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Problem connecting Signals and Slots in a modal dialog

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  • mrjjM mrjj

    Hi
    First thing is to check that connect returns true to see if its accepted

    qDebug() << "works:" << connect(ui->tabWidget,SIGNAL(currentChanged(int)),this,SLOT(onTabChanged()));

    Or use the new syntax that catches errors at compile time
    https://wiki.qt.io/New_Signal_Slot_Syntax

    One thing I did wonder.

    You show
    SettingsForm =new QDialog;

    That is creating a new normal Qt Dialog.

    However, you dialog isH17T_Settings so
    I assume you new this in some code you have not shown ?

    E Offline
    E Offline
    eschmo
    wrote on last edited by eschmo
    #3

    @mrjj

    Thanks for your input.

    i did try debug messages from the H17T_Settings class's constructor but i dont get any output.
    So i suggest, the constructor will not be called in anyway...unfortunately i dont get it.
    Maybe there is something wrong with my call. Of the DIalog as you may suggested?

    @mrjj said in Problem connecting Signals and Slots in a modal dialog:

    One thing I did wonder.

    You show
    SettingsForm =new QDialog;

    That is creating a new normal Qt Dialog.

    However, you dialog isH17T_Settings so
    I assume you new this in some code you have not shown ?

    what exactely do you mean? frm_Settings is type H17T_Settings if you mean that?

    mrjjM 1 Reply Last reply
    0
    • E eschmo

      @mrjj

      Thanks for your input.

      i did try debug messages from the H17T_Settings class's constructor but i dont get any output.
      So i suggest, the constructor will not be called in anyway...unfortunately i dont get it.
      Maybe there is something wrong with my call. Of the DIalog as you may suggested?

      @mrjj said in Problem connecting Signals and Slots in a modal dialog:

      One thing I did wonder.

      You show
      SettingsForm =new QDialog;

      That is creating a new normal Qt Dialog.

      However, you dialog isH17T_Settings so
      I assume you new this in some code you have not shown ?

      what exactely do you mean? frm_Settings is type H17T_Settings if you mean that?

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #4

      @eschmo

      Hi
      If the debug dont show up then I also doubt that the constructor is called.

      What I talk about is the creation code you shown.

       SettingsForm =new QDialog;
      

      I would expect it to be

        SettingsForm =new H17T_Settings; 
      
      

      So we do use your new class and not just the default Qt QDialog.

      so SettingsForm
      is defined as
      H17T_Settings *SettingsForm

      and we then new one of that type.

      E 1 Reply Last reply
      1
      • mrjjM mrjj

        @eschmo

        Hi
        If the debug dont show up then I also doubt that the constructor is called.

        What I talk about is the creation code you shown.

         SettingsForm =new QDialog;
        

        I would expect it to be

          SettingsForm =new H17T_Settings; 
        
        

        So we do use your new class and not just the default Qt QDialog.

        so SettingsForm
        is defined as
        H17T_Settings *SettingsForm

        and we then new one of that type.

        E Offline
        E Offline
        eschmo
        wrote on last edited by
        #5

        @mrjj

        You are absolutely right.

        I've corrected it and now i get the debug messages! Thanks!

        Tab Connect: true
        Button Connect: true
        

        But wether my slot neither the dialog close will be called.
        Button Cancel calls close() through the ui_h17t_Settings.h without any problem.

        mrjjM 1 Reply Last reply
        0
        • E eschmo

          @mrjj

          You are absolutely right.

          I've corrected it and now i get the debug messages! Thanks!

          Tab Connect: true
          Button Connect: true
          

          But wether my slot neither the dialog close will be called.
          Button Cancel calls close() through the ui_h17t_Settings.h without any problem.

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #6

          @eschmo
          Hi
          So now the right dialog show up but pressing your ui->Btn_Save_Settings
          does nothing ?

          E 1 Reply Last reply
          0
          • mrjjM mrjj

            @eschmo
            Hi
            So now the right dialog show up but pressing your ui->Btn_Save_Settings
            does nothing ?

            E Offline
            E Offline
            eschmo
            wrote on last edited by
            #7

            @mrjj

            Yes exactely, bu it was the right Dialog all the time but obviously just the appearance not the code.
            I've also switched to the new connection syntax but debug shows true for the old way as well.

                qDebug() << "Tab Connect:" <<connect(ui->tabWidget,&QTabWidget::currentChanged,this,&H17T_Settings::onTabChanged);
                qDebug() << "Button Connect:" <<connect(ui->Btn_Save_Settings,&QPushButton::clicked,this,&H17T_Settings::close);
            
            Tab Connect: true
            Button Connect: true
            
            mrjjM J.HilkJ 2 Replies Last reply
            0
            • E eschmo

              @mrjj

              Yes exactely, bu it was the right Dialog all the time but obviously just the appearance not the code.
              I've also switched to the new connection syntax but debug shows true for the old way as well.

                  qDebug() << "Tab Connect:" <<connect(ui->tabWidget,&QTabWidget::currentChanged,this,&H17T_Settings::onTabChanged);
                  qDebug() << "Button Connect:" <<connect(ui->Btn_Save_Settings,&QPushButton::clicked,this,&H17T_Settings::close);
              
              Tab Connect: true
              Button Connect: true
              
              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #8

              @eschmo
              Hi
              Super with the new syntax as then, we are very sure it's not the connect.

              Try replace the close() with accept();
              and see if it then closes.

              btw does Settings::onTabChange gets called ?

              If not I think its something else.

              E 1 Reply Last reply
              0
              • mrjjM mrjj

                @eschmo
                Hi
                Super with the new syntax as then, we are very sure it's not the connect.

                Try replace the close() with accept();
                and see if it then closes.

                btw does Settings::onTabChange gets called ?

                If not I think its something else.

                E Offline
                E Offline
                eschmo
                wrote on last edited by
                #9

                @mrjj

                no, nothing is called at all.

                I've redone the connection for the "Save Button" with the designer and it worked straight afterwards.
                I did it again in the cpp and it doesnt work. thats quite irritating.

                mrjjM 1 Reply Last reply
                0
                • E eschmo

                  @mrjj

                  no, nothing is called at all.

                  I've redone the connection for the "Save Button" with the designer and it worked straight afterwards.
                  I did it again in the cpp and it doesnt work. thats quite irritating.

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #10

                  @eschmo
                  That is very odd.

                  You only create a H17T_Settings once place right ?

                  and if it works assigning a slot in Designer for the same dialog then it must work too
                  with manual connect as its much the same.

                  Just to be sure. You go to Designer and use the "go to slot" function to create a slot
                  for it and there you call close()

                  but if you don't do this and just have the manual connects it wont work ?

                  E 1 Reply Last reply
                  0
                  • mrjjM mrjj

                    @eschmo
                    That is very odd.

                    You only create a H17T_Settings once place right ?

                    and if it works assigning a slot in Designer for the same dialog then it must work too
                    with manual connect as its much the same.

                    Just to be sure. You go to Designer and use the "go to slot" function to create a slot
                    for it and there you call close()

                    but if you don't do this and just have the manual connects it wont work ?

                    E Offline
                    E Offline
                    eschmo
                    wrote on last edited by
                    #11

                    @mrjj

                    yes exactely, i'Ve even put the connection for tabwidget currentChange() in the ui file by hand and it works with H17T_Settings close().

                    But it will not work in anyway with my connections over the cpp, even if they succeed to connect.

                    Thats quite strange...

                    mrjjM 1 Reply Last reply
                    0
                    • E eschmo

                      @mrjj

                      yes exactely, i'Ve even put the connection for tabwidget currentChange() in the ui file by hand and it works with H17T_Settings close().

                      But it will not work in anyway with my connections over the cpp, even if they succeed to connect.

                      Thats quite strange...

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #12

                      @eschmo

                      Yes its very strange as it should work when connect returns true and besides with the
                      new syntax, the compiler would tell if something fishy.

                      All seems fine with H17T_Settings soI cant I guess why onTabChanged() is not called.

                      1 Reply Last reply
                      0
                      • E eschmo

                        @mrjj

                        Yes exactely, bu it was the right Dialog all the time but obviously just the appearance not the code.
                        I've also switched to the new connection syntax but debug shows true for the old way as well.

                            qDebug() << "Tab Connect:" <<connect(ui->tabWidget,&QTabWidget::currentChanged,this,&H17T_Settings::onTabChanged);
                            qDebug() << "Button Connect:" <<connect(ui->Btn_Save_Settings,&QPushButton::clicked,this,&H17T_Settings::close);
                        
                        Tab Connect: true
                        Button Connect: true
                        
                        J.HilkJ Online
                        J.HilkJ Online
                        J.Hilk
                        Moderators
                        wrote on last edited by mrjj
                        #13

                        @eschmo said in Problem connecting Signals and Slots in a modal dialog:

                        Yes exactely, bu it was the right Dialog all the time but obviously just the appearance not the code.
                        I've also switched to the new connection syntax but debug shows true for the old way as well.

                        No it was not, It could not have been the correct dialog, when you instantiated a different dialog.

                        I think you have simply multiple dialogs instances ore something along that line.

                        can you post/link a minimal compellable example?


                        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.

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

                          @eschmo said in Problem connecting Signals and Slots in a modal dialog:

                          Yes exactely, bu it was the right Dialog all the time but obviously just the appearance not the code.
                          I've also switched to the new connection syntax but debug shows true for the old way as well.

                          No it was not, It could not have been the correct dialog, when you instantiated a different dialog.

                          I think you have simply multiple dialogs instances ore something along that line.

                          can you post/link a minimal compellable example?

                          E Offline
                          E Offline
                          eschmo
                          wrote on last edited by
                          #14

                          @mrjj
                          yes i'm a little bit confused and lost about it.
                          anyway, thanks a lot for your help.

                          @J-Hilk

                          it has appeared exactly as the dialog i've prepared in the designer.
                          Thats for sure because of

                          frm_Settings.setupUi(SettingsForm);
                          

                          and fits why not my overloaded constructor is in place but the standart one of QDialog.

                          I couldnt find any other instance in my code, but i dont see how this could affect the called dialog.

                          I've put the whole project to github if this could help.

                          https://github.com/eschmo/H17-Timing/tree/main/H17-Timing

                          Thanks a lot for your time!

                          J.HilkJ 1 Reply Last reply
                          2
                          • E eschmo

                            @mrjj
                            yes i'm a little bit confused and lost about it.
                            anyway, thanks a lot for your help.

                            @J-Hilk

                            it has appeared exactly as the dialog i've prepared in the designer.
                            Thats for sure because of

                            frm_Settings.setupUi(SettingsForm);
                            

                            and fits why not my overloaded constructor is in place but the standart one of QDialog.

                            I couldnt find any other instance in my code, but i dont see how this could affect the called dialog.

                            I've put the whole project to github if this could help.

                            https://github.com/eschmo/H17-Timing/tree/main/H17-Timing

                            Thanks a lot for your time!

                            J.HilkJ Online
                            J.HilkJ Online
                            J.Hilk
                            Moderators
                            wrote on last edited by J.Hilk
                            #15

                            @eschmo
                            inside your h17t_main.h
                            your SettingsForm member pointer is this:

                            QDialog *SettingsForm
                            

                            and it should be:

                            H17T_Settings *SettingsForm;
                            

                            That should fix your issue, but from looking at the rest of your code:

                            • You're going to leak memory with H17T_Settings instances.
                            • You're set up to do threading stuff that apparently have access to GUI stuff

                            Both are a big nono... :D


                            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.

                            E 1 Reply Last reply
                            3
                            • mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by mrjj
                              #16

                              Hi
                              Also a note

                              You do

                              void H17T_Main::onSettings()
                              {
                                  SettingsForm = new H17T_Settings; // this also calls setupUI
                              ...
                                  frm_Settings.setupUi(SettingsForm); <<< what is this for ? now you create all
                                   the widgets once more so the other ones that was connected in the constructor is no longer 
                                  the ones shown on screen. This should not be needed to call manually.
                                  SettingsForm->show();
                              }
                              
                              

                              That seems to be the reason as it works without that line :)
                              alt text

                              1 Reply Last reply
                              3
                              • J.HilkJ J.Hilk

                                @eschmo
                                inside your h17t_main.h
                                your SettingsForm member pointer is this:

                                QDialog *SettingsForm
                                

                                and it should be:

                                H17T_Settings *SettingsForm;
                                

                                That should fix your issue, but from looking at the rest of your code:

                                • You're going to leak memory with H17T_Settings instances.
                                • You're set up to do threading stuff that apparently have access to GUI stuff

                                Both are a big nono... :D

                                E Offline
                                E Offline
                                eschmo
                                wrote on last edited by
                                #17

                                @J-Hilk said in Problem connecting Signals and Slots in a modal dialog:

                                QDialog

                                Sorry, not sure why this was in the files i've uploaded but this was allready changed yesterday.

                                Finally thanks a lot, because the solution was your second tip.

                                I've removed it completely and everything is fine now!

                                Thanks a lot to both of you!!

                                J.HilkJ 1 Reply Last reply
                                2
                                • E eschmo

                                  @J-Hilk said in Problem connecting Signals and Slots in a modal dialog:

                                  QDialog

                                  Sorry, not sure why this was in the files i've uploaded but this was allready changed yesterday.

                                  Finally thanks a lot, because the solution was your second tip.

                                  I've removed it completely and everything is fine now!

                                  Thanks a lot to both of you!!

                                  J.HilkJ Online
                                  J.HilkJ Online
                                  J.Hilk
                                  Moderators
                                  wrote on last edited by
                                  #18

                                  @eschmo said in Problem connecting Signals and Slots in a modal dialog:

                                  I've removed it completely and everything is fine now!

                                  I'm afraid that credit goes to @mrjj ;)

                                  Sorry, not sure why this was in the files i've uploaded but this was allready changed yesterday.

                                  I'm talking header, not cpp
                                  d87a69c8-6117-4c3b-9fe0-b70c5734e36a-image.png


                                  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.

                                  1 Reply Last reply
                                  1

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