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    Solved How to change ui something from different class

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    • mrjj
      mrjj Lifetime Qt Champion @beqa last edited by

      @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.

      1 Reply Last reply Reply Quote 0
      • B
        beqa last edited by

        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();
        

        }

        mrjj 1 Reply Last reply Reply Quote 0
        • mrjj
          mrjj Lifetime Qt Champion @beqa last edited by mrjj

          @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
            beqa last edited by

            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

            mrjj 1 Reply Last reply Reply Quote 0
            • mrjj
              mrjj Lifetime Qt Champion @beqa last edited by

              @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
                beqa last edited by

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

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                • B
                  beqa last edited by

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

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                  • B
                    beqa last edited by

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

                    mrjj 1 Reply Last reply Reply Quote 0
                    • mrjj
                      mrjj Lifetime Qt Champion @beqa last edited by

                      @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.

                      1 Reply Last reply Reply Quote 2
                      • B
                        beqa last edited by

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

                        mrjj 1 Reply Last reply Reply Quote 1
                        • mrjj
                          mrjj Lifetime Qt Champion @beqa last edited by

                          @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.

                          1 Reply Last reply Reply Quote 2
                          • B
                            beqa last edited by

                            thanks, you are very Helpfull

                            1 Reply Last reply Reply Quote 1
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