Touchscreens (mutouch) & multiple heads

[Peter Hutterer]

On Mon, Apr 18, 2011 at 09:19:07AM -0400, Michael Smith wrote:
> Peter Hutterer wrote:
> >On Fri, Apr 15, 2011 at 12:11:09PM -0400, Michael Smith wrote:
> >>Hi,
> >>
> >>I have an Intel 915GM with two heads, each 800x600. One head feeds a
> >>touchscreen using the mutouch driver. Touchscreen input is being
> >>scaled by the total screen dimensions (1600x600), rather than just
> >>the 800x600 part of the display that is connected to the
> >>touchscreen.
> 
> >>Where is the right place to add a way to override the screen width
> >>used for converting raw coordinates? Or is there already a way to do
> >>this?
> >
> >http://www.x.org/wiki/XInputCoordinateTransformationMatrixUsage
> >run-time only though
> 
> Thanks! I ended up doing something similar by fiddling with negative
> MinY/MaxY values.
> 
> It's encouraging to know I'm not the only one with this use case
> (i.e. Wacom tablet users also solve the same problem).
> 
> The transformation matrix may be a decent way to implement this
> internally, but as a user interface it's pretty awful - it would be
> nice to have a knob that says input device X is associated with the
> bounds of screen Y so you don't have to manually recalculate your
> matrix if you dynamically add or remove a screen or change a
> resolution.

xsetwacom has such a "knob" with MapToOutput but long term something
desktop-specific is needed (i.e. gnome, kde, etc.)

Cheers,
  Peter