Mapping soft (keyboard) buttons to (resistive) touch

[Andreas Lausch / TBT]

Hello,

I've got a resistive touch screen, where the touch area
is larger than the display area. I'd like to map "soft (keyboard) buttons"
(e.g. ESC or num block ENTER) to the area outside of the screen -- similar to
android's [BACK], [HOME], [MENU] buttons at the bottom.
On the linux-side, the device is handled by AD7879-i2c driver.
Using xinput_calibrator, I can calibrate the mouse to the "display" area.

The main questions are:
* is there an existing xorg module that can map such "soft buttons" to mouse coordinates?
* if not, what would be the best starting point for writing code that solves my problem?
* would it be better to fork the AD7879 driver or use a (custom) xorg module?

I think the right way is to do it in X: the "soft button" calibration depends on the touch screen calibration
and the touch screen calibration depends on the display/GUI, which is handled by X in my case.


so long
Andy