Qt 5.10.1 EGLFS libinput Touchscreen rotation



  • Hi,

    I try to do my first development on Rapsberri PI 3 and Qt.
    I use Qt 5.10.1 with cross compilation for Raspberry 3
    I have a 7" LCD with USB touchscreen rotate a 90°.

    I found the solution to rotate the screen with config.txt adding :
    display_hdmi_rotate=3

    and the touchscreen is rotated with adding call a batch script in
    ~/.config/lxsession/LXDE-pi/autostrart
    the script is :
    xinput set-prop 'FocalTech Lab FTxxxx MultiTouch' 'Coordinate Transformation Matrix' 0 -1 1 1 0 0 0 0 1

    So the touchscreen is working in startx

    My problem is with programs in Qt using EGLFS and libinput. I can not rotate my touchscreen.
    I read a lot a post talking about wayland, tslib, ts_calibrate, evdev.... But I think it is for old development.
    I am pretty sure there is a simple solution for nowadays.

    Sébastien



  • Hi,

    Can someone help me about this issue.

    3 month I turn around and do not understand why I cannot rotate touch screen only with Qt application.

    Thanks



  • @chtioub
    Have a look at:
    https://doc.qt.io/qt-5/embedded-linux.html

    Since you have a multitouch panel it seems, you can use the evdevtouch plugin:

    export QT_QPA_GENERIC_PLUGINS=evdevtouch:/dev/input/touchscreen
    

    Replace /dev/input/touchscreen by /dev/input/eventX with the correct value for X if you haven't setup a udev rule yet.

    The same with rotation:

    export QT_QPA_GENERIC_PLUGINS=evdevtouch:/dev/input/touchscreen:rotate=90
    


  • @Diracsbracket said in Qt 5.10.1 EGLFS libinput Touchscreen rotation:

    QT_QPA_GENERIC_PLUGINS

    ouch !

    3 months to turn around, and with 3 lines, you solve my problem !
    Many thanks.

    Now I would like to understand a little why I cannot use libinput as it is the native driver for ELGFS.

    This are no solution with libinput ?
    I trough evdev was an old solution



  • Hi,

    Well, evdevtouch plugin seem to be completely buggy.
    The rotation woks very well but afin 1 to 10 secondes, the touch does not woks anymore.
    Even with example programs.

    I have this information :
    TouchPointPressed without previous release event QQuickEventPoint(accepted:false state:Pressed scenePos:QPointF(249.631,798.957) id:2000002 timeHeld:0)

    I have to reset the application to work.

    Is there any solution to workaround this bug or a solution with libinput ?