ui/events/gesture_detection/velocity_tracker_state.h

   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
  13 namespace ui {
  14
  15 class 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.
  21 class GESTURE_DETECTION_EXPORT VelocityTrackerState {
  22  public:
  23   explicit VelocityTrackerState(VelocityTracker::Strategy strategy);
  24   ~VelocityTrackerState();
  25
  26   void Clear();
  27   void AddMovement(const MotionEvent& event);
  28   void ComputeCurrentVelocity(int32_t units, float max_velocity);
  29   float GetXVelocity(int32_t id) const;
  30   float GetYVelocity(int32_t id) const;
  31
  32  private:
  33   struct Velocity {
  34     float vx, vy;
  35   };
  36
  37   void GetVelocity(int32_t id, float* out_vx, float* out_vy) const;
  38
  39   VelocityTracker velocity_tracker_;
  40   int32_t active_pointer_id_;
  41   BitSet32 calculated_id_bits_;
  42   Velocity calculated_velocity_[VelocityTracker::MAX_POINTERS];
  43
  44   DISALLOW_COPY_AND_ASSIGN(VelocityTrackerState);
  45 };
  46
  47 }  // namespace ui
  48
  49 #endif  // UI_EVENTS_GESTURE_DETECTION_VELOCITY_TRACKER_STATE_H_