Make three- and four-finger gestures on touch screen also work in Wacom mode

[Till Kamppeter]

I have a Lenovo Thinkpad Twist (convertible with touch screen) running Saucy with standard Unity desktop. With all in its default configuration, tapping on a window with three fingers added some resize buttons to it, dragging with three fingers dragged the window, and tapping anywhere with four fingers opened Dash.

All this does not work any more when running the touch screen with Wacom driver to enable screen rotation (bug 1216065) and a right-click emulation by holding a finger on the place where the right click should happen and then tapping anywhere else with a second finger.

It would be great to make the standard Unity gestures (https://wiki.ubuntu.com/Multitouch) also work under the Wacom driver.

I enabled the wacom mode by adding "|Atmel" to the "MatchProduct" line in the "InputClass" section with Identifier "Wacom class" in /etc/X11/xorg.conf.d/50-wacom.conf (copy of file /usr/share/X11/xorg.conf.d/50-wacom.conf).

[Stephen M. Webb (bregma)]

There have been no changes to the Unity stack regarding these gestures. They continue to work with the latest Saucy packages on my Dell Latitude XT2.

Can you run the Compiz config settings manager (ccsm) and verify the "Unity MT Grab Handles" plugin is still enabled?

[Till Kamppeter (till-kamppeter)]

"Unity MT Grab Handles" plugin is still enabled, but when I click on it there are three items in it which are all disabled. When I try to enable one it wants that I choose a keyboard combination for it, but I only want to use this feature via touch screen gesture.

[Till Kamppeter (till-kamppeter)]

Same problem independent whether I run Mir or X.

[Till Kamppeter (till-kamppeter)]

I have found out what made my three- and four-finger gestures go away: I have followed the instructions of the first comment (Phil) on http://www.linlap.com/lenovo_thinkpad_twist, especially activated the Wacom support to get rotation of the touchscreen working. This made the three- and four-finger gestures disappear and a two-finger gesture for the right-click (hold finger on point to right-click and tap with another finger on an arbitrary point while holding down the first finger, then slide first finger to desired entry of context menu and release to select entry) appeared. After removing the added /etc/X11/xorg.conf.d/50-wacom.conf the touch screen returned to normal.

[Till Kamppeter (till-kamppeter)]

Reported bug 1231376 for using touch screens under the Wacom driver

[Stephen M. Webb (bregma)]

Unity has no control over the kernel driver or the x.org driver used to support various hardware. If you choose to modify your system and configure it to use drives that do not support multi-touch input properly, you will get improper support for multi-touch in your system, but that is not a bug in individual applications like Unity.

The Wacom driver does not support the XInput 2.2 multi-touch protocol. Multi-touch on Ubuntu requires multi-touch support in the drivers.

[Till Kamppeter (till-kamppeter)]

Does the XInput 2.2 multi-touch protocol support screen rotation as in bug 1216065?

[Stephen M. Webb (bregma)]

XInput (input device support) and Xrandr (display resize and rotation) are disjoint. It's possible for an x.org driver to support one and not the other. This is a bug in the x.org driver.

[Till Kamppeter (till-kamppeter)]

I do not mean that XInput should rotate the screen. I want to know whether one can tell XInput with a simple command to rotate the coordinate system of the touch screen so that it matches the rotated screen output of Xrandr.

[Stephen M. Webb (bregma)]

The "xinput" tool can be used to set the coordinate transformation matrix for an input device. The hard parts are hooking that up to the appropriate udev or evdev events and calculating the correct transform matrix. It would be nice if that happened automatically inside of the X server. We've done it manually as proof-of-concept but it turns out detecting the transformation is very hardware-specific and at the time impossible to get universally correct.

Hopefully, this will be a thing for 14.04.

[Tyler Ham (tyler.ham)]

This is is still an issue in 14.04. I have a new Thinkpad T550 with a Wacom touch screen device. After installing a newer kernel to recognize the Wacom device, I am still faced with having to pick between the "wacom" driver that provides the expected two-finger gestures (like scrolling and right-click) across the board, or an alternative (like using the "evdev" driver instead) to get three- and four-finger gestures while losing a lost of the two-finger gesture functionality.

See bug 1433444.