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QLabel signals, linkActivated and linkHovered

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  • mrjjM mrjj

    @SPlatten
    well one reason is that signal and slot cannot return values as such.
    So it wont be useful for normal OOP where you overwrite virtual functions to alter logic.
    Its not easy to do with signals alone. Also very, very often you want to call base class version of the function you overrride as you only want to extend it and keep old logic too and in this case a signal system would be very clunky.

    btw. in your use case if you want hover events but dont feel like subclassing. you could use eventfilter and cheat that way.

    SPlattenS Offline
    SPlattenS Offline
    SPlatten
    wrote on last edited by
    #21

    @mrjj , thanks, I'm no newb when it comes to coding, but in this case I fail to see why enterEvent couldn't be a signal, its perfect for it.

    Kind Regards,
    Sy

    mrjjM 1 Reply Last reply
    0
    • SPlattenS SPlatten

      @mrjj , thanks, I'm no newb when it comes to coding, but in this case I fail to see why enterEvent couldn't be a signal, its perfect for it.

      mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by
      #22

      @SPlatten
      Well often its used for hover effect and used internally by same Widget so im not sure
      its a universal use case.
      But good news is that you can make them signals :)
      If you want.

      SPlattenS 1 Reply Last reply
      0
      • mrjjM mrjj

        @SPlatten
        Well often its used for hover effect and used internally by same Widget so im not sure
        its a universal use case.
        But good news is that you can make them signals :)
        If you want.

        SPlattenS Offline
        SPlattenS Offline
        SPlatten
        wrote on last edited by
        #23

        @mrjj , this is my implementation:

        void clsQtLabel::enterEvent(QEvent* pEvent) {
            QString strLink;
            if ( pEvent->type() == QEvent::Enter ) {
                strLink = text();
                emit linkHovered(strLink);
            } else if ( pEvent->type() == QEvent::Leave ) {
                emit linkHovered(strLink);
            }
        }
        

        Now I still have my connect code in place for:

        cnSignal = QObject::connect(this, &clsQtLabel::linkHovered
                                   ,this, &clsQtLabel::rptrLinkHovered);
        

        It still doesn't get into my slot.

        Kind Regards,
        Sy

        mrjjM 1 Reply Last reply
        0
        • SPlattenS SPlatten

          @mrjj , this is my implementation:

          void clsQtLabel::enterEvent(QEvent* pEvent) {
              QString strLink;
              if ( pEvent->type() == QEvent::Enter ) {
                  strLink = text();
                  emit linkHovered(strLink);
              } else if ( pEvent->type() == QEvent::Leave ) {
                  emit linkHovered(strLink);
              }
          }
          

          Now I still have my connect code in place for:

          cnSignal = QObject::connect(this, &clsQtLabel::linkHovered
                                     ,this, &clsQtLabel::rptrLinkHovered);
          

          It still doesn't get into my slot.

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #24

          @SPlatten said in QLabel signals, linkActivated and linkHovered:

          emit linkHovered(strLink);

          does it execute this line?

          SPlattenS 1 Reply Last reply
          0
          • mrjjM mrjj

            @SPlatten said in QLabel signals, linkActivated and linkHovered:

            emit linkHovered(strLink);

            does it execute this line?

            SPlattenS Offline
            SPlattenS Offline
            SPlatten
            wrote on last edited by
            #25

            @mrjj Yes, verified in debugger.

            Kind Regards,
            Sy

            mrjjM 1 Reply Last reply
            0
            • SPlattenS SPlatten

              @mrjj Yes, verified in debugger.

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #26

              @SPlatten
              maybe its due to reusing the signal. not sure.
              Does connect return valid ?

              1 Reply Last reply
              0
              • SPlattenS Offline
                SPlattenS Offline
                SPlatten
                wrote on last edited by
                #27

                @mrjj , resolved now, I was just in to much of a hurry and making silly mistakes.

                Kind Regards,
                Sy

                mrjjM 1 Reply Last reply
                2
                • SPlattenS SPlatten

                  @mrjj , resolved now, I was just in to much of a hurry and making silly mistakes.

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #28

                  @SPlatten
                  we all been there , done that :)

                  1 Reply Last reply
                  2
                  • SPlattenS Offline
                    SPlattenS Offline
                    SPlatten
                    wrote on last edited by SPlatten
                    #29

                    Now thats fixed, more testing and with the same label which has been set-up as link to the Google website by setting the text to:

                    %3ca href%3d%22http://google.com%22%3eGoogle%3c/a%3e
                    

                    and calling the function:

                    setOpenExternalLinks
                    

                    I'm connecting the signals:

                    linkActivated and linkHovered
                    

                    I've verified that the connection to each is successful by examining the return from the connect calls. The linkHovered now works perfectly, but I'm not getting the linkActivated when I click on the link, I have a breakpoint in the slot and it never gets there, the browser is launched correctly with the Google web-site.

                    I found this:
                    https://stackoverflow.com/questions/16581425/insert-clickable-link-in-qlabel-and-detect-click-on-this-link-to-provoke-an-acti

                    And calling setOpenExternalLinks with false does allow the linkActivated signal to function correctly, but then it doesn't open the browser. This looks like a bug as I cannot see why you would have a linkActivated signal that only works when the label is not configured to function as a link.

                    Kind Regards,
                    Sy

                    mrjjM 1 Reply Last reply
                    0
                    • SPlattenS SPlatten

                      Now thats fixed, more testing and with the same label which has been set-up as link to the Google website by setting the text to:

                      %3ca href%3d%22http://google.com%22%3eGoogle%3c/a%3e
                      

                      and calling the function:

                      setOpenExternalLinks
                      

                      I'm connecting the signals:

                      linkActivated and linkHovered
                      

                      I've verified that the connection to each is successful by examining the return from the connect calls. The linkHovered now works perfectly, but I'm not getting the linkActivated when I click on the link, I have a breakpoint in the slot and it never gets there, the browser is launched correctly with the Google web-site.

                      I found this:
                      https://stackoverflow.com/questions/16581425/insert-clickable-link-in-qlabel-and-detect-click-on-this-link-to-provoke-an-acti

                      And calling setOpenExternalLinks with false does allow the linkActivated signal to function correctly, but then it doesn't open the browser. This looks like a bug as I cannot see why you would have a linkActivated signal that only works when the label is not configured to function as a link.

                      mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #30

                      @SPlatten said in QLabel signals, linkActivated and linkHovered:

                      setOpenExternalLinks

                      Hi
                      Docs says
                      "Specifies whether QLabel should automatically open links using QDesktopServices::openUrl() instead of emitting the linkActivated() signal."
                      So that seems as expected.

                      SPlattenS 1 Reply Last reply
                      3
                      • mrjjM mrjj

                        @SPlatten said in QLabel signals, linkActivated and linkHovered:

                        setOpenExternalLinks

                        Hi
                        Docs says
                        "Specifies whether QLabel should automatically open links using QDesktopServices::openUrl() instead of emitting the linkActivated() signal."
                        So that seems as expected.

                        SPlattenS Offline
                        SPlattenS Offline
                        SPlatten
                        wrote on last edited by
                        #31

                        @mrjj , thank you.

                        Kind Regards,
                        Sy

                        1 Reply Last reply
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