Implement initial version of scroll end effect

chrome/browser/ui/views/frame/scroll_end_effect_controller_ash.h

 // Copyright 2013 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 CHROME_BROWSER_UI_VIEWS_FRAME_SCROLL_END_EFFECT_CONTROLLER_ASH_H_
 #define CHROME_BROWSER_UI_VIEWS_FRAME_SCROLL_END_EFFECT_CONTROLLER_ASH_H_
 
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
 #include "chrome/browser/ui/views/frame/scroll_end_effect_controller.h"
+#include "ui/compositor/layer.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/transform.h"
 
+namespace views {
+class View;
+}
+
+// Class that implements the scroll end effect by controlling the layout of
+// layers and the transforms applied to them. This class depends heavily on
+// ScrollEndEffectControllerDelegate, which is implemented in BrowserView.
 class ScrollEndEffectControllerAsh : public ScrollEndEffectController {
  public:
-  ScrollEndEffectControllerAsh();
+  explicit ScrollEndEffectControllerAsh(
+      ScrollEndEffectControllerDelegate* delegate);
   virtual ~ScrollEndEffectControllerAsh();
 
   // ScrollEndEffectController overides:
   virtual void OverscrollUpdate(int delta_y) OVERRIDE;
 
  private:
+  // Sets up the layer hierarchy for showing the effect. This involves making
+  // sure everything is on a layer and inserting clipping layers into the
+  // hierarchy.
+  void ActivateEffect();
+
+  // Utility methods used to create needed layers.
+  ui::Layer* CreateClippingLayer(std::string name);
+  ui::Layer* CreateViewLayer(views::View* view);
+
+  // Restores the layer hierarchy and states to what they were before the effect
+  // was actived.
+  void DeactivateEffect();
+
+  // Computes the transforms and counter transforms that are needed to produce
+  // the desired effect then applies them. The bounds of the layers may be
+  // adjusted due to a call to SetBoundsForEffect, so need to be stored before
+  // calling. The entire window is scaled and possibly translated to produce the
+  // squishing effect. The non-client area and the content are counter scaled to
+  // preserve their size and translated/clipped to fit in the smaller window.
+  void ApplyDelta(int delta_y);
+
+  // Adjusts the bounds for the layers of interest, so that the scroll end
+  // effect appears correctly. It is the responsibility of the caller to save
+  // and restore the bounds as needed.
+  void SetBoundsForEffect();
+
+  // For layers not at the origin they need to be translated to/from the origin
+  // in the transform for the simple inverse transform to be the correct counter
+  // tranformation. This is a utility method encapsulates this operation.
+  gfx::Transform CounterTransfromAboutPoint(int x, int y);
+
+  ScrollEndEffectControllerDelegate* delegate_;  // non-owned
+  bool is_effect_active_;
+
+  scoped_ptr<ui::Layer> frame_clipping_layer_;
+  scoped_ptr<ui::Layer> web_clipping_layer_;
+  ui::Layer* non_client_layer_;
+  ui::Layer* web_contents_layer_;  // non-owned
+  ui::Layer* devtools_layer_;  // non-owned
+  ui::Layer* download_layer_;
+
+  // Used to reparent |web_contents_layer_| when deactivating the effect.
+  ui::Layer* web_contents_parent_;  // non-owned
+
+  // Used to reparent |devtools_layer_| when deactivating the effect.
+  ui::Layer* devtools_parent_;  // non-owned
+
+  // Saved when the effect is activated, so it can be restored when the
+  // effect is deactivated.
+  gfx::Rect web_contents_bounds_;
+
+  // Saved when the effect is activated, so it can be restored when the
+  // effect is deactivated.
+  gfx::Rect devtools_bounds_;
+
+  // Used to turn off being on a layer when deactivating the effect.
+  views::View* non_client_view_;  // non-owned
+
+  // Used to turn off being on a layer when deactivating the effect.
+  views::View* download_view_;  // non-owned
+
+  // Inverse of the transform that is being applied at the top of the hiearchy
+  // for the effect.
+  gfx::Transform counter_transform_;
+
   DISALLOW_COPY_AND_ASSIGN(ScrollEndEffectControllerAsh);
  };
 
 #endif  // CHROME_BROWSER_UI_VIEWS_FRAME_SCROLL_END_EFFECT_CONTROLLER_ASH_H_