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/callback.h"
9#include "base/memory/ref_counted.h"
10#include "base/memory/scoped_ptr.h"
11#include "base/time/time.h"
12#include "ui/gfx/size_f.h"
13#include "ui/gfx/vector2d_f.h"
14
15namespace cc {
16class Layer;
17}
18
19namespace content {
20
21class EdgeEffectBase;
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  enum Edge { EDGE_TOP = 0, EDGE_LEFT, EDGE_BOTTOM, EDGE_RIGHT, EDGE_COUNT };
30
31  // Allows lazy creation of the edge effects.
32  typedef base::Callback<scoped_ptr<EdgeEffectBase>(void)> EdgeEffectProvider;
33
34  // |edge_effect_provider| must be valid for the duration of the effect's
35  // lifetime.  The effect is enabled by default, but will remain dormant until
36  // the first overscroll event.
37  explicit OverscrollGlow(const EdgeEffectProvider& edge_effect_provider);
38
39  ~OverscrollGlow();
40
41  // Enable the effect. If the effect was previously disabled, it will remain
42  // dormant until subsequent calls to |OnOverscrolled()|.
43  void Enable();
44
45  // Deactivate and detach the effect. Subsequent calls to |OnOverscrolled()| or
46  // |Animate()| will have no effect.
47  void Disable();
48
49  // Effect layers will be attached to |overscrolling_layer| if necessary.
50  // |accumulated_overscroll| and |overscroll_delta| are in device pixels, while
51  // |velocity| is in device pixels / second.
52  // Returns true if the effect still needs animation ticks.
53  bool OnOverscrolled(cc::Layer* overscrolling_layer,
54                      base::TimeTicks current_time,
55                      gfx::Vector2dF accumulated_overscroll,
56                      gfx::Vector2dF overscroll_delta,
57                      gfx::Vector2dF velocity,
58                      gfx::Vector2dF overscroll_location);
59
60  // Returns true if the effect still needs animation ticks.
61  // Note: The effect will detach itself when no further animation is required.
62  bool Animate(base::TimeTicks current_time);
63
64  // Update the effect according to the most recent display parameters,
65  // Note: All dimensions are in device pixels.
66  struct DisplayParameters {
67    DisplayParameters();
68    gfx::SizeF size;
69    float edge_offsets[EDGE_COUNT];
70  };
71  void UpdateDisplayParameters(const DisplayParameters& params);
72
73 private:
74  enum Axis { AXIS_X, AXIS_Y };
75
76  // Returns whether the effect is initialized.
77  bool InitializeIfNecessary();
78  bool NeedsAnimate() const;
79  void UpdateLayerAttachment(cc::Layer* parent);
80  void Detach();
81  void Pull(base::TimeTicks current_time,
82            const gfx::Vector2dF& overscroll_delta,
83            const gfx::Vector2dF& overscroll_location);
84  void Absorb(base::TimeTicks current_time,
85              const gfx::Vector2dF& velocity,
86              bool x_overscroll_started,
87              bool y_overscroll_started);
88  void Release(base::TimeTicks current_time);
89
90  EdgeEffectBase* GetOppositeEdge(int edge_index);
91
92  EdgeEffectProvider edge_effect_provider_;
93  scoped_ptr<EdgeEffectBase> edge_effects_[EDGE_COUNT];
94
95  DisplayParameters display_params_;
96  bool enabled_;
97  bool initialized_;
98
99  scoped_refptr<cc::Layer> root_layer_;
100
101  DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
102};
103
104}  // namespace content
105
106#endif  // CONTENT_BROWSER_ANDROID_SCROLL_GLOW_H_
107