diff --git a/include/input/VelocityTracker.h b/include/input/VelocityTracker.h
index 6d1de64..f218c51 100644
--- a/include/input/VelocityTracker.h
+++ b/include/input/VelocityTracker.h
@@ -159,6 +159,8 @@
  */
 class AccumulatingVelocityTrackerStrategy : public VelocityTrackerStrategy {
 public:
+    AccumulatingVelocityTrackerStrategy(nsecs_t horizonNanos, bool maintainHorizonDuringAdd);
+
     void addMovement(nsecs_t eventTime, int32_t pointerId, float position) override;
     void clearPointer(int32_t pointerId) override;
 
@@ -173,6 +175,16 @@
     // protected const field.
     static constexpr uint32_t HISTORY_SIZE = 20;
 
+    /**
+     * Duration, in nanoseconds, since the latest movement where a movement may be considered for
+     * velocity calculation.
+     */
+    const nsecs_t mHorizonNanos;
+    /**
+     * If true, data points outside of horizon (see `mHorizonNanos`) will be cleared after each
+     * addition of a new movement.
+     */
+    const bool mMaintainHorizonDuringAdd;
     std::map<int32_t /*pointerId*/, RingBuffer<Movement>> mMovements;
 };