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QT5.4.1 application doesn't respond to touch while evtest reports correct x,y

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  • A Offline
    A Offline
    ankurtyagi
    wrote on last edited by
    #1

    Hi,

    I am using Qt5.4.1 on Arm cortex A8 Linux based platform. I have connected a 800x480 capacitive touch screen.
    evtest reports correct x,y co-ordinates if I touch on all four corners but Qt app doesn't detect touch.

    I have tested my Qt app on a different touch device and it works.

    What else could be the reason for it not to work ?

    thanks
    Ankur

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    • SGaistS Offline
      SGaistS Offline
      SGaist
      Lifetime Qt Champion
      wrote on last edited by
      #2

      Hi,

      What plugin are you using for input ?

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

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      • L Offline
        L Offline
        Leonardo
        wrote on last edited by
        #3

        You should try using tslib.

        http://doc.qt.io/qt-5/embedded-linux.html#touch

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        • A Offline
          A Offline
          ankurtyagi
          wrote on last edited by
          #4

          Hi,

          @Qt-Champions-2015
          I have built Qt to use eglfs and eglfs has all the evdev input handling code built-in.

          @Leonardo
          I am using a capacitive touch screen based on FT5x06. As per documentation, I don't need tslib.
          Do you have any other rationale for using tslib ?

          regards
          Ankur

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          • L Offline
            L Offline
            Leonardo
            wrote on last edited by
            #5

            You shouldn't need it, but the truth is that sometimes tslib is the only one to work. In addition, I have already had the same problem with the same capacitive touch and Qt version.

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            • A Offline
              A Offline
              ankurtyagi
              wrote on last edited by
              #6

              So in order to override inbuilt evdev support for eglfs platform, I should build Qt with tslib support and set QT_QPA_EGLFS_TSLIB and TSLIB_DEVICE in environment ?

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              • L Offline
                L Offline
                Leonardo
                wrote on last edited by
                #7

                Yes. It's also possible to use a command line argument. Here's the shell script I use to launch my application:

                #!/bin/sh
                dirname=`dirname $0`
                tmp="${dirname#?}"
                if [ "${dirname%$tmp}" != "/" ]; then
                dirname=$PWD/$dirname
                fi
                LD_LIBRARY_PATH="$dirname:/lib:/usr/lib:/usr/local/lib"
                QT_QPA_PLATFORM="eglfs"
                QT_QPA_EGLFS_DISABLE_INPUT=1
                TSLIB_TSDEVICE=/dev/input/event1
                QT_QPA_EGLFS_HIDECURSOR=1
                export LD_LIBRARY_PATH
                export QT_QPA_PLATFORM
                export QT_QPA_EGLFS_DISABLE_INPUT
                export TSLIB_TSDEVICE
                export QT_QPA_EGLFS_HIDECURSOR
                $dirname/application -plugin tslib
                
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                • A Offline
                  A Offline
                  ankurtyagi
                  wrote on last edited by
                  #8

                  Thanks Leonardo, using Qt with Tslib fixed the problem.

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