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How to Detect Vertical Retraces

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  • E Offline
    E Offline
    epalmero
    wrote on last edited by
    #1

    Dear All:

    I am trying to develop an application for scientific purpose and I need to know exactly when the screen is going to begin to draw again. I think that normally the graphic card send a message call "vertical retraces" to tell the CPU he will begin to draw can someone tell me how to catch listen this from withing Qt?

    All the best and thanks a lot
    Ernesto

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    • JeroentjehomeJ Offline
      JeroentjehomeJ Offline
      Jeroentjehome
      wrote on last edited by
      #2

      I think this is more an OS thing to handle. Qt will only get a 'need to redraw' event from the OS. It does not know itself when to redraw. Maybe you could get some information from the OS itself using OS API.

      Greetz, Jeroen

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      • E Offline
        E Offline
        epalmero
        wrote on last edited by
        #3

        Hi thanks for your help I have one more question then. This redraw event will then be synchronize with the "Vertical Retraces" don't it? I mean as far as I understand then Qt will received redraw event each time the OS refresh the screen is my assumption correct?

        Best and thanks

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