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Screen flickers, double frame buffer?

  • I am running Qt on an ARM with an LCD.
    When im moving a big window on the screen, the screen flickers.

    Does Qt double buffer? Ifso what do i have to configure that it works correctly?
    Or could something else be the problem

    Im using Qt for embedded 4.7.0.

  • Double buffering is supported by Qt. We don't need to do anything. I have faced similar problem in past. Probably its the logic you have which is creating problem.

    Can you share more details like how you trying to update window? Is there an compression/decompression involved?

  • Thanks for your reply.

    The problem already occurs when iam running a demo application (like /demos/textedit). So i dont now how the window updating there is done, but i guess that is done right.

    Qt shows the application beautifull, but every now and then (every second or so) it looks like its drawing the frame at a wrong coordinate at the screen.

  • I think problem is with frame. It may happen that frame being drawn is distorted itself.

    Try to continuously copy that frame with different names using some loop on desktop before showing it on screen. The movement flicker appear stop application and check whether any of frame you tried to show were distorted.

  • Ok,
    Could you tell me where and how i can copy that frame?

  • Sounds like an issue with cursor re-drawing. Could you try to set the editable state off (or remove focus from QTextEdit), does it still reproduce?

  • Thanks for you reply,
    The problem is solved, turns out there was no problem with Qt but with the hardware.

  • Ok. Great (that it wasn't Qt issue, too bad for your HW).

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