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  1. Qt
  2. QTBUG-59660

animations run faster if the dpi setting is changed for a running application



    • 730f0df17db53b249b8680a14c40d12107c8e24e (qt/qtbase/5.12)


      DelayButton finishes in half delay time depending on the screen it's shown on

      1. Have a primary UHD-screen scaled to 200% and a secondary FullHD-screen scaled to 100%.
      2. Run the example "Qt Quick Extras - Gallery".
        It's in Examples\Qt-5.9\quickcontrols\extras\gallery\gallery.pro
      3. Click on "DelayButton".
      4. Show the example on the primary screen.
      5. Click on the DelayButton and keep the mouse button pressed.
        It will take 3 seconds until the DelayButton starts flashing. 3000ms is the default delay of a DelayButton.
      6. Click on the DelayButton.
        It stops flashing.
      7. Move the example to the secondary screen.
      8. Click on the DelayButton and keep the mouse button pressed.
        It will only take 1.5 seconds until the DelayButton starts flashing. If you set a higher delay, the example will still use only half the time on the secondary screen.

      The DelayButton should always start flashing after the set delay, or after the default if not delay was set explicitly. By no means this duration should depend on the screen the DelayButton is shown on.

      Another way to see the same effect is using the qmlpreview inside the QtDesignStudio and change the zoomfactor:

      import QtQuick 2.9
      Rectangle {
          visible: true
          width: 640
          height: 1000
          color: "blue"
          Rectangle {
              id: testRect
              y: 4
              width: parent.width
              height: 10
          NumberAnimation {
              id: testAni
              target: testRect
              property: "height"
              running: true
              to: 1000
              from: 0
              loops: -1
              duration: 10000


        1. QTBUG-59660.7z
          2 kB
        2. qtdiag.txt
          6 kB

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              qt.team.quick.subscriptions Qt Quick and Widgets Team
              rlohning Robert Löhning
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