Bug 85881 only implemented 2-finger pinch. I'd like to be able to have 3-finger pinch getting to the overview on my touchpad, as it does on touchscreens.
Maybe we can use the same strategy as 2fg pinch. Just detect swipe by checking the moving directions of all fingers. Non-swipe gestures are always considered as pinch.
There's a big problem with 3-finger pinch gestures that we'll face on many touchpads, particularly the current synaptics generation: we sometimes can't tell the difference between a swipe and a pinch gesture. Unless the thumb is placed down as first or second finger, we won't get positional information and the data stream from a three-finger swipe and three-finger pinch is identical.
Until we get RMI4 over SMBus in the kernel, this will be a problem.
Merge: 82335b0 cab2c16
Author: Peter Hutterer <firstname.lastname@example.org>
Date: Wed Jan 20 15:38:17 2016 +1000
Merge branch 'wip/3-finger-pinch-gesture'