Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. A camera problem.
Forum Updated to NodeBB v4.3 + New Features

A camera problem.

Scheduled Pinned Locked Moved Unsolved General and Desktop
91 Posts 7 Posters 18.9k Views 2 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • J jenya7

    @jsulm said in A camera problem.:

    @jenya7 said in A camera problem.:

    It's not physically allocated

    It is, see the first line in the constructor

    It doesn't work

    jsulmJ Offline
    jsulmJ Offline
    jsulm
    Lifetime Qt Champion
    wrote on last edited by
    #71

    @jenya7 said in A camera problem.:

    It doesn't work

    What doesn't work? I'm sure that line works. Do you call show() after that line or before?

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

    1 Reply Last reply
    0
    • jsulmJ jsulm

      @jenya7 said in A camera problem.:

      viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget.

      It's not "empty". And a widget does not have to be "tied" to another widget. If it is not and you call show() on it it will be shown in its own window, but it should not crash...

      J Offline
      J Offline
      jenya7
      wrote on last edited by
      #72

      @jsulm said in A camera problem.:

      @jenya7 said in A camera problem.:

      viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget.

      It's not "empty". And a widget does not have to be "tied" to another widget. If it is not and you call show() on it it will be shown in its own window, but it should not crash...

      I see. I'll try to understand what causes the crash.

      1 Reply Last reply
      0
      • J jenya7

        @JonB
        viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget. in the original example viewfinder is tied to a StackedWidget panel.

        JonBJ Offline
        JonBJ Offline
        JonB
        wrote on last edited by JonB
        #73

        @jenya7 said in A camera problem.:

        viewfinder = new QCameraViewfinder(); is an empty object, not tied to any widget

        QCameraViewfinder is a QWidget, so don't know what this means. In your case you may need to give it a parent or add it somewhere. I have suggested code you might try before turning to your own code....

        1 Reply Last reply
        0
        • JonBJ JonB

          @jenya7
          What is "not physically allocated", and why do you get an exception on what?

          There is a basic example at https://doc.qt.io/qt-5/qcameraviewfinder.html

          camera = new QCamera;
          
          viewfinder = new QCameraViewfinder();
          viewfinder->show();
          
          camera->setViewfinder(viewfinder);
          
          imageCapture = new QCameraImageCapture(camera);
          
          camera->setCaptureMode(QCamera::CaptureStillImage);
          camera->start();
          

          Did you test whether just this code might work for you?

          You also ought check those m_camera->isCaptureModeSupported(...) I mentioned, else you are whistling in the wind....

          J Offline
          J Offline
          jenya7
          wrote on last edited by jenya7
          #74

          @JonB said in A camera problem.:

          @jenya7
          What is "not physically allocated", and why do you get an exception on what?

          There is a basic example at https://doc.qt.io/qt-5/qcameraviewfinder.html
          Did you test whether just this code might work for you?

          You also ought check those m_camera->isCaptureModeSupported(...) I mentioned, else you are whistling in the wind....

          bool supported = m_camera->isCaptureModeSupported(QCamera::CaptureStillImage);
          

          Yes. It's supported.
          I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.
          Is it normal?

          jsulmJ JonBJ 2 Replies Last reply
          0
          • J jenya7

            @JonB said in A camera problem.:

            @jenya7
            What is "not physically allocated", and why do you get an exception on what?

            There is a basic example at https://doc.qt.io/qt-5/qcameraviewfinder.html
            Did you test whether just this code might work for you?

            You also ought check those m_camera->isCaptureModeSupported(...) I mentioned, else you are whistling in the wind....

            bool supported = m_camera->isCaptureModeSupported(QCamera::CaptureStillImage);
            

            Yes. It's supported.
            I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.
            Is it normal?

            jsulmJ Offline
            jsulmJ Offline
            jsulm
            Lifetime Qt Champion
            wrote on last edited by
            #75

            @jenya7 said in A camera problem.:

            I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

            Where do you see it and where do you create camera object? Can you please post relevant code?

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

            J 1 Reply Last reply
            0
            • J jenya7

              @JonB said in A camera problem.:

              @jenya7
              What is "not physically allocated", and why do you get an exception on what?

              There is a basic example at https://doc.qt.io/qt-5/qcameraviewfinder.html
              Did you test whether just this code might work for you?

              You also ought check those m_camera->isCaptureModeSupported(...) I mentioned, else you are whistling in the wind....

              bool supported = m_camera->isCaptureModeSupported(QCamera::CaptureStillImage);
              

              Yes. It's supported.
              I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.
              Is it normal?

              JonBJ Offline
              JonBJ Offline
              JonB
              wrote on last edited by JonB
              #76

              @jenya7
              OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

              J 1 Reply Last reply
              0
              • JonBJ JonB

                @jenya7
                OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

                J Offline
                J Offline
                jenya7
                wrote on last edited by
                #77

                @JonB said in A camera problem.:

                @jenya7
                OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

                It runs on Windows machine. Have to arrange some camera....

                JonBJ 1 Reply Last reply
                0
                • J jenya7

                  @JonB said in A camera problem.:

                  @jenya7
                  OK, but why not try the example from the docs, in a standalone test program? Not going to say it again.....

                  It runs on Windows machine. Have to arrange some camera....

                  JonBJ Offline
                  JonBJ Offline
                  JonB
                  wrote on last edited by
                  #78

                  @jenya7
                  What runs on Windows machine? It's just sample code, does it not run on whatever platform you are on? You may know better than I, I'll keep quiet now.

                  1 Reply Last reply
                  0
                  • jsulmJ jsulm

                    @jenya7 said in A camera problem.:

                    I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                    Where do you see it and where do you create camera object? Can you please post relevant code?

                    J Offline
                    J Offline
                    jenya7
                    wrote on last edited by
                    #79

                    @jsulm said in A camera problem.:

                    @jenya7 said in A camera problem.:

                    I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                    Where do you see it and where do you create camera object? Can you please post relevant code?

                    I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.
                    This way it works without errors

                    QCameraViewfinder *v_finder;
                    
                    MainWindow::MainWindow(QWidget *parent) :
                        QMainWindow(parent),
                        ui(new Ui::MainWindow)
                    {
                        v_finder = new QCameraViewfinder(this);
                        v_finder->show();
                    
                        ui->setupUi(this);
                        ui->textEditTerminalTx->installEventFilter(this);
                    }
                    
                    void Camera::setCamera(const QCameraInfo &cameraInfo)
                    {
                           //........................
                    
                         m_camera->setViewfinder(v_finder);
                    
                          //............................
                    }
                    
                    

                    Is it OK?

                    JonBJ 1 Reply Last reply
                    0
                    • J jenya7

                      @jsulm said in A camera problem.:

                      @jenya7 said in A camera problem.:

                      I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                      Where do you see it and where do you create camera object? Can you please post relevant code?

                      I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.
                      This way it works without errors

                      QCameraViewfinder *v_finder;
                      
                      MainWindow::MainWindow(QWidget *parent) :
                          QMainWindow(parent),
                          ui(new Ui::MainWindow)
                      {
                          v_finder = new QCameraViewfinder(this);
                          v_finder->show();
                      
                          ui->setupUi(this);
                          ui->textEditTerminalTx->installEventFilter(this);
                      }
                      
                      void Camera::setCamera(const QCameraInfo &cameraInfo)
                      {
                             //........................
                      
                           m_camera->setViewfinder(v_finder);
                      
                            //............................
                      }
                      
                      

                      Is it OK?

                      JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on last edited by JonB
                      #80

                      @jenya7 said in A camera problem.:

                      I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

                      And what was the result?!

                      I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                      At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

                      J 1 Reply Last reply
                      1
                      • JonBJ JonB

                        @jenya7 said in A camera problem.:

                        I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

                        And what was the result?!

                        I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                        At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

                        J Offline
                        J Offline
                        jenya7
                        wrote on last edited by
                        #81

                        @JonB said in A camera problem.:

                        @jenya7 said in A camera problem.:

                        I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

                        And what was the result?!

                        I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                        At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

                        m_camera->setViewfinder(v_finder) is executed first

                        JonBJ 1 Reply Last reply
                        0
                        • J jenya7

                          @JonB said in A camera problem.:

                          @jenya7 said in A camera problem.:

                          I put a break point in the MainWindow constructor and Camera constructor and see which hits the first.

                          And what was the result?!

                          I see the Camera object is created before MainWindow::MainWindow(QWidget *parent) constructor.

                          At the time your Camera::setCamera() is called, has v_finder = new QCameraViewfinder(this); been executed yet? If not then v_finder in m_camera->setViewfinder(v_finder) will be nullptr....

                          m_camera->setViewfinder(v_finder) is executed first

                          JonBJ Offline
                          JonBJ Offline
                          JonB
                          wrote on last edited by
                          #82

                          @jenya7
                          Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

                          J 2 Replies Last reply
                          1
                          • JonBJ JonB

                            @jenya7
                            Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

                            J Offline
                            J Offline
                            jenya7
                            wrote on last edited by
                            #83

                            @JonB said in A camera problem.:

                            @jenya7
                            Then obviously it is not the right place to put m_camera->setViewfinder(v_finder);.... You cannot execute that line until both m_camera & v_finder have been initialized, so move it somewhere suitable.

                            I'll try

                            1 Reply Last reply
                            0
                            • M Offline
                              M Offline
                              mchinand
                              wrote on last edited by
                              #84

                              It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

                              J 1 Reply Last reply
                              0
                              • M mchinand

                                It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

                                J Offline
                                J Offline
                                jenya7
                                wrote on last edited by
                                #85

                                @mchinand said in A camera problem.:

                                It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

                                It's a widget based example. I removed all widget related stuff cause I don't have all these controls for camera operating in my app. I control the camera with commands I type in a terminal.

                                jsulmJ 1 Reply Last reply
                                0
                                • J jenya7

                                  @mchinand said in A camera problem.:

                                  It seems your code is largely based on the Camera Example; is that correct? Does that example work for you unmodified?

                                  It's a widget based example. I removed all widget related stuff cause I don't have all these controls for camera operating in my app. I control the camera with commands I type in a terminal.

                                  jsulmJ Offline
                                  jsulmJ Offline
                                  jsulm
                                  Lifetime Qt Champion
                                  wrote on last edited by
                                  #86

                                  @jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

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

                                  J 1 Reply Last reply
                                  3
                                  • jsulmJ jsulm

                                    @jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

                                    J Offline
                                    J Offline
                                    jenya7
                                    wrote on last edited by jenya7
                                    #87

                                    @jsulm said in A camera problem.:

                                    @jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

                                    I'll try tomorrow. I have to get a camera.

                                    well...in the original example I press on Capture Photo and it stays inactive forever.

                                    J.HilkJ 1 Reply Last reply
                                    0
                                    • J Offline
                                      J Offline
                                      jenya7
                                      wrote on last edited by jenya7
                                      #88

                                      How can I pass a default camera instance to use it later?
                                      In camera.h

                                      class Camera : public QMainWindow
                                      {
                                          Q_OBJECT
                                      
                                          public:
                                          Camera();
                                          void Camera::setCamera(const QCameraInfo &cameraInfo);
                                      
                                          const QCameraInfo* default_camera;   
                                      }
                                      

                                      in camera.cpp in a constructor

                                      if (cameraInfo == QCameraInfo::defaultCamera())
                                      {
                                             default_camera = new QCameraInfo(cameraInfo );
                                              videoDeviceAction->setChecked(true);
                                      }
                                      

                                      in main.cpp

                                      g_camera.SetCamera(g_camera.default_camera );
                                      

                                      I get
                                      error: reference to type 'const QCameraInfo' could not bind to an lvalue of type 'const QCameraInfo *'

                                      1 Reply Last reply
                                      0
                                      • J jenya7

                                        @jsulm said in A camera problem.:

                                        @jenya7 Come on, the question is whether this example works with your camera or not! Can't you simply try that?

                                        I'll try tomorrow. I have to get a camera.

                                        well...in the original example I press on Capture Photo and it stays inactive forever.

                                        J.HilkJ Online
                                        J.HilkJ Online
                                        J.Hilk
                                        Moderators
                                        wrote on last edited by
                                        #89

                                        @jenya7 said in A camera problem.:

                                        I'll try tomorrow. I have to get a camera.

                                        wait!

                                        how do you expect the state to change to a ready for capture == true, when you have no camera connected that could be used ?


                                        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                                        Q: What's that?
                                        A: It's blue light.
                                        Q: What does it do?
                                        A: It turns blue.

                                        J 1 Reply Last reply
                                        0
                                        • J.HilkJ J.Hilk

                                          @jenya7 said in A camera problem.:

                                          I'll try tomorrow. I have to get a camera.

                                          wait!

                                          how do you expect the state to change to a ready for capture == true, when you have no camera connected that could be used ?

                                          J Offline
                                          J Offline
                                          jenya7
                                          wrote on last edited by jenya7
                                          #90

                                          @J-Hilk said in A camera problem.:

                                          @jenya7 said in A camera problem.:

                                          I'll try tomorrow. I have to get a camera.

                                          wait!

                                          how do you expect the state to change to a ready for capture == true, when you have no camera connected that could be used ?

                                          It's connected. The constructor detects it - "dev/video0".

                                          I just wonted to try the original example on Windows. my app is running on Linux.

                                          1 Reply Last reply
                                          0

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved