Reland: Implement features in NativeViewHostAura for scroll end effect

ui/views/controls/native/native_view_host_aura.h

 // Copyright (c) 2011 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 UI_VIEWS_CONTROLS_NATIVE_NATIVE_VIEW_HOST_AURA_H_
 #define UI_VIEWS_CONTROLS_NATIVE_NATIVE_VIEW_HOST_AURA_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/memory/scoped_ptr.h"
+#include "ui/aura/window.h"
 #include "ui/aura/window_observer.h"
 #include "ui/views/controls/native/native_view_host_wrapper.h"
 #include "ui/views/views_export.h"
 
 namespace views {
 
 class NativeViewHost;
+class ClippingWindowObserver;
 
 // Aura implementation of NativeViewHostWrapper.
 class VIEWS_EXPORT NativeViewHostAura : public NativeViewHostWrapper,
                                         public aura::WindowObserver {
  public:
   explicit NativeViewHostAura(NativeViewHost* host);
   virtual ~NativeViewHostAura();
 
   // Overridden from NativeViewHostWrapper:
-  virtual void NativeViewWillAttach() OVERRIDE;
+  virtual void AttachNativeView() OVERRIDE;
   virtual void NativeViewDetaching(bool destroyed) OVERRIDE;
   virtual void AddedToWidget() OVERRIDE;
   virtual void RemovedFromWidget() OVERRIDE;
   virtual void InstallClip(int x, int y, int w, int h) OVERRIDE;
   virtual bool HasInstalledClip() OVERRIDE;
   virtual void UninstallClip() OVERRIDE;
   virtual void ShowWidget(int x, int y, int w, int h) OVERRIDE;
   virtual void HideWidget() OVERRIDE;
   virtual void SetFocus() OVERRIDE;
   virtual gfx::NativeViewAccessible GetNativeViewAccessible() OVERRIDE;
 
  private:
+  friend class ClippingWindowObserver;
+  friend class NativeViewHostAuraTest;
+
   // Overridden from aura::WindowObserver:
   virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
 
+  // Calculates the origin of the native view for the fast resize path, so it
+  // can be clipped correctly. This value is affected by the current gravity
+  // being applied. The formula for this calulation is:
+  //
+  // x' = width_scaling_factor * (content_width - clip_width)
+  // y' = height_scaling_factor * (content_heigth - clip_height)
+  //
+  // , where the scaling factors are either 0, 0.5, or 1.0 depending on the
+  // current gravity.
+  gfx::Point CalculateNativeViewOrigin(const gfx::Rect& input_rect,
+                                       const gfx::Rect& native_rect) const;
+
+
+  // Reparents the native view with the clipping window existing between it and
+  // its old parent, so that the fast resize path works. |clipping_window_| is
+  // created by this call.
+  void AddClippingWindow();
+
+  // If the native view has been reparented via AddClippingWindow, this call
+  // undoes it. |clipping_window_| is destroyed by this call.
+  void RemoveClippingWindow();
+
+  // Update the positioning of the clipping window and the attached native
+  // view. The native view is a child of the clipping window, so is positioned
+  // relative to it.
+  void UpdateClippingWindow();
+
   // Our associated NativeViewHost.
   NativeViewHost* host_;
 
   // Have we installed a clip region?
   bool installed_clip_;
 
+  // Window that exists between the native view and the parent that allows for
+  // clipping to occur.
+  aura::Window* clipping_window_;
+
+  scoped_ptr<ClippingWindowObserver> clipping_window_observer_;
+
+  // The bounds of the content layer before any clipping actions occur. This is
+  // restored when the clip is uninstalled. This value should be in the
+  // coordinate space of host_->GetWidget().
+  gfx::Rect orig_bounds_;
+
+  // The bounds of the clipping window. When no clip is installed |orig_bounds_|
+  // and |clip_rect_| should be equal. When clip is installed |clip_rect_| is
+  // manipulated to position of the clipping window in
+  // UpdateClippingWindow. This value should be in the coordinate space of
+  // host_->GetWidget().
+  gfx::Rect clip_rect_;
+
   DISALLOW_COPY_AND_ASSIGN(NativeViewHostAura);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_CONTROLS_NATIVE_NATIVE_VIEW_HOST_AURA_H_