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bug#20173: 24.4; Rendering misallocates combining marks on ligatures
From: |
Eli Zaretskii |
Subject: |
bug#20173: 24.4; Rendering misallocates combining marks on ligatures |
Date: |
Tue, 24 Mar 2015 05:42:18 +0200 |
> Date: Mon, 23 Mar 2015 22:41:07 +0000
> From: Richard Wordingham <richard.wordingham@ntlworld.com>
> Cc: 20173@debbugs.gnu.org
>
> 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.
Sorry, I'm not sure I understand you. If the setting of composition
rules for Arabic is not the culprit, then what is? AFAIK, there are
no rules that guide Emacs's shaping except what's in
composition-function-table. Beyond that, the only other factor is the
font backend and how it shapes glyphs given the chunks of text Emacs
presents to it.
> As to what needs fixing in the Arabic section of misc-lang.el:
Thanks, I will look into these.
- 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, 2015/03/23
- bug#20173: 24.4; Rendering misallocates combining marks on ligatures,
Eli Zaretskii <=
- 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