Tweak VelocityTracker.

Bug: 5265529

Calculate the velocity using the most recent touch sample as the
point of reference instead of the oldest.  This change more heavily
weights recent touch samples and reduces the sample time window
used for calculation.  This significantly improves the accuracy
of fling gesture detection.

Change-Id: Ib1940933e786e5f6a731552a99bcd9400741d55f

1 files changed, 6 insertions, 2 deletions

diff --git a/include/ui/Input.h b/include/ui/Input.h
index f1385a0..af899ef 100644
--- a/include/ui/Input.h
+++ b/include/ui/Input.h
@@ -660,15 +660,19 @@ private:
     static const uint32_t HISTORY_SIZE = 10;
 
     // Oldest sample to consider when calculating the velocity.
-    static const nsecs_t MAX_AGE = 200 * 1000000; // 200 ms
+    static const nsecs_t MAX_AGE = 100 * 1000000; // 100 ms
 
     // The minimum duration between samples when estimating velocity.
-    static const nsecs_t MIN_DURATION = 10 * 1000000; // 10 ms
+    static const nsecs_t MIN_DURATION = 5 * 1000000; // 5 ms
 
     struct Movement {
         nsecs_t eventTime;
         BitSet32 idBits;
         Position positions[MAX_POINTERS];
+
+        inline const Position& getPosition(uint32_t id) const {
+            return positions[idBits.getIndexOfBit(id)];
+        }
     };
 
     uint32_t mIndex;