Plasma 6 font rendering issue in System Settings

spica · Guru Joined: 04 Jun 2021 Posts: 330

I observe an issue with font rendering in System Settings

https://i.postimg.cc/zDGnnGqm/Screenshot-20240920-101727-1.png

I reproduced under a new user account too.

I use plasma-meta
Display & Monitor -> Scale = 150%
Font settings https://i.postimg.cc/pXTMbzx0/Screenshot-20240920-103010.png

Profile is combined gentoo:default/linux/amd64/23.0/desktop/plasma + gentoo:default/linux/amd64/23.0/no-multilib

Is this a known issue? I understand Plasma 6 is out just recently, and something may appear here and there, but if this can be easily fixed then I am happy to know about that.

asturm · Developer Joined: 05 Apr 2007 Posts: 9276

It is possible your session just needs a restart after changing scale factor?

spica · Guru Joined: 04 Jun 2021 Posts: 330

Unfortunately, a restart does not help. But I am now sure that it is related to scaling.
With 150% scaling https://postimg.cc/2qhKgwbC - small letters are colored
With 100% scaling (no scaling) https://postimg.cc/V5DVy560 - all letters are white
With 200% like 100% no rendering issue.

150% is a fractional scaling, maybe, this is the reason that fractional scaling is not fully supported.

In Plasma 5 I used to change font DPI from 96 to 150, instead of changing display scale. But here no such option in System Settings at this moment.

Maybe, there's some trick how to force custom DPI instead of changing display scale?

asturm · Developer Joined: 05 Apr 2007 Posts: 9276

Are you in a Wayland or X11 session?

No, forget about forcing DPI, it was only ever a workaround. Fractional scaling should work perfectly fine, it does here with 160% e.g., so we should really just figure out what's wrong there.

For a start, please cleanup your ~/.cache dir to give it a clean start. Close any running session beforehand, and remove it within tty e.g.

spica · Guru Joined: 04 Jun 2021 Posts: 330

I run Wayland.
.cache cleanup does not help.

It looks to me this is a known issue https://bugs.kde.org/show_bug.cgi?id=479891
I checked their screenshots, font distortions are similar, and I think this is it.

I think I need to wait when 479891 is solved.

Thanks Andreas for the help with checking the problem.