Bug 753937

Created attachment 533635 [details]
Simple script to set the Coordinate Transform Matrix for a touchscreen

Description of problem:
Assume you have a laptop with a touchscreen and you plug an external monitor. By default your touchscreen is mapped to the whole virtual screen. The way to fix this issue, as describe in the page <http://wiki.x.org/wiki/XInputCoordinateTransformationMatrixUsage>, is to use a suitable Coordinate Transform Matrix to map the touchscreen to the laptop screen. The script fixtouchscreen attached is an attempt to compute automatically this matrix. Unfortunately, this does not work as expected. Although, touching the screen move the pointer to the right location, the pointer jumps afterwards back and forth to the edge of the screen.


Version-Release number of selected component (if applicable): 
Name        : xorg-x11-server-Xorg
Version     : 1.11.2
Release     : 3.fc16
Architecture: i686

How reproducible: each time


Steps to Reproduce:
1. Modify the Coordinate Transform Matrix using xinput to something different than the identity
2. Touch the screen...
  
Actual results:
Pointer moves back and forth from the correct position to the edge.


Expected results:
Pointer stays at the correct position.


Additional info:
* It seems that this type of behavior has already been reported in Ubuntu <https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/774938> in which a patch is proposerd. Unfortunately, the xorg code has changed so that the patch does not work anymore.
* I had tested this with Fedora 15 and I remember this was working properly.