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  1. Qt
  2. QTBUG-28214

Cannot make transparent (translucent) background for QQuickView



    • Bug
    • Resolution: Done
    • P2: Important
    • None
    • 5.0.0 Beta 2
    • Windows 7 x86 32 bit, NVIDIA GeForce GTX 460 with vendor's native latest DirectX and OpenGL drivers, Qt 5.0 beta2 (tested with "ANGLE" and "desktop OpenGL" configurations)
      Linux: works
    • a79e42b8f40317f7275b26637e6735754b21727f


      I have seen that this bug was already reported by somebody, but i decided to report it once more, because i tried everything and there are not any working solutions about it and it seems to be wrongly forgotten. And in that report it was Linux testing, here i tested it on Windows platform.

      I understand that QQuickView is not QWidget and that it's different from QDeclarativeView component. But when i was using Qt 4.8.x it was greatly usefull feature that allowed to make transparent backroud. It allowed to make QML widget hovering over the screen, splash-screens, and make impressive GUI designs with semi-transparent parts. Now it has been unfortunately regressed in Qt 5.0 and i believe that it can be improved. And i can't back to Qt 4.8 only because of this bug...

      I tested it on Windows 7 x86 32 bit platform with two configurations:
      1. Qt 5.0 beta 2 downloaded from official qt-project.org link (seems to be configured with ANGLE graphics backend).
      2. Qt 5.0 beta 2 downloaded from git on 22/Nov/12, configured with "configure -debug-and-release -opensource -confirm-license -nomake examples -nomake tests -no-icu -opengl desktop -platform win32-msvc2010" (desktop OpenGL backend) and successfully built by myself. And i have latest DirectX and OpenGL vendor's drivers on my NVidia GeForce GTX 460. Also tried all the same on other computer with AMD/ATI videocard.

      There is code below that i used to test it.

      main.cpp :

      QQuickView viewer;
      QSurfaceFormat format;

      main.qml :

      Rectangle {
        width: 360
        height: 360
        color: "transparent"
        Rectangle {
          x: 50
          y: 50
          width: 100
          height: 100
          color: "blue"

      result is:

      Important notes:
      1. I see the same visual result if i change "Rectangle" to "Item" type in root node and remove "color" property.
      2. If i set there "color" property to "#00000000" or "#FF000000" in root rectangle result is also the same
      3. If i set "opacity" property to 0.0 in root "Rectangle" visual result is the same
      4. But if i set "opacity" property to 1.0 i see result below:

      Related bug reports (not resolved and forgotten):
      1. https://bugreports.qt-project.org/browse/QTBUG-20768
      2. https://bugreports.qt-project.org/browse/QTBUG-24707


        1. bug_qml.png
          14 kB
        2. bug_qml2.png
          13 kB
        3. qtbug28214.zip
          3 kB

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              kleint Friedemann Kleint
              avassen Vasily Shchukin
              22 Vote for this issue
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