From: Eli Zaretskii <eliz@gnu.org>
To: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
Cc: rahguzar@zohomail.eu, larsi@gnus.org, 50951@debbugs.gnu.org,
visuweshm@gmail.com
Subject: bug#50951: 28.0.50; Urdu text is not displayed correctly
Date: Tue, 20 Sep 2022 14:07:12 +0300 [thread overview]
Message-ID: <835yhixq1r.fsf@gnu.org> (raw)
In-Reply-To: <wlzgeubtl7.wl-mituharu@math.s.chiba-u.ac.jp> (message from YAMAMOTO Mitsuharu on Tue, 20 Sep 2022 12:41:40 +0900)
> Date: Tue, 20 Sep 2022 12:41:40 +0900
> From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
> Cc: Visuwesh <visuweshm@gmail.com>,
> Eli Zaretskii <eliz@gnu.org>,
> larsi@gnus.org,
> 50951@debbugs.gnu.org
>
> The width of grapheme cluster corresponding to U+06AF (ARABIC LETTER
> GAF) is rounded to zero, and Emacs does not display such clusters:
>
> xdisp.c:
> 32424 gstring = composition_gstring_from_id (it->cmp_it.id);
> 32425 it->pixel_width
> 32426 = composition_gstring_width (gstring, it->cmp_it.from, it->cmp_it.to,
> 32427 &metrics);
> 32428 if (it->pixel_width == 0)
> 32429 {
> 32430 it->glyph_not_available_p = true;
> 32431 it->phys_ascent = it->ascent;
> 32432 it->phys_descent = it->descent;
> 32433 it->pixel_width = face->font->space_width;
> 32434 }
> 32435 else
>
> The attached patch avoids zero-width grapheme clusters by adding 1 to
> the width of the last glyph in such clusters.
If the problem is rounding, I think we should do this adjustment only
when the last glyph has a non-zero width that was rounded to zero, no?
Otherwise, we are inventing adjustments out of thin air, which could
adversely affect the displayed result, I think?
Or maybe we should have a variable that controls this heuristic?
Bottom line: I'm uneasy with messing with the grapheme cluster data
without some sound basis. We delegate this job to a text-shaping
engine for a reason. But if there is a sound basis for this
adjustment, could you please elaborate on it?
Thanks.
next prev parent reply other threads:[~2022-09-20 11:07 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-01 20:11 bug#50951: 28.0.50; Urdu text is not displayed correctly Rah Guzar
2021-10-02 6:07 ` Eli Zaretskii
[not found] ` <CAP094xCyzg62eHeYCUkWy+eBCbEXC_AAU5YFbhTCcCR0cAOCQw@mail.gmail.com>
2021-10-02 11:43 ` bug#50951: Fwd: " Rah Guzar
2021-10-02 12:18 ` Eli Zaretskii
2021-10-02 12:47 ` Rah Guzar
2021-10-02 13:09 ` Eli Zaretskii
2021-10-02 14:19 ` Rah Guzar
2021-10-02 14:50 ` Eli Zaretskii
[not found] ` <CAP094xBq9YjL6xS56t-C3uhSH69TawhsCrF2FdSMySeDpZfGNw@mail.gmail.com>
2021-10-02 15:09 ` Eli Zaretskii
2021-10-02 15:18 ` Rah Guzar
2021-10-02 14:18 ` Andreas Schwab
2021-10-02 14:40 ` Eli Zaretskii
2021-10-02 15:07 ` Rah Guzar
2021-10-02 15:14 ` Eli Zaretskii
[not found] ` <CAP094xAoHdQZoPL9y6aZOq-WGZe0cYtNsm9Trm+yBiyjyZ4j7g@mail.gmail.com>
2021-10-02 15:54 ` Eli Zaretskii
2021-10-02 16:06 ` Rah Guzar
2021-10-02 16:09 ` Eli Zaretskii
2022-09-04 21:07 ` Lars Ingebrigtsen
2022-09-05 11:22 ` Eli Zaretskii
2022-09-05 11:57 ` Rah Guzar via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-05 12:29 ` Eli Zaretskii
2022-09-05 13:03 ` Rah Guzar via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-05 13:55 ` Eli Zaretskii
[not found] ` <87pmg97vsg.fsf@zohomail.eu>
2022-09-05 15:47 ` Eli Zaretskii
2022-09-06 4:26 ` Visuwesh
2022-09-06 11:05 ` Eli Zaretskii
2022-09-06 13:18 ` Visuwesh
2022-09-07 6:18 ` YAMAMOTO Mitsuharu
2022-09-07 11:27 ` Eli Zaretskii
2022-09-08 6:06 ` Visuwesh
2022-09-09 15:00 ` Rah Guzar via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-17 16:37 ` Rah Guzar via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-17 17:00 ` Eli Zaretskii
2022-09-20 3:41 ` YAMAMOTO Mitsuharu
2022-09-20 11:07 ` Eli Zaretskii [this message]
2022-09-21 2:20 ` YAMAMOTO Mitsuharu
2022-09-21 2:25 ` YAMAMOTO Mitsuharu
2022-09-22 5:37 ` Eli Zaretskii
2022-09-25 7:18 ` YAMAMOTO Mitsuharu
2022-09-26 7:18 ` Eli Zaretskii
2022-09-27 0:29 ` YAMAMOTO Mitsuharu
2022-09-20 12:35 ` Rah Guzar via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-09-11 10:26 ` Visuwesh
2022-09-11 11:11 ` Visuwesh
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