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Access the UI, from multiple windows.

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  • mrjjM mrjj

    Hi
    The most common way is to provide data access functions to get the data from the
    widgets without letting rest of program know the exact type. ( as in direct access to UI object)

    so for your sample
    MainWindow MW;

    Settings_Window* C = new Settings_Window; // (This is the copy created in Window1)
    MW.SendWindowData(& C); // Here i call MainWindow object, call the function, send the copy of window,

    if( MW.getCheckerBoxStatus() )
    {
    //Do something
    }

    So getCheckerBoxStatus() returns the ui->CheckerBox status. The rest of the program do not know
    its in a checkbox and that is better design as if you later read it from a file, you need only to change
    getCheckerBoxStatus to return status from the data and rest of program do not need to change at all.
    Still works the same.

    L Offline
    L Offline
    Loc888
    wrote on last edited by Loc888
    #3

    @mrjj But ther is no way to just simply send the widnows object as reference ? Becuse ye, 75% of that setting window is just CheckerBoxe's, but some of stuff is different.
    It can help me, but i would like to find 100% solution

    I would like to have the same flexibility like in MainWindow.

    mrjjM 1 Reply Last reply
    0
    • L Loc888

      @mrjj But ther is no way to just simply send the widnows object as reference ? Becuse ye, 75% of that setting window is just CheckerBoxe's, but some of stuff is different.
      It can help me, but i would like to find 100% solution

      I would like to have the same flexibility like in MainWindow.

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

      @Loc888
      Well u can move the UI object to public section of the class and its accessible from outside but
      it leads to spaghetti code and really not recommended.
      External users of a class should not know the inner details and hence providing access functions beats
      letting everybody know what widgets a window has.

      L 1 Reply Last reply
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      • mrjjM mrjj

        @Loc888
        Well u can move the UI object to public section of the class and its accessible from outside but
        it leads to spaghetti code and really not recommended.
        External users of a class should not know the inner details and hence providing access functions beats
        letting everybody know what widgets a window has.

        L Offline
        L Offline
        Loc888
        wrote on last edited by
        #5

        @mrjj No, i dont like it, even if it helps, i mean make it public. Friend class should help, ye?

        And i am not talking about the class, i am talking about object, because like i said, i can access the class from Window1, but i need to access object S_Window from Setting_Window class, and that object is created in MainWindow, that's the problem.

        mrjjM 1 Reply Last reply
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        • L Loc888

          @mrjj No, i dont like it, even if it helps, i mean make it public. Friend class should help, ye?

          And i am not talking about the class, i am talking about object, because like i said, i can access the class from Window1, but i need to access object S_Window from Setting_Window class, and that object is created in MainWindow, that's the problem.

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

          @Loc888
          Ok, and its not possible to use signals and hook object up
          in mainwindow ?
          There is nothing stopping you from giving other class a pointer to some widget.
          like in mainwindow
          Local *local = new Local()
          Other *other= new Other()
          UseClass *useclass= new UseClass (this, local, other);

          L 1 Reply Last reply
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          • mrjjM mrjj

            @Loc888
            Ok, and its not possible to use signals and hook object up
            in mainwindow ?
            There is nothing stopping you from giving other class a pointer to some widget.
            like in mainwindow
            Local *local = new Local()
            Other *other= new Other()
            UseClass *useclass= new UseClass (this, local, other);

            L Offline
            L Offline
            Loc888
            wrote on last edited by
            #7

            @mrjj I create it with pointer already, i mean the object.
            I dont know how to use signal and slots in this example, what and wher should i type to pass the object??
            I use it with timers, but not with Windows objects.

            1 Reply Last reply
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            • mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #8

              Hi
              With signals and slots your would pass the data not the objects.
              Normally you hook things up in mainwindow as it knows most other class.
              But really depends on where its created etc.

              L 1 Reply Last reply
              2
              • mrjjM mrjj

                Hi
                With signals and slots your would pass the data not the objects.
                Normally you hook things up in mainwindow as it knows most other class.
                But really depends on where its created etc.

                L Offline
                L Offline
                Loc888
                wrote on last edited by Loc888
                #9

                @mrjj Sorry, but i rly dont understand... I can pass the object here

                void MainWindow :: GetWindowData(Settings_Window* S_Window_Temp)   
                 {
                
                     S_Window_Temp =  & S_Window;
                
                }
                

                So why i cant make a reference to it from another window, if i have the access to pass it??

                mrjjM 1 Reply Last reply
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                • L Loc888

                  @mrjj Sorry, but i rly dont understand... I can pass the object here

                  void MainWindow :: GetWindowData(Settings_Window* S_Window_Temp)   
                   {
                  
                       S_Window_Temp =  & S_Window;
                  
                  }
                  

                  So why i cant make a reference to it from another window, if i have the access to pass it??

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

                  @Loc888
                  Hi
                  Im not sure what part is causing your problems.
                  Maybe we talk about different things.

                  Yes, you can make a reference to a window.
                  or give a pointer / ref to a window to another window.

                  Like create settings_win in main.cpp
                  give it to mainwindow.
                  Mainwindow create a new Window and give settings_win to that also.

                  L 1 Reply Last reply
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                  • mrjjM mrjj

                    @Loc888
                    Hi
                    Im not sure what part is causing your problems.
                    Maybe we talk about different things.

                    Yes, you can make a reference to a window.
                    or give a pointer / ref to a window to another window.

                    Like create settings_win in main.cpp
                    give it to mainwindow.
                    Mainwindow create a new Window and give settings_win to that also.

                    L Offline
                    L Offline
                    Loc888
                    wrote on last edited by Loc888
                    #11

                    @mrjj Yes, and that's the problem. Maybe i name this topic title a little bit bad, but i dont have any problem with access, because i can access them all.

                    The problem is, when i pass the window with that function, it's seems like another copy, not reference, so when i change something, nothing happens because it change the copy variables, and i dont know why it happend.

                    If i pass ther the window object, UI stuff should be ther??

                    jsulmJ 1 Reply Last reply
                    0
                    • L Loc888

                      @mrjj Yes, and that's the problem. Maybe i name this topic title a little bit bad, but i dont have any problem with access, because i can access them all.

                      The problem is, when i pass the window with that function, it's seems like another copy, not reference, so when i change something, nothing happens because it change the copy variables, and i dont know why it happend.

                      If i pass ther the window object, UI stuff should be ther??

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #12

                      @Loc888 Let's clean up your code.

                      // You need to declare S_Window_Temp as reference to pointer, else you cannot change it inside GetWindowData!
                      void MainWindow :: GetWindowData(Settings_Window* &S_Window_Temp)   //<< Here i send Object from Settings_Window created in Window1
                      {  
                       S_Window_Temp =  &S_Window; 
                      
                       //  So i expect C (Object form Window1)  should be equal to S_Window (Object form MainWindow ), but it's not.
                      }
                      

                      Actually you should simply return the pointer from GetWindowData as your current API design is bad (it isn't a good idea to change method parameters from inside the method):

                      Settings_Window* void MainWindow :: GetWindowData()
                      {  
                          return &S_Window; 
                      }

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

                      L 1 Reply Last reply
                      2
                      • jsulmJ jsulm

                        @Loc888 Let's clean up your code.

                        // You need to declare S_Window_Temp as reference to pointer, else you cannot change it inside GetWindowData!
                        void MainWindow :: GetWindowData(Settings_Window* &S_Window_Temp)   //<< Here i send Object from Settings_Window created in Window1
                        {  
                         S_Window_Temp =  &S_Window; 
                        
                         //  So i expect C (Object form Window1)  should be equal to S_Window (Object form MainWindow ), but it's not.
                        }
                        

                        Actually you should simply return the pointer from GetWindowData as your current API design is bad (it isn't a good idea to change method parameters from inside the method):

                        Settings_Window* void MainWindow :: GetWindowData()
                        {  
                            return &S_Window; 
                        }
                        L Offline
                        L Offline
                        Loc888
                        wrote on last edited by
                        #13

                        @jsulm If i just copy and paste, your code, it gives me an error.

                        The best solution I found is just create the definition of the object in mainwindow.cpp under include, i test it with my own class, and it works exacly how i wanted it.

                        Unfortunately when i do the same thing with the Window, it crash the application and gives a message:

                        "QWidget: Must construct a QApplication before a QWidget"

                        Any way to fix it?

                        1 Reply Last reply
                        0
                        • SGaistS Offline
                          SGaistS Offline
                          SGaist
                          Lifetime Qt Champion
                          wrote on last edited by
                          #14

                          Hi,

                          The usual fix to this one is: don't create static QWidget based objects.

                          Interested in AI ? www.idiap.ch
                          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                          L 1 Reply Last reply
                          0
                          • SGaistS SGaist

                            Hi,

                            The usual fix to this one is: don't create static QWidget based objects.

                            L Offline
                            L Offline
                            Loc888
                            wrote on last edited by
                            #15

                            @SGaist I dont know what you mean.

                            mrjjM 1 Reply Last reply
                            0
                            • L Loc888

                              @SGaist I dont know what you mean.

                              mrjjM Offline
                              mrjjM Offline
                              mrjj
                              Lifetime Qt Champion
                              wrote on last edited by
                              #16

                              @Loc888
                              Hi
                              You cannot have global Widgets as they are NOT
                              allow to be constructed before QApplication in main.
                              They must be pointers and you can first new them After application is created.

                              L 1 Reply Last reply
                              1
                              • SGaistS Offline
                                SGaistS Offline
                                SGaist
                                Lifetime Qt Champion
                                wrote on last edited by
                                #17

                                If you have anything that looks like static MyClass thingy where MyClass is derived from QWidget, then remove it.

                                Interested in AI ? www.idiap.ch
                                Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                1 Reply Last reply
                                1
                                • mrjjM mrjj

                                  @Loc888
                                  Hi
                                  You cannot have global Widgets as they are NOT
                                  allow to be constructed before QApplication in main.
                                  They must be pointers and you can first new them After application is created.

                                  L Offline
                                  L Offline
                                  Loc888
                                  wrote on last edited by
                                  #18

                                  @mrjj I tried by reference, and this happend:

                                  Error: 'QWidget& QWidget::operator=(const QWidget&)' is private
                                  Class &operator=(const Class &) Q_DECL_EQ_DELETE;
                                  ^

                                  mingw48_32\include\QtWidgets\qwidget.h:728: in expansion of macro 'Q_DISABLE_COPY'
                                  Q_DISABLE_COPY(QWidget)
                                  ^

                                  It happend in this line Class &operator=(const Class &) Q_DECL_EQ_DELETE;

                                  I try later with pointers, and will see what happend.

                                  1 Reply Last reply
                                  0
                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #19

                                    For more information why, read this.

                                    Interested in AI ? www.idiap.ch
                                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                                    L 1 Reply Last reply
                                    1
                                    • SGaistS SGaist

                                      For more information why, read this.

                                      L Offline
                                      L Offline
                                      Loc888
                                      wrote on last edited by Loc888
                                      #20

                                      @SGaist

                                      Now i tried with pointers, error :

                                      error: invalid operands of types 'Settings_Window*' and 'Settings_Window*' to binary 'operator*'
                                      A* &Settings_Widget;
                                      ^

                                      void MainWindow::Get_Window_Data(Settings_Window* A)
                                      {

                                      A* &Settings_Widget;
                                      

                                      }

                                      What i did wrong?

                                      mrjjM 1 Reply Last reply
                                      0
                                      • L Loc888

                                        @SGaist

                                        Now i tried with pointers, error :

                                        error: invalid operands of types 'Settings_Window*' and 'Settings_Window*' to binary 'operator*'
                                        A* &Settings_Widget;
                                        ^

                                        void MainWindow::Get_Window_Data(Settings_Window* A)
                                        {

                                        A* &Settings_Widget;
                                        

                                        }

                                        What i did wrong?

                                        mrjjM Offline
                                        mrjjM Offline
                                        mrjj
                                        Lifetime Qt Champion
                                        wrote on last edited by
                                        #21

                                        @Loc888
                                        Hi
                                        Why not just
                                        Settings_Window* MainWindow::Get_Window_Data()
                                        {
                                        return Settings_Widget; // Settings_Widget is * (pointer) ?
                                        }

                                        L 1 Reply Last reply
                                        1
                                        • mrjjM mrjj

                                          @Loc888
                                          Hi
                                          Why not just
                                          Settings_Window* MainWindow::Get_Window_Data()
                                          {
                                          return Settings_Widget; // Settings_Widget is * (pointer) ?
                                          }

                                          L Offline
                                          L Offline
                                          Loc888
                                          wrote on last edited by
                                          #22

                                          @mrjj

                                          It run at least, but is not working. If i check something, then press the button with this code, nothing happened. Probably is another copy.
                                          I am tired, tomorrow i try something else.

                                          Is this the way how i should use it?

                                          MainWindow B;
                                          
                                          
                                          if(B.Get_Window_Data()->ui->Checker_Box_01->isChecked())
                                          {
                                          
                                              //Do something
                                          
                                          }
                                          
                                          jsulmJ 1 Reply Last reply
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