Add velocity estimate

The per-touch velocity is useful in many contexts. This patch
adds a simple estimator of the velocity, which also smooths out
position jumps caused by course-grained event updates.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/frame-xi2.c b/src/frame-xi2.c
index a78d9bf..bead751 100644
--- a/src/frame-xi2.c
+++ b/src/frame-xi2.c
@@ -217,9 +217,11 @@ static int handle_event(utouch_frame_handle fh,
         switch (fh->evmap[ix]) {
         case ABS_MT_POSITION_X:
                 slot->x = value;
+                slot->vx = 0;
                 return 1;
         case ABS_MT_POSITION_Y:
                 slot->y = value;
+                slot->vy = 0;
                 return 1;
         case ABS_MT_TOUCH_MAJOR:
                 slot->touch_major = value;