Confusing interactions between xinput mapping and xinput set-prop

[Peter Hutterer]

On Thu, Mar 14, 2019 at 10:59:06AM +0000, malcolm moore wrote:
> If I use xinput set-prop to change the calibration matrix ( because I am
> trying to use a SmartBoard as a second touch screen which are notoriously
> inaccurate ) I can set the values to whatever I like. So far so good, but
> then I have to do the xinput --map-to-output to tell the machine where the
> touch is coming from. This resets the values I first set. If I do the
> xinput --map-to-output first the xinput set-prop resets that. How do I do
> both

you can't. map-to-output is a convenience helper because it's the prime
use-case for the calibration matrix and in the end writing map-to-output
was more efficient than explaning how to set the calibration matrix to every
user that filed a bug report.

If your touchscreen needs calibration *and* screen mapping, you need to
manually calculate the matrix and then set it directly.

Cheers,
   Peter