Bug 424591 - QML-based content in System Settings shell (i.e sidebar and home page) is blurry with HiDPI
Summary: QML-based content in System Settings shell (i.e sidebar and home page) is blu...
Status: RESOLVED UPSTREAM
Alias: None
Product: kwin
Classification: Plasma
Component: wayland-generic (show other bugs)
Version: git master
Platform: Other Linux
: NOR normal
Target Milestone: ---
Assignee: KWin default assignee
URL:
Keywords:
: 427704 (view as bug list)
Depends on:
Blocks:
 
Reported: 2020-07-23 22:08 UTC by Nate Graham
Modified: 2020-10-14 16:18 UTC (History)
3 users (show)

See Also:
Latest Commit:
Version Fixed In:

Attachments
Discover crisp, System Settings blurry (2.40 MB, image/jpeg)
2020-07-23 22:08 UTC, Nate Graham 		Details
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Description Nate Graham 2020-07-23 22:08:34 UTC 
Created attachment 130353 [details]
Discover crisp, System Settings blurry

All KDE software from git master as of this afternoon, on a system with a 4K screen, using a 250% scale factor.

In System Settings, the QML-based sidebar and home screen are blurry for me with the above setup. This does not affect any KCMs, just the QML-based parts of the shell. See attached photo (not a screenshot since Spectacle can't take high DPI screenshots without losing precision, which would hide the problem in this case).

This problem is not seen in QWidgets-based KDE apps, nor other QML-based apps; just System Settings.
Comment 1 David Edmundson 2020-07-23 22:34:50 UTC 
At that point it's almost certainly an issue with QQuickWidget rather than kwin.

But as per plasma rules, I'll leave open till we have a Qt bug report/patch
Comment 2 Nicolas Fella 2020-07-23 23:31:52 UTC 
I do see blurryness/pixelation issues in QML KCMs as well.

When opening the same KCMs in plasma-settings it works fine, which would support the QQuickWidget theory
Comment 3 David Edmundson 2020-07-24 09:04:28 UTC 
Can you confirm a resize "fixes" it.

I put in some debug into QQuickWidget, it seems the initial backing store has a devicePixelRatio of 1 when the FBO gets made. Then it doesn't update correctly.
Comment 4 Nicolas Fella 2020-07-24 09:08:36 UTC 
Yes, resizing does seem to help
Comment 6 Nate Graham 2020-07-24 17:54:01 UTC 
Thanks David!
Comment 7 David Edmundson 2020-10-14 16:18:37 UTC 
*** Bug 427704 has been marked as a duplicate of this bug. ***