multi-touch-dev team mailing list archive

[Chase Douglas <chase.douglas@xxxxxxxxxxxxx>]

On 05/19/2011 03:43 AM, Paolo Olivo wrote:
> 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
> 11.04.
> 
> 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?

Hi Paolo,

This is a known issue with the current X server:
https://bugs.launchpad.net/bugs/774938. The fix has been released for
Oneiric, and hopefully will be released to Natty updates soon.

Thanks!

-- Chase