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Capture scroll event in textEditor

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  • D Offline
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    danga96
    wrote on last edited by
    #7

    @raven-worx said in Capture scroll event in textEditor:

    What are you exactly trying to achieve?

    in practice, I would like to launch a function whenever a scroll occurs; in particular, on my text I have labels, which act as some kind of little clouds, which must follow the text, so if this scrolls upwards the label must also follow it;

    raven-worxR 1 Reply Last reply
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    • D danga96

      @raven-worx said in Capture scroll event in textEditor:

      What are you exactly trying to achieve?

      in practice, I would like to launch a function whenever a scroll occurs; in particular, on my text I have labels, which act as some kind of little clouds, which must follow the text, so if this scrolls upwards the label must also follow it;

      raven-worxR Offline
      raven-worxR Offline
      raven-worx
      Moderators
      wrote on last edited by raven-worx
      #8

      @danga96
      then its easier to subclass QTextEdit:

      void MyTextEdit::scrollContentsBy(int dx, int dy) {
         // scroll happened, do whatever you want here
         QTextEdit::scrollContentsBy(dx, dy);
      }
      

      --- SUPPORT REQUESTS VIA CHAT WILL BE IGNORED ---
      If you have a question please use the forum so others can benefit from the solution in the future

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      • D Offline
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        danga96
        wrote on last edited by
        #9

        @raven-worx
        sorry again, but how can I use this virtual method? do i need to make a connect?

        jsulmJ 1 Reply Last reply
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        • D danga96

          @raven-worx
          sorry again, but how can I use this virtual method? do i need to make a connect?

          jsulmJ Offline
          jsulmJ Offline
          jsulm
          Lifetime Qt Champion
          wrote on last edited by
          #10

          @danga96 said in Capture scroll event in textEditor:

          do i need to make a connect?

          No, you simply override it in your class (scrollContentsBy is called by Qt framework). This is how virtual methods are used: if a subclass overrides it then its own implementation is called, else the implementation in the base class is called.

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

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            danga96
            wrote on last edited by
            #11

            @raven-worx said in Capture scroll event in textEditor:
            @jsulm
            thanks for answering me, but I can't get it to work; if I declare the method like this:

            QTextEdit::scrollContentsBy(int dx,int dy);
            

            it works, but not belonging to the class I can't exceed the private variables;
            do i have to do anything in .h, adding some define?
            in the .h I have tried:

            void scrollContentsBy(int dx, int dy) override;
            

            and in .cpp:

            void TextEdit::scrollContentsBy(int dx, int dy) { }
            

            and I get this error in compilation: "method with override specifier 'override' did not override any base class methods"

            jsulmJ 1 Reply Last reply
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            • D danga96

              @raven-worx said in Capture scroll event in textEditor:
              @jsulm
              thanks for answering me, but I can't get it to work; if I declare the method like this:

              QTextEdit::scrollContentsBy(int dx,int dy);
              

              it works, but not belonging to the class I can't exceed the private variables;
              do i have to do anything in .h, adding some define?
              in the .h I have tried:

              void scrollContentsBy(int dx, int dy) override;
              

              and in .cpp:

              void TextEdit::scrollContentsBy(int dx, int dy) { }
              

              and I get this error in compilation: "method with override specifier 'override' did not override any base class methods"

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

              @danga96 Is your class derived from QTextEdit?

              class MyTextEdit : public QTextEdit
              {
              ...
              };
              

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

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              • D Offline
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                danga96
                wrote on last edited by
                #13

                now yes, but the class already inherits from QMainWindow, and I don't know if this creates conflicts, so is there a way to do it through a connect?

                jsulmJ 1 Reply Last reply
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                • D danga96

                  now yes, but the class already inherits from QMainWindow, and I don't know if this creates conflicts, so is there a way to do it through a connect?

                  jsulmJ Offline
                  jsulmJ Offline
                  jsulm
                  Lifetime Qt Champion
                  wrote on last edited by jsulm
                  #14

                  @danga96 I don't get it: you want to capture scroll events in QTextEdit but in your QMainWindow? That can't work.
                  Create a new class as subclass of QTextEdit and use that subclass instead of QTextEdit...
                  Also, is MyTextEdit really derived from QMainWindow?! If so then this is really a bad name.

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

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                  • D Offline
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                    danga96
                    wrote on last edited by
                    #15

                    @jsulm
                    I'm referring to this example: richtext-textedit
                    I'm using it to do tests; at this point I would ask you how I can adapt this with the solution proposed by you?

                    jsulmJ 1 Reply Last reply
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                    • D danga96

                      @jsulm
                      I'm referring to this example: richtext-textedit
                      I'm using it to do tests; at this point I would ask you how I can adapt this with the solution proposed by you?

                      jsulmJ Offline
                      jsulmJ Offline
                      jsulm
                      Lifetime Qt Champion
                      wrote on last edited by
                      #16

                      @danga96 The solution wasn't proposed by me.
                      In the textedit.h file you will find this line:

                      QTextEdit *textEdit;
                      

                      Replace it with your own class derived from QTextEdit:

                      MyOwnTextEdit *textEdit;
                      

                      In myowntextedit.h

                      class MyOwnTextEdit : public QTextEdit
                      {
                          ...
                          void scrollContentsBy(int dx, int dy) override;
                          ...
                      }
                      

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

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                      • D Offline
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                        danga96
                        wrote on last edited by
                        #17

                        @jsulm said in Capture scroll event in textEditor:
                        thank you very much, and I apologize in advance for the insistence, but in this way I have to modify almost everything, because I will have to create a new class and adapt all the changes I have made with this new type, only to manage the scroll event;
                        Therefore I would like to know if there is another way.

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                          danga96
                          wrote on last edited by
                          #18

                          finally I solved this way:

                          connect(textEdit->verticalScrollBar(), &QScrollBar::valueChanged, this, &TextEdit::handleUsersCursors);
                          	
                          connect(textEdit->horizontalScrollBar(), &QScrollBar::valueChanged, this, &TextEdit::handleUsersCursors);
                          

                          without creating a new class;
                          thanks anyway for the tips;

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