Index: remoting/client/fling_tracker.h |
diff --git a/remoting/client/fling_tracker.h b/remoting/client/fling_tracker.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..eb8a50aac4809346bf934c680c4e1fdd9a38c568 |
--- /dev/null |
+++ b/remoting/client/fling_tracker.h |
@@ -0,0 +1,52 @@ |
+// Copyright 2017 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#ifndef REMOTING_CLIENT_FLING_TRACKER_H_ |
+#define REMOTING_CLIENT_FLING_TRACKER_H_ |
+ |
+#include "base/time/time.h" |
+ |
+namespace remoting { |
+ |
+// A class for tracking the positions of an object moving through a viscous |
+// liquid. |
+class FlingTracker { |
+ public: |
+ // time_constant: The larger the number the longer it takes to fling. |
+ explicit FlingTracker(float time_constant); |
+ |
+ ~FlingTracker(); |
+ |
+ // Sets the position of the object and start fling. This will reset the |
+ // existing fling. |
+ void StartFling(float velocity_x, float velocity_y); |
+ |
+ void StopFling(); |
+ |
+ bool IsFlingInProgress() const; |
+ |
+ // time_elapsed: The time elapsed since the animation has started. |
+ // Moves forward the object to catch up with |time_elapsed|. The change in |
+ // positions will be written to |dx| and |dy|. |
+ // Returns true if the fling is still in progress at |time_elapsed|, false |
+ // otherwise, in which case |dx| and |dy| will not be touched. |
+ bool TrackMovement(base::TimeDelta time_elapsed, float* dx, float* dy); |
+ |
+ private: |
+ float time_constant_; |
+ float initial_speed_rate_ = 0.f; |
+ float velocity_ratio_x_ = 0.f; |
+ float velocity_ratio_y_ = 0.f; |
+ float previous_position_x_ = 0.f; |
+ float previous_position_y_ = 0.f; |
+ |
+ base::TimeTicks start_time_; |
+ |
+ // FlingTracker is neither copyable nor movable. |
+ FlingTracker(const FlingTracker&) = delete; |
+ FlingTracker& operator=(const FlingTracker&) = delete; |
+}; |
+ |
+} // namespace remoting |
+#endif // REMOTING_CLIENT_FLING_TRACKER_H_ |