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Close connection qobject

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  • BjornWB BjornW

    When connecting to a lambda, you need to save the returned QMetaObject::Connection. From the docs:

    QMetaObject::Connection QObject::connect(const QObject *sender, PointerToMemberFunction signal, Functor functor)
    

    So something like.... (Can't compile right now)

    void MainWindow::escucharMouse()
    {
          auto connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, [](){ });
          ...
          QObject::disconnect(connection);      
    }
    
    

    EDIT: By "need to save" I mean that if you wish to disconnect a connection, you need to save the return value. If you're not going to, just leave it!

    J Offline
    J Offline
    Jeronimo
    wrote on last edited by Jeronimo
    #7

    @BjornW ok

    1 Reply Last reply
    0
    • BjornWB Offline
      BjornWB Offline
      BjornW
      wrote on last edited by
      #8

      If you want to disconnect elsewhere you need to save the connection object inside your class.

      Again, I did not compile this. But it should give you an idea.

      class MainWindow : public QMainWindow
      {
      ...
      private:
         QMetaObject::Connection m_connection;
      };
      
      ...
      
      void MainWindow::escucharMouse()
      {
            m_connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, [](){ });
      }
      void MainWindow::stopEscucharMouse()
      {
            QObject::disconnect(m_connection ); 
      }
      

      On a side note, today I learned that escuchar means listen. Which reminded me of the song "Equador" (by Sash) where they sing "Escuchame". Funny how things connect. And disconnect :).

      J 1 Reply Last reply
      3
      • BjornWB BjornW

        If you want to disconnect elsewhere you need to save the connection object inside your class.

        Again, I did not compile this. But it should give you an idea.

        class MainWindow : public QMainWindow
        {
        ...
        private:
           QMetaObject::Connection m_connection;
        };
        
        ...
        
        void MainWindow::escucharMouse()
        {
              m_connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, [](){ });
        }
        void MainWindow::stopEscucharMouse()
        {
              QObject::disconnect(m_connection ); 
        }
        

        On a side note, today I learned that escuchar means listen. Which reminded me of the song "Equador" (by Sash) where they sing "Escuchame". Funny how things connect. And disconnect :).

        J Offline
        J Offline
        Jeronimo
        wrote on last edited by Jeronimo
        #9

        @BjornW said in Close connection qobject:

        m_connection

        thx a lot!!

        1 Reply Last reply
        1
        • BjornWB Offline
          BjornWB Offline
          BjornW
          wrote on last edited by
          #10

          Good luck :)

          J 1 Reply Last reply
          2
          • BjornWB BjornW

            Good luck :)

            J Offline
            J Offline
            Jeronimo
            wrote on last edited by
            #11

            @BjornW your help me a lot thx but i think when someone use one hook for mouse events for example it's impossible to close this connection. thx again!

            1 Reply Last reply
            1
            • BjornWB Offline
              BjornWB Offline
              BjornW
              wrote on last edited by
              #12

              Post your code please. I don't understand. It should always be possible to close the connection.

              J 2 Replies Last reply
              1
              • BjornWB BjornW

                Post your code please. I don't understand. It should always be possible to close the connection.

                J Offline
                J Offline
                Jeronimo
                wrote on last edited by
                #13

                @BjornW maybe can be because in my main window class i defined with this way
                class MainWindow : public QObject {

                }???

                mrjjM 1 Reply Last reply
                0
                • J Jeronimo

                  @BjornW maybe can be because in my main window class i defined with this way
                  class MainWindow : public QObject {

                  }???

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #14

                  @Jeronimo
                  Actually all QWidgets are QObject too so it should not matter.

                  1 Reply Last reply
                  1
                  • BjornWB Offline
                    BjornWB Offline
                    BjornW
                    wrote on last edited by
                    #15

                    Do you inherit QMainWindow?

                    class MainWindow : public QMainWindow
                    
                    1 Reply Last reply
                    1
                    • BjornWB BjornW

                      Post your code please. I don't understand. It should always be possible to close the connection.

                      J Offline
                      J Offline
                      Jeronimo
                      wrote on last edited by
                      #16

                      @BjornW i only did one function to connect:
                      void MainWindow::escucharMouse()
                      {
                      m_connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, { });
                      }
                      Other for close:
                      void MainWindow::stopEscucharMouse()
                      {
                      QObject::disconnect(m_connection );
                      }
                      i defined in headers:
                      class MainWindow : public QMainWindow
                      {
                      ...
                      public
                      private:
                      QMetaObject::Connection m_connection;
                      public slots:
                      void escucharMouse();
                      void apagarMouse();
                      and slots to call these functions (two buttons)
                      };

                      and in the slots i call the function one to open other to close like:

                      void MainWindow::slot1(){
                      m_connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, { });
                      }

                      void MainWindow::slot1(){
                      QObject::disconnect(m_connection );
                      }
                      i'm using one hook to capture the events of my mouse.
                      seems not to close connection and still capture events.

                      1 Reply Last reply
                      0
                      • BjornWB Offline
                        BjornWB Offline
                        BjornW
                        wrote on last edited by
                        #17

                        You have two definitions of slot1()?

                        J 1 Reply Last reply
                        1
                        • BjornWB BjornW

                          You have two definitions of slot1()?

                          J Offline
                          J Offline
                          Jeronimo
                          wrote on last edited by Jeronimo
                          #18

                          @BjornW i tried two different public slots like:

                          connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(escucharMouse()));
                          connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(stopEscucharMouse()));
                          
                          void MainWindow::escucharMouse()
                          {
                                m_connection = QObject::connect(&mouselog::instance(), &mouselog::mouseEvent, [](){ });
                          }
                          void MainWindow::stopEscucharMouse()
                          {
                                QObject::disconnect(m_connection ); 
                          }
                          

                          with headers in private for metaobject::connection and slots in public slots.

                          But now how can call one slot or other i call them for example with this way:

                          escucharMouse(); -> to connect
                          stopEscucharMouse(); -> dont listen more
                          

                          I put two different slots

                          Works to connect but to disconnect not seems to work.
                          inherit of qobject

                          1 Reply Last reply
                          0
                          • J Offline
                            J Offline
                            Jeronimo
                            wrote on last edited by
                            #19

                            i solved my problem but the connection still thx all

                            1 Reply Last reply
                            1
                            • BjornWB Offline
                              BjornWB Offline
                              BjornW
                              wrote on last edited by
                              #20

                              This does not seem right:

                              connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(escucharMouse()));
                              connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(stopEscucharMouse()));
                              

                              You connect the same signal. And why does "verMouse" have a a timeout? What is it?

                              Anyway, since you say you solved your problem...

                              J 2 Replies Last reply
                              1
                              • BjornWB BjornW

                                This does not seem right:

                                connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(escucharMouse()));
                                connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(stopEscucharMouse()));
                                

                                You connect the same signal. And why does "verMouse" have a a timeout? What is it?

                                Anyway, since you say you solved your problem...

                                J Offline
                                J Offline
                                Jeronimo
                                wrote on last edited by Jeronimo
                                #21

                                @BjornW i need to use different signals to close the connection? i put timeout because these slots will repeat each time i say. I'm interesting to solve this issue because it's very useful too.

                                1 Reply Last reply
                                0
                                • BjornWB BjornW

                                  This does not seem right:

                                  connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(escucharMouse()));
                                  connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(stopEscucharMouse()));
                                  

                                  You connect the same signal. And why does "verMouse" have a a timeout? What is it?

                                  Anyway, since you say you solved your problem...

                                  J Offline
                                  J Offline
                                  Jeronimo
                                  wrote on last edited by
                                  #22

                                  @BjornW verMouse.setInterval(50); with this i was trying to stop the signal verMouse.stop() documentation https://doc.qt.io/qt-4.8/qtimer.html#stop

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                                  0
                                  • BjornWB Offline
                                    BjornWB Offline
                                    BjornW
                                    wrote on last edited by
                                    #23
                                    connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(escucharMouse()));
                                    connect(&this->verMouse,SIGNAL(timeout()),this,SLOT(stopEscucharMouse()));
                                    

                                    You have connected the same signal to both escuchar/stopEscuchar! This makes no sense. The order in which the slots are called is undefined in this case.

                                    1 Reply Last reply
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