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Forum Update on Monday, May 27th 2025

Draw basic Axes on QPixmap ?

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qpixmapqchartqlabelaxisplot
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  • R Offline
    R Offline
    R-P-H
    wrote on last edited by
    #15

    Thanks @J-Hilk and @mrjj , I will give it a try and see how it goes. ;)

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    0
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by mrjj
      #16

      Hi
      Regarding the axis.
      One option is to simply draw them in inkscape and save as SVG.
      Then just paint the SVG on top of the image.
      That should be faster than draw the ticks and values by hand using painter.
      However, if axis values change or zoom is needed then its not good idea.

      R 1 Reply Last reply
      0
      • mrjjM mrjj

        Hi
        Regarding the axis.
        One option is to simply draw them in inkscape and save as SVG.
        Then just paint the SVG on top of the image.
        That should be faster than draw the ticks and values by hand using painter.
        However, if axis values change or zoom is needed then its not good idea.

        R Offline
        R Offline
        R-P-H
        wrote on last edited by
        #17

        @mrjj said in Draw basic Axes on QPixmap ?:

        Hi
        Regarding the axis.
        One option is to simply draw them in inkscape and save as SVG.
        Then just paint the SVG on top of the image.
        That should be faster than draw the ticks and values by hand using painter.
        However, if axis values change or zoom is needed then its not good idea.

        Hi, the "plot/image" is not interactive. The axis values do change but only each time a user changes a setting. So the axis would have to somehow be made on the fly for each "session". During the "session" the axis remain the same though while the image does change ! So I'm not sure what's the most efficient way of doing it...

        mrjjM 1 Reply Last reply
        0
        • R R-P-H

          @mrjj said in Draw basic Axes on QPixmap ?:

          Hi
          Regarding the axis.
          One option is to simply draw them in inkscape and save as SVG.
          Then just paint the SVG on top of the image.
          That should be faster than draw the ticks and values by hand using painter.
          However, if axis values change or zoom is needed then its not good idea.

          Hi, the "plot/image" is not interactive. The axis values do change but only each time a user changes a setting. So the axis would have to somehow be made on the fly for each "session". During the "session" the axis remain the same though while the image does change ! So I'm not sure what's the most efficient way of doing it...

          mrjjM Offline
          mrjjM Offline
          mrjj
          Lifetime Qt Champion
          wrote on last edited by
          #18

          @r-p-h
          Well if its very dynamic then hand painting them with painter should do it.
          Overlaying a svg with only part of the axis is likely more fiddle fiddle to place the values correctly
          so just drawing it should be the way to go.
          Do you have image of the needed axis?

          R 1 Reply Last reply
          0
          • mrjjM mrjj

            @r-p-h
            Well if its very dynamic then hand painting them with painter should do it.
            Overlaying a svg with only part of the axis is likely more fiddle fiddle to place the values correctly
            so just drawing it should be the way to go.
            Do you have image of the needed axis?

            R Offline
            R Offline
            R-P-H
            wrote on last edited by
            #19

            @mrjj said in Draw basic Axes on QPixmap ?:

            @r-p-h
            Well if its very dynamic then hand painting them with painter should do it.
            Overlaying a svg with only part of the axis is likely more fiddle fiddle to place the values correctly
            so just drawing it should be the way to go.
            Do you have image of the needed axis?

            The image is live though so it's constantly being displayed in a loop, so I'm not sure if re-drawing the axes constantly is such a good idea.

            mrjjM 1 Reply Last reply
            0
            • R R-P-H

              @mrjj said in Draw basic Axes on QPixmap ?:

              @r-p-h
              Well if its very dynamic then hand painting them with painter should do it.
              Overlaying a svg with only part of the axis is likely more fiddle fiddle to place the values correctly
              so just drawing it should be the way to go.
              Do you have image of the needed axis?

              The image is live though so it's constantly being displayed in a loop, so I'm not sure if re-drawing the axes constantly is such a good idea.

              mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #20

              @r-p-h
              oh, well for that sort of overlay,
              you will need to draw the axis
              anytime the image changes regardlessly.

              R 1 Reply Last reply
              0
              • mrjjM mrjj

                @r-p-h
                oh, well for that sort of overlay,
                you will need to draw the axis
                anytime the image changes regardlessly.

                R Offline
                R Offline
                R-P-H
                wrote on last edited by
                #21

                @mrjj said in Draw basic Axes on QPixmap ?:

                @r-p-h
                oh, well for that sort of overlay,
                you will need to draw the axis
                anytime the image changes regardlessly.

                Hi, Surely I could just draw (or plot ?) the axes once in the beginning and then just display or draw the image inside the plot. I think that re-drawing the axes every time will be very inefficient. Also manually drawing the tick marks and values seems like it could become tedious, so maybe using some form of QChart is the way to go...

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

                  Hi
                  Well it sounds to me like the image is live ?
                  Like a camera feed ?

                  R 1 Reply Last reply
                  0
                  • mrjjM mrjj

                    Hi
                    Well it sounds to me like the image is live ?
                    Like a camera feed ?

                    R Offline
                    R Offline
                    R-P-H
                    wrote on last edited by
                    #23

                    @mrjj said in Draw basic Axes on QPixmap ?:

                    Hi
                    Well it sounds to me like the image is live ?
                    Like a camera feed ?

                    Yes. Pretty much.

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                    0
                    • R R-P-H

                      Hi,

                      I have a QPixmap image that I put inside a label in Qt using ui->label->setPixmap(). I simply want to add some axes to the image with just basic tick marks, values and maybe axes labels. Everything I have seen so far is overly complicated using custom charts etc.

                      Is there any easy way I can draw some simple axes onto the image and display it in the label ? Or can I draw the axis onto the label and overlay the image ? Or can I overlay the image onto an axes image already set in the label ?

                      I'm really not sure how to go about this easily. Any suggestions ? Thanks.

                      A Offline
                      A Offline
                      anil_arise
                      wrote on last edited by
                      #24

                      @r-p-h
                      QLabel *Label_backImg = new QLabel(this);
                      Label_backImg->setMinimumSize(80,80);
                      Label_backImg->setMaximumSize(80,80);
                      Label_backImg->setPixmap(QPixmap(":/images/edit-icon.png").scaled (Label_backImg->width(),Label_backImg->height(),Qt::KeepAspectRatio));

                      QLabel *labelIcon = new QLabel(Label_backImg);
                      labelIcon->setGeometry(40,8,40,40);
                      labelIcon->setPixmap(QPixmap(":/images/notification.png").scaled (labelIcon->width(),labelIcon->height(),Qt::KeepAspectRatio));
                      

                      result image is :
                      0_1566199247348_Screenshot_2019-08-19_12-49-21.png

                      R 1 Reply Last reply
                      0
                      • A anil_arise

                        @r-p-h
                        QLabel *Label_backImg = new QLabel(this);
                        Label_backImg->setMinimumSize(80,80);
                        Label_backImg->setMaximumSize(80,80);
                        Label_backImg->setPixmap(QPixmap(":/images/edit-icon.png").scaled (Label_backImg->width(),Label_backImg->height(),Qt::KeepAspectRatio));

                        QLabel *labelIcon = new QLabel(Label_backImg);
                        labelIcon->setGeometry(40,8,40,40);
                        labelIcon->setPixmap(QPixmap(":/images/notification.png").scaled (labelIcon->width(),labelIcon->height(),Qt::KeepAspectRatio));
                        

                        result image is :
                        0_1566199247348_Screenshot_2019-08-19_12-49-21.png

                        R Offline
                        R Offline
                        R-P-H
                        wrote on last edited by
                        #25

                        @anil_arise said in Draw basic Axes on QPixmap ?:

                        @r-p-h
                        QLabel *Label_backImg = new QLabel(this);
                        Label_backImg->setMinimumSize(80,80);
                        Label_backImg->setMaximumSize(80,80);
                        Label_backImg->setPixmap(QPixmap(":/images/edit-icon.png").scaled (Label_backImg->width(),Label_backImg->height(),Qt::KeepAspectRatio));

                        QLabel *labelIcon = new QLabel(Label_backImg);
                        labelIcon->setGeometry(40,8,40,40);
                        labelIcon->setPixmap(QPixmap(":/images/notification.png").scaled (labelIcon->width(),labelIcon->height(),Qt::KeepAspectRatio));
                        

                        result image is :
                        0_1566199247348_Screenshot_2019-08-19_12-49-21.png

                        Hi, with this approach I will have to first create the axis externally and save them as some sort of a transparent image ?

                        A 1 Reply Last reply
                        0
                        • R R-P-H

                          @anil_arise said in Draw basic Axes on QPixmap ?:

                          @r-p-h
                          QLabel *Label_backImg = new QLabel(this);
                          Label_backImg->setMinimumSize(80,80);
                          Label_backImg->setMaximumSize(80,80);
                          Label_backImg->setPixmap(QPixmap(":/images/edit-icon.png").scaled (Label_backImg->width(),Label_backImg->height(),Qt::KeepAspectRatio));

                          QLabel *labelIcon = new QLabel(Label_backImg);
                          labelIcon->setGeometry(40,8,40,40);
                          labelIcon->setPixmap(QPixmap(":/images/notification.png").scaled (labelIcon->width(),labelIcon->height(),Qt::KeepAspectRatio));
                          

                          result image is :
                          0_1566199247348_Screenshot_2019-08-19_12-49-21.png

                          Hi, with this approach I will have to first create the axis externally and save them as some sort of a transparent image ?

                          A Offline
                          A Offline
                          anil_arise
                          wrote on last edited by
                          #26

                          @r-p-h use only .png images

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                          • J Offline
                            J Offline
                            jhoney
                            Banned
                            wrote on last edited by jhoney
                            #27
                            This post is deleted!
                            1 Reply Last reply
                            0
                            • Pl45m4P Pl45m4

                              @r-p-h

                              A ChartView, but as you already said, you have to create it on runtime, because it`s not a Widget in Qt Designer.

                              Pl45m4P Offline
                              Pl45m4P Offline
                              Pl45m4
                              wrote on last edited by
                              #28

                              @pl45m4 said in Draw basic Axes on QPixmap ?:

                              A ChartView, but as you already said, you have to create it on runtime, because it`s not a Widget in Qt Designer.

                              @jhoney
                              I think @R-P-H doen't need the exact same answer again :)


                              If debugging is the process of removing software bugs, then programming must be the process of putting them in.

                              ~E. W. Dijkstra

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                              • R Offline
                                R Offline
                                R-P-H
                                wrote on last edited by
                                #29

                                Thanks for the support guys. I tried making a transparent QPixmap image using Qt::transparent fill for the axis and overlaying it onto my other QPixmap, however it didn't work properly. So I ended up just drawing directly onto the image itself. Not the most efficient method but it seems to work...

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