Bug 504937 - [Accessibility] Themes that rely on blur are often hardly usable without it and might need some other half opaque replacement
Summary: [Accessibility] Themes that rely on blur are often hardly usable without it a...
Status: RESOLVED DOWNSTREAM
Alias: None
Product: kwin
Classification: Plasma
Component: effects-window-management (other bugs)
Version First Reported In: 6.3.5
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-05-28 21:40 UTC by Ellie
Modified: 2025-05-29 09:14 UTC (History)
1 user (show)

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Version Fixed/Implemented In:
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Description Ellie 2025-05-28 21:40:24 UTC
SUMMARY

There is a theme I've found that relies on transparent title bars with blur. This works great on my faster machine, but on my slower machine I need to disable blur, because it will lag horribly. However, rather than leaving the transparent title bar with some sort of slightly opaque gray or e.g. some almost transparent pre-blurred version of the desktop wallpaper mixed in, it's simply left 100% transparent. As a result, the title bar text is completely unreadable half the time, since it's white text on a 100% transparent background on often something bright behind it.

It would therefore help keeping such themes usable, if instead of the regular "Blur" there was like a "Fake Blur" that either mixes in a solid color with a configurable transparency, or mixes in a pre-blurred version of the desktop wallpaper at a configurable transparency.

I suppose alternatively you could try to make the blur effect even faster, but I imagine there's a limit to how far that is feasible. The device in question where the effect isn't usable for me, is the Raspberry Pi 5, which has an extremely low-end GPU.

STEPS TO REPRODUCE

1. Use a theme with transparent blur title bars
2.  Disable the "Blur" desktop effect
3. Try to find some other effect to make the title bars usable

OBSERVED RESULT

Title bars look nice but aren't usable. Some slight gray tint would already fix this issue.

EXPECTED RESULT

Any sort of "Fake blur" alternative for low end machines that allows keeping blurred areas usable.

SOFTWARE/OS VERSIONS

Windows: 
macOS: 
(available in the Info Center app, or by running `kinfo` in a terminal window)
Linux/KDE Plasma: postmarketOS Edge ARM64
KDE Plasma Version: 6.3.5
KDE Frameworks Version: 6.13.0
Qt Version: 6.8.2

ADDITIONAL INFORMATION
Comment 1 David Edmundson 2025-05-29 06:52:13 UTC
The responsibility lies with the theme to adapt. There is nothing we can do.
Comment 2 Ellie 2025-05-29 09:10:41 UTC
Well, you could provide a "Fake Blur", that was my suggestion. It could be based for example on the desktop wallpaper. Or is that for some reason not technically possible? Sorry if I misunderstood something.
Comment 3 Ellie 2025-05-29 09:13:57 UTC
(To explain, it seems like Blur is so slow since it seems to constantly re-blur the background when something moves, which seems to overwhelm low end GPUs. But if the CPU once blurred the wallpaper, and then just rendered subsets of it as-is, that should probably be easy on the CPU, shouldn't it? And it would probably look more convincing than just transparency, and as a side effect also keep the themes more usable that don't handle the complete lack of blur well on their own.)