Qt5 application with two mouse cursors

  • Hi,

    I have a very strange issue with a Qt5 application.

    When I run my application, a new mouse cursor appears, so I have two cursors: one black (the system cursor, I know it because of its color and position on the screen do not change) and one white (my application new cursor). Both cursors are on different locations on the screen, and they move synchronized when I move the mouse. Even if I click, the white cursor interacts with my application, while the black one interacts with the desktop or window manager "in the background", and sometimes I can see the desktop blinking, for example when the black cursor is above an icon at the moment of the click. Very strange.

    I am using Qt5, cross-compiled wih Qt creator in your Fedora VM. This happens while there is matchbox desktop or twm window manager running, with -qws arg when launching the application and without it. I see this message when I execute my application:

    1. QEglFSVivIntegration will set environment variable FB_MULTI_BUFFER=2 to enable double buffering and vsync.
    2. If this is not desired, you can override this via: export QT_EGLFS_IMX6_NO_FB_MULTI_BUFFER=1
    3. Unable to query physical screen size, defaulting to 100 dpi.
    4. To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimeters).

    Any tips? Thanks in advance!

    P.S. - When I compiled Qt5, I got the error that -lpcre (perl regular expressions compatibility library) cannot be found, so I ran make -k and it finished OK.

  • When using Buildroot, Qt5 can not work together with X11. You have to build a Qt5 environment first without X11, that just uses the framebuffer. We have provided fsimx6_qt5_defconfig to do this.

    1. make clean
    2. make fsimx6_qt5_defconfig
    3. make

    This takes a while (longer than the fsimx6_std_defconfig), but after that you have a new rootfs for Qt5. When you download this to the board, you will not see any window manager, just a blank screen. But if you start your Qt application, it should show up and work as expected. Now only your own mouse cursor should be visible.

    Your F&S Support Team

    F&S Elektronik Systeme GmbH
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