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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
2 // Use of this source code is governed by a BSD-style license that can be | |
3 // found in the LICENSE file. | |
4 | |
5 #ifndef UI_EVENTS_GESTURES_VELOCITY_CALCULATOR_H_ | |
6 #define UI_EVENTS_GESTURES_VELOCITY_CALCULATOR_H_ | |
7 | |
8 #include <vector> | |
9 | |
10 #include "base/basictypes.h" | |
11 #include "base/memory/scoped_ptr.h" | |
12 #include "ui/events/events_export.h" | |
13 | |
14 namespace ui { | |
15 | |
16 class EVENTS_EXPORT VelocityCalculator { | |
17 public: | |
18 explicit VelocityCalculator(int bufferSize); | |
19 ~VelocityCalculator(); | |
20 void PointSeen(float x, float y, int64 time); | |
21 float XVelocity(); | |
22 float YVelocity(); | |
23 float VelocitySquared(); | |
24 void ClearHistory(); | |
25 | |
26 private: | |
27 struct Point { | |
28 float x; | |
29 float y; | |
30 int64 time; | |
31 }; | |
32 | |
33 void UpdateVelocity(); | |
34 | |
35 typedef scoped_ptr<Point[]> HistoryBuffer; | |
36 HistoryBuffer buffer_; | |
37 | |
38 // index_ points directly after the last point added. | |
39 int index_; | |
40 size_t num_valid_entries_; | |
41 const size_t buffer_size_; | |
42 float x_velocity_; | |
43 float y_velocity_; | |
44 bool velocities_stale_; | |
45 DISALLOW_COPY_AND_ASSIGN(VelocityCalculator); | |
46 }; | |
47 | |
48 } // namespace ui | |
49 | |
50 #endif // UI_EVENTS_GESTURES_VELOCITY_CALCULATOR_H_ | |
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