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      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 
     15 class SkBitmap;
     16 
     17 namespace cc {
     18 class Layer;
     19 }
     20 
     21 namespace 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  */
     27 class 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   // |overscroll| is the accumulated overscroll for the current gesture.
     47   // |velocity| is the instantaneous velocity for the overscroll.
     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 overscroll,
     52                       gfx::Vector2dF velocity);
     53 
     54   // Returns true if the effect still needs animation ticks.
     55   // Note: The effect will detach itself when no further animation is required.
     56   bool Animate(base::TimeTicks current_time);
     57 
     58   // Horizontal overscroll will be ignored when false.
     59   void set_horizontal_overscroll_enabled(bool enabled) {
     60     horizontal_overscroll_enabled_ = enabled;
     61   }
     62   // Vertical overscroll will be ignored when false.
     63   void set_vertical_overscroll_enabled(bool enabled) {
     64     vertical_overscroll_enabled_ = enabled;
     65   }
     66   // The size of the layer for which edges will be animated.
     67   void set_size(gfx::SizeF size) {
     68     size_ = size;
     69   }
     70 
     71  private:
     72   enum Axis { AXIS_X, AXIS_Y };
     73 
     74   OverscrollGlow(bool enabled);
     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             gfx::Vector2dF added_overscroll);
     83   void Absorb(base::TimeTicks current_time,
     84               gfx::Vector2dF velocity,
     85               gfx::Vector2dF overscroll,
     86               gfx::Vector2dF old_overscroll);
     87   void Release(base::TimeTicks current_time);
     88   void ReleaseAxis(Axis axis, base::TimeTicks current_time);
     89 
     90   EdgeEffect* GetOppositeEdge(int edge_index);
     91 
     92   scoped_ptr<EdgeEffect> edge_effects_[EdgeEffect::EDGE_COUNT];
     93 
     94   bool enabled_;
     95   bool initialized_;
     96   gfx::SizeF size_;
     97   gfx::Vector2dF old_overscroll_;
     98   gfx::Vector2dF old_velocity_;
     99   bool horizontal_overscroll_enabled_;
    100   bool vertical_overscroll_enabled_;
    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_SCROLL_GLOW_H_
    110