1 files changed, 42 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/AndroidVelocityTracker.h b/gfx/layers/apz/src/AndroidVelocityTracker.h
new file mode 100644
index 0000000000..40e346a9ea
--- /dev/null
+++ b/gfx/layers/apz/src/AndroidVelocityTracker.h
@@ -0,0 +1,42 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_layers_AndroidVelocityTracker_h
+#define mozilla_layers_AndroidVelocityTracker_h
+
+#include <utility>
+#include <cstdint>
+
+#include "Axis.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/Maybe.h"
+#include "nsTArray.h"
+
+namespace mozilla {
+namespace layers {
+
+class AndroidVelocityTracker : public VelocityTracker {
+ public:
+  explicit AndroidVelocityTracker();
+  void StartTracking(ParentLayerCoord aPos, TimeStamp aTimestamp) override;
+  Maybe<float> AddPosition(ParentLayerCoord aPos,
+                           TimeStamp aTimestamp) override;
+  Maybe<float> ComputeVelocity(TimeStamp aTimestamp) override;
+  void Clear() override;
+
+ private:
+  // A queue of (timestamp, position) pairs; these are the historical
+  // positions at the given timestamps.
+  nsTArray<std::pair<TimeStamp, ParentLayerCoord>> mHistory;
+  // The last time an event was added to the tracker, or the null moment if no
+  // events have been added.
+  TimeStamp mLastEventTime;
+};
+
+}  // namespace layers
+}  // namespace mozilla
+
+#endif