1// Copyright 2014 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_GESTURE_DETECTION_VELOCITY_TRACKER_STATE_H_
6#define UI_EVENTS_GESTURE_DETECTION_VELOCITY_TRACKER_STATE_H_
7
8#include "base/basictypes.h"
9#include "ui/events/gesture_detection/bitset_32.h"
10#include "ui/events/gesture_detection/gesture_detection_export.h"
11#include "ui/events/gesture_detection/velocity_tracker.h"
12
13namespace ui {
14
15class MotionEvent;
16
17// Port of VelocityTrackerState from Android
18// * platform/frameworks/base/core/jni/android_view_VelocityTracker.cpp
19// * Change-Id: I3517881b87b47dcc209d80dbd0ac6b5cf29a766f
20// * Please update the Change-Id as upstream Android changes are pulled.
21class GESTURE_DETECTION_EXPORT VelocityTrackerState {
22 public:
23  VelocityTrackerState();
24  explicit VelocityTrackerState(VelocityTracker::Strategy strategy);
25  ~VelocityTrackerState();
26
27  void Clear();
28  void AddMovement(const MotionEvent& event);
29  void ComputeCurrentVelocity(int32_t units, float max_velocity);
30  float GetXVelocity(int32_t id) const;
31  float GetYVelocity(int32_t id) const;
32
33 private:
34  struct Velocity {
35    float vx, vy;
36  };
37
38  void GetVelocity(int32_t id, float* out_vx, float* out_vy) const;
39
40  VelocityTracker velocity_tracker_;
41  int32_t active_pointer_id_;
42  BitSet32 calculated_id_bits_;
43  Velocity calculated_velocity_[VelocityTracker::MAX_POINTERS];
44
45  DISALLOW_COPY_AND_ASSIGN(VelocityTrackerState);
46};
47
48}  // namespace ui
49
50#endif  // UI_EVENTS_GESTURE_DETECTION_VELOCITY_TRACKER_STATE_H_
51