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  4. Freezing at QDrag::exec() on windows

Freezing at QDrag::exec() on windows

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  • V Offline
    V Offline
    vikt999
    wrote on last edited by
    #1

    hi i would like to ask if somebody knows of a workaround for this problem:

    On Windows, the Qt event loop is blocked during the operation. However, QDrag::exec() on Windows causes processEvents() to be called frequently to keep the GUI responsive. If any loops or operations are called while a drag operation is active, it will block the drag operation.

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #2

      Hi and welcome to devnet,

      What kind of loop and operations are you talking about ?

      In any case, you could use a flag that you set before calling QDrag'exec and you check before any long loop or operation and postpone its execution.

      Hope it helps

      Interested in AI ? www.idiap.ch
      Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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      • V Offline
        V Offline
        vikt999
        wrote on last edited by
        #3

        Our problem is the opposite, the other events are more important.

        We are rendering images on UI and that way creating a video playback.

        While drag operation is performed the video becomes choppy (only on windows). The problem I just posted was from Qt documentation, I am wondering if there is a workaround for it.

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #4

          What about doing the rendering in a thread and only the "showing" in your GUI ?

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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