Port the legacy velocity tracker strategy.

For comparison purposes, port the legacy velocity tracker
algorithm as it behaved prior to ICS.

Bug: 6413587
Change-Id: I7e8e56584dcdb1a3c660ca9d8f9c5bd5d868e449

1 files changed, 39 insertions, 0 deletions

diff --git a/include/androidfw/VelocityTracker.h b/include/androidfw/VelocityTracker.h
index 3e6436a..8c24219 100644
--- a/include/androidfw/VelocityTracker.h
+++ b/include/androidfw/VelocityTracker.h
@@ -225,6 +225,45 @@ private:
     void populateEstimator(const State& state, VelocityTracker::Estimator* outEstimator) const;
 };
 
+
+/*
+ * Velocity tracker strategy used prior to ICS.
+ */
+class LegacyVelocityTrackerStrategy : public VelocityTrackerStrategy {
+public:
+    LegacyVelocityTrackerStrategy();
+    virtual ~LegacyVelocityTrackerStrategy();
+
+    virtual void clear();
+    virtual void clearPointers(BitSet32 idBits);
+    virtual void addMovement(nsecs_t eventTime, BitSet32 idBits,
+            const VelocityTracker::Position* positions);
+    virtual bool getEstimator(uint32_t id, VelocityTracker::Estimator* outEstimator) const;
+
+private:
+    // Oldest sample to consider when calculating the velocity.
+    static const nsecs_t HORIZON = 200 * 1000000; // 100 ms
+
+    // Number of samples to keep.
+    static const uint32_t HISTORY_SIZE = 20;
+
+    // The minimum duration between samples when estimating velocity.
+    static const nsecs_t MIN_DURATION = 10 * 1000000; // 10 ms
+
+    struct Movement {
+        nsecs_t eventTime;
+        BitSet32 idBits;
+        VelocityTracker::Position positions[MAX_POINTERS];
+
+        inline const VelocityTracker::Position& getPosition(uint32_t id) const {
+            return positions[idBits.getIndexOfBit(id)];
+        }
+    };
+
+    uint32_t mIndex;
+    Movement mMovements[HISTORY_SIZE];
+};
+
 } // namespace android
 
 #endif // _ANDROIDFW_VELOCITY_TRACKER_H