{display} properties, if any, are not used.
@item (image . @var{image-props})
This kind of display specification is an image descriptor (@pxref{Image Descriptors}).
When used as a display specification, it means to display the image
instead of the text that has the display specification.
@item (slice @var{x} @var{y} @var{width} @var{height})
This specification together with @code{image} specifies a @dfn{slice}
(a partial area) of the image to display. The elements @var{y} and
@var{x} specify the top left corner of the slice, within the image;
@var{width} and @var{height} specify the width and height of the
slice. Integers are numbers of pixels. A floating-point number
in the range 0.0--1.0 stands for that fraction of the width or height
of the entire image.
@item ((margin nil) @var{string})
A display specification of this form means to display @var{string}
instead of the text that has the display specification, at the same
position as that text. It is equivalent to using just @var{string},
but it is done as a special case of marginal display (@pxref{Display
Margins}).
@item (left-fringe @var{bitmap} @r{[}@var{face}@r{]})
@itemx (right-fringe @var{bitmap} @r{[}@var{face}@r{]})
This display specification on any character of a line of text causes
the specified @var{bitmap} be displayed in the left or right fringes
for that line, instead of the characters that have the display
specification. The optional @var{face} specifies the face whose
colors are to be used for the bitmap display. @xref{Fringe Bitmaps},
for the details.
It also possible to add context help for fringe bitmaps through the
@code{show-help-function} mechanism by using @code{left-fringe-help} and
@code{right-fringe-help} text properties (@pxref{Special Properties}).
@item (space-width @var{factor})
This display specification affects all the space characters within the
text that has the specification. It displays all of these spaces
@var{factor} times as wide as normal. The element @var{factor} should
be an integer or float. Characters other than spaces are not affected
at all; in particular, this has no effect on tab characters.
@item (min-width (@var{width}))
This display specification ensures the text that has it takes at least
@var{width} space on display, by adding a stretch of white space to
the end of the text if the text is shorter than @var{width}. The text
is partitioned using the identity of the parameter, which is why the
parameter is a list with one element. For instance:
@lisp
(insert (propertize "foo" 'display '(min-width (6.0))))
@end lisp
This will add padding after @samp{foo} bringing the total width up to
the width of six normal characters. Note that the affected characters
are identified by the @code{(6.0)} list in the display property,
compared with @code{eq}. The element @var{width} can be either an
integer or a float specifying the required minimum width of the text
(@pxref{Pixel Specification}).
@item (height @var{height})
This display specification makes the text taller or shorter.
Here are the possibilities for @var{height}:
@table @asis
@item @code{(+ @var{n})}
@c FIXME: Add an index for "step"? --xfq
This means to use a font that is @var{n} steps larger. A @dfn{step} is
defined by the set of available fonts---specifically, those that match
what was otherwise specified for this text, in all attributes except
height. Each size for which a suitable font is available counts as
another step. @var{n} should be an integer.
@item @code{(- @var{n})}
This means to use a font that is @var{n} steps smaller.
@item a number, @var{factor}
A number, @var{factor}, means to use a font that is @var{factor} times
as tall as the default font.
@item a symbol, @var{function}
A symbol is a function to compute the height. It is called with the
current height as argument, and should return the new height to use.
@item anything else, @var{form}
If the @var{height} value doesn't fit the previous possibilities, it is
a form. Emacs evaluates it to get the new height, with the symbol
@code{height} bound to the current specified font height.
@end table
@item (raise @var{factor})
This kind of display specification raises or lowers the text
it applies to, relative to the baseline of the line. It is mainly
meant to support display of subscripts and superscripts.
The @var{factor} must be a number, which is interpreted as a multiple
of the height of the affected text. If it is positive, that means to
display the characters raised. If it is negative, that means to
display them lower down.
Note that if the text also has a @code{height} display specification,
which was specified before (i.e.@: to the left of) @code{raise}, the
latter will affect the amount of raising or lowering in pixels,
because that is based on the height of the text being raised.
Therefore, if you want to display a sub- or superscript that is
smaller than the normal text height, consider specifying @code{raise}
before @code{height}.
@end table
@c We put all the '@code{(when ...)}' on one line to encourage
@c makeinfo's end-of-sentence heuristics to DTRT. Previously, the dot
@c was at eol; the info file ended up with two spaces rendered after it.
You can make any display specification conditional. To do that,
package it in another list of the form
@code{(when @var{condition} . @var{spec})}.
Then the specification @var{spec} applies only when
@var{condition} evaluates to a non-@code{nil} value. During the
evaluation, @code{object} is bound to the string or buffer having the
conditional @code{display} property. @code{position} and
@code{buffer-position} are bound to the position within @code{object}
and the buffer position where the @code{display} property was found,
respectively. Both positions can be different when @code{object} is a
string.
Note that @var{condition} will only be evaluated when redisplay
examines the text where this display spec is located, so this feature
is best suited for conditions that are relatively stable, i.e.@:
yield, for each particular buffer position, the same results on every
evaluation. If the results change for the same text location, e.g.,
if the result depends on the position of point, then the conditional
specification might not do what you want, because redisplay examines
only those parts of buffer text where it has reasons to assume that
something changed since the last display cycle.
@node Display Margins
@subsection Displaying in the Margins
@cindex display margins
@cindex margins, display
A buffer can have blank areas called @dfn{display margins} on the
left and on the right. Ordinary text never appears in these areas,
but you can put things into the display margins using the
@code{display} property. There is currently no way to make text or
images in the margin mouse-sensitive.
The way to display something in the margins is to specify it in a
margin display specification in the @code{display} property of some
text. This is a replacing display specification, meaning that the
text you put it on does not get displayed; the margin display appears,
but that text does not.
A margin display specification looks like @code{((margin
right-margin) @var{spec})} or @code{((margin left-margin) @var{spec})}.
Here, @var{spec} is another display specification that says what to
display in the margin. Typically it is a string of text to display,
or an image descriptor.
To display something in the margin @emph{in association with}
certain buffer text, without altering or preventing the display of
that text, put on that text an overlay with a @code{before-string}
property, and put the margin display specification on the contents of
the before-string.
Note that if the string to be displayed in the margin doesn't
specify a face, its face is determined using the same rules and
priorities as it is for strings displayed in the text area
(@pxref{Displaying Faces}). If this results in undesirable
``leaking'' of faces into the margin, make sure the string has an
explicit face specified for it.
Before the display margins can display anything, you must give
them a nonzero width. The usual way to do that is to set these
variables:
@defvar left-margin-width
This variable specifies the width of the left margin, in character
cell (a.k.a.@: ``column'') units. It is buffer-local in all buffers.
A value of @code{nil} means no left marginal area.
@end defvar
@defvar right-margin-width
This variable specifies the width of the right margin, in character
cell units. It is buffer-local in all buffers. A value of @code{nil}
means no right marginal area.
@end defvar
Setting these variables does not immediately affect the window. These
variables are checked when a new buffer is displayed in the window.
Thus, you can make changes take effect by calling
@code{set-window-buffer}. Do not use these variables to try to
determine the current width of the left or right margin. Instead, use
the function @code{window-margins}.
You can also set the margin widths immediately.
@defun set-window-margins window left &optional right
This function specifies the margin widths for window @var{window}, in
character cell units. The argument @var{left} controls the left
margin, and @var{right} controls the right margin (default @code{0}).
If @var{window} is not large enough to accommodate margins of the
desired width, this leaves the margins of @var{window} unchanged.
The values specified here may be later overridden by invoking
@code{set-window-buffer} (@pxref{Buffers and Windows}) on @var{window}
with its @var{keep-margins} argument @code{nil} or omitted.
@end defun
@defun window-margins &optional window
This function returns the width of the left and right margins of
@var{window} as a cons cell of the form @w{@code{(@var{left}
. @var{right})}}. If one of the two marginal areas does not exist,
its width is returned as @code{nil}; if neither of the two margins exist,
the function returns @code{(nil)}. If @var{window} is @code{nil}, the
selected window is used.
@end defun
@node Images
@section Images
@cindex images in buffers
To display an image in an Emacs buffer, you must first create an image
descriptor, then use it as a display specifier in the @code{display}
property of text that is displayed (@pxref{Display Property}).
Emacs is usually able to display images when it is run on a
graphical terminal. Images cannot be displayed in a text terminal, on
certain graphical terminals that lack the support for this, or if
Emacs is compiled without image support. You can use the function
@code{display-images-p} to determine if images can in principle be
displayed (@pxref{Display Feature Testing}).
@menu
* Image Formats:: Supported image formats.
* Image Descriptors:: How to specify an image for use in @code{:display}.
* XBM Images:: Special features for XBM format.
* XPM Images:: Special features for XPM format.
* ImageMagick Images:: Special features available through ImageMagick.
* SVG Images:: Creating and manipulating SVG images.
* Other Image Types:: Various other formats are supported.
* Defining Images:: Convenient ways to define an image for later use.
* Showing Images:: Convenient ways to display an image once it is defined.
* Multi-Frame Images:: Some images contain more than one frame.
* Image Cache:: Internal mechanisms of image display.
@end menu
@node Image Formats
@subsection Image Formats
@cindex image formats
@cindex image types
Emacs can display a number of different image formats. Some of
these image formats are supported only if particular support libraries
are installed. On some platforms, Emacs can load support libraries on
demand; if so, the variable @code{dynamic-library-alist} can be used
to modify the set of known names for these dynamic libraries.
@xref{Dynamic Libraries}.
Supported image formats (and the required support libraries) include
PBM and XBM (which do not depend on support libraries and are always
available), XPM (@code{libXpm}), GIF (@code{libgif} or
@code{libungif}), JPEG (@code{libjpeg}), TIFF (@code{libtiff}), PNG
(@code{libpng}), SVG (@code{librsvg}), and WebP (@code{libwebp}).
Each of these image formats is associated with an @dfn{image type
symbol}. The symbols for the above formats are, respectively,
@code{pbm}, @code{xbm}, @code{xpm}, @code{gif}, @code{jpeg},
@code{tiff}, @code{png}, @code{svg}, and @code{webp}.
On some platforms, the built-in image support that doesn't require
any optional libraries includes BMP images.@footnote{
On MS-Windows, this requires @code{w32-use-native-image-API} to be set
non-@code{nil}.
}
Furthermore, if you build Emacs with ImageMagick
(@code{libMagickWand}) support, Emacs can display any image format
that ImageMagick can. @xref{ImageMagick Images}. All images
displayed via ImageMagick have type symbol @code{imagemagick}.
@defvar image-types
This variable contains a list of type symbols for image formats which
are potentially supported in the current configuration.
``Potentially'' means that Emacs knows about the image types, not
necessarily that they can be used (for example, they could depend on
unavailable dynamic libraries). To know which image types are really
available, use @code{image-type-available-p}.
@end defvar
@defun image-type-available-p type
This function returns non-@code{nil} if images of type @var{type} can
be loaded and displayed. @var{type} must be an image type symbol.
For image types whose support libraries are statically linked, this
function always returns @code{t}. For image types whose support
libraries are dynamically loaded, it returns @code{t} if the library
could be loaded and @code{nil} otherwise.
@end defun
@node Image Descriptors
@subsection Image Descriptors
@cindex image descriptor
An @dfn{image descriptor} is a list which specifies the underlying
data for an image, and how to display it. It is typically used as the
value of a @code{display} overlay or text property (@pxref{Other
Display Specs}); but @xref{Showing Images}, for convenient helper
functions to insert images into buffers.
Each image descriptor has the form @code{(image . @var{props})},
where @var{props} is a property list of alternating keyword symbols
and values, including at least the pair @code{:type @var{type}} that
specifies the image type.
Image descriptors which define image dimensions, @code{:width},
@code{:height}, @code{:max-width} and @code{:max-height}, may take
either an integer, which represents the dimension in pixels, or a pair
@code{(@var{value} . em)}, where @var{value} is the dimension's
length in @dfn{ems}@footnote{In typography an em is a distance
equivalent to the height of the type. For example when using 12 point
type 1 em is equal to 12 points. Its use ensures distances and type
remain proportional.}. One em is equivalent to the size of the font
and @var{value} may be an integer or a float. Also, dimension can be
specified in @code{(@var{value} . ch)} and @code{(@var{value} . cw)}
forms, where @code{ch} means height of the canonical character and
@code{cw} means width of the canonical character.
The following is a list of properties that are meaningful for all
image types (there are also properties which are meaningful only for
certain image types, as documented in the following subsections):
@table @code
@item :type @var{type}
The image type.
@ifnottex
@xref{Image Formats}.
@end ifnottex
Every image descriptor must include this property.
@item :file @var{file}
This says to load the image from file @var{file}. If @var{file} is
not an absolute file name, it is expanded relative to each of the
directories mentioned by @code{image-load-path} (@pxref{Defining
Images}).
@item :data @var{data}
This specifies the raw image data. Each image descriptor must have
either @code{:data} or @code{:file}, but not both.
For most image types, the value of a @code{:data} property should be a
string containing the image data. Some image types do not support
@code{:data}; for some others, @code{:data} alone is not enough, so
you need to use other image properties along with @code{:data}. See
the following subsections for details.
@item :margin @var{margin}
This specifies how many pixels to add as an extra margin around the
image. The value, @var{margin}, must be a non-negative number, or a
pair @code{(@var{x} . @var{y})} of such numbers. If it is a pair,
@var{x} specifies how many pixels to add horizontally, and @var{y}
specifies how many pixels to add vertically. If @code{:margin} is not
specified, the default is zero.
@item :ascent @var{ascent}
This specifies the amount of the image's height to use for its
ascent---that is, the part above the baseline. The value,
@var{ascent}, must be a number in the range 0 to 100, or the symbol
@code{center}.
If @var{ascent} is a number, that percentage of the image's height is
used for its ascent.
If @var{ascent} is @code{center}, the image is vertically centered
around a centerline which would be the vertical centerline of text drawn
at the position of the image, in the manner specified by the text
properties and overlays that apply to the image.
If this property is omitted, it defaults to 50.
@item :relief @var{relief}
This adds a shadow rectangle around the image. The value,
@var{relief}, specifies the width of the shadow lines, in pixels. If
@var{relief} is negative, shadows are drawn so that the image appears
as a pressed button; otherwise, it appears as an unpressed button.
@item :width @var{width}, :height @var{height}
The @code{:width} and @code{:height} keywords are used for scaling the
image. If only one of them is specified, the other one will be
calculated so as to preserve the aspect ratio. If both are specified,
aspect ratio may not be preserved.
@item :max-width @var{max-width}, :max-height @var{max-height}
The @code{:max-width} and @code{:max-height} keywords are used for
scaling if the size of the image exceeds these values. If
@code{:width} is set, it will have precedence over @code{max-width},
and if @code{:height} is set, it will have precedence over
@code{max-height}, but you can otherwise mix these keywords as you
wish.
If both @code{:max-width} and @code{:height} are specified, but
@code{:width} is not, preserving the aspect ratio might require that
width exceeds @code{:max-width}. If this happens, scaling will use a
smaller value for the height so as to preserve the aspect ratio while
not exceeding @code{:max-width}. Similarly when both
@code{:max-height} and @code{:width} are specified, but @code{:height}
is not. For example, if you have a 200x100 image and specify that
@code{:width} should be 400 and @code{:max-height} should be 150,
you'll end up with an image that is 300x150: Preserving the aspect
ratio and not exceeding the ``max'' setting. This combination of
parameters is a useful way of saying ``display this image as large as
possible, but no larger than the available display area''.
@item :scale @var{scale}
This should be a number, where values higher than 1 means to increase
the size, and lower means to decrease the size, by multiplying both
the width and height. For instance, a value of 0.25 will make the
image a quarter size of what it originally was. If the scaling makes
the image larger than specified by @code{:max-width} or
@code{:max-height}, the resulting size will not exceed those two
values. If both @code{:scale} and @code{:height}/@code{:width} are
specified, the height/width will be adjusted by the specified scaling
factor.
@item :rotation @var{angle}
Specifies a rotation angle in degrees. Only multiples of 90 degrees
are supported, unless the image type is @code{imagemagick}. Positive
values rotate clockwise, negative values counter-clockwise. Rotation
is performed after scaling and cropping.
@item :flip @var{flip}
If this is @code{t}, the image will be horizontally flipped.
Currently it has no effect if the image type is @code{imagemagick}.
Vertical flipping can be achieved by rotating the image 180 degrees
and toggling this value.
@item :transform-smoothing @var{smooth}
If this is @code{t}, any image transform will have smoothing applied;
if @code{nil}, no smoothing will be applied. The exact algorithm used
is platform dependent, but should be equivalent to bilinear
filtering. Disabling smoothing will use the nearest neighbor
algorithm.
If this property is not specified, @code{create-image} will use the
@code{image-transform-smoothing} user option to say whether scaling
should be done or not. This option can be @code{nil} (no smoothing),
@code{t} (use smoothing) or a predicate function that's called with
the image object as the only parameter, and should return either
@code{nil} or @code{t}. The default is for down-scaling to apply
smoothing, and for large up-scaling to not apply smoothing.
@item :index @var{frame}
@xref{Multi-Frame Images}.
@item :conversion @var{algorithm}
This specifies a conversion algorithm that should be applied to the
image before it is displayed; the value, @var{algorithm}, specifies
which algorithm.
@table @code
@item laplace
@itemx emboss
Specifies the Laplace edge detection algorithm, which blurs out small
differences in color while highlighting larger differences. People
sometimes consider this useful for displaying the image for a
disabled button.
@item (edge-detection :matrix @var{matrix} :color-adjust @var{adjust})
@cindex edge detection, images
Specifies a general edge-detection algorithm. @var{matrix} must be
either a nine-element list or a nine-element vector of numbers. A pixel
at position @math{x/y} in the transformed image is computed from
original pixels around that position. @var{matrix} specifies, for each
pixel in the neighborhood of @math{x/y}, a factor with which that pixel
will influence the transformed pixel; element @math{0} specifies the
factor for the pixel at @math{x-1/y-1}, element @math{1} the factor for
the pixel at @math{x/y-1} etc., as shown below:
@iftex
@tex
$$\pmatrix{x-1/y-1 & x/y-1 & x+1/y-1 \cr
x-1/y & x/y & x+1/y \cr
x-1/y+1& x/y+1 & x+1/y+1 \cr}$$
@end tex
@end iftex
@ifnottex
@display
(x-1/y-1 x/y-1 x+1/y-1
x-1/y x/y x+1/y
x-1/y+1 x/y+1 x+1/y+1)
@end display
@end ifnottex
The resulting pixel is computed from the color intensity of the color
resulting from summing up the RGB values of surrounding pixels,
multiplied by the specified factors, and dividing that sum by the sum
of the factors' absolute values.
Laplace edge-detection currently uses a matrix of
@iftex
@tex
$$\pmatrix{1 & 0 & 0 \cr
0& 0 & 0 \cr
0 & 0 & -1 \cr}$$
@end tex
@end iftex
@ifnottex
@display
(1 0 0
0 0 0
0 0 -1)
@end display
@end ifnottex
Emboss edge-detection uses a matrix of
@iftex
@tex
$$\pmatrix{ 2 & -1 & 0 \cr
-1 & 0 & 1 \cr
0 & 1 & -2 \cr}$$
@end tex
@end iftex
@ifnottex
@display
( 2 -1 0
-1 0 1
0 1 -2)
@end display
@end ifnottex
@item disabled
Specifies transforming the image so that it looks disabled.
@end table
@item :mask @var{mask}
If @var{mask} is @code{heuristic} or @code{(heuristic @var{bg})}, build
a clipping mask for the image, so that the background of a frame is
visible behind the image. If @var{bg} is not specified, or if @var{bg}
is @code{t}, determine the background color of the image by looking at
the four corners of the image, assuming the most frequently occurring
color from the corners is the background color of the image. Otherwise,
@var{bg} must be a list @code{(@var{red} @var{green} @var{blue})}
specifying the color to assume for the background of the image.
If @var{mask} is @code{nil}, remove a mask from the image, if it has
one. Images in some formats include a mask which can be removed by
specifying @code{:mask nil}.
@item :pointer @var{shape}
This specifies the pointer shape when the mouse pointer is over this
image. @xref{Pointer Shape}, for available pointer shapes.
@item :map @var{map}
@cindex image maps
This associates an image map of @dfn{hot spots} with this image.
An image map is an alist where each element has the format
@code{(@var{area} @var{id} @var{plist})}. An @var{area} is specified
as either a rectangle, a circle, or a polygon.
A rectangle is a cons
@code{(rect . ((@var{x0} . @var{y0}) . (@var{x1} . @var{y1})))}
which specifies the pixel coordinates of the upper left and bottom right
corners of the rectangle area.
A circle is a cons
@code{(circle . ((@var{x0} . @var{y0}) . @var{r}))}
which specifies the center and the radius of the circle; @var{r} may
be a float or integer.
A polygon is a cons
@code{(poly . [@var{x0} @var{y0} @var{x1} @var{y1} ...])}
where each pair in the vector describes one corner in the polygon.
When the mouse pointer lies on a hot-spot area of an image, the
@var{plist} of that hot-spot is consulted; if it contains a @code{help-echo}
property, that defines a tool-tip for the hot-spot, and if it contains
a @code{pointer} property, that defines the shape of the mouse cursor when
it is on the hot-spot.
@xref{Pointer Shape}, for available pointer shapes.
When you click the mouse when the mouse pointer is over a hot-spot, an
event is composed by combining the @var{id} of the hot-spot with the
mouse event; for instance, @code{[area4 mouse-1]} if the hot-spot's
@var{id} is @code{area4}.
@findex image-compute-scaling-factor
Note that the map's coordinates should reflect the displayed image
after all transforms have been done (rotation, scaling and so on), and
also note that Emacs (by default) performs auto-scaling of images, so
to make things match up, you should either specify @code{:scale 1.0}
when creating the image, or use the result of
@code{image-compute-scaling-factor} to compute the elements of the
map.
When an image's @code{:scale}, @code{:rotation}, or @code{:flip} is
changed, @code{:map} will be recomputed based on the value of
@code{:original-map} and the values of those transformation.
@item :original-map @var{original-map}
@cindex original image map
This specifies the untransformed image map which will be used to
recompute @code{:map} after the image's @code{:scale}, @code{:rotation},
or @code{:flip} is changed.
If @code{:original-map} is not specified when creating an image with
@code{create-image}, it will be computed based on the supplied
@code{:map}, as well as any of @code{:scale}, @code{:rotation}, or
@code{:flip} which are non-nil.
Conversely, if @code{:original-map} is specified but @code{:map} is not,
@code{:map} will be computed based on @code{:original-map},
@code{:scale}, @code{:rotation}, and @code{:flip}.
@defopt image-recompute-map-p
Set this user option to nil to prevent Emacs from automatically
recomputing an image @code{:map} based on its @code{:original-map}.
@end defopt
@end table
@defun image-mask-p spec &optional frame
This function returns @code{t} if image @var{spec} has a mask bitmap.
@var{frame} is the frame on which the image will be displayed.
@var{frame} @code{nil} or omitted means to use the selected frame
(@pxref{Input Focus}).
@end defun
@defun image-transforms-p &optional frame
This function returns non-@code{nil} if @var{frame} supports image
scaling and rotation. @var{frame} @code{nil} or omitted means to use
the selected frame (@pxref{Input Focus}). The returned list includes
symbols that indicate which image transform operations are supported:
@table @code
@item scale
Image scaling is supported by @var{frame} via the @code{:scale},
@code{:width}, @code{:height}, @code{:max-width}, and
@code{:max-height} properties.
@item rotate90
Image rotation is supported by @var{frame} if the rotation angle is an
integral multiple of 90 degrees.
@end table
If image transforms are not supported, @code{:rotation}, @code{:crop},
@code{:width}, @code{:height}, @code{:scale}, @code{:max-width} and
@code{:max-height} will only be usable through ImageMagick, if
available (@pxref{ImageMagick Images}).
@end defun
@node XBM Images
@subsection XBM Images
@cindex XBM
To use XBM format, specify @code{xbm} as the image type. This image
format doesn't require an external library, so images of this type are
always supported.
Additional image properties supported for the @code{xbm} image type are:
@table @code
@item :foreground @var{foreground}
The value, @var{foreground}, should be a string specifying the image
foreground color, or @code{nil} for the default color. This color is
used for each pixel in the XBM that is 1. The default is the frame's
foreground color.
@item :background @var{background}
The value, @var{background}, should be a string specifying the image
background color, or @code{nil} for the default color. This color is
used for each pixel in the XBM that is 0. The default is the frame's
background color.
@end table
If you specify an XBM image using data within Emacs instead of an
external file, use the following three properties:
@table @code
@item :data @var{data}
The value, @var{data}, specifies the contents of the image.
There are three formats you can use for @var{data}:
@itemize @bullet
@item
A vector of strings or bool-vectors, each specifying one line of the
image. Do specify @code{:data-height} and @code{:data-width}.
@item
A string containing the same byte sequence as an XBM file would contain.
@item
A string or a bool-vector containing the bits of the image (plus
perhaps some extra bits at the end that will not be used). It should
contain at least @w{@code{@var{stride} * @var{height}}} bits, where
@var{stride} is the smallest multiple of 8 greater than or equal to
the width of the image. In this case, you should specify
@code{:data-height}, @code{:data-width} and @code{:stride}, both to
indicate that the string contains just the bits rather than a whole
XBM file, and to specify the size of the image.
@end itemize
@item :stride @var{stride}
The number of bool vector entries stored for each row; the smallest
multiple of 8 greater than or equal to @var{width}.
@end table
@node XPM Images
@subsection XPM Images
@cindex XPM
To use XPM format, specify @code{xpm} as the image type. The
additional image property @code{:color-symbols} is also meaningful with
the @code{xpm} image type:
@table @code
@item :color-symbols @var{symbols}
The value, @var{symbols}, should be an alist whose elements have the
form @code{(@var{name} . @var{color})}. In each element, @var{name} is
the name of a color as it appears in the image file, and @var{color}
specifies the actual color to use for displaying that name.
@end table
@node ImageMagick Images
@subsection ImageMagick Images
@cindex ImageMagick images
@cindex images, support for more formats
If your Emacs build has ImageMagick support, you can use the
ImageMagick library to load many image formats (@pxref{File
Conveniences,,, emacs, The GNU Emacs Manual}). The image type symbol
for images loaded via ImageMagick is @code{imagemagick}, regardless of
the actual underlying image format.
To check for ImageMagick support, use the following:
@lisp
(image-type-available-p 'imagemagick)
@end lisp
@defun imagemagick-types
This function returns a list of image file extensions supported by the
current ImageMagick installation. Each list element is a symbol
representing an internal ImageMagick name for an image type, such as
@code{BMP} for @file{.bmp} images.
@end defun
@defopt imagemagick-enabled-types
The value of this variable is a list of ImageMagick image types which
Emacs may attempt to render using ImageMagick. Each list element
should be one of the symbols in the list returned by
@code{imagemagick-types}, or an equivalent string. Alternatively, a
value of @code{t} enables ImageMagick for all possible image types.
Regardless of the value of this variable,
@code{imagemagick-types-inhibit} (see below) takes precedence.
@end defopt
@defopt imagemagick-types-inhibit
The value of this variable lists the ImageMagick image types which
should never be rendered using ImageMagick, regardless of the value of
@code{imagemagick-enabled-types}. A value of @code{t} disables
ImageMagick entirely.
@end defopt
@defvar image-format-suffixes
This variable is an alist mapping image types to file name extensions.
Emacs uses this in conjunction with the @code{:format} image property
(see below) to give a hint to the ImageMagick library as to the type
of an image. Each element has the form @code{(@var{type}
@var{extension})}, where @var{type} is a symbol specifying an image
content-type, and @var{extension} is a string that specifies the
associated file name extension.
@end defvar
Images loaded with ImageMagick support the following additional
image descriptor properties:
@table @code
@item :background @var{background}
@var{background}, if non-@code{nil}, should be a string specifying a
color, which is used as the image's background color if the image
supports transparency. If the value is @code{nil}, it defaults to the
frame's background color.
@item :format @var{type}
The value, @var{type}, should be a symbol specifying the type of the
image data, as found in @code{image-format-suffixes}. This is used
when the image does not have an associated file name, to provide a
hint to ImageMagick to help it detect the image type.
@item :crop @var{geometry}
The value of @var{geometry} should be a list of the form
@code{(@var{width} @var{height} @var{x} @var{y})}. @var{width} and
@var{height} specify the width and height of the cropped image. If
@var{x} is a positive number it specifies the offset of the cropped
area from the left of the original image, and if negative the offset
from the right. If @var{y} is a positive number it specifies the
offset from the top of the original image, and if negative from the
bottom. If @var{x} or @var{y} are @code{nil} or unspecified the crop
area will be centered on the original image.
If the crop area is outside or overlaps the edge of the image it will
be reduced to exclude any areas outside of the image. This means it
is not possible to use @code{:crop} to increase the size of the image
by entering large @var{width} or @var{height} values.
Cropping is performed after scaling but before rotation.
@end table
@node SVG Images
@subsection SVG Images
@cindex SVG images
SVG (Scalable Vector Graphics) is an XML format for specifying images.
SVG images support the following additional image descriptor
properties:
@table @code
@item :foreground @var{foreground}
@var{foreground}, if non-@code{nil}, should be a string specifying a
color, which is used as the image's foreground color. If the value is
@code{nil}, it defaults to the current face's foreground color.
@item :background @var{background}
@var{background}, if non-@code{nil}, should be a string specifying a
color, which is used as the image's background color if the image
supports transparency. If the value is @code{nil}, it defaults to the
current face's background color.
@item :css @var{css}
@var{css}, if non-@code{nil}, should be a string specifying the CSS to
override the default CSS used when generating the image.
@end table
@subsubheading SVG library
If your Emacs build has SVG support, you can create and manipulate
these images with the following functions from the @file{svg.el}
library.
@defun svg-create width height &rest args
Create a new, empty SVG image with the specified dimensions.
@var{args} is an argument plist with you can specify following:
@table @code
@item :stroke-width
The default width (in pixels) of any lines created.
@item :stroke
The default stroke color on any lines created.
@end table
@cindex SVG object
This function returns an @dfn{SVG object}, a Lisp data structure that
specifies an SVG image, and all the following functions work on that
structure. The argument @var{svg} in the following functions
specifies such an SVG object.
@end defun
@defun svg-gradient svg id type stops
Create a gradient in @var{svg} with identifier @var{id}. @var{type}
specifies the gradient type, and can be either @code{linear} or
@code{radial}. @var{stops} is a list of percentage/color pairs.
The following will create a linear gradient that goes from red at the
start, to green 25% of the way, to blue at the end:
@lisp
(svg-gradient svg "gradient1" 'linear
'((0 . "red") (25 . "green") (100 . "blue")))
@end lisp
The gradient created (and inserted into the SVG object) can later be
used by all functions that create shapes.
@end defun
All the following functions take an optional list of keyword
parameters that alter the various attributes from their default
values. Valid attributes include:
@table @code
@item :stroke-width
The width (in pixels) of lines drawn, and outlines around solid
shapes.
@item :stroke-color
The color of lines drawn, and outlines around solid shapes.
@item :fill-color
The color used for solid shapes.
@item :id
The identified of the shape.
@item :gradient
If given, this should be the identifier of a previously defined
gradient object.
@item :clip-path
Identifier of a clip path.
@end table
@defun svg-rectangle svg x y width height &rest args
Add to @var{svg} a rectangle whose upper left corner is at
position @var{x}/@var{y} and whose size is @var{width}/@var{height}.
@lisp
(svg-rectangle svg 100 100 500 500 :gradient "gradient1")
@end lisp
@end defun
@defun svg-circle svg x y radius &rest args
Add to @var{svg} a circle whose center is at @var{x}/@var{y} and whose
radius is @var{radius}.
@end defun
@defun svg-ellipse svg x y x-radius y-radius &rest args
Add to @var{svg} an ellipse whose center is at @var{x}/@var{y}, and
whose horizontal radius is @var{x-radius} and the vertical radius is
@var{y-radius}.
@end defun
@defun svg-line svg x1 y1 x2 y2 &rest args
Add to @var{svg} a line that starts at @var{x1}/@var{y1} and extends
to @var{x2}/@var{y2}.
@end defun
@defun svg-polyline svg points &rest args
Add to @var{svg} a multiple-segment line (a.k.a.@: ``polyline'') that
goes through @var{points}, which is a list of X/Y position pairs.
@lisp
(svg-polyline svg '((200 . 100) (500 . 450) (80 . 100))
:stroke-color "green")
@end lisp
@end defun
@defun svg-polygon svg points &rest args
Add a polygon to @var{svg} where @var{points} is a list of X/Y pairs
that describe the outer circumference of the polygon.
@lisp
(svg-polygon svg '((100 . 100) (200 . 150) (150 . 90))
:stroke-color "blue" :fill-color "red")
@end lisp
@end defun
@defun svg-path svg commands &rest args
Add the outline of a shape to @var{svg} according to @var{commands},
see @ref{SVG Path Commands}.
Coordinates by default are absolute. To use coordinates relative to
the last position, or -- initially -- to the origin, set the attribute
@var{:relative} to @code{t}. This attribute can be specified for the
function or for individual commands. If specified for the function,
then all commands use relative coordinates by default. To make an
individual command use absolute coordinates, set @var{:relative} to
@code{nil}.
@lisp
(svg-path svg
'((moveto ((100 . 100)))
(lineto ((200 . 0) (0 . 200) (-200 . 0)))
(lineto ((100 . 100)) :relative nil))
:stroke-color "blue"
:fill-color "lightblue"
:relative t)
@end lisp
@end defun
@defun svg-text svg text &rest args
Add the specified @var{text} to @var{svg}.
@lisp
(svg-text
svg "This is a text"
:font-size "40"
:font-weight "bold"
:stroke "black"
:fill "white"
:font-family "impact"
:letter-spacing "4pt"
:x 300
:y 400
:stroke-width 1)
@end lisp
@end defun
@defun svg-embed svg image image-type datap &rest args
Add an embedded (raster) image to @var{svg}. If @var{datap} is
@code{nil}, @var{image} should be a file name; otherwise it should be a
string containing the image data as raw bytes. @var{image-type} should be a
@acronym{MIME} image type, for instance @code{"image/jpeg"}.
@lisp
(svg-embed svg "~/rms.jpg" "image/jpeg" nil
:width "100px" :height "100px"
:x "50px" :y "75px")
@end lisp
@end defun
@defun svg-embed-base-uri-image svg relative-filename &rest args
To @var{svg} add an embedded (raster) image placed at
@var{relative-filename}. @var{relative-filename} is searched inside
@code{file-name-directory} of the @code{:base-uri} svg image property.
@code{:base-uri} specifies a (possibly non-existing) file name of the
svg image to be created, thus all the embedded files are searched
relatively to the @code{:base-uri} filename's directory. If
@code{:base-uri} is omitted, then filename from where svg image is
loaded is used. Using @code{:base-uri} improves the performance of
embedding large images, comparing to @code{svg-embed}, because all the
work is done directly by librsvg.
@lisp
;; Embedding /tmp/subdir/rms.jpg and /tmp/another/rms.jpg
(svg-embed-base-uri-image svg "subdir/rms.jpg"
:width "100px" :height "100px"
:x "50px" :y "75px")
(svg-embed-base-uri-image svg "another/rms.jpg"
:width "100px" :height "100px"
:x "75px" :y "50px")
(svg-image svg :scale 1.0
:base-uri "/tmp/dummy"
:width 175 :height 175)
@end lisp
@end defun
@defun svg-clip-path svg &rest args
Add a clipping path to @var{svg}. If applied to a shape via the
@var{:clip-path} property, parts of that shape which lie outside of
the clipping path are not drawn.
@lisp
(let ((clip-path (svg-clip-path svg :id "foo")))
(svg-circle clip-path 200 200 175))
(svg-rectangle svg 50 50 300 300
:fill-color "red"
:clip-path "url(#foo)")
@end lisp
@end defun
@defun svg-node svg tag &rest args
Add the custom node @var{tag} to @var{svg}.
@lisp
(svg-node svg
'rect
:width 300 :height 200 :x 50 :y 100 :fill-color "green")
@end lisp
@end defun
@defun svg-remove svg id
Remove the element with identifier @code{id} from the @code{svg}.
@end defun
@defun svg-image svg
Finally, the @code{svg-image} takes an SVG object as its argument and
returns an image object suitable for use in functions like
@code{insert-image}.
@end defun
Here's a complete example that creates and inserts an image with a
circle:
@lisp
(let ((svg (svg-create 400 400 :stroke-width 10)))
(svg-gradient svg "gradient1" 'linear '((0 . "red") (100 . "blue")))
(svg-circle svg 200 200 100 :gradient "gradient1"
:stroke-color "green")
(insert-image (svg-image svg)))
@end lisp
@subsubheading SVG Path Commands
@cindex svg path commands
@anchor{SVG Path Commands}
@dfn{SVG paths} allow creation of complex images by combining lines,
curves, arcs, and other basic shapes. The functions described below
allow invoking SVG path commands from a Lisp program.
@deffn Command moveto points
Move the pen to the first point in @var{points}. Additional points
are connected with lines. @var{points} is a list of X/Y coordinate
pairs. Subsequent @command{moveto} commands represent the start of a
new @dfn{subpath}.
@lisp
(svg-path svg '((moveto ((200 . 100) (100 . 200) (0 . 100))))
:fill "white" :stroke "black")
@end lisp
@end deffn
@deffn Command closepath
End the current subpath by connecting it back to its initial point. A
line is drawn along the connection.
@lisp
(svg-path svg '((moveto ((200 . 100) (100 . 200) (0 . 100)))
(closepath)
(moveto ((75 . 125) (100 . 150) (125 . 125)))
(closepath))
:fill "red" :stroke "black")
@end lisp
@end deffn
@deffn Command lineto points
Draw a line from the current point to the first element in
@var{points}, a list of X/Y position pairs. If more than one point is
specified, draw a polyline.
@lisp
(svg-path svg '((moveto ((200 . 100)))
(lineto ((100 . 200) (0 . 100))))
:fill "yellow" :stroke "red")
@end lisp
@end deffn
@deffn Command horizontal-lineto x-coordinates
Draw a horizontal line from the current point to the first element in
@var{x-coordinates}. Specifying multiple coordinates is possible,
although this usually doesn't make sense.
@lisp
(svg-path svg '((moveto ((100 . 200)))
(horizontal-lineto (300)))
:stroke "green")
@end lisp
@end deffn
@deffn Command vertical-lineto y-coordinates
Draw vertical lines.
@lisp
(svg-path svg '((moveto ((200 . 100)))
(vertical-lineto (300)))
:stroke "green")
@end lisp
@end deffn
@deffn Command curveto coordinate-sets
Using the first element in @var{coordinate-sets}, draw a cubic Bézier
curve from the current point. If there are multiple coordinate sets,
draw a polybezier. Each coordinate set is a list of the form
@code{(@var{x1} @var{y1} @var{x2} @var{y2} @var{x} @var{y})}, where
@w{(@var{x}, @var{y})} is the curve's end point. @w{(@var{x1},
@var{y1})} and @w{(@var{x2}, @var{y2})} are control points at the
beginning and at the end, respectively.
@lisp
(svg-path svg '((moveto ((100 . 100)))
(curveto ((200 100 100 200 200 200)
(300 200 0 100 100 100))))
:fill "transparent" :stroke "red")
@end lisp
@end deffn
@deffn Command smooth-curveto coordinate-sets
Using the first element in @var{coordinate-sets}, draw a cubic Bézier
curve from the current point. If there are multiple coordinate sets,
draw a polybezier. Each coordinate set is a list of the form
@code{(@var{x2} @var{y2} @var{x} @var{y})}, where @w{(@var{x},
@var{y})} is the curve's end point and @w{(@var{x2}, @var{y2})} is the
corresponding control point. The first control point is the
reflection of the second control point of the previous command
relative to the current point, if that command was @command{curveto}
or @command{smooth-curveto}. Otherwise the first control point
coincides with the current point.
@lisp
(svg-path svg '((moveto ((100 . 100)))
(curveto ((200 100 100 200 200 200)))
(smooth-curveto ((0 100 100 100))))
:fill "transparent" :stroke "blue")
@end lisp
@end deffn
@deffn Command quadratic-bezier-curveto coordinate-sets
Using the first element in @var{coordinate-sets}, draw a quadratic
Bézier curve from the current point. If there are multiple coordinate
sets, draw a polybezier. Each coordinate set is a list of the form
@code{(@var{x1} @var{y1} @var{x} @var{y})}, where @w{(@var{x},
@var{y})} is the curve's end point and @w{(@var{x1}, @var{y1})} is the
control point.
@lisp
(svg-path svg '((moveto ((200 . 100)))
(quadratic-bezier-curveto ((300 100 300 200)))
(quadratic-bezier-curveto ((300 300 200 300)))
(quadratic-bezier-curveto ((100 300 100 200)))
(quadratic-bezier-curveto ((100 100 200 100))))
:fill "transparent" :stroke "pink")
@end lisp
@end deffn
@deffn Command smooth-quadratic-bezier-curveto coordinate-sets
Using the first element in @var{coordinate-sets}, draw a quadratic
Bézier curve from the current point. If there are multiple coordinate
sets, draw a polybezier. Each coordinate set is a list of the form
@code{(@var{x} @var{y})}, where @w{(@var{x}, @var{y})} is the curve's
end point. The control point is the reflection of the control point
of the previous command relative to the current point, if that command
was @command{quadratic-bezier-curveto} or
@command{smooth-quadratic-bezier-curveto}. Otherwise the control
point coincides with the current point.
@lisp
(svg-path svg '((moveto ((200 . 100)))
(quadratic-bezier-curveto ((300 100 300 200)))
(smooth-quadratic-bezier-curveto ((200 300)))
(smooth-quadratic-bezier-curveto ((100 200)))
(smooth-quadratic-bezier-curveto ((200 100))))
:fill "transparent" :stroke "lightblue")
@end lisp
@end deffn
@deffn Command elliptical-arc coordinate-sets
Using the first element in @var{coordinate-sets}, draw an elliptical
arc from the current point. If there are multiple coordinate sets,
draw a sequence of elliptical arcs. Each coordinate set is a list of
the form @code{(@var{rx} @var{ry} @var{x} @var{y})}, where
@w{(@var{x}, @var{y})} is the end point of the ellipse, and
@w{(@var{rx}, @var{ry})} are its radii. Attributes may be appended to
the list:
@table @code
@item :x-axis-rotation
The angle in degrees by which the x-axis of the ellipse is rotated
relative to the x-axis of the current coordinate system.
@item :large-arc
If set to @code{t}, draw an arc sweep greater than or equal to 180
degrees. Otherwise, draw an arc sweep smaller than or equal to 180
degrees.
@item :sweep
If set to @code{t}, draw an arc in @dfn{positive angle direction}.
Otherwise, draw it in @dfn{negative angle direction}.
@end table
@lisp
(svg-path svg '((moveto ((200 . 250)))
(elliptical-arc ((75 75 200 350))))
:fill "transparent" :stroke "red")
(svg-path svg '((moveto ((200 . 250)))
(elliptical-arc ((75 75 200 350 :large-arc t))))
:fill "transparent" :stroke "green")
(svg-path svg '((moveto ((200 . 250)))
(elliptical-arc ((75 75 200 350 :sweep t))))
:fill "transparent" :stroke "blue")
(svg-path svg '((moveto ((200 . 250)))
(elliptical-arc ((75 75 200 350 :large-arc t
:sweep t))))
:fill "transparent" :stroke "gray")
(svg-path svg '((moveto ((160 . 100)))
(elliptical-arc ((40 100 80 0)))
(elliptical-arc ((40 100 -40 -70
:x-axis-rotation -120)))
(elliptical-arc ((40 100 -40 70
:x-axis-rotation -240))))
:stroke "pink" :fill "lightblue"
:relative t)
@end lisp
@end deffn
@node Other Image Types
@subsection Other Image Types
@cindex PBM
For PBM images, specify image type @code{pbm}. Color, gray-scale and
monochromatic images are supported. For mono PBM images, two additional
image properties are supported.
@table @code
@item :foreground @var{foreground}
The value, @var{foreground}, should be a string specifying the image
foreground color, or @code{nil} for the default color. This color is
used for each pixel in the PBM that is 1. The default is the frame's
foreground color.
@item :background @var{background}
The value, @var{background}, should be a string specifying the image
background color, or @code{nil} for the default color. This color is
used for each pixel in the PBM that is 0. The default is the frame's
background color.
@end table
@noindent
The remaining image types that Emacs can support are:
@table @asis
@item GIF
Image type @code{gif}.
Supports the @code{:index} property. @xref{Multi-Frame Images}.
@item JPEG
Image type @code{jpeg}.
@item PNG
Image type @code{png}.
@item TIFF
Image type @code{tiff}.
Supports the @code{:index} property. @xref{Multi-Frame Images}.
@item WebP
Image type @code{webp}.
@end table
@node Defining Images
@subsection Defining Images
@cindex define image
The functions @code{create-image}, @code{defimage} and
@code{find-image} provide convenient ways to create image descriptors.
@defun create-image file-or-data &optional type data-p &rest props
This function creates and returns an image descriptor which uses the
data in @var{file-or-data}. @var{file-or-data} can be a file name or
a string containing the image data; @var{data-p} should be @code{nil}
for the former case, non-@code{nil} for the latter case. If
@var{file-or-data} is a relative file name, the function will search
for it in directories mentioned in @code{image-load-path}.
The optional argument @var{type} is a symbol specifying the image type.
If @var{type} is omitted or @code{nil}, @code{create-image} tries to
determine the image type from the file's first few bytes, or else
from the file's name.
The remaining arguments, @var{props}, specify additional image
properties---for example,
@example
(create-image "foo.xpm" 'xpm nil :mask 'heuristic)
@end example
@noindent
@xref{Image Descriptors}, for the list of supported properties. Some
properties are specific to certain image types, and are described in
subsections specific to those types.
The function returns @code{nil} if images of this type are not
supported. Otherwise it returns an image descriptor.
@end defun
@defmac defimage symbol specs &optional doc
This macro defines @var{symbol} as an image name. The arguments
@var{specs} is a list which specifies how to display the image.
The third argument, @var{doc}, is an optional documentation string.
Each argument in @var{specs} has the form of a property list, and each
one should specify at least the @code{:type} property and either the
@code{:file} or the @code{:data} property. The value of @code{:type}
should be a symbol specifying the image type, the value of
@code{:file} is the file to load the image from, and the value of
@code{:data} is a string containing the actual image data. Here is an
example:
@example
(defimage test-image
((:type xpm :file "~/test1.xpm")
(:type xbm :file "~/test1.xbm")))
@end example
@code{defimage} tests each argument, one by one, to see if it is
usable---that is, if the type is supported and the file exists. The
first usable argument is used to make an image descriptor which is
stored in @var{symbol}.
If none of the alternatives will work, then @var{symbol} is defined
as @code{nil}.
@end defmac
@defun image-property image property
Return the value of @var{property} in @var{image}. Properties can be
set by using @code{setf}. Setting a property to @code{nil} will
remove the property from the image.
@end defun
@defun find-image specs
This function provides a convenient way to find an image satisfying one
of a list of image specifications @var{specs}.
Each specification in @var{specs} is a property list with contents
depending on image type. All specifications must at least contain the
properties @code{:type @var{type}} and either @w{@code{:file @var{file}}}
or @w{@code{:data @var{data}}}, where @var{type} is a symbol specifying
the image type, e.g., @code{xbm}, @var{file} is the file to load the
image from, and @var{data} is a string containing the actual image data.
The first specification in the list whose @var{type} is supported, and
@var{file} exists, is used to construct the image specification to be
returned. If no specification is satisfied, @code{nil} is returned.
The image is looked for in @code{image-load-path}.
@end defun
@defopt image-load-path
This variable's value is a list of locations in which to search for
image files. If an element is a string or a variable symbol whose
value is a string, the string is taken to be the name of a directory
to search. If an element is a variable symbol whose value is a list,
that is taken to be a list of directories to search.
The default is to search in the @file{images} subdirectory of the
directory specified by @code{data-directory}, then the directory
specified by @code{data-directory}, and finally in the directories in
@code{load-path}. Subdirectories are not automatically included in
the search, so if you put an image file in a subdirectory, you have to
supply the subdirectory explicitly. For example, to find the
image @file{images/foo/bar.xpm} within @code{data-directory}, you
should specify the image as follows:
@example
(defimage foo-image '((:type xpm :file "foo/bar.xpm")))
@end example
@end defopt
@defun image-load-path-for-library library image &optional path no-error
This function returns a suitable search path for images used by the
Lisp package @var{library}.
The function searches for @var{image} first using @code{image-load-path},
excluding @file{@code{data-directory}/images}, and then in
@code{load-path}, followed by a path suitable for @var{library}, which
includes @file{../../etc/images} and @file{../etc/images} relative to
the library file itself, and finally in
@file{@code{data-directory}/images}.
Then this function returns a list of directories which contains first
the directory in which @var{image} was found, followed by the value of
@code{load-path}. If @var{path} is given, it is used instead of
@code{load-path}.
If @var{no-error} is non-@code{nil} and a suitable path can't be
found, don't signal an error. Instead, return a list of directories as
before, except that @code{nil} appears in place of the image directory.
Here is an example of using @code{image-load-path-for-library}:
@example
(defvar image-load-path) ; shush compiler
(let* ((load-path (image-load-path-for-library
"mh-e" "mh-logo.xpm"))
(image-load-path (cons (car load-path)
image-load-path)))
(mh-tool-bar-folder-buttons-init))
@end example
@end defun
@vindex image-scaling-factor
Images are automatically scaled when created based on the
@code{image-scaling-factor} variable. The value is either a floating
point number (where numbers higher than 1 means to increase the size
and lower means to shrink the size), or the symbol @code{auto}, which
will compute a scaling factor based on the font pixel size.
@node Showing Images
@subsection Showing Images
@cindex show image
You can use an image descriptor by setting up the @code{display}
property yourself, but it is easier to use the functions in this
section.
@defun insert-image image &optional string area slice inhibit-isearch
This function inserts @var{image} in the current buffer at point. The
value @var{image} should be an image descriptor; it could be a value
returned by @code{create-image}, or the value of a symbol defined with
@code{defimage}. The argument @var{string} specifies the text to put
in the buffer to hold the image. If it is omitted or @code{nil},
@code{insert-image} uses @code{" "} by default.
The argument @var{area} specifies whether to put the image in a margin.
If it is @code{left-margin}, the image appears in the left margin;
@code{right-margin} specifies the right margin. If @var{area} is
@code{nil} or omitted, the image is displayed at point within the
buffer's text.
The argument @var{slice} specifies a slice of the image to insert. If
@var{slice} is @code{nil} or omitted the whole image is inserted.
(However, note that images are chopped on display at the window's
right edge, because wrapping images is not supported.) Otherwise,
@var{slice} is a list @code{(@var{x} @var{y} @var{width}
@var{height})} which specifies the @var{x} and @var{y} positions and
@var{width} and @var{height} of the image area to insert. Integer
values are in units of pixels. A floating-point number in the range
0.0--1.0 stands for that fraction of the width or height of the entire
image.
Internally, this function inserts @var{string} in the buffer, and gives
it a @code{display} property which specifies @var{image}. @xref{Display
Property}. By default, doing interactive searches in the buffer will
consider @var{string} when searching. If @var{inhibit-isearch} is
non-@code{nil}, this is inhibited.
@end defun
@cindex slice, image
@cindex image slice
@defun insert-sliced-image image &optional string area rows cols
This function inserts @var{image} in the current buffer at point, like
@code{insert-image}, but splits the image into @var{rows}x@var{cols}
equally sized slices.
Emacs displays each slice as a
separate image, and allows more intuitive scrolling up/down, instead of
jumping up/down the entire image when paging through a buffer that
displays (large) images.
@end defun
@defun put-image image pos &optional string area
This function puts image @var{image} in front of @var{pos} in the
current buffer. The argument @var{pos} should be an integer or a
marker. It specifies the buffer position where the image should appear.
The argument @var{string} specifies the text that should hold the image
as an alternative to the default @samp{x}.
The argument @var{image} must be an image descriptor, perhaps returned
by @code{create-image} or stored by @code{defimage}.
The argument @var{area} specifies whether to put the image in a margin.
If it is @code{left-margin}, the image appears in the left margin;
@code{right-margin} specifies the right margin. If @var{area} is
@code{nil} or omitted, the image is displayed at point within the
buffer's text.
Internally, this function creates an overlay, and gives it a
@code{before-string} property containing text that has a @code{display}
property whose value is the image. (Whew! that was a mouthful@dots{})
@end defun
@defun remove-images start end &optional buffer
This function removes images in @var{buffer} between positions
@var{start} and @var{end}. If @var{buffer} is omitted or @code{nil},
images are removed from the current buffer.
This removes only images that were put into @var{buffer} the way
@code{put-image} does it, not images that were inserted with
@code{insert-image} or in other ways.
@end defun
@defun image-size spec &optional pixels frame
@cindex size of image
This function returns the size of an image as a pair
@w{@code{(@var{width} . @var{height})}}. @var{spec} is an image
specification. @var{pixels} non-@code{nil} means return sizes measured
in pixels, otherwise return sizes measured in the default character size
of @var{frame} (@pxref{Frame Font}). @var{frame} is the frame on which
the image will be displayed. @var{frame} @code{nil} or omitted means
use the selected frame (@pxref{Input Focus}).
@end defun
@defvar max-image-size
This variable is used to define the maximum size of image that Emacs
will load. Emacs will refuse to load (and display) any image that is
larger than this limit.
If the value is an integer, it directly specifies the maximum
image height and width, measured in pixels. If it is floating
point, it specifies the maximum image height and width
as a ratio to the frame height and width. If the value is
non-numeric, there is no explicit limit on the size of images.
The purpose of this variable is to prevent unreasonably large images
from accidentally being loaded into Emacs. It only takes effect the
first time an image is loaded. Once an image is placed in the image
cache, it can always be displayed, even if the value of
@code{max-image-size} is subsequently changed (@pxref{Image Cache}).
@end defvar
@defun image-at-point-p
This function returns @code{t} if point is on an image, and @code{nil}
otherwise.
@end defun
@cindex operations on images
Images inserted with the insertion functions above also get a local
keymap installed in the text properties (or overlays) that span the
displayed image. This keymap defines the following commands:
@table @kbd
@findex image-increase-size
@item i +
Increase the image size (@code{image-increase-size})
@findex image-decrease-size
@item i -
Decrease the image size (@code{image-decrease-size}).
@findex image-rotate
@item i r
Rotate the image (@code{image-rotate}).
@findex image-flip-horizontally
@item i h
Flip the image horizontally (@code{image-flip-horizontally}).
@findex image-flip-vertically
@item i v
Flip the image vertically (@code{image-flip-vertically}).
@findex image-save
@item i o
Save the image to a file (@code{image-save}).
@findex image-crop
@item i c
Interactively crop the image (@code{image-crop}).
@findex image-cut
@item i x
Interactively cut a rectangle from the image (@code{image-cut}).
@end table
@xref{Image Mode,,, emacs, The GNU Emacs Manual}, for more details
about these image-specific key bindings.
@node Multi-Frame Images
@subsection Multi-Frame Images
@cindex multi-frame images
@cindex animation
@cindex image animation
@cindex image frames
Some image files can contain more than one image. We say that there
are multiple ``frames'' in the image. At present, Emacs supports
multiple frames for GIF, TIFF, and certain ImageMagick formats such as
DJVM@.
The frames can be used either to represent multiple pages (this is
usually the case with multi-frame TIFF files, for example), or to
create animation (usually the case with multi-frame GIF files).
A multi-frame image has a property @code{:index}, whose value is an
integer (counting from 0) that specifies which frame is being displayed.
@defun image-multi-frame-p image
This function returns non-@code{nil} if @var{image} contains more than
one frame. The actual return value is a cons @code{(@var{nimages}
. @var{delay})}, where @var{nimages} is the number of frames and
@var{delay} is the delay in seconds between them, or @code{nil}
if the image does not specify a delay. Images that are intended to be
animated usually specify a frame delay, whereas ones that are intended
to be treated as multiple pages do not.
@end defun
@defun image-current-frame image
This function returns the index of the current frame number for
@var{image}, counting from 0.
@end defun
@defun image-show-frame image n &optional nocheck
This function switches @var{image} to frame number @var{n}. It
replaces a frame number outside the valid range with that of the end
of the range, unless @var{nocheck} is non-@code{nil}. If @var{image}
does not contain a frame with the specified number, the image displays
as a hollow box.
@end defun
@defun image-animate image &optional index limit
This function animates @var{image}. The optional integer @var{index}
specifies the frame from which to start (default 0). The optional
argument @var{limit} controls the length of the animation. If omitted
or @code{nil}, the image animates once only; if @code{t} it loops
forever; if a number animation stops after that many seconds.
@end defun
@vindex image-minimum-frame-delay
@vindex image-default-frame-delay
@noindent Animation operates by means of a timer. Note that Emacs imposes a
minimum frame delay of 0.01 (@code{image-minimum-frame-delay}) seconds.
If the image itself does not specify a delay, Emacs uses
@code{image-default-frame-delay}.
@defun image-animate-timer image
This function returns the timer responsible for animating @var{image},
if there is one.
@end defun
@node Image Cache
@subsection Image Cache
@cindex image cache
Emacs caches images so that it can display them again more
efficiently. When Emacs displays an image, it searches the image
cache for an existing image specification @code{equal} to the desired
specification. If a match is found, the image is displayed from the
cache. Otherwise, Emacs loads the image normally.
@defun image-flush spec &optional frame
This function removes the image with specification @var{spec} from the
image cache of frame @var{frame}. Image specifications are compared
using @code{equal}. If @var{frame} is @code{nil}, it defaults to the
selected frame. If @var{frame} is @code{t}, the image is flushed on
all existing frames.
In Emacs's current implementation, each graphical terminal possesses an
image cache, which is shared by all the frames on that terminal
(@pxref{Multiple Terminals}). Thus, refreshing an image in one frame
also refreshes it in all other frames on the same terminal.
@end defun
One use for @code{image-flush} is to tell Emacs about a change in an
image file. If an image specification contains a @code{:file}
property, the image is cached based on the file's contents when the
image is first displayed. Even if the file subsequently changes,
Emacs continues displaying the old version of the image. Calling
@code{image-flush} flushes the image from the cache, forcing Emacs to
re-read the file the next time it needs to display that image.
Another use for @code{image-flush} is for memory conservation. If
your Lisp program creates a large number of temporary images over a
period much shorter than @code{image-cache-eviction-delay} (see
below), you can opt to flush unused images yourself, instead of
waiting for Emacs to do it automatically.
@defun clear-image-cache &optional filter
This function clears an image cache, removing all the images stored in
it. If @var{filter} is omitted or @code{nil}, it clears the cache for
the selected frame. If @var{filter} is a frame, it clears the cache
for that frame. If @var{filter} is @code{t}, all image caches are
cleared. Otherwise, @var{filter} is taken to be a file name, and all
images associated with that file name are removed from all image
caches.
@end defun
If an image in the image cache has not been displayed for a specified
period of time, Emacs removes it from the cache and frees the
associated memory.
@defvar image-cache-eviction-delay
This variable specifies the number of seconds an image can remain in
the cache without being displayed. When an image is not displayed for
this length of time, Emacs removes it from the image cache.
Under some circumstances, if the number of images in the cache grows
too large, the actual eviction delay may be shorter than this.
If the value is @code{nil}, Emacs does not remove images from the cache
except when you explicitly clear it. This mode can be useful for
debugging.
@end defvar
@defun image-cache-size
This function returns the total size of the current image cache, in
bytes. An image of size 200x100 with 24 bits per color will have a
cache size of 60000 bytes, for instance.
@end defun
@node Icons
@section Icons
Emacs sometimes uses buttons (for clicking on) or small graphics (to
illustrate something). Since Emacs is available on a wide variety of
systems with different capabilities, and users have different
preferences, Emacs provides a facility to handle this in a convenient
way, allowing customization, graceful degradation, accessibility, as
well as themability: @dfn{Icons}.
The central macro here is @code{define-icon}, and here's a simple
example:
@lisp
(define-icon outline-open button
'((image "right.svg" "open.xpm" "open.pbm" :height line)
(emoji "▶️")
(symbol "▶" "➤")
(text "open" :face icon-button))
"Icon used for buttons for opening a section in outline buffers."
:version "29.1"
:help-echo "Open this section")
@end lisp
Which alternative will actually be displayed depends on the value of
the user option @code{icon-preference} (@pxref{Icons,,, emacs, The GNU
Emacs Manual}) and on the results of run-time checks for what the
current frame's terminal can actually display.
The macro in the example above defines @code{outline-open} as an icon,
and inherits properties from the icon called @code{button} (so this is
meant as a clickable button to be inserted in a buffer). It is
followed by a list of @dfn{icon types} along with the actual icon
shapes themselves. In addition, there's a doc string and various
keywords that contain additional information and properties.
To instantiate an icon, you use @code{icon-string}, which will
consult the current Customize theming, and the @code{icon-preference}
user option, and finally what the Emacs is able to actually display.
If @code{icon-preference} is @code{(image emoji symbol text)} (i.e.,
allowing all of these forms of icons), in this case,
@code{icon-string} will first check that Emacs is able to display
images at all, and then whether it has support for each of those
different image formats. If that fails, Emacs will check whether
Emacs can display emojis (in the current frame). If that fails, it'll
check whether it can display the symbol in question. If that fails,
it'll use the plain text version.
For instance, if @code{icon-preference} doesn't contain @code{image}
or @code{emoji}, it'll skip those entries.
Code can confidently call @code{icon-string} in all circumstances and
be sure that something readable will appear on the screen, no
matter whether the user is on a graphical terminal or a text terminal,
and no matter which features Emacs was built with.
@defmac define-icon name parent specs doc &rest keywords
Define an icon @var{name}, a symbol, with the display alternatives in
@var{spec}, that can be later instantiated using @code{icon-string}.
The @var{name} is the name of the resulting keyword.
The resulting icon will inherit specs from @var{parent}, and from
their parent's parents, and so on, and the lowest descendent element
wins.
@var{specs} is a list of icon specifications. The first element of each
specification is the type, and the rest is something that can be used
as an icon of that type, and then optionally followed by a keyword
list. The following icon types are available:
@cindex icon types
@table @code
@item image
In this case, there may be many images listed as candidates. Emacs
will choose the first one that the current Emacs instance can show.
If an image is listed is an absolute file name, it's used as is, but it's
otherwise looked up in the list @code{image-load-path}
(@pxref{Defining Images}).
@item emoji
This should be a (possibly colorful) emoji.
@item symbol
This should be a (monochrome) symbol character.
@item text
Icons should also have a textual fallback. This can also be used for
the visually impaired: if @code{icon-preference} is just
@code{(text)}, all icons will be replaced by text.
@end table
Various keywords may follow the list of icon specifications. For
instance:
@example
(symbol "▶" "➤" :face icon-button)
@end example
Unknown keywords are ignored. The following keywords are allowed:
@cindex icon keywords
@table @code
@item :face
The face to be used for the icon.
@item :height
This is only valid for @code{image} icons, and can be either a number
(which specifies the height in pixels), or the symbol @code{line},
which will use the default line height in the currently selected
window.
@item :width
This is only valid for @code{image} icons, and can be either a number
(which specifies the width in pixels), or the symbol @code{font},
which will use the width in pixels of the current buffer's default
face font.
@end table
@var{doc} should be a doc string.
@var{keywords} is a list of keyword/value pairs. The following
keywords are allowed:
@table @code
@item :version
The (approximate) Emacs version this button first appeared. (This
keyword is mandatory.)
@item :group
The customization group this icon belongs in. If not present, it is
inferred.
@item :help-echo
The help string shown when hovering over the icon with the mouse
pointer.
@end table
@end defmac
@defun icon-string icon
This function returns a string suitable for display in the current
buffer for @var{icon}.
@end defun
@defun icon-elements icon
Alternatively, you can get a ``deconstructed'' version of @var{icon}
with this function. It returns a plist (@pxref{Property Lists}) where
the keys are @code{string}, @code{face} and @var{image}. (The latter
is only present if the icon is represented by an image.) This can be
useful if the icon isn't to be inserted directly in the buffer, but
needs some sort of pre-processing first.
@end defun
Icons can be customized with @kbd{M-x customize-icon}. Themes can
specify changes to icons with, for instance:
@lisp
(custom-theme-set-icons
'my-theme
'(outline-open ((image :height 100)
(text " OPEN ")))
'(outline-close ((image :height 100)
(text " CLOSE " :face warning))))
@end lisp
@node Xwidgets
@section Embedded Native Widgets
@cindex xwidget
@cindex embedded widgets
@cindex webkit browser widget
Emacs is able to display native widgets, such as GTK+ WebKit widgets,
in Emacs buffers when it was built with the necessary support
libraries and is running on a graphical terminal. To test whether
Emacs supports display of embedded widgets, check that the
@code{xwidget-internal} feature is available (@pxref{Named Features}).
To display an embedded widget in a buffer, you must first create an
xwidget object, and then use that object as the display specifier
in a @code{display} text or overlay property (@pxref{Display
Property}).
Embedded widgets can send events notifying Lisp code about changes
occurring within them. (@pxref{Xwidget Events}).
@defun make-xwidget type title width height arguments &optional buffer related
This creates and returns an xwidget object. If
@var{buffer} is omitted or @code{nil}, it defaults to the current
buffer. If @var{buffer} names a buffer that doesn't exist, it will be
created. The @var{type} identifies the type of the xwidget component,
it can be one of the following:
@table @code
@item webkit
The WebKit component.
@end table
The @var{width} and @var{height} arguments specify the widget size in
pixels, and @var{title}, a string, specifies its title. @var{related}
is used internally by the WebKit widget, and specifies another WebKit
widget that the newly created widget should share settings and
subprocesses with.
The xwidget that is returned will be killed alongside its buffer
(@pxref{Killing Buffers}). You can also kill it using
@code{kill-xwidget}. Once it is killed, the xwidget may continue to
exist as a Lisp object and act as a @code{display} property until all
references to it are gone, but most actions that can be performed on
live xwidgets will no longer be available.
@end defun
@defun xwidgetp object
This function returns @code{t} if @var{object} is an xwidget,
@code{nil} otherwise.
@end defun
@defun xwidget-live-p object
This function returns @code{t} if @var{object} is an xwidget that
hasn't been killed, and @code{nil} otherwise.
@end defun
@defun kill-xwidget xwidget
This function kills @var{xwidget}, by removing it from its buffer and
releasing window system resources it holds.
@end defun
@cindex xwidget property list
@defun xwidget-plist xwidget
This function returns the property list of @var{xwidget}.
@end defun
@defun set-xwidget-plist xwidget plist
This function replaces the property list of @var{xwidget} with a new
property list given by @var{plist}.
@end defun
@defun xwidget-buffer xwidget
This function returns the buffer of @var{xwidget}. If @var{xwidget}
has been killed, it returns @code{nil}.
@end defun
@defun set-xwidget-buffer xwidget buffer
This function sets the buffer of @var{xwidget} to @var{buffer}.
@end defun
@defun get-buffer-xwidgets buffer
This function returns a list of xwidget objects associated with the
@var{buffer}, which can be specified as a buffer object or a name of
an existing buffer, a string. The value is @code{nil} if @var{buffer}
contains no xwidgets.
@end defun
@defun xwidget-webkit-goto-uri xwidget uri
This function browses the specified @var{uri} in the given
@var{xwidget}. The @var{uri} is a string that specifies the name of a
file or a URL. @c FIXME: What else can a URI specify in this context?
@end defun
@defun xwidget-webkit-execute-script xwidget script
This function causes the browser widget specified by @var{xwidget} to
execute the specified JavaScript @code{script}.
@end defun
@defun xwidget-webkit-execute-script-rv xwidget script &optional default
This function executes the specified @var{script} like
@code{xwidget-webkit-execute-script} does, but it also returns the
script's return value as a string. If @var{script} doesn't return a
value, this function returns @var{default}, or @code{nil} if
@var{default} was omitted.
@end defun
@defun xwidget-webkit-get-title xwidget
This function returns the title of @var{xwidget} as a string.
@end defun
@defun xwidget-resize xwidget width height
This function resizes the specified @var{xwidget} to the size
@var{width}x@var{height} pixels.
@end defun
@defun xwidget-size-request xwidget
This function returns the desired size of @var{xwidget} as a list of
the form @code{(@var{width} @var{height})}. The dimensions are in
pixels.
@end defun
@defun xwidget-info xwidget
This function returns the attributes of @var{xwidget} as a vector of
the form @code{[@var{type} @var{title} @var{width} @var{height}]}.
The attributes are usually determined by @code{make-xwidget} when the
xwidget is created.
@end defun
@defun set-xwidget-query-on-exit-flag xwidget flag
This function allows you to arrange that Emacs will ask the user for
confirmation before exiting or before killing a buffer that has
@var{xwidget} associated with it. If @var{flag} is non-@code{nil},
Emacs will query the user, otherwise it will not.
@end defun
@defun xwidget-query-on-exit-flag xwidget
This function returns the current setting of @var{xwidget}s
query-on-exit flag, either @code{t} or @code{nil}.
@end defun
@defun xwidget-perform-lispy-event xwidget event frame
Send an input event @var{event} to @var{xwidget}. The precise action
performed is platform-specific. @xref{Input Events}.
You can optionally pass the frame on which the event was generated via
@var{frame}. On X11, modifier keys in key events will not be
considered if @var{frame} is @code{nil}, and the selected frame is not
an X-Windows frame.
On GTK, only keyboard and function key events are supported. Mouse,
motion, and click events are dispatched to the xwidget without going
through Lisp code, and as such shouldn't require this function to be
called.
@end defun
@defun xwidget-webkit-search query xwidget &optional case-insensitive backwards wrap-around
Start an incremental search on the WebKit widget @var{xwidget} with
the string @var{query} as the query. @var{case-insensitive} denotes
whether or not the search is case-insensitive, @var{backwards}
determines if the search is performed backwards towards the start of
the document, and @var{wrap-around} determines whether or not the
search terminates at the end of the document.
If the function is called while a search query is already present,
then the query specified here will replace the existing query.
To stop a search query, use @code{xwidget-webkit-finish-search}.
@end defun
@defun xwidget-webkit-next-result xwidget
Display the next search result in @var{xwidget}. This function will
signal an error if a search query has not been already started in
@var{xwidget} through @code{xwidget-webkit-search}.
If @code{wrap-around} was non-@code{nil} when @code{xwidget-webkit-search}
was called, then the search will restart from the beginning of the
document when its end is reached.
@end defun
@defun xwidget-webkit-previous-result xwidget
Display the previous search result in @var{xwidget}. This function
signals an error if a search query has not been already started in
@var{xwidget} through @code{xwidget-webkit-search}.
If @code{wrap-around} was non-@code{nil} when @code{xwidget-webkit-search}
was called, then the search will restart from the end of the
document when its beginning is reached.
@end defun
@defun xwidget-webkit-finish-search xwidget
Finish a search operation started with @code{xwidget-webkit-search} in
@var{xwidget}. If there is no query currently ongoing, this function
signals an error.
@end defun
@defun xwidget-webkit-load-html xwidget text &optional base-uri
Load @var{text}, a string, into @var{xwidget}, which should be a
WebKit xwidget. Any HTML markup in @var{text} will be processed
by @var{xwidget} while rendering the text.
Optional argument @var{base-uri}, which should be a string, specifies
the absolute location of the web resources referenced by @var{text},
to be used for resolving relative links in @var{text}.
@end defun
@defun xwidget-webkit-goto-history xwidget rel-pos
Make @var{xwidget}, a WebKit widget, load the @var{rel-pos}th element
in its navigation history.
If @var{rel-pos} is zero, the current page will be reloaded instead.
@end defun
@defun xwidget-webkit-back-forward-list xwidget &optional limit
Return the navigation history of @var{xwidget}, up to @var{limit}
items in each direction. If not specified, @var{limit} defaults to
50.
The returned value is a list of the form @w{@code{(@var{back}
@var{here} @var{forward})}}, where @var{here} is the current
navigation item, while @var{back} is a list of items containing the
items recorded by WebKit before the current navigation item, and
@var{forward} is a list of items recorded after the current navigation
item. @var{back}, @var{here} and @var{forward} can all be @code{nil}.
When @var{here} is @code{nil}, it means that no items have been
recorded yet; if @var{back} or @var{forward} are @code{nil}, it means
that there is no history recorded before or after the current item
respectively.
Navigation items are themselves lists of the form @w{@code{(@var{idx}
@var{title} @var{uri})}}. In these lists, @var{idx} is an index that
can be passed to @code{xwidget-webkit-goto-history}, @var{title} is
the human-readable title of the item, and @var{uri} is the URI of the
item. The user should normally have no reason to load @var{uri}
manually to reach a specific history item. Instead, @var{idx} should
be passed as an index to @code{xwidget-webkit-goto-history}.
@end defun
@defun xwidget-webkit-estimated-load-progress xwidget
Return an estimate of how much data is remaining to be transferred
before the page displayed by the WebKit widget @var{xwidget} is fully
loaded.
The value returned is a float ranging between 0.0 and 1.0.
@end defun
@defun xwidget-webkit-set-cookie-storage-file xwidget file
Make the WebKit widget @var{xwidget} store cookies in @var{file}.
@var{file} must be an absolute file name. The new setting will also
affect any xwidget that was created with @var{xwidget} as the
@code{related} argument to @code{make-xwidget}, and widgets related to
those as well.
If this function is not called at least once on @var{xwidget} or a
related widget, @var{xwidget} will not store cookies on disk at all.
@end defun
@defun xwidget-webkit-stop-loading xwidget
Terminate any data transfer still in progress in the WebKit widget
@var{xwidget} as part of a page-loading operation. If a page is not
being loaded, this function does nothing.
@end defun
@node Buttons
@section Buttons
@cindex buttons in buffers
@cindex clickable buttons in buffers
The Button package defines functions for inserting and manipulating
@dfn{buttons} that can be activated with the mouse or via keyboard
commands. These buttons are typically used for various kinds of
hyperlinks.
A button is essentially a set of text or overlay properties,
attached to a stretch of text in a buffer. These properties are
called @dfn{button properties}. One of these properties, the
@dfn{action property}, specifies a function which is called when the
user invokes the button using the keyboard or the mouse. The action
function may examine the button and use its other properties as
desired.
In some ways, the Button package duplicates the functionality in the
Widget package. @xref{Top, , Introduction, widget, The Emacs Widget
Library}. The advantage of the Button package is that it is faster,
smaller, and simpler to program. From the point of view of the user,
the interfaces produced by the two packages are very similar.
@menu
* Button Properties:: Button properties with special meanings.
* Button Types:: Defining common properties for classes of buttons.
* Making Buttons:: Adding buttons to Emacs buffers.
* Manipulating Buttons:: Getting and setting properties of buttons.
* Button Buffer Commands:: Buffer-wide commands and bindings for buttons.
@end menu
@node Button Properties
@subsection Button Properties
@cindex button properties
Each button has an associated list of properties defining its
appearance and behavior, and other arbitrary properties may be used
for application specific purposes. The following properties have
special meaning to the Button package:
@table @code
@item action
@kindex action @r{(button property)}
The function to call when the user invokes the button, which is passed
the single argument @var{button}. By default this is @code{ignore},
which does nothing.
@item mouse-action
@kindex mouse-action @r{(button property)}
This is similar to @code{action}, and when present, will be used
instead of @code{action} for button invocations resulting from
mouse-clicks (instead of the user hitting @key{RET}). If not
present, mouse-clicks use @code{action} instead.
@item face
@kindex face @r{(button property)}
This is an Emacs face controlling how buttons of this type are
displayed; by default this is the @code{button} face.
@item mouse-face
@kindex mouse-face @r{(button property)}
This is an additional face which controls appearance during
mouse-overs (merged with the usual button face); by default this is
the usual Emacs @code{highlight} face.
@item keymap
@kindex keymap @r{(button property)}
@vindex button-map
The button's keymap, defining bindings active within the button
region. By default this is the usual button region keymap, stored
in the variable @code{button-map}, which defines @key{RET} and
@key{mouse-2} to invoke the button.
@item type
@kindex type @r{(button property)}
The button type. @xref{Button Types}.
@item help-echo
@kindex help-echo @r{(button property)}
A string displayed by the Emacs tooltip help system; by default,
@code{"mouse-2, RET: Push this button"}. Alternatively, a function
that returns, or a form that evaluates to, a string to be displayed or
@code{nil}. For details see @ref{Text help-echo}.
The function is called with three arguments, @var{window},
@var{object}, and @var{pos}. The second argument, @var{object}, is
either the overlay that had the property (for overlay buttons), or the
buffer containing the button (for text property buttons). The other
arguments have the same meaning as for the special text property
@code{help-echo}.
@item follow-link
@kindex follow-link @r{(button property)}
The @code{follow-link} property, defining how a @key{mouse-1} click
behaves on this button, @xref{Clickable Text}.
@item button
@kindex button @r{(button property)}
All buttons have a non-@code{nil} @code{button} property, which may be useful
in finding regions of text that comprise buttons (which is what the
standard button functions do).
@end table
There are other properties defined for the regions of text in a
button, but these are not generally interesting for typical uses.
@node Button Types
@subsection Button Types
@cindex button types
Every button has a @dfn{button type}, which defines default values
for the button's properties. Button types are arranged in a
hierarchy, with specialized types inheriting from more general types,
so that it's easy to define special-purpose types of buttons for
specific tasks.
@defun define-button-type name &rest properties
Define a button type called @var{name} (a symbol).
The remaining arguments
form a sequence of @var{property value} pairs, specifying default
property values for buttons with this type (a button's type may be set
by giving it a @code{type} property when creating the button, using
the @code{:type} keyword argument).
In addition, the keyword argument @code{:supertype} may be used to
specify a button-type from which @var{name} inherits its default
property values. Note that this inheritance happens only when
@var{name} is defined; subsequent changes to a supertype are not
reflected in its subtypes.
@end defun
Using @code{define-button-type} to define default properties for
buttons is not necessary---buttons without any specified type use the
built-in button-type @code{button}---but it is encouraged, since
doing so usually makes the resulting code clearer and more efficient.
@node Making Buttons
@subsection Making Buttons
@cindex making buttons
Buttons are associated with a region of text, using an overlay or
text properties to hold button-specific information, all of which are
initialized from the button's type (which defaults to the built-in
button type @code{button}). Like all Emacs text, the appearance of
the button is governed by the @code{face} property; by default (via
the @code{face} property inherited from the @code{button} button-type)
this is a simple underline, like a typical web-page link.
For convenience, there are two sorts of button-creation functions,
those that add button properties to an existing region of a buffer,
called @code{make-...button}, and those that also insert the button
text, called @code{insert-...button}.
The button-creation functions all take the @code{&rest} argument
@var{properties}, which should be a sequence of @var{property value}
pairs, specifying properties to add to the button; see @ref{Button
Properties}. In addition, the keyword argument @code{:type} may be
used to specify a button-type from which to inherit other properties;
see @ref{Button Types}. Any properties not explicitly specified
during creation will be inherited from the button's type (if the type
defines such a property).
The following functions add a button using an overlay
(@pxref{Overlays}) to hold the button properties:
@defun make-button beg end &rest properties
This makes a button from @var{beg} to @var{end} in the
current buffer, and returns it.
@end defun
@defun insert-button label &rest properties
This inserts a button with the label @var{label} at point,
and returns it.
@end defun
The following functions are similar, but using text properties
(@pxref{Text Properties}) to hold the button properties. Such buttons
do not add markers to the buffer, so editing in the buffer does not
slow down if there is an extremely large numbers of buttons. However,
if there is an existing face text property on the text (e.g., a face
assigned by Font Lock mode), the button face may not be visible. Both
of these functions return the starting position of the new button.
@defun make-text-button beg end &rest properties
This makes a button from @var{beg} to @var{end} in the current buffer,
using text properties.
@end defun
@defun insert-text-button label &rest properties
This inserts a button with the label @var{label} at point, using text
properties.
@end defun
@defun buttonize string callback &optional data
Sometimes it's more convenient to make a string into a button without
inserting it into a buffer immediately, for instance when creating
data structures that may then, later, be inserted into a buffer. This
function makes @var{string} into such a string, and @var{callback}
will be called when the user clicks on the button. The optional
@var{data} parameter will be used as the parameter when @var{callback}
is called. If @code{nil}, the button is used as the parameter instead.
@end defun
@node Manipulating Buttons
@subsection Manipulating Buttons
@cindex manipulating buttons
These are functions for getting and setting properties of buttons.
Often these are used by a button's invocation function to determine
what to do.
Where a @var{button} parameter is specified, it means an object
referring to a specific button, either an overlay (for overlay
buttons), or a buffer-position or marker (for text property buttons).
Such an object is passed as the first argument to a button's
invocation function when it is invoked.
@defun button-start button
Return the position at which @var{button} starts.
@end defun
@defun button-end button
Return the position at which @var{button} ends.
@end defun
@defun button-get button prop
Get the property of button @var{button} named @var{prop}.
@end defun
@defun button-put button prop val
Set @var{button}'s @var{prop} property to @var{val}.
@end defun
@defun button-activate button &optional use-mouse-action
Call @var{button}'s @code{action} property (i.e., invoke the function
that is the value of that property, passing it the single argument
@var{button}). If @var{use-mouse-action} is non-@code{nil}, try to
invoke the button's @code{mouse-action} property instead of
@code{action}; if the button has no @code{mouse-action} property, use
@code{action} as normal. If the @code{button-data} property is
present in @var{button}, use that as the argument for the
@code{action} function instead of @var{button}.
@end defun
@defun button-label button
Return @var{button}'s text label.
@end defun
@defun button-type button
Return @var{button}'s button-type.
@end defun
@defun button-has-type-p button type
Return @code{t} if @var{button} has button-type @var{type}, or one of
@var{type}'s subtypes.
@end defun
@defun button-at pos
Return the button at position @var{pos} in the current buffer, or
@code{nil}. If the button at @var{pos} is a text property button, the
return value is a marker pointing to @var{pos}.
@end defun
@defun button-type-put type prop val
Set the button-type @var{type}'s @var{prop} property to @var{val}.
@end defun
@defun button-type-get type prop
Get the property of button-type @var{type} named @var{prop}.
@end defun
@defun button-type-subtype-p type supertype
Return @code{t} if button-type @var{type} is a subtype of @var{supertype}.
@end defun
@node Button Buffer Commands
@subsection Button Buffer Commands
@cindex button buffer commands
These are commands and functions for locating and operating on
buttons in an Emacs buffer.
@cindex buffer-button-map
@code{push-button} is the command that a user uses to actually push
a button, and is bound by default in the button itself to @key{RET}
and to @key{mouse-2} using a local keymap in the button's overlay or
text properties. Commands that are useful outside the buttons itself,
such as @code{forward-button} and @code{backward-button} are
additionally available in the keymap stored in
@code{button-buffer-map}; a mode which uses buttons may want to use
@code{button-buffer-map} as a parent keymap for its keymap.
Alternatively, the @code{button-mode} can be switched on for much the
same effect: It's a minor mode that does nothing else than install
@code{button-buffer-map} as a minor mode keymap.
If the button has a non-@code{nil} @code{follow-link} property, and
@code{mouse-1-click-follows-link} is set, a quick @key{mouse-1} click
will also activate the @code{push-button} command.
@xref{Clickable Text}.
@deffn Command push-button &optional pos use-mouse-action
Perform the action specified by a button at location @var{pos}.
@var{pos} may be either a buffer position or a mouse-event. If
@var{use-mouse-action} is non-@code{nil}, or @var{pos} is a
mouse-event (@pxref{Mouse Events}), try to invoke the button's
@code{mouse-action} property instead of @code{action}; if the button
has no @code{mouse-action} property, use @code{action} as normal.
@var{pos} defaults to point, except when @code{push-button} is invoked
interactively as the result of a mouse-event, in which case, the mouse
event's position is used. If there's no button at @var{pos}, do
nothing and return @code{nil}, otherwise return @code{t}.
@end deffn
@deffn Command forward-button n &optional wrap display-message no-error
Move to the @var{n}th next button, or @var{n}th previous button if
@var{n} is negative. If @var{n} is zero, move to the start of any
button at point. If @var{wrap} is non-@code{nil}, moving past either
end of the buffer continues from the other end. If
@var{display-message} is non-@code{nil}, the button's help-echo string
is displayed. Any button with a non-@code{nil} @code{skip} property
is skipped over. Returns the button found, and signals an error if no
buttons can be found. If @var{no-error} is non-@code{nil}, return @code{nil}
instead of signaling the error.
@end deffn
@deffn Command backward-button n &optional wrap display-message no-error
Move to the @var{n}th previous button, or @var{n}th next button if
@var{n} is negative. If @var{n} is zero, move to the start of any
button at point. If @var{wrap} is non-@code{nil}, moving past either
end of the buffer continues from the other end. If
@var{display-message} is non-@code{nil}, the button's help-echo string
is displayed. Any button with a non-@code{nil} @code{skip} property
is skipped over. Returns the button found, and signals an error if no
buttons can be found. If @var{no-error} is non-@code{nil}, return @code{nil}
instead of signaling the error.
@end deffn
@defun next-button pos &optional count-current
@defunx previous-button pos &optional count-current
Return the next button after (for @code{next-button}) or before (for
@code{previous-button}) position @var{pos} in the current buffer. If
@var{count-current} is non-@code{nil}, count any button at @var{pos}
in the search, instead of starting at the next button.
@end defun
@node Abstract Display
@section Abstract Display
@cindex ewoc
@cindex display, abstract
@cindex display, arbitrary objects
@cindex model/view/controller
@cindex view part, model/view/controller
The Ewoc package constructs buffer text that represents a structure
of Lisp objects, and updates the text to follow changes in that
structure. This is like the ``view'' component in the
``model--view--controller'' design paradigm. Ewoc means ``Emacs's
Widget for Object Collections''.
An @dfn{ewoc} is a structure that organizes information required to
construct buffer text that represents certain Lisp data. The buffer
text of the ewoc has three parts, in order: first, fixed @dfn{header}
text; next, textual descriptions of a series of data elements (Lisp
objects that you specify); and last, fixed @dfn{footer} text.
Specifically, an ewoc contains information on:
@itemize @bullet
@item
The buffer which its text is generated in.
@item
The text's start position in the buffer.
@item
The header and footer strings.
@item
@cindex node, ewoc
@c or "@cindex node, abstract display"?
A doubly-linked chain of @dfn{nodes}, each of which contains:
@itemize
@item
A @dfn{data element}, a single Lisp object.
@item
Links to the preceding and following nodes in the chain.
@end itemize
@item
A @dfn{pretty-printer} function which is responsible for
inserting the textual representation of a data
element value into the current buffer.
@end itemize
Typically, you define an ewoc with @code{ewoc-create}, and then pass
the resulting ewoc structure to other functions in the Ewoc package to
build nodes within it, and display it in the buffer. Once it is
displayed in the buffer, other functions determine the correspondence
between buffer positions and nodes, move point from one node's textual
representation to another, and so forth. @xref{Abstract Display
Functions}.
@cindex encapsulation, ewoc
@c or "@cindex encapsulation, abstract display"?
A node @dfn{encapsulates} a data element much the way a variable
holds a value. Normally, encapsulation occurs as a part of adding a
node to the ewoc. You can retrieve the data element value and place a
new value in its place, like so:
@lisp
(ewoc-data @var{node})
@result{} value
(ewoc-set-data @var{node} @var{new-value})
@result{} @var{new-value}
@end lisp
@noindent
You can also use, as the data element value, a Lisp object (list or
vector) that is a container for the real value, or an index into
some other structure. The example (@pxref{Abstract Display Example})
uses the latter approach.
When the data changes, you will want to update the text in the
buffer. You can update all nodes by calling @code{ewoc-refresh}, or
just specific nodes using @code{ewoc-invalidate}, or all nodes
satisfying a predicate using @code{ewoc-map}. Alternatively, you can
delete invalid nodes using @code{ewoc-delete} or @code{ewoc-filter},
and add new nodes in their place. Deleting a node from an ewoc deletes
its associated textual description from buffer, as well.
@menu
* Abstract Display Functions:: Functions in the Ewoc package.
* Abstract Display Example:: Example of using Ewoc.
@end menu
@node Abstract Display Functions
@subsection Abstract Display Functions
In this subsection, @var{ewoc} and @var{node} stand for the
structures described above (@pxref{Abstract Display}), while
@var{data} stands for an arbitrary Lisp object used as a data element.
@defun ewoc-create pretty-printer &optional header footer nosep
This constructs and returns a new ewoc, with no nodes (and thus no data
elements). @var{pretty-printer} should be a function that takes one
argument, a data element of the sort you plan to use in this ewoc, and
inserts its textual description at point using @code{insert} (and never
@code{insert-before-markers}, because that would interfere with the
Ewoc package's internal mechanisms).
Normally, a newline is automatically inserted after the header,
the footer and every node's textual description. If @var{nosep}
is non-@code{nil}, no newline is inserted. This may be useful for
displaying an entire ewoc on a single line, for example, or for
making nodes invisible by arranging for @var{pretty-printer}
to do nothing for those nodes.
An ewoc maintains its text in the buffer that is current when
you create it, so switch to the intended buffer before calling
@code{ewoc-create}.
@end defun
@defun ewoc-buffer ewoc
This returns the buffer where @var{ewoc} maintains its text.
@end defun
@defun ewoc-get-hf ewoc
This returns a cons cell @code{(@var{header} . @var{footer})}
made from @var{ewoc}'s header and footer.
@end defun
@defun ewoc-set-hf ewoc header footer
This sets the header and footer of @var{ewoc} to the strings
@var{header} and @var{footer}, respectively.
@end defun
@defun ewoc-enter-first ewoc data
@defunx ewoc-enter-last ewoc data
These add a new node encapsulating @var{data}, putting it, respectively,
at the beginning or end of @var{ewoc}'s chain of nodes.
@end defun
@defun ewoc-enter-before ewoc node data
@defunx ewoc-enter-after ewoc node data
These add a new node encapsulating @var{data}, adding it to
@var{ewoc} before or after @var{node}, respectively.
@end defun
@defun ewoc-prev ewoc node
@defunx ewoc-next ewoc node
These return, respectively, the previous node and the next node of @var{node}
in @var{ewoc}.
@end defun
@defun ewoc-nth ewoc n
This returns the node in @var{ewoc} found at zero-based index @var{n}.
A negative @var{n} means count from the end. @code{ewoc-nth} returns
@code{nil} if @var{n} is out of range.
@end defun
@defun ewoc-data node
This extracts the data encapsulated by @var{node} and returns it.
@end defun
@defun ewoc-set-data node data
This sets the data encapsulated by @var{node} to @var{data}.
@end defun
@defun ewoc-locate ewoc &optional pos guess
This determines the node in @var{ewoc} which contains point (or
@var{pos} if specified), and returns that node. If @var{ewoc} has no
nodes, it returns @code{nil}. If @var{pos} is before the first node,
it returns the first node; if @var{pos} is after the last node, it returns
the last node. The optional third arg @var{guess}
should be a node that is likely to be near @var{pos}; this doesn't
alter the result, but makes the function run faster.
@end defun
@defun ewoc-location node
This returns the start position of @var{node}.
@end defun
@defun ewoc-goto-prev ewoc arg
@defunx ewoc-goto-next ewoc arg
These move point to the previous or next, respectively, @var{arg}th node
in @var{ewoc}. @code{ewoc-goto-prev} does not move if it is already at
the first node or if @var{ewoc} is empty, whereas @code{ewoc-goto-next}
moves past the last node, returning @code{nil}. Excepting this special
case, these functions return the node moved to.
@end defun
@defun ewoc-goto-node ewoc node
This moves point to the start of @var{node} in @var{ewoc}.
@end defun
@defun ewoc-refresh ewoc
This function regenerates the text of @var{ewoc}. It works by
deleting the text between the header and the footer, i.e., all the
data elements' representations, and then calling the pretty-printer
function for each node, one by one, in order.
@end defun
@defun ewoc-invalidate ewoc &rest nodes
This is similar to @code{ewoc-refresh}, except that only @var{nodes} in
@var{ewoc} are updated instead of the entire set.
@end defun
@defun ewoc-delete ewoc &rest nodes
This deletes each node in @var{nodes} from @var{ewoc}.
@end defun
@defun ewoc-filter ewoc predicate &rest args
This calls @var{predicate} for each data element in @var{ewoc} and
deletes those nodes for which @var{predicate} returns @code{nil}.
Any @var{args} are passed to @var{predicate}.
@end defun
@defun ewoc-collect ewoc predicate &rest args
This calls @var{predicate} for each data element in @var{ewoc}
and returns a list of those elements for which @var{predicate}
returns non-@code{nil}. The elements in the list are ordered
as in the buffer. Any @var{args} are passed to @var{predicate}.
@end defun
@defun ewoc-map map-function ewoc &rest args
This calls @var{map-function} for each data element in @var{ewoc} and
updates those nodes for which @var{map-function} returns non-@code{nil}.
Any @var{args} are passed to @var{map-function}.
@end defun
@node Abstract Display Example
@subsection Abstract Display Example
Here is a simple example using functions of the ewoc package to
implement a @dfn{color components} display, an area in a buffer that
represents a vector of three integers (itself representing a 24-bit RGB
value) in various ways.
@example
(setq colorcomp-ewoc nil
colorcomp-data nil
colorcomp-mode-map nil
colorcomp-labels ["Red" "Green" "Blue"])
(defun colorcomp-pp (data)
(if data
(let ((comp (aref colorcomp-data data)))
(insert (aref colorcomp-labels data) "\t: #x"
(format "%02X" comp) " "
(make-string (ash comp -2) ?#) "\n"))
(let ((cstr (format "#%02X%02X%02X"
(aref colorcomp-data 0)
(aref colorcomp-data 1)
(aref colorcomp-data 2)))
(samp " (sample text) "))
(insert "Color\t: "
(propertize samp 'face
`(foreground-color . ,cstr))
(propertize samp 'face
`(background-color . ,cstr))
"\n"))))
(defun colorcomp (color)
"Allow fiddling with COLOR in a new buffer.
The buffer is in Color Components mode."
(interactive "sColor (name or #RGB or #RRGGBB): ")
(when (string= "" color)
(setq color "green"))
(unless (color-values color)
(error "No such color: %S" color))
(switch-to-buffer
(generate-new-buffer (format "originally: %s" color)))
(kill-all-local-variables)
(setq major-mode 'colorcomp-mode
mode-name "Color Components")
(use-local-map colorcomp-mode-map)
(erase-buffer)
(buffer-disable-undo)
(let ((data (apply 'vector (mapcar (lambda (n) (ash n -8))
(color-values color))))
(ewoc (ewoc-create 'colorcomp-pp
"\nColor Components\n\n"
(substitute-command-keys
"\n\\@{colorcomp-mode-map@}"))))
(set (make-local-variable 'colorcomp-data) data)
(set (make-local-variable 'colorcomp-ewoc) ewoc)
(ewoc-enter-last ewoc 0)
(ewoc-enter-last ewoc 1)
(ewoc-enter-last ewoc 2)
(ewoc-enter-last ewoc nil)))
@end example
@cindex controller part, model/view/controller
This example can be extended to be a color selection widget (in
other words, the ``controller'' part of the ``model--view--controller''
design paradigm) by defining commands to modify @code{colorcomp-data}
and to finish the selection process, and a keymap to tie it all
together conveniently.
@smallexample
(defun colorcomp-mod (index limit delta)
(let ((cur (aref colorcomp-data index)))
(unless (= limit cur)
(aset colorcomp-data index (+ cur delta)))
(ewoc-invalidate
colorcomp-ewoc
(ewoc-nth colorcomp-ewoc index)
(ewoc-nth colorcomp-ewoc -1))))
(defun colorcomp-R-more () (interactive) (colorcomp-mod 0 255 1))
(defun colorcomp-G-more () (interactive) (colorcomp-mod 1 255 1))
(defun colorcomp-B-more () (interactive) (colorcomp-mod 2 255 1))
(defun colorcomp-R-less () (interactive) (colorcomp-mod 0 0 -1))
(defun colorcomp-G-less () (interactive) (colorcomp-mod 1 0 -1))
(defun colorcomp-B-less () (interactive) (colorcomp-mod 2 0 -1))
(defun colorcomp-copy-as-kill-and-exit ()
"Copy the color components into the kill ring and kill the buffer.
The string is formatted #RRGGBB (hash followed by six hex digits)."
(interactive)
(kill-new (format "#%02X%02X%02X"
(aref colorcomp-data 0)
(aref colorcomp-data 1)
(aref colorcomp-data 2)))
(kill-buffer nil))
(setq colorcomp-mode-map
(define-keymap :suppress t
"i" 'colorcomp-R-less
"o" 'colorcomp-R-more
"k" 'colorcomp-G-less
"l" 'colorcomp-G-more
"," 'colorcomp-B-less
"." 'colorcomp-B-more
"SPC" 'colorcomp-copy-as-kill-and-exit))
@end smallexample
Note that we never modify the data in each node, which is fixed when the
ewoc is created to be either @code{nil} or an index into the vector
@code{colorcomp-data}, the actual color components.
@node Blinking
@section Blinking Parentheses
@cindex parenthesis matching
@cindex blinking parentheses
@cindex balancing parentheses
This section describes the mechanism by which Emacs shows a matching
open parenthesis when the user inserts a close parenthesis.
@defvar blink-paren-function
The value of this variable should be a function (of no arguments) to
be called whenever a character with close parenthesis syntax is inserted.
The value of @code{blink-paren-function} may be @code{nil}, in which
case nothing is done.
@end defvar
@defopt blink-matching-paren
If this variable is @code{nil}, then @code{blink-matching-open} does
nothing.
@end defopt
@defopt blink-matching-paren-distance
This variable specifies the maximum distance to scan for a matching
parenthesis before giving up.
@end defopt
@defopt blink-matching-delay
This variable specifies the number of seconds to keep indicating the
matching parenthesis. A fraction of a second often gives good
results, but the default is 1, which works on all systems.
@end defopt
@deffn Command blink-matching-open
This function is the default value of @code{blink-paren-function}. It
assumes that point follows a character with close parenthesis syntax
and applies the appropriate effect momentarily to the matching opening
character. If that character is not already on the screen, it
displays the character's context in the echo area. To avoid long
delays, this function does not search farther than
@code{blink-matching-paren-distance} characters.
Here is an example of calling this function explicitly.
@smallexample
@group
(defun interactive-blink-matching-open ()
"Indicate momentarily the start of parenthesized sexp before point."
(interactive)
@end group
@group
(let ((blink-matching-paren-distance
(buffer-size))
(blink-matching-paren t))
(blink-matching-open)))
@end group
@end smallexample
@end deffn
@node Character Display
@section Character Display
This section describes how characters are actually displayed by
Emacs. Typically, a character is displayed as a @dfn{glyph} (a
graphical symbol which occupies one character position on the screen),
whose appearance corresponds to the character itself. For example,
the character @samp{a} (character code 97) is displayed as @samp{a}.
Some characters, however, are displayed specially. For example, the
formfeed character (character code 12) is usually displayed as a
sequence of two glyphs, @samp{^L}, while the newline character
(character code 10) starts a new screen line.
You can modify how each character is displayed by defining a
@dfn{display table}, which maps each character code into a sequence of
glyphs. @xref{Display Tables}.
@menu
* Usual Display:: The usual conventions for displaying characters.
* Display Tables:: What a display table consists of.
* Active Display Table:: How Emacs selects a display table to use.
* Glyphs:: How to define a glyph, and what glyphs mean.
* Glyphless Chars:: How glyphless characters are drawn.
@end menu
@node Usual Display
@subsection Usual Display Conventions
Here are the conventions for displaying each character code (in the
absence of a display table, which can override these
@iftex
conventions).
@end iftex
@ifnottex
conventions; @pxref{Display Tables}).
@end ifnottex
@cindex printable ASCII characters
@itemize @bullet
@item
The @dfn{printable @acronym{ASCII} characters}, character codes 32
through 126 (consisting of numerals, English letters, and symbols like
@samp{#}) are displayed literally.
@item
The tab character (character code 9) displays as whitespace stretching
up to the next tab stop column. @xref{Text Display,,, emacs, The GNU
Emacs Manual}. The variable @code{tab-width} controls the number of
spaces per tab stop (see below).
@item
The newline character (character code 10) has a special effect: it
ends the preceding line and starts a new line.
@cindex ASCII control characters
@item
The non-printable @dfn{@acronym{ASCII} control characters}---character
codes 0 through 31, as well as the @key{DEL} character (character code
127)---display in one of two ways according to the variable
@code{ctl-arrow}. If this variable is non-@code{nil} (the default),
these characters are displayed as sequences of two glyphs, where the
first glyph is @samp{^} (a display table can specify a glyph to use
instead of @samp{^}); e.g., the @key{DEL} character is displayed as
@samp{^?}.
If @code{ctl-arrow} is @code{nil}, these characters are displayed as
octal escapes (see below).
This rule also applies to carriage return (character code 13), if that
character appears in the buffer. But carriage returns usually do not
appear in buffer text; they are eliminated as part of end-of-line
conversion (@pxref{Coding System Basics}).
@cindex octal escapes
@item
@dfn{Raw bytes} are non-@acronym{ASCII} characters with codes 128
through 255 (@pxref{Text Representations}). These characters display
as @dfn{octal escapes}: sequences of four glyphs, where the first
glyph is the @acronym{ASCII} code for @samp{\}, and the others are
digit characters representing the character code in octal. (A display
table can specify a glyph to use instead of @samp{\}.)
@item
Each non-@acronym{ASCII} character with code above 255 is displayed
literally, if the terminal supports it. If the terminal does not
support it, the character is said to be @dfn{glyphless}, and it is
usually displayed using a placeholder glyph. For example, if a
graphical terminal has no font for a character, Emacs usually displays
a box containing the character code in hexadecimal. @xref{Glyphless
Chars}.
@end itemize
The above display conventions apply even when there is a display
table, for any character whose entry in the active display table is
@code{nil}. Thus, when you set up a display table, you need only
specify the characters for which you want special display behavior.
The following variables affect how certain characters are displayed
on the screen. Since they change the number of columns the characters
occupy, they also affect the indentation functions. They also affect
how the mode line is displayed; if you want to force redisplay of the
mode line using the new values, call the function
@code{force-mode-line-update} (@pxref{Mode Line Format}).
@defopt ctl-arrow
@cindex control characters in display
This buffer-local variable controls how control characters are
displayed. If it is non-@code{nil}, they are displayed as a caret
followed by the character: @samp{^A}. If it is @code{nil}, they are
displayed as octal escapes: a backslash followed by three octal
digits, as in @samp{\001}.
@end defopt
@defopt tab-width
The value of this buffer-local variable is the spacing between tab
stops used for displaying tab characters in Emacs buffers. The value
is in units of columns, and the default is 8. Note that this feature
is completely independent of the user-settable tab stops used by the
command @code{tab-to-tab-stop}. @xref{Indent Tabs}.
@end defopt
@node Display Tables
@subsection Display Tables
@cindex display table
A display table is a special-purpose char-table
(@pxref{Char-Tables}), with @code{display-table} as its subtype, which
is used to override the usual character display conventions. This
section describes how to make, inspect, and assign elements to a
display table object. The next section (@pxref{Active Display Table})
describes the various standard display tables and their precedence.
@defun make-display-table
This creates and returns a display table. The table initially has
@code{nil} in all elements.
@end defun
The ordinary elements of the display table are indexed by character
codes; the element at index @var{c} says how to display the character
code @var{c}. The value should be @code{nil} (which means to display
the character @var{c} according to the usual display conventions;
@pxref{Usual Display}), or a vector of glyph codes (which means to
display the character @var{c} as those glyphs; @pxref{Glyphs}).
@strong{Warning:} if you use the display table to change the display
of newline characters, the whole buffer will be displayed as one long
line.
The display table also has six @dfn{extra slots} which serve special
purposes. Here is a table of their meanings; @code{nil} in any slot
means to use the default for that slot, as stated below.
@table @asis
@item 0
The glyph for the end of a truncated screen line (the default for this
is @samp{$}). @xref{Glyphs}. On graphical terminals, Emacs by
default uses arrows in the fringes to indicate truncation, so the
display table has no effect, unless you disable the fringes
(@pxref{Fringes,, Window Fringes, emacs, the GNU Emacs Manual}).
@item 1
The glyph for the end of a continued line (the default is @samp{\}).
On graphical terminals, Emacs by default uses curved arrows in the
fringes to indicate continuation, so the display table has no effect,
unless you disable the fringes.
@item 2
The glyph for indicating a character displayed as an octal character
code (the default is @samp{\}).
@item 3
The glyph for indicating a control character (the default is @samp{^}).
@item 4
A vector of glyphs for indicating the presence of invisible lines (the
default is @samp{...}). @xref{Selective Display}.
@item 5
The glyph used to draw the border between side-by-side windows (the
default is @samp{|}). @xref{Splitting Windows}. This currently has
effect only on text terminals; on graphical terminals, if vertical
scroll bars are supported and in use, a scroll bar separates the two
windows, and if there are no vertical scroll bars and no dividers
(@pxref{Window Dividers}), Emacs uses a thin line to indicate the
border.
@end table
For example, here is how to construct a display table that mimics
the effect of setting @code{ctl-arrow} to a non-@code{nil} value
(@pxref{Glyphs}, for the function @code{make-glyph-code}):
@example
(setq disptab (make-display-table))
(dotimes (i 32)
(or (= i ?\t)
(= i ?\n)
(aset disptab i
(vector (make-glyph-code ?^ 'escape-glyph)
(make-glyph-code (+ i 64) 'escape-glyph)))))
(aset disptab 127
(vector (make-glyph-code ?^ 'escape-glyph)
(make-glyph-code ?? 'escape-glyph)))
@end example
@defun display-table-slot display-table slot
This function returns the value of the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
5 inclusive, or a slot name (symbol). Valid symbols are
@code{truncation}, @code{wrap}, @code{escape}, @code{control},
@code{selective-display}, and @code{vertical-border}.
@end defun
@defun set-display-table-slot display-table slot value
This function stores @var{value} in the extra slot @var{slot} of
@var{display-table}. The argument @var{slot} may be a number from 0 to
5 inclusive, or a slot name (symbol). Valid symbols are
@code{truncation}, @code{wrap}, @code{escape}, @code{control},
@code{selective-display}, and @code{vertical-border}.
@end defun
@defun describe-display-table display-table
This function displays a description of the display table
@var{display-table} in a help buffer.
@end defun
@deffn Command describe-current-display-table
This command displays a description of the current display table in a
help buffer.
@end deffn
@node Active Display Table
@subsection Active Display Table
@cindex active display table
Each window can specify a display table, and so can each buffer.
The window's display table, if there is one, takes precedence over the
buffer's display table. If neither exists, Emacs tries to use the
standard display table; if that is @code{nil}, Emacs uses the usual
character display conventions (@pxref{Usual Display}). (Emacs does
not ``merge'' display tables: For instance, if the window has a
display table, the buffer's display table and the standard display
table are completely ignored.)
Note that display tables affect how the mode line is displayed, so
if you want to force redisplay of the mode line using a new display
table, call @code{force-mode-line-update} (@pxref{Mode Line Format}).
@defun window-display-table &optional window
This function returns @var{window}'s display table, or @code{nil} if
there is none. The default for @var{window} is the selected window.
@end defun
@defun set-window-display-table window table
This function sets the display table of @var{window} to @var{table}.
The argument @var{table} should be either a display table or
@code{nil}.
@end defun
@defvar buffer-display-table
This variable is automatically buffer-local in all buffers; its value
specifies the buffer's display table. If it is @code{nil}, there is
no buffer display table.
@end defvar
@defvar standard-display-table
The value of this variable is the standard display table, which is
used when Emacs is displaying a buffer in a window with neither a
window display table nor a buffer display table defined, or when Emacs
is outputting text to the standard output or error streams. Although its
default is typically @code{nil}, in an interactive session if the
terminal cannot display curved quotes, its default maps curved quotes
to ASCII approximations. @xref{Text Quoting Style}.
@end defvar
The @file{disp-table} library defines several functions for changing
the standard display table.
@node Glyphs
@subsection Glyphs
@cindex glyph
@cindex glyph code
A @dfn{glyph} is a graphical symbol which occupies a single
character position on the screen. Each glyph is represented in Lisp
as a @dfn{glyph code}, which specifies a character and optionally a
face to display it in (@pxref{Faces}). The main use of glyph codes is
as the entries of display tables (@pxref{Display Tables}). The
following functions are used to manipulate glyph codes:
@defun make-glyph-code char &optional face
This function returns a glyph code representing char @var{char} with
face @var{face}. If @var{face} is omitted or @code{nil}, the glyph
uses the default face; in that case, the glyph code is an integer. If
@var{face} is non-@code{nil}, the glyph code is not necessarily an
integer object.
@end defun
@defun glyph-char glyph
This function returns the character of glyph code @var{glyph}.
@end defun
@defun glyph-face glyph
This function returns face of glyph code @var{glyph}, or @code{nil} if
@var{glyph} uses the default face.
@end defun
@ifnottex
You can set up a @dfn{glyph table} to change how glyph codes are
actually displayed on text terminals. This feature is semi-obsolete;
use @code{glyphless-char-display} instead (@pxref{Glyphless Chars}).
@defvar glyph-table
The value of this variable, if non-@code{nil}, is the current glyph
table. It takes effect only on character terminals; on graphical
displays, all glyphs are displayed literally. The glyph table should
be a vector whose @var{g}th element specifies how to display glyph
code @var{g}, where @var{g} is the glyph code for a glyph whose face
is unspecified. Each element should be one of the following:
@table @asis
@item @code{nil}
Display this glyph literally.
@item a string
Display this glyph by sending the specified string to the terminal.
@item a glyph code
Display the specified glyph code instead.
@end table
Any integer glyph code greater than or equal to the length of the
glyph table is displayed literally.
@end defvar
@end ifnottex
@node Glyphless Chars
@subsection Glyphless Character Display
@cindex glyphless characters
@dfn{Glyphless characters} are characters which are displayed in a
special way, e.g., as a box containing a hexadecimal code, instead of
being displayed literally. These include characters which are
explicitly defined to be glyphless, as well as characters for which
there is no available font (on a graphical display), and characters
which cannot be encoded by the terminal's coding system (on a text
terminal).
@findex glyphless-display-mode
The @code{glyphless-display-mode} minor mode can be used to toggle
displaying glyphless characters in a convenient manner in the current
buffer. If this mode is enabled, all the glyphless characters are
displayed as boxes that display acronyms of their character names.
@defvar glyphless-char-display
For more fine-grained (and global) control, this variable can be used.
The value of this variable is a char-table which defines glyphless
characters and how they are displayed. Each entry must be one of the
following display methods:
@table @asis
@item @code{nil}
Display the character in the usual way.
@item @code{zero-width}
Don't display the character.
@item @code{thin-space}
Display a thin space, 1-pixel wide on graphical displays, or
1-character wide on text terminals.
@item @code{empty-box}
Display an empty box.
@item @code{hex-code}
Display a box containing the Unicode codepoint of the character, in
hexadecimal notation.
@item an @acronym{ASCII} string
Display a box containing that string. The string should contain at
most 6 @acronym{ASCII} characters. As an exception, if the string
includes just one character, on text-mode terminals that character
will be displayed without a box; this enables treating such
``acronyms'' as replacement characters for characters that cannot be
displayed by the terminal.
@item a cons cell @code{(@var{graphical} . @var{text})}
Display with @var{graphical} on graphical displays, and with
@var{text} on text terminals. Both @var{graphical} and @var{text}
must be one of the display methods described above.
@end table
@vindex glyphless-char@r{ face}
@noindent
The @code{thin-space}, @code{empty-box}, @code{hex-code}, and
@acronym{ASCII} string display methods are drawn with the
@code{glyphless-char} face. On text terminals, a box is emulated by
square brackets, @samp{[]}.
The char-table has one extra slot, which determines how to display any
character that cannot be displayed with any available font, or cannot
be encoded by the terminal's coding system. Its value should be one
of the above display methods, except @code{zero-width}.
If a character has a non-@code{nil} entry in an active display table,
the display table takes effect; in this case, Emacs does not consult
@code{glyphless-char-display} at all.
@end defvar
@defopt glyphless-char-display-control
This user option provides a convenient way to set
@code{glyphless-char-display} for groups of similar characters. Do
not set its value directly from Lisp code; the value takes effect only
via a custom @code{:set} function (@pxref{Variable Definitions}),
which updates @code{glyphless-char-display}.
Its value should be an alist of elements @code{(@var{group}
. @var{method})}, where @var{group} is a symbol specifying a group of
characters, and @var{method} is a symbol specifying how to display
them.
@var{group} should be one of the following:
@table @code
@item c0-control
@acronym{ASCII} control characters @code{U+0000} to @code{U+001F},
excluding the newline and tab characters (normally displayed as escape
sequences like @samp{^A}; @pxref{Text Display,, How Text Is Displayed,
emacs, The GNU Emacs Manual}).
@item c1-control
Non-@acronym{ASCII}, non-printing characters @code{U+0080} to
@code{U+009F} (normally displayed as octal escape sequences like
@samp{\230}).
@item format-control
Characters of Unicode General Category [Cf], such as U+200E
@sc{left-to-right mark}, but excluding characters that have graphic
images, such as U+00AD @sc{soft hyphen}.
@item bidi-control
This is a subset of @code{format-control}, but only includes
characters that are related to bidirectional formatting control, like
U+2069 @sc{pop directional isolate} and U+202A @sc{left-to-right
embedding}. @xref{Bidirectional Display}.
Characters of Unicode General Category [Cf], such as U+200E
@sc{left-to-right mark}, but excluding characters that have graphic
images, such as U+00AD @sc{soft hyphen}.
@item variation-selectors
Unicode VS-1 through VS-256 (U+FE00 through U+FE0F and U+E0100 through
U+E01EF), which are used to select between different glyphs for the same
codepoints (typically emojis).
@item no-font
Characters for which there is no suitable font, or which cannot be
encoded by the terminal's coding system, or those for which the
text-mode terminal has no glyphs.
@end table
@c FIXME: this can also be 'acronym', but that's not currently
@c completely implemented; it applies only to the format-control
@c group, and only works if the acronym is in 'char-acronym-table'.
The @var{method} symbol should be one of @code{zero-width},
@code{thin-space}, @code{empty-box}, or @code{hex-code}. These have
the same meanings as in @code{glyphless-char-display}, above.
@end defopt
@node Beeping
@section Beeping
@cindex bell
This section describes how to make Emacs ring the bell (or blink the
screen) to attract the user's attention. Be conservative about how
often you do this; frequent bells can become irritating. Also be
careful not to use just beeping when signaling an error is more
appropriate (@pxref{Errors}).
@defun ding &optional do-not-terminate
@cindex keyboard macro termination
This function beeps, or flashes the screen (see @code{visible-bell} below).
It also terminates any keyboard macro currently executing unless
@var{do-not-terminate} is non-@code{nil}.
@end defun
@defun beep &optional do-not-terminate
This is a synonym for @code{ding}.
@end defun
@defopt visible-bell
This variable determines whether Emacs should flash the screen to
represent a bell. Non-@code{nil} means yes, @code{nil} means no.
This is effective on graphical displays, and on text terminals
provided the terminal's Termcap entry defines the visible bell
capability (@samp{vb}).
@end defopt
@defopt ring-bell-function
If this is non-@code{nil}, it specifies how Emacs should ring the
bell. Its value should be a function of no arguments. If this is
non-@code{nil}, it takes precedence over the @code{visible-bell}
variable.
@end defopt
@node Window Systems
@section Window Systems
Emacs works with several window systems, most notably the X Window
System. Both Emacs and X use the term ``window'', but use it
differently. An Emacs frame is a single window as far as X is
concerned; the individual Emacs windows are not known to X at all.
@defvar window-system
This terminal-local variable tells Lisp programs what window system
Emacs is using for displaying the frame. The possible values are
@table @code
@item x
@cindex X Window System
Emacs is displaying the frame using X.
@item w32
Emacs is displaying the frame using native MS-Windows GUI.
@item ns
Emacs is displaying the frame using the Nextstep interface (used on
GNUstep and macOS).
@item pc
Emacs is displaying the frame using MS-DOS direct screen writes.
@item haiku
Emacs is displaying the frame using the Application Kit on Haiku.
@item pgtk
Emacs is displaying the frame using pure GTK facilities.
@item android
Emacs is displaying the frame on Android.
@item nil
Emacs is displaying the frame on a character-based terminal.
@end table
@end defvar
@defvar initial-window-system
This variable holds the value of @code{window-system} used for the
first frame created by Emacs during startup. (When Emacs is invoked
as a daemon, it does not create any initial
frames, so @code{initial-window-system} is @code{nil}, except on
MS-Windows, where it is still @code{w32}. @xref{Initial Options,
daemon,, emacs, The GNU Emacs Manual}.)
@end defvar
@defun window-system &optional frame
This function returns a symbol whose name tells what window system is
used for displaying @var{frame} (which defaults to the currently
selected frame). The list of possible symbols it returns is the same
one documented for the variable @code{window-system} above.
@end defun
Do @emph{not} use @code{window-system} and
@code{initial-window-system} as predicates or boolean flag variables,
if you want to write code that works differently on text terminals and
graphic displays. That is because @code{window-system} is not a good
indicator of Emacs capabilities on a given display type. Instead, use
@code{display-graphic-p} or any of the other @code{display-*-p}
predicates described in @ref{Display Feature Testing}.
@node Tooltips
@section Tooltips
@cindex tooltips
@dfn{Tooltips} are special frames (@pxref{Frames}) that are used to
display helpful hints (a.k.a.@: ``tips'') related to the current
position of the mouse pointer. Emacs uses tooltips to display help
strings about active portions of text (@pxref{Special Properties}) and
about various UI elements, such as menu items (@pxref{Extended Menu
Items}) and tool-bar buttons (@pxref{Tool Bar}).
@defun tooltip-mode
Tooltip Mode is a minor mode that enables display of tooltips.
Turning off this mode causes the tooltips be displayed in the echo
area. On text-mode (a.k.a.@: ``TTY'') frames, tooltips are always
displayed in the echo area.
@end defun
@cindex system tooltips
@vindex use-system-tooltips
When Emacs is built with the GTK+ toolkit or Haiku windowing support,
it by default displays tooltips using toolkit functions, and the
appearance of the tooltips is then controlled by the toolkit's
settings. Toolkit-provided tooltips can be disabled by changing the
value of the variable @code{use-system-tooltips} to @code{nil}. The
rest of this subsection describes how to control non-toolkit tooltips,
which are presented by Emacs itself.
@cindex tooltip frames
Tooltips are displayed in special frames called tooltip frames, which
have their own frame parameters (@pxref{Frame Parameters}). Unlike
other frames, the default parameters for tooltip frames are stored in a
special variable.
@defopt tooltip-frame-parameters
This customizable option holds the default frame parameters used for
displaying tooltips. Any font and color parameters are ignored, and the
corresponding attributes of the @code{tooltip} face are used instead.
If @code{left} or @code{top} parameters are included, they are used as
absolute frame-relative coordinates where the tooltip should be shown.
(Mouse-relative position of the tooltip can be customized using the
variables described in @ref{Tooltips,,, emacs, The GNU Emacs Manual}.)
Note that the @code{left} and @code{top} parameters, if present,
override the values of mouse-relative offsets.
@end defopt
@vindex tooltip@r{ face}
The @code{tooltip} face determines the appearance of text shown in
tooltips. It should generally use a variable-pitch font of size that
is preferably smaller than the default frame font.
@findex tooltip-help-tips
@defvar tooltip-functions
This abnormal hook is a list of functions to call when Emacs needs to
display a tooltip. Each function is called with a single argument
@var{event} which is a copy of the last mouse movement event. If a
function on this list actually displays the tooltip, it should return
non-@code{nil}, and then the rest of the functions will not be
called. The default value of this variable is a single function
@code{tooltip-help-tips}.
@end defvar
If you write your own function to be put on the
@code{tooltip-functions} list, you may need to know the buffer of the
mouse event that triggered the tooltip display. The following
function provides that information.
@defun tooltip-event-buffer event
This function returns the buffer over which @var{event} occurred.
Call it with the argument of the function from
@code{tooltip-functions} to obtain the buffer whose text triggered the
tooltip. Note that the event might occur not over a buffer (e.g.,
over the tool bar), in which case this function will return
@code{nil}.
@end defun
Other aspects of tooltip display are controlled by several
customizable settings; see @ref{Tooltips,,, emacs, The GNU Emacs
Manual}.
@node Bidirectional Display
@section Bidirectional Display
@cindex bidirectional display
@cindex right-to-left text
Emacs can display text written in scripts, such as Arabic, Farsi,
and Hebrew, whose natural ordering for horizontal text display runs
from right to left. Furthermore, segments of Latin script and digits
embedded in right-to-left text are displayed left-to-right, while
segments of right-to-left script embedded in left-to-right text
(e.g., Arabic or Hebrew text in comments or strings in a program
source file) are appropriately displayed right-to-left. We call such
mixtures of left-to-right and right-to-left text @dfn{bidirectional
text}. This section describes the facilities and options for editing
and displaying bidirectional text.
@cindex logical order
@cindex reading order
@cindex visual order
@cindex unicode bidirectional algorithm
@cindex UBA
@cindex bidirectional reordering
@cindex reordering, of bidirectional text
Text is stored in Emacs buffers and strings in @dfn{logical} (or
@dfn{reading}) order, i.e., the order in which a human would read
each character. In right-to-left and bidirectional text, the order in
which characters are displayed on the screen (called @dfn{visual
order}) is not the same as logical order; the characters' screen
positions do not increase monotonically with string or buffer
position. In performing this @dfn{bidirectional reordering}, Emacs
follows the Unicode Bidirectional Algorithm (a.k.a.@: @acronym{UBA}),
which is described in Annex #9 of the Unicode standard
(@url{https://www.unicode.org/reports/tr9/}). Emacs provides a ``Full
Bidirectionality'' class implementation of the @acronym{UBA},
consistent with the requirements of the Unicode Standard v9.0. Note,
however, that the way Emacs displays continuation lines when text
direction is opposite to the base paragraph direction deviates from
the UBA, which requires performing line wrapping before reordering
text for display.
@defvar bidi-display-reordering
If the value of this buffer-local variable is non-@code{nil} (the
default), Emacs performs bidirectional reordering for display. The
reordering affects buffer text, as well as display strings and overlay
strings from text and overlay properties in the buffer (@pxref{Overlay
Properties}, and @pxref{Display Property}). If the value is
@code{nil}, Emacs does not perform bidirectional reordering in the
buffer.
The default value of @code{bidi-display-reordering} controls the
reordering of strings which are not directly supplied by a buffer,
including the text displayed in mode lines (@pxref{Mode Line Format})
and header lines (@pxref{Header Lines}).
@end defvar
@cindex unibyte buffers, and bidi reordering
Emacs never reorders the text of a unibyte buffer, even if
@code{bidi-display-reordering} is non-@code{nil} in the buffer. This
is because unibyte buffers contain raw bytes, not characters, and thus
lack the directionality properties required for reordering.
Therefore, to test whether text in a buffer will be reordered for
display, it is not enough to test the value of
@code{bidi-display-reordering} alone. The correct test is this:
@example
(if (and enable-multibyte-characters
bidi-display-reordering)
;; Buffer is being reordered for display
)
@end example
However, unibyte display and overlay strings @emph{are} reordered if
their parent buffer is reordered. This is because plain-@sc{ascii}
strings are stored by Emacs as unibyte strings. If a unibyte display
or overlay string includes non-@sc{ascii} characters, these characters
are assumed to have left-to-right direction.
@cindex display properties, and bidi reordering of text
Text covered by @code{display} text properties, by overlays with
@code{display} properties whose value is a string, and by any other
properties that replace buffer text, is treated as a single unit when
it is reordered for display. That is, the entire chunk of text
covered by these properties is reordered together. Moreover, the
bidirectional properties of the characters in such a chunk of text are
ignored, and Emacs reorders them as if they were replaced with a
single character @code{U+FFFC}, known as the @dfn{Object Replacement
Character}. This means that placing a display property over a portion
of text may change the way that the surrounding text is reordered for
display. To prevent this unexpected effect, always place such
properties on text whose directionality is identical with text that
surrounds it.
@cindex base direction of a paragraph
Each paragraph of bidirectional text has a @dfn{base direction},
either right-to-left or left-to-right. Left-to-right paragraphs are
displayed beginning at the left margin of the window, and are
truncated or continued when the text reaches the right margin.
Right-to-left paragraphs are displayed beginning at the right margin,
and are continued or truncated at the left margin.
@cindex paragraph-start, and bidirectional display
@cindex paragraph-separate, and bidirectional display
Where exactly paragraphs start and end, for the purpose of the Emacs
@acronym{UBA} implementation, is determined by the following two
buffer-local variables (note that @code{paragraph-start} and
@code{paragraph-separate} have no influence on this). By default both
of these variables are @code{nil}, and paragraphs are bounded by empty
lines, i.e., lines that consist entirely of zero or more whitespace
characters followed by a newline.
@defvar bidi-paragraph-start-re
If non-@code{nil}, this variable's value should be a regular
expression matching a line that starts or separates two paragraphs.
The regular expression is always matched after a newline, so it is
best to anchor it, i.e., begin it with a @code{"^"}.
@end defvar
@defvar bidi-paragraph-separate-re
If non-@code{nil}, this variable's value should be a regular
expression matching a line separates two paragraphs. The regular
expression is always matched after a newline, so it is best to anchor
it, i.e., begin it with a @code{"^"}.
@end defvar
If you modify any of these two variables, you should normally modify
both, to make sure they describe paragraphs consistently. For
example, to have each new line start a new paragraph for
bidi-reordering purposes, set both variables to @code{"^"}.
By default, Emacs determines the base direction of each paragraph by
looking at the text at its beginning. The precise method of
determining the base direction is specified by the @acronym{UBA}; in a
nutshell, the first character in a paragraph that has an explicit
directionality determines the base direction of the paragraph.
However, sometimes a buffer may need to force a certain base direction
for its paragraphs. For example, buffers containing program source
code should force all paragraphs to be displayed left-to-right. You
can use following variable to do this:
@defopt bidi-paragraph-direction
If the value of this buffer-local variable is the symbol
@code{right-to-left} or @code{left-to-right}, all paragraphs in the
buffer are assumed to have that specified direction. Any other value
is equivalent to @code{nil} (the default), which means to determine
the base direction of each paragraph from its contents.
@cindex @code{prog-mode}, and @code{bidi-paragraph-direction}
Modes for program source code should set this to @code{left-to-right}.
Prog mode does this by default, so modes derived from Prog mode do not
need to set this explicitly (@pxref{Basic Major Modes}).
@end defopt
@defun current-bidi-paragraph-direction &optional buffer
This function returns the paragraph direction at point in the named
@var{buffer}. The returned value is a symbol, either
@code{left-to-right} or @code{right-to-left}. If @var{buffer} is
omitted or @code{nil}, it defaults to the current buffer. If the
buffer-local value of the variable @code{bidi-paragraph-direction} is
non-@code{nil}, the returned value will be identical to that value;
otherwise, the returned value reflects the paragraph direction
determined dynamically by Emacs. For buffers whose value of
@code{bidi-display-reordering} is @code{nil} as well as unibyte
buffers, this function always returns @code{left-to-right}.
@end defun
@cindex visual-order cursor motion
Sometimes there's a need to move point in strict visual order,
either to the left or to the right of its current screen position.
Emacs provides a primitive to do that.
@defun move-point-visually direction
This function moves point of the currently selected window to the
buffer position that appears immediately to the right or to the left
of point on the screen. If @var{direction} is positive, point will
move one screen position to the right, otherwise it will move one
screen position to the left. Note that, depending on the surrounding
bidirectional context, this could potentially move point many buffer
positions away. If invoked at the end of a screen line, the function
moves point to the rightmost or leftmost screen position of the next
or previous screen line, as appropriate for the value of
@var{direction}.
The function returns the new buffer position as its value.
@end defun
@cindex layout on display, and bidirectional text
@cindex jumbled display of bidirectional text
@cindex concatenating bidirectional strings
Bidirectional reordering can have surprising and unpleasant effects
when two strings with bidirectional content are juxtaposed in a
buffer, or otherwise programmatically concatenated into a string of
text. A typical problematic case is when a buffer consists of
sequences of text fields separated by whitespace or punctuation
characters, like Buffer Menu mode or Rmail Summary Mode. Because the
punctuation characters used as separators have @dfn{weak
directionality}, they take on the directionality of surrounding text.
As result, a numeric field that follows a field with bidirectional
content can be displayed @emph{to the left} of the preceding field,
messing up the expected layout. There are several ways to avoid this
problem:
@itemize @minus
@item
Append the special character U+200E @sc{left-to-right mark}, or
@acronym{LRM}, to the end of each field that may have bidirectional
content, or prepend it to the beginning of the following field. The
function @code{bidi-string-mark-left-to-right}, described below, comes
in handy for this purpose. (In a right-to-left paragraph, use
U+200F @sc{right-to-left mark}, or @acronym{RLM}, instead.) This
is one of the solutions recommended by the UBA.
@item
Include the tab character in the field separator. The tab character
plays the role of @dfn{segment separator} in bidirectional reordering,
causing the text on either side to be reordered separately.
@cindex @code{space} display spec, and bidirectional text
@item
Separate fields with a @code{display} property or overlay with a
property value of the form @code{(space . PROPS)} (@pxref{Specified
Space}). Emacs treats this display specification as a @dfn{paragraph
separator}, and reorders the text on either side separately.
@end itemize
@defun bidi-string-mark-left-to-right string
This function returns its argument @var{string}, possibly modified,
such that the result can be safely concatenated with another string,
or juxtaposed with another string in a buffer, without disrupting the
relative layout of this string and the next one on display. If the
string returned by this function is displayed as part of a
left-to-right paragraph, it will always appear on display to the left
of the text that follows it. The function works by examining the
characters of its argument, and if any of those characters could cause
reordering on display, the function appends the @acronym{LRM}
character to the string. The appended @acronym{LRM} character is made
invisible by giving it an @code{invisible} text property of @code{t}
(@pxref{Invisible Text}).
@end defun
The reordering algorithm uses the bidirectional properties of the
characters stored as their @code{bidi-class} property
(@pxref{Character Properties}). Lisp programs can change these
properties by calling the @code{put-char-code-property} function.
However, doing this requires a thorough understanding of the
@acronym{UBA}, and is therefore not recommended. Any changes to the
bidirectional properties of a character have global effect: they
affect all Emacs frames and windows.
Similarly, the @code{mirroring} property is used to display the
appropriate mirrored character in the reordered text. Lisp programs
can affect the mirrored display by changing this property. Again, any
such changes affect all of Emacs display.
@cindex overriding bidirectional properties
@cindex directional overrides
@cindex LRO
@cindex RLO
The bidirectional properties of characters can be overridden by
inserting into the text special directional control characters,
LEFT-TO-RIGHT OVERRIDE (@acronym{LRO}) and RIGHT-TO-LEFT OVERRIDE
(@acronym{RLO}). Any characters between a @acronym{RLO} and the
following newline or POP DIRECTIONAL FORMATTING (@acronym{PDF})
control character, whichever comes first, will be displayed as if they
were strong right-to-left characters, i.e.@: they will be reversed on
display. Similarly, any characters between @acronym{LRO} and
@acronym{PDF} or newline will display as if they were strong
left-to-right, and will @emph{not} be reversed even if they are strong
right-to-left characters.
@cindex phishing using directional overrides
@cindex malicious use of directional overrides
These overrides are useful when you want to make some text
unaffected by the reordering algorithm, and instead directly control
the display order. But they can also be used for malicious purposes,
known as @dfn{phishing}. Specifically, a URL on a Web page or a link
in an email message can be manipulated to make its visual appearance
unrecognizable, or similar to some popular benign location, while the
real location, interpreted by a browser in the logical order, is very
different.
Emacs provides a primitive that applications can use to detect
instances of text whose bidirectional properties were overridden so as
to make a left-to-right character display as if it were a
right-to-left character, or vice versa.
@defun bidi-find-overridden-directionality from to &optional object
This function looks at the text of the specified @var{object} between
positions @var{from} (inclusive) and @var{to} (exclusive), and returns
the first position where it finds a strong left-to-right character
whose directional properties were forced to display the character as
right-to-left, or for a strong right-to-left character that was forced
to display as left-to-right. If it finds no such characters in the
specified region of text, it returns @code{nil}.
The optional argument @var{object} specifies which text to search, and
defaults to the current buffer. If @var{object} is non-@code{nil}, it
can be some other buffer, or it can be a string or a window. If it is
a string, the function searches that string. If it is a window, the
function searches the buffer displayed in that window. If a buffer
whose text you want to examine is displayed in some window, we
recommend to specify it by that window, rather than pass the buffer to
the function. This is because telling the function about the window
allows it to correctly account for window-specific overlays, which
might change the result of the function if some text in the buffer is
covered by overlays.
@end defun
@cindex copying bidirectional text, preserve visual order
@cindex visual order, preserve when copying bidirectional text
When text that includes mixed right-to-left and left-to-right
characters and bidirectional controls is copied into a different
location, it can change its visual appearance, and also can affect the
visual appearance of the surrounding text at destination. This is
because reordering of bidirectional text specified by the
@acronym{UBA} has non-trivial context-dependent effects both on the
copied text and on the text at copy destination that will surround it.
Sometimes, a Lisp program may need to preserve the exact visual
appearance of the copied text at destination, and of the text that
surrounds the copy. Lisp programs can use the following function to
achieve that effect.
@defun buffer-substring-with-bidi-context start end &optional no-properties
This function works similar to @code{buffer-substring} (@pxref{Buffer
Contents}), but it prepends and appends to the copied text bidi
directional control characters necessary to preserve the visual
appearance of the text when it is inserted at another place. Optional
argument @var{no-properties}, if non-@code{nil}, means remove the text
properties from the copy of the text.
@end defun
|