bug#56695: closed (A new and old font problem with Arabic)

[GNU bug Tracking System]

Your message dated Mon, 25 Jul 2022 19:06:42 +0300
with message-id <83k081dvn1.fsf@gnu.org>
and subject line Re: bug#56695: A new and old font problem with Arabic
has caused the debbugs.gnu.org bug report #56695,
regarding A new and old font problem with Arabic
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs@gnu.org.)


-- 
56695: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=56695
GNU Bug Tracking System
Contact help-debbugs@gnu.org with problems

--- Begin Message --- Subject: A new and old font problem with Arabic Date: Fri, 22 Jul 2022 10:11:16 +0200 (CEST)

 

Hello,

Since Emacs 28 I have a new problem with Arabic fonts.

1. I can't change the Arabic characters to the font of DejaVu Sans
Mono (or others). This wasn't a problem before.
2. The old one: As you can see the glyphs aren't correct, the '-'
after س is not correctly placed. It's in the place of the glyph of
س. Sometimes I have the opposite problem: gaps between the
characters. It depends usually of 'text-scale-adjust', if I change
the scale the problem can disappear.

(Of course I started Emacs with the '-Q' option.)

Attachment: To see the difference: a screenshot in Word/LibreOffice Writer:
In LibreOffice:
1. The font is correct (also for the Arabic characters)
2. The '-' is at the correct place

Can Harfbuzz be a problem? In the older emacs version (maybe 3 or 4 years ago?) I never had these problems.

Kind regards
Frank



with_emacs.png
Description: PNG image

with_writer.png
Description: PNG image

--- End Message ---

> --- Begin Message ---
>
>
>
> Subject: 
>
> Re: bug#56695: A new and old font problem with Arabic
>
>
>
>
> Date: 
>
> Mon, 25 Jul 2022 19:06:42 +0300
>
>
>
>
> > Date: Mon, 25 Jul 2022 17:29:23 +0200 (CEST)
> > From: "fr_ml@t-online.de" <fr_ml@t-online.de>
> > Cc: "56695@debbugs.gnu.org" <56695@debbugs.gnu.org>
> > 
> > > This is expected: Emacs caches the results of previous text-shaping.
> > > You should invoke
> > > 
> > >   M-: (clear-composition-cache) RET
> > > 
> > > to force Emacs to forget the old text-shaping results.
> > If I have the positioning problem, this command doesn't solve it.
>
> It doesn't always work, indeed.
>
> > > > It works, Emacs uses the font correctly.
> > > > And it seems that the positioning is then much better. The old problem is 
> > > > still there but not so often.
> > > 
> > > Does this mean we can close this bug?
> > It's better but it's strange. And unfortunately  some years ago this
> > problem wasn't there at all.
>
> I'm guessing "some years ago" you used different versions of the same
> fonts.  A font that was OK in the past could regress later.
>
> For correct complex shaping, it is very important to find good fonts.
> I suggest to look for a good Arabic font that is fixed-pitch, and use
> it instead of DejaVu Sans.
>
> > But it's ok.  We can close it.  Many thanks.
>
> Done.
>
>
> --- End Message ---