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  1. Qt
  2. QTBUG-87321

QDesktopWidget::devicePixelRatioF() reports wrong ratio on Plasma Wayland

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Details

    • Bug
    • Resolution: Invalid
    • P2: Important
    • None
    • 5.12.7, 5.15.1
    • QPA: Wayland

    Description

      OS: OpenSUSE Leap 15.2
      DE: KDE Plasma 5.18.5 - Full Wayland

      I have set my Screen Scaling to 150% as seen on the attached screenshot. In my application following code reports device pixel ratio of 2, expected would 1.5:

      auto desktopWidget = QApplication::desktop();
return desktopWidget->devicePixelRatioF();    // returns 2, expected 1.5

      Also, tested on Arch Linux running Sway Wayland and screen scaling set to 250%, following is reported:

      DesktopWidget devicePixelRatio: 3
DesktopWidget devicePixelRatioF: 3
DesktopWidget logicalDpiX: 96
DesktopWidget logicalDpiY: 96
DesktopWidget physicalDpiX: 135
DesktopWidget physicalDpiY: 135
QScreen devicePixelRatio: 3
QScreen logicalDotsPerInch: 96
QScreen logicalDotsPerInchX: 96
QScreen logicalDotsPerInchY: 96
QScreen physicalDotsPerInch: 135
QScreen physicalDotsPerInchX: 134.532
QScreen physicalDotsPerInchY: 135.467
QWindow devicePixelRatio: 3

       

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            qt.team.graphics.and.multimedia Qt Graphics Team
            dporobic Damir Porobic
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              Resolved:

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