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How to take desktop screenshot on Mac OS X?

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  • G Offline
    G Offline
    Ganster41
    wrote on last edited by
    #3

    I don't know it's correct or not, but not NULL. There is "screenshot":https://www.dropbox.com/s/qqpm45xsn0idyaa/debug.png (image are to large for attach to post) of debug window with all values.

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #4

      The image is not accessible

      What does winId() return ?

      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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      • G Offline
        G Offline
        Ganster41
        wrote on last edited by
        #5

        winId() returns 4317431408.

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        • G Offline
          G Offline
          Ganster41
          wrote on last edited by
          #6

          Hmm, I check this code on Mac OS X 10.8, and it works OK. But on 10.6 it crashes :(

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          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #7

            If you can, could you build your application directly on 10.6 and retry ?

            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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            • G Offline
              G Offline
              Ganster41
              wrote on last edited by
              #8

              I made all builds on same systems, where made tests. So, it crashes on 10.6 if compiled on 10.6 too.
              I can't find code for taking screenshot in Qt sources, but looks like it uses CGDisplayCreateImage() function. It's buggy on Mac OS 10.6, and crashes app if used. For now I changed code to this, and it works on both Mac OS versions:
              @#ifdef Q_OS_MAC
              // This line crashes app on 10.6, use second instead
              // CGImageRef windowImage = CGDisplayCreateImage(CGMainDisplayID());
              CGImageRef windowImage = CGWindowListCreateImage(CGRectNull, kCGWindowListOptionOnScreenOnly,
              0, kCGWindowImageBoundsIgnoreFraming);
              QPixmap screenshot = fromMacCGImageRef(windowImage);
              CGImageRelease(windowImage);
              #else
              QPixmap screenshot = mainScreen->grabWindow(QApplication::desktop()->winId());
              #endif@

              I got fromMacCGImageRef() from old revision of qtmacports.

              But now I got other issue - MyQMainWindow->showFullScreen() does't open window fullscreen. O_o

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              • G Offline
                G Offline
                Ganster41
                wrote on last edited by
                #9

                I needed to take it from my app. I know how to take it with system hotkeys.
                Now I see some critical bugs in Qt on Mac OS X, so now I trying to use Java.
                Anyway, thanks for the help!

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #10

                  Can you provide a minimal compilable example that shows the crash ?

                  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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                  • G Offline
                    G Offline
                    Ganster41
                    wrote on last edited by
                    #11

                    It's in first post. Just call this code on Mac OS 10.6, and app will crash.
                    I can take screenshot with Mac-specific code from my "post":http://qt-project.org/forums/viewreply/150944/ but I got two issues with fullscreen window now:

                    1. On 10.6 QMainWindow::showFullScreen() does nothing. Just shows window not fullscreen. Strange, but Java has same issue. Looks like it fixed now with "this":https://codereview.qt-project.org/#change,70543 path, but I didn't try it, because I can't install Qt 5.2 beta to Mac OS 10.6 previosly;
                    2. On 10.8 calling QMainWindow::showFullScreen() opens fullscreen window normally, but when I call QMainWindow::close() - blank frame still appears on screen. Don't know how to fix that.
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                    • V Offline
                      V Offline
                      vezprog
                      wrote on last edited by
                      #12

                      You can render a QWidget using QPixmap. This is how you would render the QWidget.
                      @
                      // render the widget to QPixmap
                      QPixmap screenshot(widget->size());
                      widget->render(&screenshot);

                      // save the screen shot
                      screenshot.save("fileName.jpg");
                      @

                      Edit: I had to change my post, I misunderstood your question...I thought you wanted to grab a screen shot of the whole screen.

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                      • G Offline
                        G Offline
                        Ganster41
                        wrote on last edited by
                        #13

                        [quote author="dvez43" date="1387217447"]You might be able to create a transparent widget to the size of the screen (using QDesktopWidget to get the dimensions), and get the screen shot.[/quote]
                        And it really will work on both systems? Looks so hacky.
                        For example, I can't open non-fullscreen window with all screen dimensions. Upper menu bar are unreachable for this windows.

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                        • V Offline
                          V Offline
                          vezprog
                          wrote on last edited by
                          #14

                          The edited code example above should work.

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                          • B Offline
                            B Offline
                            belab
                            wrote on last edited by
                            #15

                            Maybe the problem in your original code is in line 16:
                            @this->screenshot = &screenshot;@
                            You are assigning the pointer of a local object to a member. Going out of scope destroys the pixmap.

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                            • G Offline
                              G Offline
                              Ganster41
                              wrote on last edited by
                              #16

                              Yes, it was wrong, and I already changed this code. But problem are not here.

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                              • SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by
                                #17

                                Did you retry with a more recent version of Qt ?

                                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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                                • G Offline
                                  G Offline
                                  Ganster41
                                  wrote on last edited by
                                  #18

                                  I no longer have machine with Mac OS 10.6, so I can't test it anymore.
                                  Now I trying to support 10.8+ only.

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