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Qt Gui App on Rasppberry pi Touch Screen Problem

  • I am working on a kiosk app on rasbian stretch with 10.1 inc HDMI screen. I installed qt-creator and required libraries on raspberry pi and copied my project file on it. I am able to run my app while I am on startx which causes my first touch to control only cursor. After my cursor is pointed on pushbutton, then I need to push one more time to push my pushbutton. The problem in there is I would like to use pushbuttons when my first touch is pressed on screen.

    Solutiouns I have tried:

    I thought using my app without startx I mean without no rasbian gui. When I run my app from with terminal booted rasbian, that delivers another problem;
        qxcbconnection could not connect to display

    I searched on google this and tried possible solution:

    export display=:0 or export display=:0.0

    which doesn't solve problem but change this;

    qxcbconnection could not connect to display:0 or :0.0
    I have tried also running my app with using ssh;

    ssh -X root@raspberry ./project1 (while my current directory is build folder)

    It did not solve either. Thanks for any suggestion.

  • Lifetime Qt Champion

    @qtross said in Qt Gui App on Rasppberry pi Touch Screen Problem:

    qxcbconnection could not connect to display

    Without XServer running (startx) you can't use X11 applications. So, this is not a solution. You should rather find out what is wrong with the touch display.
    Does the touchscreen work properly with other applications?

  • @jsulm Thank you for the reply.
    Here is the model of my touch display. I am trying to find out what the problem is.

    I tried with another kiosk project of qt which I found on internet, it works same as mine, needs to be touched two times for pressing the button. However, the person who shared this project can use this with pressing one touch. So as you say, I have problem with the touch display or I am missing something that I need to fix on rasbian.


  • Lifetime Qt Champion

    @qtross Did you try to use this touchscreen with the default Raspbian desktop environment? Does it behave same way?

  • @jsulm Yes, in desktop blank area when cursor is someplace and when i press another blank place, it behaves like I am selecting these between area. In mouse act, I need to keep pressing left click of the mouse and pull the mouse to make this behave.

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