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, 4 insertions, 0 deletions

diff --git a/include/utouch/frame.h b/include/utouch/frame.h
index 03a44aa..60195ef 100644
--- a/include/utouch/frame.h
+++ b/include/utouch/frame.h
@@ -115,6 +115,8 @@ struct utouch_surface {
  * @orientation: direction of ellipse (left: -Pi/2, up: 0, right: Pi/2)
  * @pressure: pressure of contact (pressure units)
  * @distance: distance of contact (surface units)
+ * @vx: horizontal velocity coordinate (units / millisecond)
+ * @vy: vertical velocity coordinate (units / millisecond)
  *
  * Surface contact details. Later versions of this struct may grow in
  * size, but will remain binary compatible with older versions.
@@ -138,6 +140,8 @@ struct utouch_contact {
         float orientation;
         float pressure;
         float distance;
+        float vx;
+        float vy;
 };
 
 /* time in milliseconds */