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