content/browser/android/overscroll_glow.h

   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_base.h"
  12 #include "ui/gfx/geometry/size_f.h"
  13 #include "ui/gfx/geometry/vector2d_f.h"
  14
  15 namespace cc {
  16 class Layer;
  17 }
  18
  19 namespace content {
  20
  21 // Provides lazy, customized EdgeEffect creation.
  22 class OverscrollGlowClient {
  23  public:
  24   virtual ~OverscrollGlowClient() {}
  25
  26   // Called lazily, after the initial overscrolling event.
  27   virtual scoped_ptr<EdgeEffectBase> CreateEdgeEffect() = 0;
  28 };
  29
  30 /* |OverscrollGlow| mirrors its Android counterpart, OverscrollGlow.java.
  31  * Conscious tradeoffs were made to align this as closely as possible with the
  32  * original Android Java version.
  33  */
  34 class OverscrollGlow {
  35  public:
  36   // |client| must be valid for the duration of the effect's lifetime.
  37   // The effect is enabled by default, but will remain dormant until the first
  38   // overscroll event.
  39   explicit OverscrollGlow(OverscrollGlowClient* client);
  40   ~OverscrollGlow();
  41
  42   // Called when the root content layer overscrolls.
  43   // |accumulated_overscroll| and |overscroll_delta| are in device pixels, while
  44   // |velocity| is in device pixels / second.
  45   // |overscroll_location| is the coordinate of the causal overscrolling event.
  46   // Returns true if the effect still needs animation ticks.
  47   bool OnOverscrolled(base::TimeTicks current_time,
  48                       const gfx::Vector2dF& accumulated_overscroll,
  49                       gfx::Vector2dF overscroll_delta,
  50                       gfx::Vector2dF velocity,
  51                       const gfx::Vector2dF& overscroll_location);
  52
  53   // Returns true if the effect still needs animation ticks, with effect layers
  54   // attached to |parent_layer| if necessary.
  55   // Note: The effect will detach itself when no further animation is required.
  56   bool Animate(base::TimeTicks current_time, cc::Layer* parent_layer);
  57
  58   // Update the effect according to the most recent display parameters,
  59   // Note: All dimensions are in device pixels.
  60   void OnFrameUpdated(const gfx::SizeF& viewport_size,
  61                       const gfx::SizeF& content_size,
  62                       const gfx::Vector2dF& content_scroll_offset);
  63
  64   // Reset the effect to its inactive state, clearing any active effects.
  65   void Reset();
  66
  67   // Whether the effect is active, either being pulled or receding.
  68   bool IsActive() const;
  69
  70   // The maximum alpha value (in the range [0,1]) of any animated edge layers.
  71   // If the effect is inactive, this will be 0.
  72   float GetVisibleAlpha() const;
  73
  74  private:
  75   enum Axis { AXIS_X, AXIS_Y };
  76   enum { EDGE_COUNT = EdgeEffectBase::EDGE_COUNT };
  77
  78   // Returns whether the effect has been properly initialized.
  79   bool InitializeIfNecessary();
  80   bool CheckNeedsAnimate();
  81   void UpdateLayerAttachment(cc::Layer* parent);
  82   void Detach();
  83   void Pull(base::TimeTicks current_time,
  84             const gfx::Vector2dF& overscroll_delta,
  85             const gfx::Vector2dF& overscroll_location);
  86   void Absorb(base::TimeTicks current_time,
  87               const gfx::Vector2dF& velocity,
  88               bool x_overscroll_started,
  89               bool y_overscroll_started);
  90   void Release(base::TimeTicks current_time);
  91
  92   EdgeEffectBase* GetOppositeEdge(int edge_index);
  93
  94   OverscrollGlowClient* const client_;
  95   scoped_ptr<EdgeEffectBase> edge_effects_[EDGE_COUNT];
  96
  97   gfx::SizeF viewport_size_;
  98   float edge_offsets_[EDGE_COUNT];
  99   bool initialized_;
 100   bool allow_horizontal_overscroll_;
 101   bool allow_vertical_overscroll_;
 102
 103   scoped_refptr<cc::Layer> root_layer_;
 104
 105   DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
 106 };
 107
 108 }  // namespace content
 109
 110 #endif  // CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_