Created attachment 168847 [details] Discover Font Rendering SUMMARY Some text is rendered with unusual artifacting at certain window sizes when using fractional scaling. The width/position of the containing element is also likely to play a role. When resizing the window, the text will jump around a little bit to the sides as it goes between being artifacted and rendering correctly. However, if you resize the window and get one part of the application to look correct, other parts will not look correct, causing a constant game of cat-and-mouse. I have not yet found a window size that renders correctly. On a display without fractional scaling, text renders correctly. This affects the following software: - Discover - NeoChat (resizing doesn't always help in the case of the "About KDE" section, where the text is always rendered with artifacts). - Kasts (probably the least impacted except for one case that I will attach a screenshot of) - Application Dashboard - Info Center, to a minimal degree These issues are usually most visible on the "About" page. I filed this under "I don't know" because this only affects some (QML?) applications. Some applications, like Dolphin, are entirely unaffected. STEPS TO REPRODUCE For this example, I will use Discover. 1. Open Discover and go to the About page, with a scale factor of 150% 2. If not observe the issue, resize slowly until observed. 3. Text will jump around to the sides by a few pixels while resizing. OBSERVED RESULT Some applications will render fonts ugly at 150% scaling. EXPECTED RESULT All applications render fonts cleanly regardless of scale factor. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 6.8.7 Linux Zen KDE Plasma Version: 6.0.4 KDE Frameworks Version: 6.1.0 Qt Version: 6.7.0 ADDITIONAL INFORMATION On my system I am using the "Inter Display" font set to Medium 10pt, but this also affects Noto.
Created attachment 168848 [details] Kasts "Add Button" Rendering
Created attachment 168849 [details] Application Dashboard Rendering
I forgot to note this on my OP, but this was not an issue in Plasma 5.27. Perhaps this is related to the Fractional Scaling Wayland protocol, like Bug 480171.
I noticed recently that this affects Elisa particularly badly, and it can even be seen on a screenshot for this week's "This Week in KDE", although it is not quite as bad as it is on my system, it may help confirm that this is not a bug specific to my system. This is the screenshot in question where this is visible, along the lefthand side text like the highlighted "Artists" section can show this issue: https://pointieststick.com/wp-content/uploads/2024/07/screenshot_20240719_104718.jpeg In my case, however, this is more apparent. But that may be a case of varying scale factors/window sizes.
Thank you for the bug report! This issue has already been filed; please follow the linked bug report for updates on a fix. In particular, there is a workaround involving setting an environment variable that seems to work for several users; consider setting this if you are badly affected by this bug until a proper solution is implemented. *** This bug has been marked as a duplicate of bug 479891 ***
Thanks for resolving! I will keep an eye on the linked issue. To my understanding, the workaround of `QT_SCALE_FACTOR_ROUNDING_POLICY=RoundPreferFloor` disables fractional scaling which might not be viable for my setup. I may still try it if the situation worsens, but good to know the cause is at least being looked into and that this is known!