** Description changed: - Binary package hint: xserver-xorg-input-evdev + SRU Justification: + ================== + In previous releases of xserver-xorg-input-evdev there was an option to invert and/or swap axes. This allowed for simple screen rotation support. In the latest version of the module in Ubuntu, this option has been deprecated in favor of the server-side input coordinate transformation matrix support. See https://wiki.ubuntu.com/X/InputCoordinateTransformation for details. Unfortunately, the XInput 2.1 changes caused the input coordinate transformation matrix support to cause erratic pointer behavior. Without a fix, users cannot reliably use a rotated touchscreen. + + The fix involves maintaining and using the proper previous states of the + X and Y event coordinates when performing the input coordinate + transformation. If one coordinate is updated but not the other, the + other's previous untransformed coordinate must be used to compute the + correct new transformed coordinates. Then, the new transformed + coordinates must be compared to the previous transformed coordinates to + see if they should be reported to the client. Unchanged values are not + reported in some XI 1.x and 2.x events. The current X server conflates + the previous untransformed and previous transformed values and ends up + calculating the new transformed values incorrectly. + + To reproduce, use xinput to set a new coordinate transformation matrix + with a rotation. For example, use a 90 degree turn by setting the input + coordinate transformation matrix to 0 -1 1 1 0 0 0 0 1. See the above + wiki page for details on how to set the matrix. Then, try to touch the + touchscreen and move the cursor. The cursor will jump arround + erratically when moving in pure horizontal or pure vertical motions. + + The risk of regression is minimal because the only time the fix will + cause a change is when the transformation matrix has been modified from + the identity matrix to a matrix including some amount of rotation. The + patch was also tested in the xorg-edgers ppa for a few weeks before it + was even uploaded to Oneiric. + + Original Bug Report: + ==================== When using something like `xinput set-float-prop $INPUTDEV "Coordinate Transformation Matrix" 0.0 -1.0 1.0 1.0 0.0 0.0 0.0 0.0 1.0` to match the coordinates of a touchscreen/tablet to a rotated (transformed) screen, the cursor moves around erratically. From the original report of david-dklevine (https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input-evdev/+bug/742567/comments/32): when a horizontal or vertical drag is performed the cursor jumps wildly - it appears to jump between what it should be according to the coordinate transformation and what it would be if x=0 and y=1 (that is if the second line of the matrix was the identity). With a diagonal drag or a touch the cursor appears where it should be. In addition to the Cando Multi Touch Panel reported at https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-input- evdev/+bug/742567/comments/32, it also affects me with a AsusTek, Inc. MultiTouch(TTI) (on Asus EeePC T101MT) lsb_release -rd Description: Ubuntu 11.04 Release: 11.04 $ apt-cache policy xserver-xorg-input-evdev xserver-xorg-input-evdev: - Installed: 1:2.6.0-1ubuntu12 - Candidate: 1:2.6.0-1ubuntu12 - Version table: - *** 1:2.6.0-1ubuntu12 0 - 500 http://gd.tuwien.ac.at/opsys/linux/ubuntu/archive/ natty/main amd64 Packages - 100 /var/lib/dpkg/status + Installed: 1:2.6.0-1ubuntu12 + Candidate: 1:2.6.0-1ubuntu12 + Version table: + *** 1:2.6.0-1ubuntu12 0 + 500 http://gd.tuwien.ac.at/opsys/linux/ubuntu/archive/ natty/main amd64 Packages + 100 /var/lib/dpkg/status
** Patch added: "503_fix_masked_transformed_valuators.patch" https://bugs.launchpad.net/ubuntu/+source/xorg-server/+bug/774938/+attachment/2131372/+files/503_fix_masked_transformed_valuators.patch -- You received this bug notification because you are a member of Ubuntu-X, which is subscribed to xorg-server in Ubuntu. https://bugs.launchpad.net/bugs/774938 Title: Erratic cursor movement when using "Coordinate Transformation Matrix" _______________________________________________ Mailing list: https://launchpad.net/~ubuntu-x-swat Post to : ubuntu-x-swat@lists.launchpad.net Unsubscribe : https://launchpad.net/~ubuntu-x-swat More help : https://help.launchpad.net/ListHelp
