Bug 499824

Summary:	Using shake cursor and qogir, the upscaled baked in shadow looks broken
Product:	[Plasma] kwin	Reporter:	Répási Dávid <hu.repasidavid>
Component:	effects-various	Assignee:	KWin default assignee <kwin-bugs-null>
Status:	RESOLVED UPSTREAM
Severity:	minor
Priority:	NOR
Version First Reported In:	6.2.5
Target Milestone:	---
Platform:	Arch Linux
OS:	Linux
URL:	https://bugreports.qt.io/browse/QTBUG-133693
Latest Commit:		Version Fixed/Implemented In:
Sentry Crash Report:
Attachments:	broken-shadows size-72-nice-shadows size-18

Description Répási Dávid 2025-02-11 16:48:53 UTC

Created attachment 178151 [details]
broken-shadows

SUMMARY

-Qogir just added support for svg cursors, but when it gets zoomed out, the baked in shadows look very bad
-I also checked the default.svg file, there the shadows look fine, so I'm opening this issue here, instead of on their github
-The issue does not appear when using cursor sizes 48 or above

STEPS TO REPRODUCE
1. enable shake cursors, set magnification to max for visibility
2. download qogir icons from within system settings
3. change cursor theme to qogir or qogir-dark
3.5 change cursor size to 18, 24 or 32, size 18 looking the most broken
4. shake the cursor
5. look at your screen in an off angle, so as to see the artifacting better, use a bright white screen to see it better

OBSERVED RESULT

broken baked in shadows

EXPECTED RESULT

nice shadows

SOFTWARE/OS VERSIONS
Linux: 6.12.10
KDE Plasma Version: 6.2.5
KDE Frameworks Version: 6.10.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION
wayland
link to the cursors and the repo: https://github.com/vinceliuice/Qogir-icon-theme/tree/master/src/cursors/src

Comment 1 Répási Dávid 2025-02-11 16:49:31 UTC

Created attachment 178152 [details]
size-72-nice-shadows

non broken big boy cursor shadow

Comment 2 Vlad Zahorodnii 2025-02-11 16:57:50 UTC

Perhaps the drop shadows fills the space all the way to the left edge. The magnification filter then samples darker than expected texels from the left edge. It should be easy to solve by introducing a bit of space between the drop shadow and the image borders.

Comment 3 Répási Dávid 2025-02-11 17:10:41 UTC

Created attachment 178153 [details]
size-18

Just wanted to drop this here as well, since I have mentioned it being the most borked, the shadow is full pixelated at size 18

Comment 4 Vlad Zahorodnii 2025-02-11 17:24:44 UTC

There's enough of space around the drop shadow. It looks like a rendering bug in QtSVG.

Comment 5 Vlad Zahorodnii 2025-02-11 18:07:52 UTC

(In reply to Vlad Zahorodnii from comment #4)
> There's enough of space around the drop shadow. It looks like a rendering
> bug in QtSVG.

It seems QtSVG still incorrectly renders gaussian blur