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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   // |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(cc::Layer* overscrolling_layer,
     50                       base::TimeTicks current_time,
     51                       gfx::Vector2dF accumulated_overscroll,
     52                       gfx::Vector2dF overscroll_delta,
     53                       gfx::Vector2dF velocity);
     54 
     55   // Returns true if the effect still needs animation ticks.
     56   // Note: The effect will detach itself when no further animation is required.
     57   bool Animate(base::TimeTicks current_time);
     58 
     59   // Update the effect according to the most recent display parameters,
     60   // Note: All dimensions are in device pixels.
     61   struct DisplayParameters {
     62     DisplayParameters();
     63     gfx::SizeF size;
     64     float edge_offsets[EdgeEffect::EDGE_COUNT];
     65     float device_scale_factor;
     66   };
     67   void UpdateDisplayParameters(const DisplayParameters& params);
     68 
     69 
     70  private:
     71   enum Axis { AXIS_X, AXIS_Y };
     72 
     73   OverscrollGlow(bool enabled);
     74 
     75   // Returns whether the effect is initialized.
     76   bool InitializeIfNecessary();
     77   bool NeedsAnimate() const;
     78   void UpdateLayerAttachment(cc::Layer* parent);
     79   void Detach();
     80   void Pull(base::TimeTicks current_time, gfx::Vector2dF overscroll_delta);
     81   void Absorb(base::TimeTicks current_time,
     82               gfx::Vector2dF velocity,
     83               bool x_overscroll_started,
     84               bool y_overscroll_started);
     85   void Release(base::TimeTicks current_time);
     86   void ReleaseAxis(Axis axis, base::TimeTicks current_time);
     87 
     88   EdgeEffect* GetOppositeEdge(int edge_index);
     89 
     90   scoped_ptr<EdgeEffect> edge_effects_[EdgeEffect::EDGE_COUNT];
     91 
     92   DisplayParameters display_params_;
     93   bool enabled_;
     94   bool initialized_;
     95 
     96   scoped_refptr<cc::Layer> root_layer_;
     97 
     98   DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
     99 };
    100 
    101 }  // namespace content
    102 
    103 #endif  // CONTENT_BROWSER_ANDROID_SCROLL_GLOW_H_
    104