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Performance difference (Qt4 vs Qt5)

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  • W Offline
    W Offline
    Welshman
    wrote on last edited by
    #5

    I have just migrated my project of a simple moving dial using QML and there is
    a reduction in performance in Qt5

    The needle jitters as it moves, smooth in Qt4

    The QML is launched using QQuickview in QT5

    Qdeclarativeview in QT4

    How can I fix the QT5 issue ?

    ...just realised this post is a year old not a few days

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    • sierdzioS Offline
      sierdzioS Offline
      sierdzio
      Moderators
      wrote on last edited by
      #6

      In Qt5, you can tell QtQuick to offload to a different thread. But treat that as a last resort - I think the problem lies somewhere else. What are the changes in your QML for Qt5? Maybe your code is suboptimal, or you are running on Mesa drivers? Are you using the newest version (Qt 5.2.0)?

      (Z(:^

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      • W Offline
        W Offline
        Welshman
        wrote on last edited by
        #7

        Thanks for picking this up

        Only changed

        import QtQuick 1.0

        to

        import QtQuick 2.0

        This is the moving element in qml

        @
        Image {
        id: needle2
        x: 678; y: 107
        smooth: true
        source: "needle.png"
        transform: Rotation {
        id: needle2Rotation
        origin.x: 17.5; origin.y:151
        //! [needle angle]
        angle: Math.min(Math.max(-60, root2.value*1.215 - 60), 200)

                        Behavior on angle {
                            SpringAnimation {
                                spring: 1.4
                                damping:.15
                            }
                        }
        }
        }
        

        @

        I see the same QT4 to QT5 difference in Windows and Linux
        Linux is my main development platform

        The OpenGL example apps run fine

        Im running 5.2

        The qml code above is the dial with slider example shipped with QT4.8 (its not in QT5)

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        • sierdzioS Offline
          sierdzioS Offline
          sierdzio
          Moderators
          wrote on last edited by
          #8

          Please edit your post and wrap the code between '@' tags: it will be much easier to read.

          I can recognize the code, yes. In Qt 5.2, you can actually bump the import to:
          @
          import QtQuick 2.1 // or maybe even 2.2, I'm not sure
          @

          Maybe you are indeed on to something wrong in Qt itself: it should be running smoothly.

          (Z(:^

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          • N Offline
            N Offline
            nezticle
            wrote on last edited by
            #9

            Regarding Performance differences between Qt 4 and Qt 5, as always it depends on your use case. In the Widget stack, I would expect painting performance between 4.8 and 5.0 to be very similar. In 4.8 we deprecated the "native" painting in favour of raster, and in Qt 5 almost any use of QPainter will result in the use of the raster paint engine (except for a few cases where you will us the OpenGL paint engine instead).

            For the QML cases, QtQuick 1.x -> QtQuick 2.x will almost always be more performant in Qt 5 vs Qt 4. Here for the majority of cases (except for QQuickPaintedItem) we'll be rendering your scene in OpenGL and avoiding the QPainter abstraction all together.

            There are of course other factors than painting/rendering performance at play when discussing comparisons between Qt 4 and Qt 5, but in the case of graphics performance Qt 5 should be equal to or better than in Qt 4.

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            • W Offline
              W Offline
              Welshman
              wrote on last edited by
              #10

              QtQuick 2.1 and 2.2 had the same results

              UI Componenets Dial Control Example in Qt 4.8
              ported to Qt5.2

              if its just me seeing the degraded dial movement then I need to see what im doing different, im not an experienced Qt programmer ,Qt is my first C++ experience after using C in embedded products.

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              • W Offline
                W Offline
                Welshman
                wrote on last edited by
                #11

                Looking closer this dial control QML is in Qt5 install

                it doesn't appear in the welcome page of examples , but it does sit in the Qt5 install directory , all the porting changes already done.

                I loaded ready ported qml with the same problem.

                running Qt4 dialcontrol and Qt5 dialcontrol side by side on the same monitor will show the obvious difference

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                • JKSHJ Offline
                  JKSHJ Offline
                  JKSH
                  Moderators
                  wrote on last edited by
                  #12

                  Hi,

                  How did you run the example? I opened <Qt>/examples/declarative/ui-components/dialcontrol/dialcontrol.pro in Qt Creator, built it and ran it. It was perfectly smooth for me -- MSVC 2012 x64, OpenGL. (Although, I'm using a gaming PC with a powerful graphics card).

                  Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                  • W Offline
                    W Offline
                    Welshman
                    wrote on last edited by
                    #13

                    I think thats the Qt4 version using QtQuick 1.0

                    there is another in C:\Qt\Qt5.2.0\5.2.0\Src\qtdeclarative\examples\quick\ui-components\dialcontrol

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                    • JKSHJ Offline
                      JKSHJ Offline
                      JKSH
                      Moderators
                      wrote on last edited by
                      #14

                      Ah, you're right. Anyway, I ran both versions, and here are the results:

                      If I drag the slider from one end to the other, both versions are equally (very) smooth.

                      If I drag the slider really slowly across, then the Qt Quick 2 version is a bit jerkier.

                      I'm guessing that you saw the effects of trial #2? I think the degradation here is due to how the QML engine delivers bound values to Behavior/SpringAnimation, not due to slower graphics performace. If graphics were degraded, then you'd see the jerkiness in trial #1 too.

                      Also, if you delete the "Behavior on angle" part in Dial.qml, you'll find that the graphics updates are really snappy.

                      Nonetheless, it's still a degradation from Qt Quick 1. Would you like to report it to http://bugreports.qt-project.org/ ?

                      Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                      • W Offline
                        W Offline
                        Welshman
                        wrote on last edited by
                        #15

                        Thanks

                        And yes it is test 2. slow movements , initial acceleration i would say is jerky

                        Yes I would like to report it, never reported a bug before tho

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                        • JKSHJ Offline
                          JKSHJ Offline
                          JKSH
                          Moderators
                          wrote on last edited by
                          #16

                          Go to http://bugreports.qt-project.org/

                          Create an account and log in

                          Click "Create Issue" (top-right)

                          Enter the following, plus your own details:

                          Project: Qt

                          Issue Type: Bug

                          Component/s: QtQuick: Core

                          Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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                          • W Offline
                            W Offline
                            Welshman
                            wrote on last edited by
                            #17

                            Bug posted,

                            QTBUG-36709

                            thanks guys for all your help

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                            • JKSHJ Offline
                              JKSHJ Offline
                              JKSH
                              Moderators
                              wrote on last edited by
                              #18

                              Thank you for your report!

                              Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

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