Bug 515568

Summary:	The blur effect updates only partially
Product:	[Plasma] kwin	Reporter:	fililip <team>
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	CONFIRMED ---
Severity:	normal	CC:	team, xaver.hugl
Priority:	NOR
Version First Reported In:	6.5.5
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	blur effect artifact

Description fililip 2026-02-05 18:56:09 UTC

SUMMARY
The blur effect updates only partially for a surface, which is especially noticeable during video playback and low blur intensity + high opacity values

STEPS TO REPRODUCE
1. Edit /usr/share/plasma/desktoptheme/default/plasmarc to remove the contrast effect for better visibility (set it to false)
2. Reload the Breeze theme
3. Set the blur and noise strength values to the 7th position
4. Open a window that's constantly updating (like Firefox/Chromium/whatever playing a video)
5. Open Konsole, enable the background blur effect and set the background opacity to ~40-50%
6. Move the Konsole window so that it's on top of the updating window but doesn't fully cover it

OBSERVED RESULT
There is a seam where the blur effect "cuts off" where the underlying window's edges end due to partial effect repaints

EXPECTED RESULT
There should be no seam visible at all

SOFTWARE/OS VERSIONS
Operating System: Arch Linux 
KDE Plasma Version: 6.5.5
KDE Frameworks Version: 6.22.0
Qt Version: 6.10.2
Kernel Version: 6.18.7-arch1-1 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 5800X 8-Core Processor
Memory: 64 GiB of RAM (62.7 GiB usable)
Graphics Processor: AMD Radeon RX 9070

Comment 1 fililip 2026-02-05 18:57:57 UTC

Created attachment 189250 [details]
blur effect artifact

Here's what the artifact looks like

Comment 2 Zamundaaa 2026-02-09 23:37:32 UTC

IIRC some damage tracking changes meant the blur effect doesn't expand the repaint area like it used to anymore. We need to find out how to solve that better.