[ECOS] synth framebuffer and touchscreen emulation

[Rutger Hofman <rutger at cs dot vu dot nl>]

Good afternoon list,

our board will have a TFT screen with touchscreen. I want to develop 
higher-level software using the synthetic target, and I succeeded in 
drawing images on the synthetic frame buffer window. So far so good.

However, I also want to add touchscreen emulation: the mouse should 
generate synthetic touchscreen events. Two questions:

 1) When I try to enable mouse awareness in the synthetic target by
    adding ButtonPressMask to the call to XSelectInput() in
    devs/framebuf/synth/current/host/framebuf.c, in handle_mapped()
    around line 1175, I get a runtime error from X during startup:

    X Error of failed request:  BadAccess (attempt to access private 
resource denied)
      Major opcode of failed request:  2 (X_ChangeWindowAttributes)
      Serial number of failed request:  10
      Current serial number in output stream:  12

    The return value from XSelectInput() is 1, BadRequest.
    Surprisingly, the return value is also 1 when I don't enable
    ButtonPressMask, although drawing and refreshing works fine.

    How should I proceed to get mouse events from X11? Is there some
    magic going on in the Tcl/Tk X stuff that already forbids mouse
    events? I am not fluent in Tcl/Tk although I can read manuals.

    Useless aside: I can get keyboard events, the same as refresh
    events.

 2) What is the preferred way to create a synthetic touchscreen
    driver? It must necessarily be integrated into the framebuffer
    driver, because that one owns the X stuff. I wonder about
    integration in the synthetic communication between target,
    framebuffer and auxiliary.

Rutger Hofman
VU Amsterdam
http://www.rfidguardian.org

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