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QCamera + QCameraViewfinder: how to mirror the the image displayed in the viewfinder?

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  • V Offline
    V Offline
    Violet Giraffe
    wrote on last edited by
    #29

    Here's the list. Can't see anything named WMF, but I guess I need to know the exact name to look for.

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    • V Violet Giraffe

      Thanks, but still no. rendererControl is null, and I tried executing your snippet both before and after camera.start() call.

      N Offline
      N Offline
      nicesw123
      wrote on last edited by
      #30

      @Violet-Giraffe said:

      Thanks, but still no. rendererControl is null

      Same for Debian (and it's variants [Ubuntu, etc.])

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      • N Offline
        N Offline
        nicesw123
        wrote on last edited by
        #31

        Maby the way to do this for now...
        (i.e. until the qt developers realize the value of extending QCameraImageProcessing or QCameraViewfinder to allow mirroring (flipping) the image)

        ...is to "derive from QAbstractVideoSurface" as shown here: http://doc.qt.io/qt-5/cameraoverview.html#viewfinder (find some example code there, showing rotation)

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #32

          DSEngine -> DirectShow. The plugin it self has the control but it seems it's not accessible yet.

          If you are wiling to re-build the plugin, that can be modified.

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          V 1 Reply Last reply
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          • SGaistS SGaist

            DSEngine -> DirectShow. The plugin it self has the control but it seems it's not accessible yet.

            If you are wiling to re-build the plugin, that can be modified.

            V Offline
            V Offline
            Violet Giraffe
            wrote on last edited by
            #33

            @SGaist, it depends on how difficult it is to build Qt 5 nowadays (I remember it being a pain because of WebKit that I didn't even need, hopefully that's fixed now). Let me check nicesw123's suggestion first.

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            • D Offline
              D Offline
              Devopia53
              wrote on last edited by
              #34

              Qt/C++ already provides that functionality. You can easily implement flipping feature if you use the following classes.

              QGraphicsView, QGraphicsScene, QCamera, QVideoWidget, QTramsform

              V 1 Reply Last reply
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              • D Devopia53

                Qt/C++ already provides that functionality. You can easily implement flipping feature if you use the following classes.

                QGraphicsView, QGraphicsScene, QCamera, QVideoWidget, QTramsform

                V Offline
                V Offline
                Violet Giraffe
                wrote on last edited by Violet Giraffe
                #35

                @Devopia53, how can I connect those to QCamera if the only thing camera accepts is QCameraViewfinder?
                P. S. Nvm, it accepts QVideoWidget. Still not quite sure how to connect the parts you've listed. A little help, please? :)

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                • V Violet Giraffe

                  @Devopia53, how can I connect those to QCamera if the only thing camera accepts is QCameraViewfinder?
                  P. S. Nvm, it accepts QVideoWidget. Still not quite sure how to connect the parts you've listed. A little help, please? :)

                  D Offline
                  D Offline
                  Devopia53
                  wrote on last edited by
                  #36

                  @Violet-Giraffe
                  QCameraViewfinder is not a solution for flipping. Instead, use the QAbstractVideoSurface. But it is poor display performance.

                  Samples on how to use the QGraphicsView are as follows: I wish you a note.

                  auto camera = new QCamera;
                  auto widget = new QVideoWidget;
                  QTransform matrix(-1,0,0,0,1,0,0,0,1); // m11=-1 : flipping horizontal

                  graphicsView->setScene(new QGraphicsScene);
                  graphicsView->show();

                  auto proxyWidget = graphicsView->scene()->addWidget(widget);

                  proxyWidget->setTransform(matrix);
                  camera->setViewfinder(widget);
                  camera->start();

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                  • D Devopia53

                    @Violet-Giraffe
                    QCameraViewfinder is not a solution for flipping. Instead, use the QAbstractVideoSurface. But it is poor display performance.

                    Samples on how to use the QGraphicsView are as follows: I wish you a note.

                    auto camera = new QCamera;
                    auto widget = new QVideoWidget;
                    QTransform matrix(-1,0,0,0,1,0,0,0,1); // m11=-1 : flipping horizontal

                    graphicsView->setScene(new QGraphicsScene);
                    graphicsView->show();

                    auto proxyWidget = graphicsView->scene()->addWidget(widget);

                    proxyWidget->setTransform(matrix);
                    camera->setViewfinder(widget);
                    camera->start();

                    V Offline
                    V Offline
                    Violet Giraffe
                    wrote on last edited by
                    #37

                    @Devopia53, thanks, but I think you're missing something. proxyWidget is not used here. AndQTransform has no effect on the widget, although I do see the image just as I did with QCameraViewfinder.

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                    • V Offline
                      V Offline
                      Violet Giraffe
                      wrote on last edited by
                      #38

                      Any further ideas? I'm stuck here.

                      kshegunovK 1 Reply Last reply
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                      • V Violet Giraffe

                        Any further ideas? I'm stuck here.

                        kshegunovK Offline
                        kshegunovK Offline
                        kshegunov
                        Moderators
                        wrote on last edited by
                        #39

                        @Violet-Giraffe

                        D3D11CreateDevice: Flags (0x2) were specified which require the D3D11 SDK Layers for Windows 10, but they are not present on the system.
                        These flags must be removed, or the Windows 10 SDK must be installed.
                        Flags include: D3D11_CREATE_DEVICE_DEBUG

                        Have you tried installing the DX11 SDK?

                        Read and abide by the Qt Code of Conduct

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                        • V Offline
                          V Offline
                          Violet Giraffe
                          wrote on last edited by
                          #40

                          I have not. Frankly, I doubt this message is related to my task/problem.

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                          0
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #41

                            You don't have to rebuild all of Qt just to modify one module. But the solution I have in mind might not be an optimal use of the API.

                            Interested in AI ? www.idiap.ch
                            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                            1 Reply Last reply
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                            • V Violet Giraffe

                              I need the live view image from the camera being displayed in the QCameraViewfinder to be mirrored (flipped horizontally). What are my options for doing this?

                              HymerB534H Offline
                              HymerB534H Offline
                              HymerB534
                              wrote on last edited by
                              #42

                              @Violet-Giraffe Hi Violet-Giraffe, I've just bought 3 USB wide angle cameras for my van - I was looking at writing an app to display reversing cameras - did you solve the mirroring issue ?

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                              • veryqtpersonV Offline
                                veryqtpersonV Offline
                                veryqtperson
                                wrote on last edited by veryqtperson
                                #43

                                I've encountered the same necessity - to mirror the video output of the camera.

                                I found a solution which involves a custom wrapper:

                                class VideoWrapper : public QAbstractVideoSurface
                                

                                Then you'll be able to control QVideoSurfaceFormat and perform setMirrored in its start method.

                                That's actually similar to what @SGaist proposed back then.

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