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 CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
6#define CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
7
8#include "base/memory/ref_counted.h"
9#include "base/memory/scoped_ptr.h"
10#include "base/time/time.h"
11#include "content/browser/android/edge_effect.h"
12#include "ui/gfx/size_f.h"
13#include "ui/gfx/vector2d_f.h"
14
15class SkBitmap;
16
17namespace cc {
18class Layer;
19}
20
21namespace content {
22
23/* |OverscrollGlow| mirrors its Android counterpart, OverscrollGlow.java.
24 * Conscious tradeoffs were made to align this as closely as possible with the
25 * original Android Java version.
26 */
27class OverscrollGlow {
28 public:
29  // Create a new effect. If |enabled| is false, the effect will remain
30  // deactivated until explicitly enabled.
31  // Note: No resources will be allocated until the effect is both
32  //       enabled and an overscroll event has occurred.
33  static scoped_ptr<OverscrollGlow> Create(bool enabled);
34
35  ~OverscrollGlow();
36
37  // Enable the effect. If the effect was previously disabled, it will remain
38  // dormant until subsequent calls to |OnOverscrolled()|.
39  void Enable();
40
41  // Deactivate and detach the effect. Subsequent calls to |OnOverscrolled()| or
42  // |Animate()| will have no effect.
43  void Disable();
44
45  // Effect layers will be attached to |overscrolling_layer| if necessary.
46  // |accumulated_overscroll| and |overscroll_delta| are in device pixels, while
47  // |velocity| is in device pixels / second.
48  // Returns true if the effect still needs animation ticks.
49  bool OnOverscrolled(cc::Layer* overscrolling_layer,
50                      base::TimeTicks current_time,
51                      gfx::Vector2dF accumulated_overscroll,
52                      gfx::Vector2dF overscroll_delta,
53                      gfx::Vector2dF velocity);
54
55  // Returns true if the effect still needs animation ticks.
56  // Note: The effect will detach itself when no further animation is required.
57  bool Animate(base::TimeTicks current_time);
58
59  // Update the effect according to the most recent display parameters,
60  // Note: All dimensions are in device pixels.
61  struct DisplayParameters {
62    DisplayParameters();
63    gfx::SizeF size;
64    float edge_offsets[EdgeEffect::EDGE_COUNT];
65    float device_scale_factor;
66  };
67  void UpdateDisplayParameters(const DisplayParameters& params);
68
69
70 private:
71  enum Axis { AXIS_X, AXIS_Y };
72
73  OverscrollGlow(bool enabled);
74
75  // Returns whether the effect is initialized.
76  bool InitializeIfNecessary();
77  bool NeedsAnimate() const;
78  void UpdateLayerAttachment(cc::Layer* parent);
79  void Detach();
80  void Pull(base::TimeTicks current_time, gfx::Vector2dF overscroll_delta);
81  void Absorb(base::TimeTicks current_time,
82              gfx::Vector2dF velocity,
83              bool x_overscroll_started,
84              bool y_overscroll_started);
85  void Release(base::TimeTicks current_time);
86  void ReleaseAxis(Axis axis, base::TimeTicks current_time);
87
88  EdgeEffect* GetOppositeEdge(int edge_index);
89
90  scoped_ptr<EdgeEffect> edge_effects_[EdgeEffect::EDGE_COUNT];
91
92  DisplayParameters display_params_;
93  bool enabled_;
94  bool initialized_;
95
96  scoped_refptr<cc::Layer> root_layer_;
97
98  DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
99};
100
101}  // namespace content
102
103#endif  // CONTENT_BROWSER_ANDROID_SCROLL_GLOW_H_
104