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How to use Windows Message Loop and Qt Application Exec?

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  • mrjjM mrjj

    @YJCN
    Hi
    in case that nativeEvent simply cannot work with decade-old COM crap (1998)
    there is always the options of using a plain c++ app that will handle the downloading / save to file and
    you simply call it with QProcess from Qt GUI app.

    Y Offline
    Y Offline
    YJCN
    wrote on last edited by
    #9

    @mrjj The Canon 's demo is using MFC. Why MFC could use?

    jsulmJ mrjjM 2 Replies Last reply
    0
    • Y YJCN

      @mrjj The Canon 's demo is using MFC. Why MFC could use?

      jsulmJ Online
      jsulmJ Online
      jsulm
      Lifetime Qt Champion
      wrote on last edited by
      #10

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

      Why MFC could use?

      Because it is Microsofts own GUI framework using the Windows event loop...

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

      1 Reply Last reply
      2
      • Y YJCN

        @mrjj The Canon 's demo is using MFC. Why MFC could use?

        mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #11

        @YJCN
        MFC is very old too :)

        Anyway i wonder with that line

        if(msg->message==275)

        means ? where did u get this magic number from ?

        Y 1 Reply Last reply
        0
        • mrjjM mrjj

          @YJCN
          MFC is very old too :)

          Anyway i wonder with that line

          if(msg->message==275)

          means ? where did u get this magic number from ?

          Y Offline
          Y Offline
          YJCN
          wrote on last edited by
          #12

          @mrjj
          This my CMD programm code

          int main (){       
                  EdsCameraRef camera;
          	EdsUInt32 tv;
                  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))
          	{
          		cout << "in while" << " msg.message:"<<msg.message<<endl;
          		TranslateMessage(&msg);
          		cout << "TranslateMessage" << endl;
          		DispatchMessage(&msg); // Ends up calling objectEventFnc
          		cout << "DispatchMessage" << endl;
          		break;
          	}
          	cout << "after message" << endl;
                  EdsCloseSession(camera);
          	cout << "EdsCloseSession(camera);";
          	EdsTerminateSDK();
          	system("pause");
                  return 0;
          

          This is output
          0_1537429196448_3c672381-54c0-4382-832e-91e484ab0433-image.png

          1 Reply Last reply
          0
          • 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 Online
                    jsulmJ Online
                    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
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