bug#23137: 25.1.50; Subpixel rendering is broken when not running under gnome-session

[Matthew Leach <matthew@mattleach.net>]

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Hi Eli,

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Matthew Leach <matthew@mattleach.net>
>> Cc: 23137@debbugs.gnu.org
>> Date: Tue, 29 Mar 2016 22:13:14 +0100
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> >> > What is "subpixel rendering"?
>> >> 
>> >> [1] gives an overview of what it is and the 'rgba' values in [2] show
>> >> how to configure it.  I think MS use the term ClearType on their Windows
>> >> platform.
>> >
>> > Then why do you think it's an Emacs problem?
>> 
>> I think it's an Emacs problem, because it is not behaving as configured,
>> even though other GTK applications do.
>
> What configuration options were supposed to tell Emacs to use subpixel
> rendering?

There are two: ~/.Xresources (attached).  On some systems there is
/etc/fonts/conf.avail/10-sub-pixel-*.conf and you can symlink one of
those to /etc/fonts/conf.d (I have attached the one I use).  The 'rgba'
value in both configs controls subpixel rendering.

Thanks,
-- 
Matt

[-- Attachment #2: .Xresources --]
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Xft.antialias:  1
Xft.hinting:    1
Xft.hintstyle:  hintfull
Xft.lcdfilter:  lcddefault
Xft.rgba:       rgb


[-- Attachment #3: 10-sub-pixel-rgb.conf --]
[-- Type: application/octet-stream, Size: 489 bytes --]

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
<!--  Enable sub-pixel rendering --> 
  <match target="pattern">
    <!--
      This configuration is available on the major desktop environments.
      We shouldn't overwrite it with "assign" unconditionally.
      Most clients may picks up the first value only. so using "append"
      may simply works to avoid it.
    -->
    <edit name="rgba" mode="append"><const>rgb</const></edit>
  </match>
</fontconfig>