2 files changed, 61 insertions, 0 deletions
diff --git a/include/ui/Input.h b/include/ui/Input.h
index d9d77c4..e9cacf4 100644
--- a/include/ui/Input.h
+++ b/include/ui/Input.h
@@ -27,6 +27,7 @@
 #include <utils/Timers.h>
 #include <utils/RefBase.h>
 #include <utils/String8.h>
+#include <utils/BitSet.h>
 
 #ifdef HAVE_ANDROID_OS
 class SkMatrix;
@@ -208,6 +209,13 @@ struct PointerCoords {
     status_t writeToParcel(Parcel* parcel) const;
 #endif
 
+    bool operator==(const PointerCoords& other) const;
+    inline bool operator!=(const PointerCoords& other) const {
+        return !(*this == other);
+    }
+
+    void copyFrom(const PointerCoords& other);
+
 private:
     void tooManyAxes(int axis);
 };
@@ -543,6 +551,53 @@ private:
 };
 
 /*
+ * Calculates the velocity of pointer motions over time.
+ * Uses essentially the same algorithm as android.view.VelocityTracker.
+ */
+class VelocityTracker {
+public:
+    struct Position {
+        float x, y;
+    };
+
+    VelocityTracker();
+
+    // Resets the velocity tracker state.
+    void clear();
+
+    // Adds movement information for a set of pointers.
+    // The idBits bitfield specifies the pointer ids of the pointers whose positions
+    // are included in the movement.
+    // The positions array contains position information for each pointer in order by
+    // increasing id.  Its size should be equal to the number of one bits in idBits.
+    void addMovement(nsecs_t eventTime, BitSet32 idBits, const Position* positions);
+
+    // Gets the velocity of the specified pointer id in position units per second.
+    // Returns false and sets the velocity components to zero if there is no movement
+    // information for the pointer.
+    bool getVelocity(uint32_t id, float* outVx, float* outVy) const;
+
+private:
+    // Number of samples to keep.
+    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
+
+    // The minimum duration between samples when estimating velocity.
+    static const nsecs_t MIN_DURATION = 5 * 1000000; // 5 ms
+
+    struct Movement {
+        nsecs_t eventTime;
+        BitSet32 idBits;
+        Position positions[MAX_POINTERS];
+    };
+
+    uint32_t mIndex;
+    Movement mMovements[HISTORY_SIZE];
+};
+
+/*
  * Describes the characteristics and capabilities of an input device.
  */
 class InputDeviceInfo {
diff --git a/include/utils/BitSet.h b/include/utils/BitSet.h
index f5dbcd9..f03825a 100644
--- a/include/utils/BitSet.h
+++ b/include/utils/BitSet.h
@@ -61,6 +61,12 @@ struct BitSet32 {
     // Result is undefined if all bits are marked.
     inline uint32_t firstUnmarkedBit() const { return __builtin_clz(~ value); }
 
+    // Gets the index of the specified bit in the set, which is the number of
+    // marked bits that appear before the specified bit.
+    inline uint32_t getIndexOfBit(uint32_t n) const {
+        return __builtin_popcount(value & ~(0xffffffffUL >> n));
+    }
+
     inline bool operator== (const BitSet32& other) const { return value == other.value; }
     inline bool operator!= (const BitSet32& other) const { return value != other.value; }
 };