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Weird cursor behavior after setting coordinate transformation matrix with xinput 1.5.3 an XI server 2.1


Hi all,

thank you for all the suggestion for the previous topic.

I have another issue I found testing multi-touch on Ubuntu 11.04.

I obtain a weird cursor behavior when I set the coordinate
transformation matrix of the N-Trig multi-touch screen on Ubuntu

I observed this problem since I wanted to use a DELL XT2 in portrait
format. To rotate the desktop was easy, but then it was also necessary
to inform the xinput server how to map the touch point to the portrait
reference frame.

I already did this on Ubuntu 10.10 and the result was good using the command:

xinput set-prop "N-Trig MultiTouch" "Coordinate Transformation Matrix"
0 -1 1 1 0 0 0 0 1

On Ubuntu 11.04 this leads to a cursor that flickers around as you can
see in the video I put here http://vimeo.com/23907071 . The cursor
actually follows my finger, but it also jumps to 3 or 4 different
places, so it is impossible to do anything.

I noticed that this problem does not  happen if the transformation
matrix is only for scale, for example
2 0 0 0 1 0 0 0 1, but it happens if I want to invert the axes, like 0
-1 1 1 0 0 0 0 1.

I also noticed that on my Ubuntu 10.10 the xinput was at version 1.5.2
with XI version on server 2.0, while on the Ubuntu 11.04 I have xinput
version 1.5.3 with XI version on server 2.1.

I got the same problem also using a 3M touch-screen.

Any idea?

Thank you all,


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