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/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
  15 namespace cc {
  16 class Layer;
  17 }
  18
  19 namespace content {
  20
  21 class 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  */
  27 class 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_