Bug 26446

Summary:	subpixel rendering is broken in GTK programs
Product:	Mageia	Reporter:	Aurélien Murith <aurelienmurith>
Component:	RPM Packages	Assignee:	Thomas Backlund <tmb>
Status:	NEW ---	QA Contact:
Severity:	major
Priority:	Normal	CC:	fri, mageia, olav, thierry.vignaud
Version:	8
Target Milestone:	---
Hardware:	All
OS:	Linux
Whiteboard:
Source RPM:		CVE:
Status comment:

Description Aurélien Murith 2020-04-07 01:09:19 CEST

Changing the font antialiasing settings in Plasma breaks the rendering in GTK programs.

For example setting RGB subpixel rendering with slight hinting gives a fine (much better than default) result in Qt programs (including Plasma) but looks terrible in everything using GTK (Firefox...).

I tried the same settings on other Linux systems and some managed it properly (Solus, Kubuntu, OpenMandriva...) while others brought me the same problem (Fedora, Void).

Comment 1 Lewis Smith 2020-04-07 10:24:55 CEST

Thank you for pointing this out; and the comparisons.

Assigning to tmb for 'gtk+3.0', CC'ing Olav as its recent committer, Thierry for GTK4.0, in the hope that someone will be able to throw light on this. Please re-assign as you see fit.

Assignee: bugsquad => tmb
CC: (none) => olav, thierry.vignaud
Summary: GTK programs ignore Plasma font antialiasing settings => GTK programs ignore Qt font antialiasing settings

Comment 2 Thierry Vignaud 2020-04-07 11:39:49 CEST

Isn't that a Plasma bug instead?

CC: (none) => mageia

Comment 3 Olav Vitters 2020-04-07 12:48:17 CEST

It might also be a problem within xsettings-kde. This syncs the KDE settings with xsettings. Under X11 GTK should follow these settings. I think Mageia installs this by default. I requested commit rights ages ago. Seems last commit was in 2016. Though if I check the Fedora package, they mention it's old and replaced by kde-gtk-config. More investigation needed. ;)

Comment 4 Aurélien Murith 2020-04-28 01:26:05 CEST

I just tried the Xfce live ISO and to my surprise I got the same problem with it: enabling RGB subpixel rendering gave me a poor rendering across the whole desktop. This means that the problem has nothing to do with Plasma but is related to subpixel rendering in GTK.

Summary: GTK programs ignore Qt font antialiasing settings => subpixel rendering is broken in GTK programs

Morgan Leijström 2020-04-28 12:14:23 CEST

CC: (none) => fri

Comment 5 Aurélien Murith 2021-05-18 00:51:39 CEST

Still a major annoyance in Mageia 8.

Version: 7 => 8
Severity: normal => major

Comment 6 Morgan Leijström 2021-05-18 14:44:04 CEST

Where are the settings for this found?

Comment 7 Aurélien Murith 2021-05-25 18:43:16 CEST

In the fonts settings.

For example in Xfce settings panel -> Appearance -> Fonts -> Rendering.

Plasma has a similar option in its settings panel, as probably most desktop environments do.