[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#33885: 27.0.50; PUA character makes emacs crash
From: |
Eli Zaretskii |
Subject: |
bug#33885: 27.0.50; PUA character makes emacs crash |
Date: |
Fri, 28 Dec 2018 17:33:07 +0200 |
> Date: Fri, 28 Dec 2018 15:58:50 +0100 (CET)
> Cc: 33885@debbugs.gnu.org
> From: Werner LEMBERG <wl@gnu.org>
>
> OK. `XftFontOpenPattern' returns the following data for `Cardo':
>
> (gdb) p *xftfont
> $12 = {
> ascent = 16,
> descent = -5,
> height = 6,
> max_advance_width = 91,
> charset = 0x7fffe23d52d8,
> pattern = 0x1f01050
> }
>
> This is problematic, since it only reflects the Apple values for
> ascent and descent (i.e., the data in the font's `hhea' table). To
> solve the issue, there are two possible solutions IMHO.
>
> (1) Simply accept whatever `XftFontOpenPattern' returns, including
> negative values for `descent' – actually, such font might exist:
> for example, consider a special font that only contains dashes of
> different length.
I don't think this is a good idea.
> (2) Improve the heuristics to get sensible global ascent and descent
> values of a font. In particular, use the FreeType library to
> access a TrueType's or OpenType's `OS/2' table and compare its
> vertical metrics values with the `hhea' data to eliminate bugs in
> the font – sign problems with `descent' do happen especially in
> older fonts that were either designed for Apple or for Windows,
> and the fields for the `other' OS were filled out arbitrarily,
> more or less.
I'd appreciate more details on how this could be done. I'm no expert
on fonts nor on FreeType, and last I checked we have no one else.
Thanks.
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/27
- bug#33885: 27.0.50; PUA character makes emacs crash, Eli Zaretskii, 2018/12/27
- bug#33885: 27.0.50; PUA character makes emacs crash, Eli Zaretskii, 2018/12/27
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Eli Zaretskii, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Eli Zaretskii, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash,
Eli Zaretskii <=
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Werner LEMBERG, 2018/12/28
- bug#33885: 27.0.50; PUA character makes emacs crash, Eli Zaretskii, 2018/12/28