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How to use Windows Message Loop and Qt Application Exec?

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  • mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by mrjj
    #13

    HI
    ahh, so 275 is the ID for what SDK is doing.
    So you call
    init_camera(camera); in main window also ?
    (and take_photo(camera,1,1000);
    and camera is a member variable in main window so it doesn't run out of scope?

    but you never see 275 ? in natvieEvent?

    Y 1 Reply Last reply
    0
    • mrjjM mrjj

      HI
      ahh, so 275 is the ID for what SDK is doing.
      So you call
      init_camera(camera); in main window also ?
      (and take_photo(camera,1,1000);
      and camera is a member variable in main window so it doesn't run out of scope?

      but you never see 275 ? in natvieEvent?

      Y Offline
      Y Offline
      YJCN
      wrote on last edited by
      #14

      @mrjj Yes. I put the code(init_camera(camera) and take_photo(camera,1,1000) ) in Button's slot function, after taking picture, the programm can't enter callback function(handleObjectEvent) and there is no 275 in natvieEvent.

      mrjjM 1 Reply Last reply
      0
      • Y YJCN

        @mrjj Yes. I put the code(init_camera(camera) and take_photo(camera,1,1000) ) in Button's slot function, after taking picture, the programm can't enter callback function(handleObjectEvent) and there is no 275 in natvieEvent.

        mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #15

        Hi
        and just to be 100% sure
        camera is NOT a local variable in Button's slot function, but in the .h file as a true member of
        main maindiw (in .h file) ?
        (im checking its not a death by scope issue)

        If unsure what i ask, please show full Button's slot function. :)

        Y 1 Reply Last reply
        0
        • mrjjM mrjj

          Hi
          and just to be 100% sure
          camera is NOT a local variable in Button's slot function, but in the .h file as a true member of
          main maindiw (in .h file) ?
          (im checking its not a death by scope issue)

          If unsure what i ask, please show full Button's slot function. :)

          Y Offline
          Y Offline
          YJCN
          wrote on last edited by
          #16

          @mrjj This is Button's slot function code

          void MainWindow::on_pushButton_2_clicked()
          {
              EdsCameraRef camera;
              init_camera(camera);
              //start_liveview(camera);
              //TakePicture(camera);
              take_photo(camera,1,1000);
              //TakePhoto();
              //dispose(camera);
              cout << "before message" << endl;
              MSG msg;
              while (::GetMessage(&msg, NULL, NULL, NULL))
              {
                  TranslateMessage(&msg);
                  DispatchMessage(&msg); // Ends up calling objectEventFnc
                  break;
              }
              cout << "after message" << endl;
              EdsCloseSession(camera);
              cout << "EdsCloseSession(camera);";
              EdsTerminateSDK();
          }
          
          
          jsulmJ 1 Reply Last reply
          0
          • Y YJCN

            @mrjj This is Button's slot function code

            void MainWindow::on_pushButton_2_clicked()
            {
                EdsCameraRef camera;
                init_camera(camera);
                //start_liveview(camera);
                //TakePicture(camera);
                take_photo(camera,1,1000);
                //TakePhoto();
                //dispose(camera);
                cout << "before message" << endl;
                MSG msg;
                while (::GetMessage(&msg, NULL, NULL, NULL))
                {
                    TranslateMessage(&msg);
                    DispatchMessage(&msg); // Ends up calling objectEventFnc
                    break;
                }
                cout << "after message" << endl;
                EdsCloseSession(camera);
                cout << "EdsCloseSession(camera);";
                EdsTerminateSDK();
            }
            
            
            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by jsulm
            #17

            @YJCN said in How to use Windows Message Loop and Qt Application Exec?:

            while (::GetMessage(&msg, NULL, NULL, NULL))
            {
            TranslateMessage(&msg);
            DispatchMessage(&msg); // Ends up calling objectEventFnc
            break;
            }

            You execute this loop only once (because of the break).
            Shouldn't you call break after you got the message you need?

            @mrjj camera is local :-) but I don't thin this is the issue here.

            https://forum.qt.io/topic/113070/qt-code-of-conduct

            mrjjM JonBJ 2 Replies Last reply
            4
            • jsulmJ jsulm

              @YJCN said in How to use Windows Message Loop and Qt Application Exec?:

              while (::GetMessage(&msg, NULL, NULL, NULL))
              {
              TranslateMessage(&msg);
              DispatchMessage(&msg); // Ends up calling objectEventFnc
              break;
              }

              You execute this loop only once (because of the break).
              Shouldn't you call break after you got the message you need?

              @mrjj camera is local :-) but I don't thin this is the issue here.

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #18

              @jsulm
              I agree, it should not run out of scope if it works like we think :)
              But you are right, maybe it just get first MSG as then it breaks.

              1 Reply Last reply
              0
              • jsulmJ jsulm

                @YJCN said in How to use Windows Message Loop and Qt Application Exec?:

                while (::GetMessage(&msg, NULL, NULL, NULL))
                {
                TranslateMessage(&msg);
                DispatchMessage(&msg); // Ends up calling objectEventFnc
                break;
                }

                You execute this loop only once (because of the break).
                Shouldn't you call break after you got the message you need?

                @mrjj camera is local :-) but I don't thin this is the issue here.

                JonBJ Offline
                JonBJ Offline
                JonB
                wrote on last edited by
                #19

                @YJCN

                @jsulm said in How to use Windows Message Loop and Qt Application Exec?:

                Shouldn't you call break after you got the message you need?

                Indeed, the loop picks up the first message and that's it. What makes you think that message is the right/only one which needs to be processed this way? It could be any old message....

                Y 1 Reply Last reply
                1
                • JonBJ JonB

                  @YJCN

                  @jsulm said in How to use Windows Message Loop and Qt Application Exec?:

                  Shouldn't you call break after you got the message you need?

                  Indeed, the loop picks up the first message and that's it. What makes you think that message is the right/only one which needs to be processed this way? It could be any old message....

                  Y Offline
                  Y Offline
                  YJCN
                  wrote on last edited by
                  #20

                  @jsulm @JonB @mrjj Yes, you are right !!! I comment the "break" . It works well!! THANK YOU!☺☺☺☺☺☺☺☺☺☺

                  JonBJ 1 Reply Last reply
                  3
                  • Y YJCN

                    @jsulm @JonB @mrjj Yes, you are right !!! I comment the "break" . It works well!! THANK YOU!☺☺☺☺☺☺☺☺☺☺

                    JonBJ Offline
                    JonBJ Offline
                    JonB
                    wrote on last edited by
                    #21

                    @YJCN
                    You have to do more than just comment out the break, if that's what you're saying. If that's all you do the ::GetMessage() loop will never exit, and your code will never return from on_pushButton_2_clicked(), e.g. you cannot press it again to take another photo. Presumably you need to find out whatever is the final message your camera issues on taking a photo and exit the loop once that has been received.

                    Y 1 Reply Last reply
                    2
                    • JonBJ JonB

                      @YJCN
                      You have to do more than just comment out the break, if that's what you're saying. If that's all you do the ::GetMessage() loop will never exit, and your code will never return from on_pushButton_2_clicked(), e.g. you cannot press it again to take another photo. Presumably you need to find out whatever is the final message your camera issues on taking a photo and exit the loop once that has been received.

                      Y Offline
                      Y Offline
                      YJCN
                      wrote on last edited by
                      #22

                      @JonB Yes. I just use a five times for loop to solve it . ^_^

                      JonBJ 1 Reply Last reply
                      0
                      • Y YJCN

                        @JonB Yes. I just use a five times for loop to solve it . ^_^

                        JonBJ Offline
                        JonBJ Offline
                        JonB
                        wrote on last edited by
                        #23

                        @YJCN
                        I don't know if your response is serious or amused. Doing it "five times" is very flaky. Isn't there a particular message number you get which you need to wait for to indicate it's now OK to leave the loop?

                        1 Reply Last reply
                        2

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