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bug#31315: wrong font encoding for fallback font
From: |
Werner LEMBERG |
Subject: |
bug#31315: wrong font encoding for fallback font |
Date: |
Fri, 04 May 2018 07:11:37 +0200 (CEST) |
>> Alas, my Elisp knowledge is ... well ... not impressive.
>> Basically, I'm just an Emacs user, not an Emacs developer.
>
> Almost all of the relevant code is in C, not in Lisp.
OK.
>> With Xft, there is no possibility for improvement IMHO. The
>> probably best choice is to switch to Pango for font access (in case
>> you don't do that already).
>
> There are several back-ends besides Xft, the most advanced being
> xftfont.c. They all didn't see any serious development for the past
> several years. And yes, acquiring new back-ends is also a worthy
> goal.
>
> All of that requires a level of expertise that IMO we currently
> don't have.
What I can certainly offer is advice. However, I'm not sure to be
right person for working on the innards of Emacs, given the usual lack
of time (sigh).
>> An Emacs charset essentially triggers a language and script
>> setting, and those two parameters can be passed to Pango, AFAIK.
>
> Emacs handles charsets and scripts separately. A script is matched
> against OTF/TTF features of fonts to make sure the necessary shaping
> features required by a script are supported.
Interesting. Access to OpenType features is exactly what's needed to
improve font display for selected charsets. Where can I find the
related code in Emacs?
Additionally, I suggest that the Emacs maintainers set up a GSoC
project, namely to improve font rendering. This is a broad topic,
which could be further split into smaller subprojects.
Emacs uses Handa-san's libotf library (are there any other projects
that use this library?), but AFAICS it doesn't receive a lot of
testing. On the other hand, there is Behdad Esfahbod's `HarfBuzz'
shaping engine that comes with a large suite of tests. One of such
subprojects could be to take these tests and use them to improve
libotf, especially for Indic scripts.
https://www.freedesktop.org/wiki/Software/HarfBuzz/
Werner
- bug#31315: wrong font encoding for fallback font, Werner LEMBERG, 2018/05/01
- bug#31315: wrong font encoding for fallback font, Eli Zaretskii, 2018/05/01
- bug#31315: wrong font encoding for fallback font, Werner LEMBERG, 2018/05/01
- bug#31315: wrong font encoding for fallback font, Werner LEMBERG, 2018/05/02
- bug#31315: wrong font encoding for fallback font, Eli Zaretskii, 2018/05/02
- bug#31315: wrong font encoding for fallback font, Werner LEMBERG, 2018/05/03
- bug#31315: wrong font encoding for fallback font, Eli Zaretskii, 2018/05/03
- bug#31315: wrong font encoding for fallback font, Werner LEMBERG, 2018/05/03
- bug#31315: wrong font encoding for fallback font, Eli Zaretskii, 2018/05/03
- bug#31315: wrong font encoding for fallback font,
Werner LEMBERG <=
- bug#31315: wrong font encoding for fallback font, Eli Zaretskii, 2018/05/04