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QML performance concerns

  • I have a lot of experience developing desktop apps for medical and scientific apps using Qt and VTK, OpenGL, and CUDA.

    These include "real time" image guided surgery etc.

    I now am trying to figure out if Qt quick will be useful fir a tablet ( Android, iOS ) for displyonh brain waves in pseudo real time coming in over WiFi.

    A little googling and research says to me NO. QML is great for the UI, but not for drawing thousands of points ( with smoothing, etc).

    Am I right?

    The ( old school?) way I would do this is have a timer fire 30 FPS to draw each view ( I need to draw 6 or more wave forms) .

    I would love to use Qt mobile forthis but I'm wary...can someone give me some advice?



  • Moderators

    QtWidgets still work on iOS and Android, so you can go with them - no problem.

    As for QML drawing - indeed, drawing thousands of points is not going to be fast in "plain" QML. But there are many ways to address that:

    • use QQuickPaintedItem - there you can paint anything with QPainter, like in the old days ;-)
    • use QQuickItem and draw pre-rendered textures with your points
    • use QQuickItem and draw using OpenGL / Vulkan / whatever - probably the fastest, but also hardest to do

  • Moderators

    Ah, I forgot. There is also QNanoPainter: Haven't tried it myself, but I've heard a lot of good opinions about it.

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