[Android] Implementation of overscroll effect for Android L

content/browser/android/overscroll_glow.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
 #define CONTENT_BROWSER_ANDROID_OVERSCROLL_GLOW_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "content/browser/android/edge_effect.h"
 #include "ui/gfx/size_f.h"
 #include "ui/gfx/vector2d_f.h"
 
 class SkBitmap;
 
 namespace cc {
 class Layer;
 }
 
 namespace content {
 
 /* |OverscrollGlow| mirrors its Android counterpart, OverscrollGlow.java.
  * Conscious tradeoffs were made to align this as closely as possible with the
  * original Android Java version.
  */
 class OverscrollGlow {
  public:
+  enum Edge {
+    EDGE_TOP = 0,
+    EDGE_LEFT,
+    EDGE_BOTTOM,
+    EDGE_RIGHT,
+    EDGE_COUNT
+  };
+
   // Create a new effect. If |enabled| is false, the effect will remain
   // deactivated until explicitly enabled.
   // Note: No resources will be allocated until the effect is both
   //       enabled and an overscroll event has occurred.
   static scoped_ptr<OverscrollGlow> Create(bool enabled);
 
   ~OverscrollGlow();
 
   // Enable the effect. If the effect was previously disabled, it will remain
   // dormant until subsequent calls to |OnOverscrolled()|.
   void Enable();
 
   // Deactivate and detach the effect. Subsequent calls to |OnOverscrolled()| or
   // |Animate()| will have no effect.
   void Disable();
 
   // Effect layers will be attached to |overscrolling_layer| if necessary.
   // |accumulated_overscroll| and |overscroll_delta| are in device pixels, while
   // |velocity| is in device pixels / second.
   // Returns true if the effect still needs animation ticks.
   bool OnOverscrolled(cc::Layer* overscrolling_layer,
                       base::TimeTicks current_time,
                       gfx::Vector2dF accumulated_overscroll,
                       gfx::Vector2dF overscroll_delta,
-                      gfx::Vector2dF velocity);
+                      gfx::Vector2dF velocity,
+                      gfx::Vector2dF overscroll_location);
 
   // Returns true if the effect still needs animation ticks.
   // Note: The effect will detach itself when no further animation is required.
   bool Animate(base::TimeTicks current_time);
 
   // Update the effect according to the most recent display parameters,
   // Note: All dimensions are in device pixels.
   struct DisplayParameters {
     DisplayParameters();
     gfx::SizeF size;
-    float edge_offsets[EdgeEffect::EDGE_COUNT];
-    float device_scale_factor;
+    float edge_offsets[EDGE_COUNT];
   };
   void UpdateDisplayParameters(const DisplayParameters& params);
 
 
  private:
   enum Axis { AXIS_X, AXIS_Y };
 
   OverscrollGlow(bool enabled);
 
   // Returns whether the effect is initialized.
   bool InitializeIfNecessary();
   bool NeedsAnimate() const;
   void UpdateLayerAttachment(cc::Layer* parent);
   void Detach();
-  void Pull(base::TimeTicks current_time, gfx::Vector2dF overscroll_delta);
+  void Pull(base::TimeTicks current_time,
+            const gfx::Vector2dF& overscroll_delta,
+            const gfx::Vector2dF& overscroll_location);
   void Absorb(base::TimeTicks current_time,
-              gfx::Vector2dF velocity,
+              const gfx::Vector2dF& velocity,
               bool x_overscroll_started,
               bool y_overscroll_started);
   void Release(base::TimeTicks current_time);
   void ReleaseAxis(Axis axis, base::TimeTicks current_time);
 
-  EdgeEffect* GetOppositeEdge(int edge_index);
+  EdgeEffectBase* GetOppositeEdge(int edge_index);
 
-  scoped_ptr<EdgeEffect> edge_effects_[EdgeEffect::EDGE_COUNT];
+  scoped_ptr<EdgeEffectBase> edge_effects_[EDGE_COUNT];
 
   DisplayParameters display_params_;
   bool enabled_;
   bool initialized_;
 
   scoped_refptr<cc::Layer> root_layer_;
 
   DISALLOW_COPY_AND_ASSIGN(OverscrollGlow);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_ANDROID_SCROLL_GLOW_H_