libinput: Disable tap-and-drag

[Caibin Chen]

Hi,

I've been working on disabling tap-and-drag feature in libinput because I'm
not used to it. The code is on my Github branch:
https://github.com/tigersoldier/libinput/tree/wip/disable-tap-to-drag

The basic idea is adding a branch at STATE_TOUCHED + EVENT_RELEASE
transition:

   STATE_TOUCHED
         |
         |
   EVENT_RELEASE
         |
         |
         v
tap-and-drag enabled?  --- yes ---> (unchanged)
         |
         no
         |
         v
    button press
    button release
         |
         v
    STATE_IDLE

Aside from disabling the feature, this reduces the tapping latency as well,
because we don't have to wait for the timeout for STATE_IDLE to
STATE_DRAGGING_OR_DOUBLE_TAP/STATE_IDLE transition.

What do you guys think? If this makes sense, I can work on the
documentation and tests and send patches to the list.

Thanks,
-Caibin Chen
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/wayland-devel/attachments/20160102/6b1e707d/attachment.html>