Bug 412091

Summary: Icon of several KDE apps is pixelated in the task switcher when fractional display scale is used on Wayland
Product: [Plasma] kwin Reporter: Patrick Silva <bugseforuns>
Component: tabboxAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: meven.car, meven29, null
Priority: NOR Keywords: wayland-only
Version First Reported In: 5.20.90   
Target Milestone: ---   
Platform: Arch Linux   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:

Description Patrick Silva 2019-09-19 22:31:29 UTC 
STEPS TO REPRODUCE
1. start Wayland session
2. set "Large icons" task switcher in system settings > window management > task switcher
3. set fractional display scaling in display and monitor > display configuration (I use 1.2 scale factor)
4.. open konsole, gwenview, discover, ksysguard
5.. press alt+tab and hold alt key

OBSERVED RESULT
all apps mentioned above shows a pixelated icon in the task switcher

EXPECTED RESULT
crisp icons

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 5.16.90
KDE Frameworks Version: 5.62.0
Qt Version: 5.13.1
Comment 1 Méven Car 2020-06-11 16:29:09 UTC 
Scale factor of 1.2 (where the fractional division are not multiple of 2) cause problems.
In the display settings UI nowadays, we simply force users to use such a value as scale factor.

Could you try with 1.25 ?
Comment 2 Patrick Silva 2020-06-11 16:40:25 UTC 
Same result with display scale 125%.

Operating System: Arch Linux 
KDE Plasma Version: 5.19.0
KDE Frameworks Version: 5.70.0
Qt Version: 5.15.0
Comment 3 Méven Car 2021-01-25 09:01:48 UTC 
I have noticed that if you use the preview button in the systemsettings for the task switcher, the rendering is then correct.
So this is an error in the code, failing to take into account the scale factor along the way, which is taken care of in systemsettings.
Comment 5 Méven Car 2021-03-01 07:19:24 UTC 
(In reply to soredake from comment #4)
> https://www.reddit.com/r/kde/comments/lficfe/
> wayland_fractional_scaling_may_be_sort_of_a/

It is not related to this issue highlighted in reddit which concerns Applications.
Comment 6 Patrick Silva 2022-09-18 17:24:44 UTC 
Cannot reproduce with display scale 125%.

Operating System: Arch Linux
KDE Plasma Version: 5.25.90
KDE Frameworks Version: 5.98.0
Qt Version: 5.15.6
Graphics Platform: Wayland