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bug#20173: 24.4; Rendering misallocates combining marks on ligatures
From: |
Richard Wordingham |
Subject: |
bug#20173: 24.4; Rendering misallocates combining marks on ligatures |
Date: |
Mon, 23 Mar 2015 22:41:07 +0000 |
On Mon, 23 Mar 2015 17:38:52 +0200
Eli Zaretskii <eliz@gnu.org> wrote:
> > Date: Mon, 23 Mar 2015 01:06:26 +0000
> > From: Richard Wordingham <richard.wordingham@ntlworld.com>
> Is it possible that some rule(s) are missing from the end of
> lisp/language/misc-lang.el? Could you please take a look and see if
> something needs to be fixed/added in how we set up the compositions
> for Arabic?
There's no relevant problem there. I demonstrated the bug to myself by
first rendering Tai Tham <NA, TONE-2, SIGN AA> and confirming that
TONE-2 rendered above the first component of the ligature NAA, fromed
from <NA, SIGN AA>. I then hacked my font so that the glyph for TONE-2
was decomposed into the glyphs for MAI KANG and TONE-2, in that order,
and observing TONE-2 being rendered on the second component of the
ligature. I then turned to Arabic so that a custom font would not be
needed to demonstrate the bug.
As to what needs fixing in the Arabic section of misc-lang.el:
Clusters containing letters should be limited to letters and marks on
them. Otherwise, the digits 1, 2, 3 are reversed in a variable name
like بج١٢٣د. (I'm not sure why the problem doesn't appear with بج١٢٣.)
(set-char-table-range
composition-function-table
'(#x600 . #x6FF)
(list ["[\u0600-\u06FF]+" 0 font-shape-gstring]))
should change to something like
(set-char-table-range
composition-function-table
'(#x610 . #x615)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0
font-shape-gstring]))
; Skip punctuation
(set-char-table-range
composition-function-table
'(#x621 . #x65F)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0 font-shape-gstring]))
; skip digits and punctuation
(set-char-table-range
composition-function-table
'(#x66E . #x6D3)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0 font-shape-gstring]))
; skip punctuation
(set-char-table-range
composition-function-table
'(#x6D5 . #x6EF)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0 font-shape-gstring]))
; Skip digits
(set-char-table-range
composition-function-table
'(#x6FA . #x6FC)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0 font-shape-gstring]))
; Skip symbols
(set-char-table-range
composition-function-table
'(#x6FF . #x6FF)
(list
["[\u0610-\u0615\u0621-\u065F\u066E-\u06D3\u06D5-\u06EF\u06FA-\u06FC\u06FF]+"
0 font-shape-gstring]))
There are more elegant ways of expressing this, which is just as well,
for there are also blocks Arabic Supplement (U+0750 to U+077F) and
Arabic Extended-A (U+08A0 to U+08FF). Being an international script,
the Arabic script has a lot of letters, just like the Latin script.
Richard.
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Richard Wordingham, 2015/03/22
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Eli Zaretskii, 2015/03/23
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures,
Richard Wordingham <=
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Eli Zaretskii, 2015/03/23
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Richard Wordingham, 2015/03/24
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Eli Zaretskii, 2015/03/24
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Richard Wordingham, 2015/03/24
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Richard Wordingham, 2015/03/27
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures, Eli Zaretskii, 2015/03/27