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Maintaining aspect ratio of qlabel

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  • J.HilkJ J.Hilk

    @Kira I don't think so,

    you can access your modified/scaled pixmap by calling pixmap() and QPainter has a drawPixmap method as well.


    just noticed, that what I wrote, does not actually match what you want.

    Do I understand it correctly, that you want a way to rescale your QLabel, so that it fits the Pixmap ?

    KiraK Offline
    KiraK Offline
    Kira
    wrote on last edited by
    #10

    @J-Hilk : yes
    I tried running your code its shrinks my pixmap a bit :p

    J.HilkJ 1 Reply Last reply
    0
    • KiraK Offline
      KiraK Offline
      Kira
      wrote on last edited by
      #11

      @jsulm : Just a strange thing the program crashes after some time without throwing any specific error

      1 Reply Last reply
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      • KiraK Kira

        @J-Hilk : yes
        I tried running your code its shrinks my pixmap a bit :p

        J.HilkJ Offline
        J.HilkJ Offline
        J.Hilk
        Moderators
        wrote on last edited by
        #12

        @Kira well, is your label part of a layout or do you resize it manually?

        because you will have to resize it manually, having it in a layout will make things tricky


        Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


        Q: What's that?
        A: It's blue light.
        Q: What does it do?
        A: It turns blue.

        KiraK 1 Reply Last reply
        1
        • J.HilkJ J.Hilk

          @Kira well, is your label part of a layout or do you resize it manually?

          because you will have to resize it manually, having it in a layout will make things tricky

          KiraK Offline
          KiraK Offline
          Kira
          wrote on last edited by
          #13

          @J-Hilk : My label is part of the Grid layout.
          I have seen various articles related to the issue, but none of them provide an exact solution. Is there a specific way to handle such a scenario.

          J.HilkJ 1 Reply Last reply
          0
          • KiraK Kira

            @J-Hilk : My label is part of the Grid layout.
            I have seen various articles related to the issue, but none of them provide an exact solution. Is there a specific way to handle such a scenario.

            J.HilkJ Offline
            J.HilkJ Offline
            J.Hilk
            Moderators
            wrote on last edited by
            #14

            @Kira
            Ok, I suggest the following, I used it before with moderate success rate.

            set the SizePolcy of either width or height to fixed.

            inside the overloaded resizeEvent, set the min width/height of your fixed side to the appropriate length (according to the pixmap ratio)

            It should work, but be beware of potential recursive resizeEvents, as this is a clunky workaround.


            Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


            Q: What's that?
            A: It's blue light.
            Q: What does it do?
            A: It turns blue.

            KiraK 1 Reply Last reply
            0
            • J.HilkJ J.Hilk

              @Kira
              Ok, I suggest the following, I used it before with moderate success rate.

              set the SizePolcy of either width or height to fixed.

              inside the overloaded resizeEvent, set the min width/height of your fixed side to the appropriate length (according to the pixmap ratio)

              It should work, but be beware of potential recursive resizeEvents, as this is a clunky workaround.

              KiraK Offline
              KiraK Offline
              Kira
              wrote on last edited by
              #15

              @J-Hilk :
              OK, thanks, understood.
              What does moderate success mean?
              How can I determine the aspect ratio ?
              I will figure the code but would be grateful if you have any working sample.

              J.HilkJ 1 Reply Last reply
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              • KiraK Kira

                @J-Hilk :
                OK, thanks, understood.
                What does moderate success mean?
                How can I determine the aspect ratio ?
                I will figure the code but would be grateful if you have any working sample.

                J.HilkJ Offline
                J.HilkJ Offline
                J.Hilk
                Moderators
                wrote on last edited by
                #16

                @Kira

                What does moderate success mean

                when actively resizing the window, you may get "flickering" as the new min size may tricker a new recalculating of the other widgets inside the layout

                How can I determine the aspect ratio
                I will figure the code but would be grateful if you have any working sample

                untested:

                //Assuming horizontal size policy is fixed
                void LabelAnnotation::resizeEvent(QResizeEvent *pQEvent)
                {
                    double minw = (static_cast<double>(_qPixmap.width()) * height()) / _qPixmap.height();
                   setMinimumWidth(static_cast<int>(minw));
                }
                

                Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                Q: What's that?
                A: It's blue light.
                Q: What does it do?
                A: It turns blue.

                KiraK 3 Replies Last reply
                2
                • J.HilkJ J.Hilk

                  @Kira

                  What does moderate success mean

                  when actively resizing the window, you may get "flickering" as the new min size may tricker a new recalculating of the other widgets inside the layout

                  How can I determine the aspect ratio
                  I will figure the code but would be grateful if you have any working sample

                  untested:

                  //Assuming horizontal size policy is fixed
                  void LabelAnnotation::resizeEvent(QResizeEvent *pQEvent)
                  {
                      double minw = (static_cast<double>(_qPixmap.width()) * height()) / _qPixmap.height();
                     setMinimumWidth(static_cast<int>(minw));
                  }
                  
                  KiraK Offline
                  KiraK Offline
                  Kira
                  wrote on last edited by
                  #17

                  @J-Hilk :Thanks a lot will implement it and let you know.

                  1 Reply Last reply
                  0
                  • J.HilkJ J.Hilk

                    @Kira

                    What does moderate success mean

                    when actively resizing the window, you may get "flickering" as the new min size may tricker a new recalculating of the other widgets inside the layout

                    How can I determine the aspect ratio
                    I will figure the code but would be grateful if you have any working sample

                    untested:

                    //Assuming horizontal size policy is fixed
                    void LabelAnnotation::resizeEvent(QResizeEvent *pQEvent)
                    {
                        double minw = (static_cast<double>(_qPixmap.width()) * height()) / _qPixmap.height();
                       setMinimumWidth(static_cast<int>(minw));
                    }
                    
                    KiraK Offline
                    KiraK Offline
                    Kira
                    wrote on last edited by
                    #18

                    @J-Hilk : Here are we resizing the window or the QLabel.
                    I implemented the following, but still, there is space left when I make the window to full screen.

                    J.HilkJ 1 Reply Last reply
                    0
                    • KiraK Kira

                      @J-Hilk : Here are we resizing the window or the QLabel.
                      I implemented the following, but still, there is space left when I make the window to full screen.

                      J.HilkJ Offline
                      J.HilkJ Offline
                      J.Hilk
                      Moderators
                      wrote on last edited by
                      #19

                      @Kira said in Maintaining aspect ratio of qlabel:

                      I implemented the following

                      I don't see it. May be lost in the depth of the forum ?


                      Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                      Q: What's that?
                      A: It's blue light.
                      Q: What does it do?
                      A: It turns blue.

                      1 Reply Last reply
                      0
                      • J.HilkJ J.Hilk

                        @Kira

                        What does moderate success mean

                        when actively resizing the window, you may get "flickering" as the new min size may tricker a new recalculating of the other widgets inside the layout

                        How can I determine the aspect ratio
                        I will figure the code but would be grateful if you have any working sample

                        untested:

                        //Assuming horizontal size policy is fixed
                        void LabelAnnotation::resizeEvent(QResizeEvent *pQEvent)
                        {
                            double minw = (static_cast<double>(_qPixmap.width()) * height()) / _qPixmap.height();
                           setMinimumWidth(static_cast<int>(minw));
                        }
                        
                        KiraK Offline
                        KiraK Offline
                        Kira
                        wrote on last edited by
                        #20

                        @J-Hilk said in Maintaining aspect ratio of qlabel:

                        void LabelAnnotation::resizeEvent(QResizeEvent *pQEvent)
                        {
                        double minw = (static_cast<double>(_qPixmap.width()) * height()) / _qPixmap.height();
                        setMinimumWidth(static_cast<int>(minw));
                        }

                        This one :)

                        1 Reply Last reply
                        0
                        • J.HilkJ Offline
                          J.HilkJ Offline
                          J.Hilk
                          Moderators
                          wrote on last edited by
                          #21

                          can you show us a screenshot of the image inside the layout, it's still difficult for me to visualize what the issue is exactly ;)


                          Be aware of the Qt Code of Conduct, when posting : https://forum.qt.io/topic/113070/qt-code-of-conduct


                          Q: What's that?
                          A: It's blue light.
                          Q: What does it do?
                          A: It turns blue.

                          KiraK 1 Reply Last reply
                          1
                          • J.HilkJ J.Hilk

                            can you show us a screenshot of the image inside the layout, it's still difficult for me to visualize what the issue is exactly ;)

                            KiraK Offline
                            KiraK Offline
                            Kira
                            wrote on last edited by
                            #22

                            @J-Hilk : Sure

                            1 Reply Last reply
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