* IT testing for multiple characters (ִרֹ) that occupy 1 display string.
@ 2018-10-01 0:14 Keith David Bershatsky
2018-10-01 6:35 ` Eli Zaretskii
0 siblings, 1 reply; 3+ messages in thread
From: Keith David Bershatsky @ 2018-10-01 0:14 UTC (permalink / raw)
To: Emacs Devel
I am working on feature requests #17684 (crosshairs) and #22873 (multiple fake cursors).
When using move_it_in_display_line_to, ִרֹ is treated as one display string; however, it is 3 different characters occupying 3 HPOS. it->c only reports 1460.
I initially guessed that this was a composition situation, however, it.what returns a 0, which is the same as any other regular character.
Q: How do we test for this situation, so that we know all of the different characters and each of their individual pixel widths?
Thanks,
Keith
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: IT testing for multiple characters (ִרֹ) that occupy 1 display string.
2018-10-01 0:14 IT testing for multiple characters (ִרֹ) that occupy 1 display string Keith David Bershatsky
@ 2018-10-01 6:35 ` Eli Zaretskii
0 siblings, 0 replies; 3+ messages in thread
From: Eli Zaretskii @ 2018-10-01 6:35 UTC (permalink / raw)
To: Keith David Bershatsky; +Cc: emacs-devel
> Date: Sun, 30 Sep 2018 17:14:04 -0700
> From: Keith David Bershatsky <esq@lawlist.com>
>
> When using move_it_in_display_line_to, ִרֹ is treated as one display string; however, it is 3 different characters occupying 3 HPOS. it->c only reports 1460.
>
> I initially guessed that this was a composition situation, however, it.what returns a 0, which is the same as any other regular character.
It is definitely a composition, but you've put the individual
codepoints in the wrong order, at least in your email. The correct
order should be: first u+05e8, the base character, and after that
u+5b4 (1460 decimal) and u+5b9, in any order.
Here's what Emacs reports about this composition on my system:
position: 1 of 3 (0%), column: 0
character: ר (displayed as ר) (codepoint 1512, #o2750, #x5e8)
preferred charset: unicode (Unicode (ISO10646))
code point in charset: 0x05E8
script: hebrew
syntax: w which means: word
category: .:Base, R:Right-to-left (strong)
to input: type "C-x 8 RET 5e8" or "C-x 8 RET HEBREW LETTER RESH"
buffer code: #xD7 #xA8
file code: not encodable by coding system iso-latin-1-dos
display: composed to form "רִֹ" (see below)
Composed with the following character(s) "ִֹ" using this font:
uniscribe:-outline-Courier New-normal-normal-normal-mono-13-*-*-*-c-*-iso10646-1
by these glyphs:
[0 2 1512 696 8 1 6 6 0 nil]
[0 2 1465 662 8 4 5 8 -7 [-9 0 0]]
[0 2 1460 657 8 4 5 -1 2 [-9 0 0]]
> Q: How do we test for this situation, so that we know all of the different characters and each of their individual pixel widths?
If I put a breakpoint in move_it_in_display_line_to, at or after the
call to PRODUCE_GLYPHS, I see a composition:
(gdb) p it->what
$2 = IT_COMPOSITION
(gdb) p it->c
$3 = 1512
(gdb) p it->cmp_it
$4 = {
stop_pos = 1,
id = 0,
ch = 1465,
rule_idx = 2,
lookback = 1,
nglyphs = 3,
reversed_p = false,
charpos = 1,
nchars = 3,
nbytes = 6,
from = 0,
to = 3,
width = 1
}
The nchars and nbytes members of the cmp_it structure clearly show
that Emacs composes 3 characters whose combined length in the internal
buffer representation is 6 bytes.
You didn't tell how and where you took the iterator information, so I
don't know why this didn't look like a composition to you. Maybe you
had the codepoints in the wrong order, like in your mail, in which
case the u+5b4 character will indeed not compose with the other 2.
As for knowing how many pixels this composed character takes -- the
answer as the same as with any other display element: you subtract the
X coordinate (it->current_x) before the glyph from the X coordinate
after it.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: IT testing for multiple characters (ִרֹ) that occupy 1 display string.
@ 2018-10-01 20:45 Keith David Bershatsky
0 siblings, 0 replies; 3+ messages in thread
From: Keith David Bershatsky @ 2018-10-01 20:45 UTC (permalink / raw)
To: Eli Zaretskii; +Cc: emacs-devel
Thank you, Eli, for helping me to understand how to analyze composition characters.
I had disabled auto-composition-mode several years ago in my init.el, which affected the ability to compose the characters.
When creating the email seeking assistance, I probably copied what should have been just one composition character, along with one-half of another composition character.
I am now able to properly test the existence of a composition character when moving IT.
As always, your help is greatly appreciated!
Keith
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2018-10-01 20:45 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2018-10-01 0:14 IT testing for multiple characters (ִרֹ) that occupy 1 display string Keith David Bershatsky
2018-10-01 6:35 ` Eli Zaretskii
-- strict thread matches above, loose matches on Subject: below --
2018-10-01 20:45 Keith David Bershatsky
Code repositories for project(s) associated with this external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.