Bug 462164 - Window contents are blurry when restoring a maximized window by dragging the title bar
Summary: Window contents are blurry when restoring a maximized window by dragging the ...
Status: RESOLVED FIXED
Alias: None
Product: kwin
Classification: Plasma
Component: compositing (show other bugs)
Version: 5.26.3
Platform: Arch Linux Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords: regression
: 465382 (view as bug list)
Depends on:
Blocks:
 
Reported: 2022-11-23 12:37 UTC by Marcus Gursch
Modified: 2023-02-07 08:15 UTC (History)
5 users (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:

Attachments
Window content blur demonstration. (3.59 MB, video/x-matroska)
2022-11-23 12:37 UTC, Marcus Gursch 		Details
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Description Marcus Gursch 2022-11-23 12:37:40 UTC 
Created attachment 153974 [details]
Window content blur demonstration.

SUMMARY
***
As mentioned in the title, window contents become blurry when restoring a maximized window by dragging the title bar. The amount of blur seems to vary each time I try this but it happens basically every time I do it. This happens only with compositing enabled. To me it seems like window coordinates are not rounded to full pixels and due to this subpixel shift to the window coordinates it appears blurry. E.g. when I screenshot only the blurred window with spectacle, it appears sharp, but when I screenshot the whole desktop the blur is visible.
***


STEPS TO REPRODUCE

See the attached video for a demonstration which also includes the steps to reproduce. Please watch it at native 1920x1080 resolution without scaling to better see the difference in sharpness. 

OBSERVED RESULT
Window contents appear blurry.


EXPECTED RESULT
Window contents appear sharp with no additional blur added by the compositor.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux / 5.26.3
(available in About System)
KDE Plasma Version: 5.26.3
KDE Frameworks Version: 5.100.0
Qt Version: 5.15.7+kde+r175-1
Comment 1 Marcus Gursch 2022-11-24 13:33:41 UTC 
I just checked and this also happens with the wayland session.
Comment 2 Marcus Gursch 2022-11-28 21:44:08 UTC 
In search of a workaround for this I found out that the bug only happens with the following setting:
    window behaviour --> movement --> screen edge snap zone   :=  None
(This is roughly translated from german where it's called "Fensterverwaltung  -->  Fensterverhalten  -->  Verschiebung  -->  Bildschirmrand-Einrastzone".)
When setting this to 1px or using the default value of 10px, the blurriness can be avoided.
Comment 3 Nate Graham 2022-11-30 21:29:14 UTC 
Possibly related to Bug 461283, maybe?
Comment 4 Antonio Orefice 2022-12-31 11:54:05 UTC 
Confirmed for me.
It also happens in firefox (or all gtk apps?) that uses CSD when you unmaximize them.
Worst part is that firefox stays blurry until maximized again or compositor not disabled ofc.
Comment 5 David Edmundson 2023-01-23 13:46:06 UTC 
We made some changes in Plasma 5.27 that should help with this case. Please reopen if an issue persists in the new release with a new screenshot.
Comment 6 Vlad Zahorodnii 2023-02-07 08:15:39 UTC 
*** Bug 465382 has been marked as a duplicate of this bug. ***