Bug 455759

Summary: Display scaling aliasing issues when displays have different display scales in Wayland
Product: [Plasma] kwin Reporter: Mark S <wolfendeathx>
Component: multi-screenAssignee: KWin default assignee <kwin-bugs-null>
Status: RESOLVED FIXED    
Severity: normal CC: nate, xaver.hugl
Priority: NOR Keywords: wayland-only
Version First Reported In: 5.25.1   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: https://invent.kde.org/plasma/kwin/-/commit/d1083a4db0c4e0bdf20c421b6609cd332e5c7085 Version Fixed In: 6.0
Sentry Crash Report:

Description Mark S 2022-06-21 21:49:59 UTC 
SUMMARY

When using multiple displays with different, fractional display scales in Wayland, the display(s) with the lower scale factor have scaling artifacts as if it were using the higher fractional scaling.

STEPS TO REPRODUCE

1. Use a Wayland session
2. Use multiple displays
3. Set the display scaling on one display to 100% and another to 125%
4. Activate the Present Windows effect (Ctrl+F9 or Ctrl+F10)

OBSERVED RESULT

The scaling on the display with the 100% scaling looks really bad (as if it were at 125% scaling without aliasing)

EXPECTED RESULT

The scaling on each display is correct

SYSTEM INFO

Operating System: Arch Linux
KDE Plasma Version: 5.25.1
KDE Frameworks Version: 5.95.0
Qt Version: 5.15.5
Kernel Version: 5.18.5-arch1-1 (64-bit)
Graphics Platform: Wayland
Comment 1 Nate Graham 2022-06-22 16:03:54 UTC 
Seen outside Present Windows too.
Comment 2 Zamundaaa 2024-06-09 16:34:31 UTC 
This was fixed with https://invent.kde.org/plasma/kwin/-/merge_requests/5041 for Plasma 6.0