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    Unsolved QQuickFramebufferObject eats CPU and battery as a horse

    QML and Qt Quick
    qquick fbo framebuffer cpu horse
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    • Dmitry87
      Dmitry87 last edited by Dmitry87

      I'm trying to implement a OpenGL item in QML using QQuickFramebufferObject . I noticed that QQuickFramebufferObject eats CPU like a horse even if render function is not implemented. The CPU core usage is always 100% and in addition to that it eats battery very fast. If there are 3-4 such items, the programm begins to lag ( Windows 7 Core i7). The same problem is in the Scene Graph - Rendering FBOs example. How can I take updating under control?

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      • SGaist
        SGaist Lifetime Qt Champion last edited by

        Hi and welcome to devnet,

        You should also add which version of Qt your are using.

        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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        • Dmitry87
          Dmitry87 last edited by Dmitry87

          Kubuntu 14 Qt5.5; Windows 7 Qt5.3.1 & Qt5.4 (tested on 2 PC's) ), Android 4.2.1. One core is always 100% (even in idle state), but when I disable FB item, the usage is 0%

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          • SGaist
            SGaist Lifetime Qt Champion last edited by

            Hi,

            Then you should consider upgrading to 5.6 IIRC, there was some work done on the performance side.

            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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            • Dmitry87
              Dmitry87 last edited by

              Unfortunately 5.6 has the same bug. In addition to that it spams this message: "libpng warning: iCCP: known incorrect sRGB profile" and sometimes crashes with: "QQmlEngine: Illegal attempt to connect to QQmlDMAbstractItemModelData(0x332dc7b8) that is in a different thread than the QML engine QQmlEngine(0x198f870.", this happens in a single-threaded application.

              Well, seems QML is just not for portable devices.

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              • SGaist
                SGaist Lifetime Qt Champion last edited by

                The libpng warning comes from libpng, nothing Qt can do about it.

                The QML engine crash is unrelated to libpng warning.

                Can you reproduce this crash with a simple app ?

                What do you mean by portable devices ? QML applications run on the RPi, BeagleBoneBlack, i.MX boards or iOS and android based phone.

                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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