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QtWS25 Last Chance

Combine Multiple Images Into a Single PDF

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pdfsavewidget
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  • M mrjj
    25 Jul 2016, 17:48

    @geor
    well a screen is 72/96 DPI
    and a printer is 600/1200/2400 DPI
    so images do get really small.

    As far as I remember, QPdfWriter have some setting for pdf resolution.
    maybe it can produce better output.

    G Offline
    G Offline
    geor
    wrote on 25 Jul 2016, 18:28 last edited by
    #29

    @mrjj yeah I saw that but unfortunately I am using qt 5.2.1

    M 1 Reply Last reply 25 Jul 2016, 18:34
    0
    • G geor
      25 Jul 2016, 18:28

      @mrjj yeah I saw that but unfortunately I am using qt 5.2.1

      M Offline
      M Offline
      mrjj
      Lifetime Qt Champion
      wrote on 25 Jul 2016, 18:34 last edited by
      #30

      @geor
      maybe you could try to scale it before
      drawing it to pdf.
      the scale function can be adjusted to aim for quality
      http://doc.qt.io/qt-5/qpixmap.html#scaled
      with Qt::SmoothTransformation

      note. it returns the scaled pixmap not modify the original.
      so something like
      mypixmap = mypixmap.scaled(xx)

      G 1 Reply Last reply 25 Jul 2016, 18:51
      1
      • M mrjj
        25 Jul 2016, 18:34

        @geor
        maybe you could try to scale it before
        drawing it to pdf.
        the scale function can be adjusted to aim for quality
        http://doc.qt.io/qt-5/qpixmap.html#scaled
        with Qt::SmoothTransformation

        note. it returns the scaled pixmap not modify the original.
        so something like
        mypixmap = mypixmap.scaled(xx)

        G Offline
        G Offline
        geor
        wrote on 25 Jul 2016, 18:51 last edited by
        #31

        @mrjj It is abit better but still low quality

        M 1 Reply Last reply 25 Jul 2016, 18:58
        0
        • G geor
          25 Jul 2016, 18:51

          @mrjj It is abit better but still low quality

          M Offline
          M Offline
          mrjj
          Lifetime Qt Champion
          wrote on 25 Jul 2016, 18:58 last edited by
          #32

          @geor
          well it was worth a shot.
          I assume you play around with different scales?
          Have you tried huge image like 1920x1080 and scale it down?
          You are using http://doc.qt.io/qt-5/qpaintdevice.html#logicalDpiX
          to calc how much to scale it?

          I dont remember quality being so bad but i was using a fairly
          large resolution so the widget was not that small.

          G 1 Reply Last reply 25 Jul 2016, 19:08
          0
          • M mrjj
            25 Jul 2016, 18:58

            @geor
            well it was worth a shot.
            I assume you play around with different scales?
            Have you tried huge image like 1920x1080 and scale it down?
            You are using http://doc.qt.io/qt-5/qpaintdevice.html#logicalDpiX
            to calc how much to scale it?

            I dont remember quality being so bad but i was using a fairly
            large resolution so the widget was not that small.

            G Offline
            G Offline
            geor
            wrote on 25 Jul 2016, 19:08 last edited by
            #33

            @mrjj yes I am using it the quality is not so good however if I save it into an image its gives me a good quality so it seems taking an image instead of a pixmap a lot better.
            just like this
            ui->myWidget->grab().save("image.png");
            but this make me save 5 usless Images and I could not find a way to just use it temporarly..

            M 1 Reply Last reply 25 Jul 2016, 19:13
            0
            • G geor
              25 Jul 2016, 19:08

              @mrjj yes I am using it the quality is not so good however if I save it into an image its gives me a good quality so it seems taking an image instead of a pixmap a lot better.
              just like this
              ui->myWidget->grab().save("image.png");
              but this make me save 5 usless Images and I could not find a way to just use it temporarly..

              M Offline
              M Offline
              mrjj
              Lifetime Qt Champion
              wrote on 25 Jul 2016, 19:13 last edited by mrjj
              #34

              @geor
              Im not sure what grab() is.
              Does it return QImage?
              Im wondering if u could just draw this directly?
              No reason to save first.

              G 1 Reply Last reply 25 Jul 2016, 19:21
              0
              • M mrjj
                25 Jul 2016, 19:13

                @geor
                Im not sure what grab() is.
                Does it return QImage?
                Im wondering if u could just draw this directly?
                No reason to save first.

                G Offline
                G Offline
                geor
                wrote on 25 Jul 2016, 19:21 last edited by
                #35

                @mrjj it returns a pixmap

                M 1 Reply Last reply 25 Jul 2016, 19:22
                0
                • G geor
                  25 Jul 2016, 19:21

                  @mrjj it returns a pixmap

                  M Offline
                  M Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on 25 Jul 2016, 19:22 last edited by mrjj
                  #36

                  @geor
                  have you tried to convert to qimage and draw it?
                  http://doc.qt.io/qt-4.8/qpixmap.html#toImage
                  Not sure why saving as png makes any difference.

                  1 Reply Last reply
                  1
                  • D Offline
                    D Offline
                    drich
                    wrote on 12 Jul 2017, 01:23 last edited by
                    #37
                    This post is deleted!
                    1 Reply Last reply
                    0
                    • JonBJ Offline
                      JonBJ Offline
                      JonB
                      wrote on 24 Apr 2018, 13:58 last edited by JonB
                      #38

                      @MarieBurgan
                      Thanks for the plug. I'm sure @geor will thank you for this tip, if he visits here now two years after he last posted... ;-)

                      1 Reply Last reply
                      1
                      • Pl45m4P Pl45m4 referenced this topic on 27 Apr 2023, 13:31

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