xinput -> core pointer - Transformation?

[Peter Hutterer]

On Wed, Sep 28, 2011 at 11:36:41PM +0200, roman wrote:
> Hi!
> 
> I have a tablet and i want to use an external monitor that covers
> just a part of the screen. This is no problem concering xrandr as i
> can set a scale and a position.
> 
> The problem is with the pen. The pen core pointer is automatically
> postioned the right way - even in this situation. But no
> transformation matrix whatsoever is set in the xinput settings for
> the device.
> 
> Sounds nice BUT I want to use direct xinput for using xournal.
> 
> So i would like to modify the Transformation matrix. If i do so the
> xinput can be set to be in line with the monitors - but then the
> core pointer is wrong.
> 
> How is the xinput transformed into postions on screen for the core pointer?
> 
> Is there any way to get infos on the transformation that takes place?
> 
> Is it possible to modify it?

I don't quite understand. Changing the device matrix should also change the
XI coordinates and map them into the same range. What isn't working here?
Does xournal scale somehow differently again?

Cheers,
  Peter