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Mouse Input on virtual Framebuffer not working

  • Hey Guys,
    I'm having a Problem regarding libinput on QT_QPA_PLATFORM=linuxFB. We are developing a testing framework for a pretty big QT5 embedded application (without any display server involved). Usually the application runs on arm7 hardware, and we are testing on amd64.

    In order to test the binary, we load the Linux virtual frame buffer kernel module and set QT_QPA_PLATFORM=linuxFB:fb=/dev/fb1, so that the binary writes to the virtual frame buffer instead to the real one. This works pretty well, and we are able to stream the virtual frame buffer over the network. Currently I can't get the mouse input via libinput working (the keyboard works out of the box).

    Using strace, i have figured out that QT5/libinput is using /dev/input/event2 for getting its mouse events. Click events do have their usual effect on the application but the Position of the cursor does not change at all. Maybe the different resolution of the real frame buffer and the virtual one causes this issue, or the mouse driver itself does send wrong x -and y-positions of the cursor. Does anyone here has experiences withe use cases like this and could give me a hint what I might have done wrong ?


  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Interesting setup ! I'd recommend bringing this question to the interest mailing list. You'll find there Qt's developers/maintainers. This forum is more user oriented. This forum is more user oriented.

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