Re: new *Help* argument highlighting

["Robert J. Chassell" <bob@rattlesnake.com>]

    But playing with font size is pretty safe ...

No, it is not.

    Bold sometimes causes problems...

Yes, you are right.  But the word `sometimes' is not accurate.  Bold
*always* causes a problem when I change font size to 10x20.  In a mode
line, `m' becomes unreadable.  (That font size is best for the display
I mostly use.  Everything looks fine in the default font.)

Back in December 2002, Miles Bader fixed the problem by providing a
patch to emacs/src/xfaces.c and an Emacs Lisp file to load.  The patch
works fine.  I have been incorporating it with the current xfaces.c
source ever since.

Because I do not understand it, I have held back from committing
Miles' change.

First, will someone who understands the patch review it?  Or should I
commit the merged version of xfaces.c and see whether it breaks others
people's installations?

Here is the patch itself.  As I said, the patch works fine with the
current CVS.


RCS file: /cvsroot/emacs/emacs/src/xfaces.c,v
retrieving revision 1.266
diff -u -r1.266 xfaces.c
--- src/xfaces.c	17 Nov 2002 23:51:19 -0000	1.266
+++ src/xfaces.c	18 Dec 2002 05:26:34 -0000
@@ -422,6 +422,13 @@
 
 Lisp_Object Vtty_defined_color_alist;
 
+/* A list of functions to perturb faces before final realization.
+   They are passed a lisp-vector containing all the attributes of the
+   fully-specified face, and can change any that they wish. */
+
+Lisp_Object Vrealize_face_filter_functions;
+
+
 /* Counter for calls to clear_face_cache.  If this counter reaches
    CLEAR_FONT_TABLE_COUNT, and a frame has more than
    CLEAR_FONT_TABLE_NFONTS load, unused fonts are freed.  */
@@ -481,7 +488,7 @@
 static unsigned char *xstrlwr P_ ((unsigned char *));
 static void signal_error P_ ((char *, Lisp_Object));
 static struct frame *frame_or_selected_frame P_ ((Lisp_Object, int));
-static void load_face_font P_ ((struct frame *, struct face *, int));
+static void load_face_font P_ ((struct frame *, struct face *, Lisp_Object *, int));
 static void load_face_colors P_ ((struct frame *, struct face *, Lisp_Object *));
 static void free_face_colors P_ ((struct frame *, struct face *));
 static int face_color_gray_p P_ ((struct frame *, char *));
@@ -502,10 +509,10 @@
 static int cmp_font_names P_ ((const void *, const void *));
 static struct face *realize_face P_ ((struct face_cache *, Lisp_Object *, int,
 				      struct face *, int));
-static struct face *realize_x_face P_ ((struct face_cache *,
-					Lisp_Object *, int, struct face *));
-static struct face *realize_tty_face P_ ((struct face_cache *,
-					  Lisp_Object *, int));
+static void realize_x_face P_ ((struct face *, struct face_cache *,
+				Lisp_Object *, int, struct face *));
+static void realize_tty_face P_ ((struct face *, struct face_cache *,
+				  Lisp_Object *, int));
 static int realize_basic_faces P_ ((struct frame *));
 static int realize_default_face P_ ((struct frame *));
 static void realize_named_face P_ ((struct frame *, Lisp_Object, int));
@@ -1245,14 +1252,15 @@
 
 #ifdef HAVE_WINDOW_SYSTEM
 
-/* Load font of face FACE which is used on frame F to display
-   character C.  The name of the font to load is determined by lface
-   and fontset of FACE.  */
+/* Load font of face FACE with attributes ATTRS which is used on frame F to
+   display character C.  The name of the font to load is determined by
+   lface and fontset of FACE.  */
 
 static void
-load_face_font (f, face, c)
+load_face_font (f, face, attrs, c)
      struct frame *f;
      struct face *face;
+     Lisp_Object *attrs;
      int c;
 {
   struct font_info *font_info = NULL;
@@ -1262,7 +1270,7 @@
   face->font_info_id = -1;
   face->font = NULL;
 
-  font_name = choose_face_font (f, face->lface, face->fontset, c,
+  font_name = choose_face_font (f, attrs, face->fontset, c,
 				&needs_overstrike);
   if (!font_name)
     return;
@@ -6678,6 +6686,11 @@
      int former_face_id;
 {
   struct face *face;
+  /* The set of attributes this face is know by to the user, as opposed to
+     the set actually used to render the face.  They're usually the same
+     as, but may be different if some attribute is changed by
+     realize-face-filter.  */
+  Lisp_Object *orig_attrs = attrs;
 
   /* LFACE must be fully specified.  */
   xassert (cache != NULL);
@@ -6691,41 +6704,70 @@
       free_realized_face (cache->f, former_face);
     }
 
+  if (CONSP (Vrealize_face_filter_functions))
+    {
+      /* Call these user-defined functions to perturb the face attributes
+	 before realization.  */
+      Lisp_Object filters, cycle_check;
+      Lisp_Object lface = Fmake_vector (make_number (LFACE_VECTOR_SIZE),
+					Qunspecified);
+
+      bcopy (attrs, XVECTOR (lface)->contents,
+	     LFACE_VECTOR_SIZE * (sizeof *attrs));
+
+      cycle_check = Qnil;
+      for (filters = Vrealize_face_filter_functions;
+	   CONSP (filters);
+	   filters = XCDR (filters))
+	{
+	  safe_call1 (XCAR (filters), lface);
+	  cycle_check = CYCLE_CHECK (cycle_check, filters, 50);
+	  if (NILP (cycle_check))
+	    break;		/* cycle detected */
+	}
+
+      attrs = XVECTOR (lface)->contents;
+    }      
+
+  /* Allocate a new realized face.  */
+  face = make_realized_face (orig_attrs);
+
+  /* Fill it in.  */
   if (FRAME_WINDOW_P (cache->f))
-    face = realize_x_face (cache, attrs, c, base_face);
+    realize_x_face (face, cache, attrs, c, base_face);
   else if (FRAME_TERMCAP_P (cache->f) || FRAME_MSDOS_P (cache->f))
-    face = realize_tty_face (cache, attrs, c);
+    realize_tty_face (face, cache, attrs, c);
   else
     abort ();
 
   /* Insert the new face.  */
-  cache_face (cache, face, lface_hash (attrs));
+  cache_face (cache, face, lface_hash (orig_attrs));
 #ifdef HAVE_WINDOW_SYSTEM
   if (FRAME_WINDOW_P (cache->f) && face->font == NULL)
-    load_face_font (cache->f, face, c);
+    load_face_font (cache->f, face, attrs, c);
 #endif  /* HAVE_WINDOW_SYSTEM */
   return face;
 }
 
 
-/* Realize the fully-specified face with attributes ATTRS in face
-   cache CACHE for character C.  Do it for X frame CACHE->f.  If C is
-   a multibyte character, BASE_FACE is a face that has the same
-   attributes.  Otherwise, BASE_FACE is ignored.  If the new face
-   doesn't share font with the default face, a fontname is allocated
-   from the heap and set in `font_name' of the new face, but it is not
-   yet loaded here.  Value is a pointer to the newly created realized
-   face.  */
+/* Realize into FACE the fully-specified face with attributes ATTRS in face
+   cache CACHE for character C.  Do it for X frame CACHE->f.  If C is a
+   multibyte character, BASE_FACE is a face that has the same attributes.
+   Otherwise, BASE_FACE is ignored.  If the new face doesn't share font
+   with the default face, a fontname is allocated from the heap and set in
+   `font_name' of the new face, but it is not yet loaded here.  Value is a
+   pointer to the newly created realized face.  */
 
-static struct face *
-realize_x_face (cache, attrs, c, base_face)
+static void
+realize_x_face (face, cache, attrs, c, base_face)
+     struct face *face;
      struct face_cache *cache;
      Lisp_Object *attrs;
      int c;
      struct face *base_face;
 {
 #ifdef HAVE_WINDOW_SYSTEM
-  struct face *face, *default_face;
+  struct face *default_face;
   struct frame *f;
   Lisp_Object stipple, overline, strike_through, box;
 
@@ -6733,9 +6775,6 @@
   xassert (SINGLE_BYTE_CHAR_P (c)
 	   || base_face);
 
-  /* Allocate a new realized face.  */
-  face = make_realized_face (attrs);
-
   f = cache->f;
 
   /* If C is a multibyte character, we share all face attirbutes with
@@ -6751,7 +6790,7 @@
 
       /* to force realize_face to load font */
       face->font = NULL;
-      return face;
+      return;
     }
 
   /* Now we are realizing a face for ASCII (and unibyte) characters.  */
@@ -6921,7 +6960,6 @@
     face->stipple = load_pixmap (f, stipple, &face->pixmap_w, &face->pixmap_h);
 
   xassert (FACE_SUITABLE_FOR_CHAR_P (face, c));
-  return face;
 #endif /* HAVE_WINDOW_SYSTEM */
 }
 
@@ -7012,17 +7050,16 @@
 }
 
 
-/* Realize the fully-specified face with attributes ATTRS in face
-   cache CACHE for character C.  Do it for TTY frame CACHE->f.  Value is a
-   pointer to the newly created realized face.  */
+/* Realize into FACE the fully-specified face with attributes ATTRS in face
+   cache CACHE for character C.  Do it for TTY frame CACHE->f.  */
 
-static struct face *
-realize_tty_face (cache, attrs, c)
+static void
+realize_tty_face (face, cache, attrs, c)
+     struct face *face;
      struct face_cache *cache;
      Lisp_Object *attrs;
      int c;
 {
-  struct face *face;
   int weight, slant;
   int face_colors_defaulted = 0;
   struct frame *f = cache->f;
@@ -7030,8 +7067,6 @@
   /* Frame must be a termcap frame.  */
   xassert (FRAME_TERMCAP_P (cache->f) || FRAME_MSDOS_P (cache->f));
 
-  /* Allocate a new realized face.  */
-  face = make_realized_face (attrs);
   face->font_name = FRAME_MSDOS_P (cache->f) ? "ms-dos" : "tty";
 
   /* Map face attributes to TTY appearances.  We map slant to
@@ -7068,8 +7103,6 @@
       && face->background == FACE_TTY_DEFAULT_FG_COLOR
       && face->foreground == FACE_TTY_DEFAULT_BG_COLOR)
     face->tty_bold_p = 0;
-
-  return face;
 }
 
 
@@ -7670,6 +7703,14 @@
 Each element is a regular expression that matches names of fonts to
 ignore.  */);
   Vface_ignored_fonts = Qnil;
+
+  DEFVAR_LISP ("realize-face-filter-functions",
+	       &Vrealize_face_filter_functions,
+	       doc:/* A list of functions to perturb faces before final realization.
+They are passed a lisp-vector containing all the attributes of the
+fully-specified face, and can change any that they wish. */);
+  Vrealize_face_filter_functions = Qnil;
+
 
 #ifdef HAVE_WINDOW_SYSTEM
   defsubr (&Sbitmap_spec_p);



-- 
    Robert J. Chassell                         Rattlesnake Enterprises
    As I slowly update it,                     bob@rattlesnake.com
        I rewrite a "What's New" segment for   http://www.rattlesnake.com