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No show of QPixmap

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  • Christian EhrlicherC Offline
    Christian EhrlicherC Offline
    Christian Ehrlicher
    Lifetime Qt Champion
    wrote on last edited by
    #14

    @Stan-Huang said in No show of QPixmap:

    setPixmap(pixmap_RoadFault) is void, so no return.

    Pleae read my link: http://doc.qt.io/qt-5/qpixmap.html#isNull - no setPixmap() but QPixmap::isNull() ...

    Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
    Visit the Qt Academy at https://academy.qt.io/catalog

    Stan HuangS 1 Reply Last reply
    0
    • JKSHJ JKSH

      @Stan-Huang said in No show of QPixmap:

      The return of "file /exe/bv/image/sdkpic.jpg" is:

      root@mitacimx6:/opt/BVDemo/smartbox# file /exe/bv/image/sdkpic.jpg
      /exe/bv/image/sdkpic.jpg: JPEG image data, JFIF standard 1.01, aspect ratio, density 1x1, segment length 16, baseline, precision 8, 1108x1478, frames 3

      OK, it looks like the file is valid.

      Next, check if Qt can understand the file format. What do you get when you call
      qDebug() << QImageReader::supportedImageFormats() ? (remember #include <QDebug> and #include <QImageReader>)

      Stan HuangS Offline
      Stan HuangS Offline
      Stan Huang
      wrote on last edited by
      #15

      @JKSH The return is:
      ("bmp", "cur", "gif", "ico", "jpeg", "jpg", "pbm", "pgm", "png", "ppm", "xbm", "xpm")

      1 Reply Last reply
      0
      • Christian EhrlicherC Christian Ehrlicher

        @Stan-Huang said in No show of QPixmap:

        setPixmap(pixmap_RoadFault) is void, so no return.

        Pleae read my link: http://doc.qt.io/qt-5/qpixmap.html#isNull - no setPixmap() but QPixmap::isNull() ...

        Stan HuangS Offline
        Stan HuangS Offline
        Stan Huang
        wrote on last edited by
        #16

        @Christian-Ehrlicher said in No show of QPixmap:

        setPixmap

        QPixmap::isNull() returned 'false'

        J.HilkJ 1 Reply Last reply
        0
        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #17

          What if you set the pixmap directly on the QLabel rather than using a brush in the palette ?

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

          Stan HuangS 2 Replies Last reply
          0
          • Stan HuangS Stan Huang

            @Christian-Ehrlicher said in No show of QPixmap:

            setPixmap

            QPixmap::isNull() returned 'false'

            J.HilkJ Offline
            J.HilkJ Offline
            J.Hilk
            Moderators
            wrote on last edited by J.Hilk
            #18

            @Stan-Huang
            It's not quite clear from the code you posted, but are you sure that palette_RoadFault is not set to something invalid somewhere else in your code, and that palette_RoadFault persists outside the scope of your function?

            QBrush expects a const reference to a QPixmap, I don't think it will take ownership or make a copy of the QPixmap for drawing.


            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.

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            • SGaistS SGaist

              What if you set the pixmap directly on the QLabel rather than using a brush in the palette ?

              Stan HuangS Offline
              Stan HuangS Offline
              Stan Huang
              wrote on last edited by
              #19

              @SGaist I did it but still doesn't work:
              ui->label->setGeometry(20,20,60,20);
              ui->label->setPixmap(pixmap_RoadFault);
              ui->label->show();

              1 Reply Last reply
              0
              • SGaistS SGaist

                What if you set the pixmap directly on the QLabel rather than using a brush in the palette ?

                Stan HuangS Offline
                Stan HuangS Offline
                Stan Huang
                wrote on last edited by
                #20

                @SGaist I did but still doesn't work:

                				ui->label->setGeometry(20,20,60,20);
                				ui->label->setPixmap(pixmap_RoadFault);
                				ui->label->show();
                
                1 Reply Last reply
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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #21

                  Don't set the geometry since you have a designer based UI, that will let QLabel in its original place to show the pixmap.

                  If it's still not working, then test again with another image. And if possible, share that file with us so that we can test it on our ends.

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

                  1 Reply Last reply
                  1
                  • Stan HuangS Offline
                    Stan HuangS Offline
                    Stan Huang
                    wrote on last edited by
                    #22

                    That's my mistake. A clear statement was executed right after ->show() was executed. That's, show() did its good job, but the shown picture was cleaned immediately. I apologize for my mistake.

                    JKSHJ 1 Reply Last reply
                    0
                    • Stan HuangS Stan Huang

                      That's my mistake. A clear statement was executed right after ->show() was executed. That's, show() did its good job, but the shown picture was cleaned immediately. I apologize for my mistake.

                      JKSHJ Offline
                      JKSHJ Offline
                      JKSH
                      Moderators
                      wrote on last edited by
                      #23

                      @Stan-Huang said in No show of QPixmap:

                      That's my mistake. A clear statement was executed right after ->show() was executed. That's, show() did its good job, but the shown picture was cleaned immediately. I apologize for my mistake.

                      I'm glad to hear that you've got it working now.

                      Like I said 10 days ago, it's best to use simple examples. I even wrote a full program for you that works, but you didn't use it.

                      Qt Doc Search for browsers: forum.qt.io/topic/35616/web-browser-extension-for-improved-doc-searches

                      Stan HuangS 1 Reply Last reply
                      2
                      • JKSHJ JKSH

                        @Stan-Huang said in No show of QPixmap:

                        That's my mistake. A clear statement was executed right after ->show() was executed. That's, show() did its good job, but the shown picture was cleaned immediately. I apologize for my mistake.

                        I'm glad to hear that you've got it working now.

                        Like I said 10 days ago, it's best to use simple examples. I even wrote a full program for you that works, but you didn't use it.

                        Stan HuangS Offline
                        Stan HuangS Offline
                        Stan Huang
                        wrote on last edited by
                        #24

                        @JKSH Yes. I didn't do it 10 days ago due to 9-day lunar new year vacation. Thanks very much.

                        1 Reply Last reply
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