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bug#54646: 29.0.50; set-fontset-font and font clipping issues
From: |
Visuwesh |
Subject: |
bug#54646: 29.0.50; set-fontset-font and font clipping issues |
Date: |
Fri, 01 Apr 2022 17:08:59 +0530 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/29.0.50 (gnu/linux) |
[வெள்ளி ஏப்ரல் 01, 2022] Eli Zaretskii wrote:
>> From: Robert Pluim <rpluim@gmail.com>
>> Cc: 54646@debbugs.gnu.org,Eli Zaretskii <eliz@gnu.org>
>> Date: Fri, 01 Apr 2022 10:49:21 +0200
>>
>> Visuwesh> I can reproduce it in HarfBuzz 4.2.0. Maybe this could be
>> related to
>> Visuwesh> the toolkit being used? I have only tested so far with Lucid.
>> I will
>> Visuwesh> try GTK some time later.
>>
>> Iʼve managed to reproduce this, but only once, with HarfBuzz 4.2.0
>> using lucid and Kurinto Seri. I guess that points more at HarfBuzz
>> than at Emacs, but maybe the lucid build is doing things slightly
>> differently to gtk.
>
> I think at this point we need to establish whether we pass the same
> information to HarfBuzz in the "good" and the "bad" cases. In
> particular, we tell it how to scale the glyph metrics:
>
> hb_font_t *hb_font
> = font->driver->begin_hb_font
> ? font->driver->begin_hb_font (font, &position_unit)
> : NULL;
>
> The value of position_unit then affects the values returned in the
> Lisp glyph object used to display the grapheme cluster:
>
> xoff = lround (pos[i].x_offset * position_unit);
> yoff = - lround (pos[i].y_offset * position_unit);
> wadjust = lround (pos[i].x_advance * position_unit);
> if (xoff || yoff || wadjust != metrics.width)
> LGLYPH_SET_ADJUSTMENT (lglyph, CALLN (Fvector,
> make_fixnum (xoff),
> make_fixnum (yoff),
> make_fixnum (wadjust)));
>
> I'd be interested in what happens there in the "good" vs the "bad"
> cases.
>
> If we pass the same information to HarfBuzz, and it returns different
> results, then it's probably a problem in HarfBuzz.
If you can give some instructions on how to get started, I can try
getting the value of position_unit in the good and the bad cases.
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Robert Pluim, 2022/04/01
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Visuwesh, 2022/04/01
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Eli Zaretskii, 2022/04/01
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Visuwesh, 2022/04/01
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Eli Zaretskii, 2022/04/01
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Visuwesh, 2022/04/03
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Eli Zaretskii, 2022/04/03
- bug#54646: 29.0.50; set-fontset-font and font clipping issues, Visuwesh, 2022/04/03