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How to change ui something from different class

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  • B beqa

    While certain function finish, I want to call different class's function , in which i update ui data, but nothing change. When i call this function from this class it works.

    mrjjM Offline
    mrjjM Offline
    mrjj
    Lifetime Qt Champion
    wrote on last edited by
    #2

    @beqa
    Hi
    Can you show some code?

    The normal way is to ask the other window to update a widget.
    Or use signals and slots so "when certain function finish" it emit a signal
    that you have connected to a slot in the other class. this slot then
    updates.

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    • B Offline
      B Offline
      beqa
      wrote on last edited by
      #3

      Hi

      void Tunnelqtworking::on_actionResidual_triggered()

      {

      dif.Residual();   // solving
      
      ResidualForm res;     // different class object 
      res.update_data();    // update this data
      

      }

      void ResidualForm::update_data() // this update_data()
      {
      ....

      ui.lcdNumber->display(r1);
      ui.lcdNumber->update();
      

      }

      mrjjM 1 Reply Last reply
      0
      • B beqa

        Hi

        void Tunnelqtworking::on_actionResidual_triggered()

        {

        dif.Residual();   // solving
        
        ResidualForm res;     // different class object 
        res.update_data();    // update this data
        

        }

        void ResidualForm::update_data() // this update_data()
        {
        ....

        ui.lcdNumber->display(r1);
        ui.lcdNumber->update();
        

        }

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

        @beqa
        Well, ResidualForm res; is a local variable and it will deleted as soon as
        on_actionResidual_triggered ends so it only be shown on screen for a very short time.

        Try to new it

        ResidualForm *res= new ResidualForm(this); // use this to give it a parent, else you leak
        res->update_data(); // update this data
        res->show();

        Also is ResidualForm ment to be a Dialog and popup or how was it planned to be shown ?
        You are not inserting it into anything.

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        • B Offline
          B Offline
          beqa
          wrote on last edited by
          #5

          I have tried signal and slot, but has not worked.
          I emit like this

          void Tunnelqtworking::on_actionResidual_triggered()
          {
          dif.Residual(); // solving

          ResidualForm res; // different class object
          emit update_data(5); // I figured out ,that it needs a parameter
          }
          but in ResidualForm i can't create Tunnelqtworking object, its big and give me unclear errors

          mrjjM 1 Reply Last reply
          0
          • B beqa

            I have tried signal and slot, but has not worked.
            I emit like this

            void Tunnelqtworking::on_actionResidual_triggered()
            {
            dif.Residual(); // solving

            ResidualForm res; // different class object
            emit update_data(5); // I figured out ,that it needs a parameter
            }
            but in ResidualForm i can't create Tunnelqtworking object, its big and give me unclear errors

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

            @beqa

            What should ResidualForm res; do ?
            It will die there.
            So this can never work if its any kind of window.

            You want it to popup there ?

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            • B Offline
              B Offline
              beqa
              wrote on last edited by
              #7

              I have tabWidget and add this widget
              ui.tabWidget->addTab(new ResidualForm(), "Residual");

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              • B Offline
                B Offline
                beqa
                wrote on last edited by
                #8

                I take ResidualForm *res in my .h;
                and definit res = new ResidualForm(this);
                but nothing change

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                • B Offline
                  B Offline
                  beqa
                  wrote on last edited by
                  #9

                  i try on debug and it enter ordinary this update_data function, but dont change ui element. Seems, ui has restriction from outside

                  mrjjM 1 Reply Last reply
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                  • B beqa

                    i try on debug and it enter ordinary this update_data function, but dont change ui element. Seems, ui has restriction from outside

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

                    @beqa
                    well in this case, you should NOT make a new one. you should
                    use the one you insert.

                    ui.tabWidget->addTab(new ResidualForm(), "Residual");

                    --->

                    ResidualForm *res; // THIS IN H

                    and u add it
                    res=new ResidualForm()
                    ui.tabWidget->addTab(res, "Residual");

                    so its the same.
                    res->update_data() is for the same shown on screen.

                    Do NOT create new one as its not related to the one shown on screen.

                    So the error is. You insert one , you see on screen.
                    Then you create a SECOND one that you update but its never shown on screen.

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                    • B Offline
                      B Offline
                      beqa
                      wrote on last edited by
                      #11

                      THANK YOU, YOU ARE WELCOME. ITS WORK.
                      Differently, I wonder is it possible to change different class's ui?

                      mrjjM 1 Reply Last reply
                      1
                      • B beqa

                        THANK YOU, YOU ARE WELCOME. ITS WORK.
                        Differently, I wonder is it possible to change different class's ui?

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

                        @beqa said in How to change ui something from different class:

                        , I wonder is it possible to change different class's ui?

                        They are private for the reason, that one should not directly access another's Windows
                        widgets.
                        But you can move it to public and you can access ui-> from outside but this leads
                        to bad code and not a good idea.
                        Its much better to provide function the outside can use
                        Like your update_data

                        If you allow the outside to know the inner details of other classes, you get spaghetti code and
                        a little change will result in many other changes in rest of program.

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                        • B Offline
                          B Offline
                          beqa
                          wrote on last edited by
                          #13

                          thanks, you are very Helpfull

                          1 Reply Last reply
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