anyone intimately familiar with QT?

This is a discussion on anyone intimately familiar with QT? within the C++ Programming forums, part of the General Programming Boards category; i posted a question on a qt forum, but i am impatient, and thought perhaps some here might know the ...

  1. #1
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    anyone intimately familiar with QT?

    i posted a question on a qt forum, but i am impatient, and thought perhaps some here might know the answer

    update widget from separate thread - Qt Centre Forum

  2. #2
    and the hat of wrongness Salem's Avatar
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    > but i am impatient
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    Tried calling repaint() on the widget in question?

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    yes. it fails a thread-safety assertion when i try to call repaint(...) from my image acquisition thread.

    it just doesn't do anything if i call update.

    the solution i've come up with so far is to have paint event recurse by calling update at the end of the method, but that is a bit of a resource hog. if i am sampling at 1Hz, i am wastefully updating the same image many times.

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    You probably need to emit a signal from your worker thread to the main thread, the have the main thread update the widget. I don't know much about QT though, so it's just a guess.

  7. #7
    Cat without Hat CornedBee's Avatar
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    bithub is right. The Qt way for cross-thread communication is to connect a signal on an object that belongs to the sender thread to a slot on an object that belongs to the receiver thread.
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    got it. i was stupidly trying to emit a slot.

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