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  1. Qt
  2. QTBUG-113574

Incorrect sizing and bad text rendering with WebEngine using fractional scaling on Wayland



    • Bug
    • Resolution: Unresolved
    • P1: Critical
    • None
    • 6.5.0
    • WebEngine
    • None
    • Fedora 38, GNOME 44.1, Wayland, Qt 6.5.0
      Fedora 38, KDE Plasma 5.27.4, Wayland, Qt 6.5.0
    • Linux/Wayland


      After Anki updated to Qt 6.5.0, Text rendered inside a webview looked worse and some content was too small unless the window was resized. This problem can be reproduced outside of Anki.

      The sizing issue doesn't always occur; using the attached test script, I noticed that it only appeared if the webview was resized to a height of at least 596 px (on my 1080p display).

      Since Qt 6.5.0 added support for the fractional_scale_v1 wayland extension, I guess that this problem might be caused by an incomplete implementation on the WebEngine side, although I have no deeper insight into this.

      Original report: https://github.com/ankitects/anki/issues/1767#issuecomment-1535050698

      Steps to reproduce:

      •  Use the latest version of GNOME or KDE and enable fractional scaling
        • (only GNOME): 
          gsettings set org.gnome.mutter experimental-features "['scale-monitor-framebuffer']"
        • set your screen to 125% scaling in GNOME Settings/KDE System Settings
      • run the attached script to render a web page
        python3 -m venv venv
        ./venv/bin/pip install pyside6
        ./venv/bin/python qt_webengine_fractional_scaling.py

      If you need more information, I will be happy to provide it. 


        Issue Links

          For Gerrit Dashboard: QTBUG-113574
          # Subject Branch Project Status CR V



              qt_webengine_team Qt WebEngine Team
              d-k-bo David C.
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