[Android] Implementation of overscroll effect for Android L

content/browser/android/edge_effect_l.h

+// Copyright 2014 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_EDGE_EFFECT_L_H_
+#define CONTENT_BROWSER_ANDROID_EDGE_EFFECT_L_H_
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "content/browser/android/edge_effect_base.h"
+#include "ui/gfx/geometry/rect_f.h"
+#include "ui/gfx/geometry/size.h"
+
+namespace cc {
+class Layer;
+}
+
+namespace content {
+
+// |EdgeEffectL| mirrors its Android L counterpart, EdgeEffect.java.
+// Conscious tradeoffs were made to align this as closely as possible with the
+// the original Android java version.
+// All coordinates and dimensions are in device pixels.
+class EdgeEffectL : public EdgeEffectBase {
+public:
+  static scoped_ptr<EdgeEffectL> Create(cc::Layer* root_layer);
+
+  virtual ~EdgeEffectL();
+
+  virtual void Pull(base::TimeTicks current_time,
+                    float delta_distance) OVERRIDE;
+  virtual void Pull(base::TimeTicks current_time,
+                    float delta_distance,
+                    float displacement) OVERRIDE;
+  virtual void Absorb(base::TimeTicks current_time, float velocity) OVERRIDE;
+  virtual bool Update(base::TimeTicks current_time) OVERRIDE;
+  virtual void Release(base::TimeTicks current_time) OVERRIDE;
+
+  virtual void Finish() OVERRIDE;
+  virtual bool IsFinished() const OVERRIDE;
+
+  virtual void ApplyToLayers(const gfx::SizeF& size,
+                             const gfx::Transform& transform) OVERRIDE;
+
+  // Thread-safe trigger to load resources.
+  static void EnsureResources();
+
+private:
+  explicit EdgeEffectL(const scoped_refptr<cc::Layer>& glow);
+
+  scoped_refptr<cc::Layer> glow_;
+
+  float glow_alpha_;
+  float glow_scale_y_;
+
+  float glow_alpha_start_;
+  float glow_alpha_finish_;
+  float glow_scale_y_start_;
+  float glow_scale_y_finish_;
+
+  gfx::RectF arc_rect_;
+  gfx::Size bounds_;
+  float displacement_;
+  float target_displacement_;
+
+  base::TimeTicks start_time_;
+  base::TimeDelta duration_;
+
+  State state_;
+
+  float pull_distance_;
+
+  DISALLOW_COPY_AND_ASSIGN(EdgeEffectL);
+};
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_ANDROID_EDGE_EFFECT_L_H_