Reland: Implement features in NativeViewHostAura for scroll end effect

ui/views/controls/native/native_view_host_aura.cc

Index: ui/views/controls/native/native_view_host_aura.cc
diff --git a/ui/views/controls/native/native_view_host_aura.cc b/ui/views/controls/native/native_view_host_aura.cc
index a71e230be4762b502b08d0537b547d599764a20e..a4d887f5dd77e95b46df0b7f247e8add4d48ccd9 100644
--- a/ui/views/controls/native/native_view_host_aura.cc
+++ b/ui/views/controls/native/native_view_host_aura.cc
@@ -7,49 +7,88 @@
 #include "base/logging.h"
 #include "ui/aura/client/focus_client.h"
 #include "ui/aura/window.h"
+#include "ui/gfx/safe_integer_conversions.h"
 #include "ui/views/controls/native/native_view_host.h"
 #include "ui/views/view_constants_aura.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
+// Watches for the clipping window to enter its destructor, so it can clear the
+// NVHA's reference to the clipping window.
+class ClippingWindowObserver : public aura::WindowObserver {
+ public:
+  explicit ClippingWindowObserver(NativeViewHostAura* host) :
+      host_(host),
+      clipping_window_(NULL) {}
+
+  virtual ~ClippingWindowObserver() {
+    if (clipping_window_)
+      clipping_window_->RemoveObserver(this);
+  }
+
+  void SetClippingWindow(aura::Window* window) {
+    if (clipping_window_)
+      clipping_window_->RemoveObserver(this);
+    clipping_window_ = window;
+    if (clipping_window_)
+      clipping_window_->AddObserver(this);
+  }
+
+  // Overridden from aura::WindowObserver:
+  virtual void OnWindowDestroying(aura::Window* window) OVERRIDE {
+    host_->clipping_window_ = NULL;
+    SetClippingWindow(NULL);
+  }
+
+ private:
+  NativeViewHostAura* host_;
+  aura::Window* clipping_window_;
+
+  DISALLOW_COPY_AND_ASSIGN(ClippingWindowObserver);
+};
+
 NativeViewHostAura::NativeViewHostAura(NativeViewHost* host)
     : host_(host),
-      installed_clip_(false) {
-}
+      installed_clip_(false),
+      clipping_window_(NULL),
+      clipping_window_observer_(new ClippingWindowObserver(this)) {}
 
 NativeViewHostAura::~NativeViewHostAura() {
-  if (host_->native_view()) {
+  if (clipping_window_)
     host_->native_view()->ClearProperty(views::kHostViewKey);
+
+  if (host_->native_view()) {
     host_->native_view()->RemoveObserver(this);
+    host_->native_view()->ClearProperty(views::kHostViewKey);
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NativeViewHostAura, NativeViewHostWrapper implementation:
-void NativeViewHostAura::NativeViewWillAttach() {
+void NativeViewHostAura::AttachNativeView() {
   host_->native_view()->AddObserver(this);
   host_->native_view()->SetProperty(views::kHostViewKey,
-      static_cast<View*>(host_));
+                                    static_cast<View*>(host_));
+  AddClippingWindow();
 }
 
 void NativeViewHostAura::NativeViewDetaching(bool destroyed) {
   if (!destroyed) {
-    host_->native_view()->ClearProperty(views::kHostViewKey);
     host_->native_view()->RemoveObserver(this);
+    host_->native_view()->ClearProperty(views::kHostViewKey);
     host_->native_view()->Hide();
-    if (host_->native_view()->parent())
-      Widget::ReparentNativeView(host_->native_view(), NULL);
+    RemoveClippingWindow();
+  } else {
+    if (clipping_window_)
+      delete clipping_window_;
   }
 }
 
 void NativeViewHostAura::AddedToWidget() {
   if (!host_->native_view())
     return;
-
-  aura::Window* widget_window = host_->GetWidget()->GetNativeView();
-  if (host_->native_view()->parent() != widget_window)
-    widget_window->AddChild(host_->native_view());
+  AddClippingWindow();
   if (host_->IsDrawn())
     host_->native_view()->Show();
   else
@@ -60,15 +99,18 @@ void NativeViewHostAura::AddedToWidget() {
 void NativeViewHostAura::RemovedFromWidget() {
   if (host_->native_view()) {
     host_->native_view()->Hide();
-    if (host_->native_view()->parent())
-      host_->native_view()->parent()->RemoveChild(host_->native_view());
   }
+  RemoveClippingWindow();
 }
 
 void NativeViewHostAura::InstallClip(int x, int y, int w, int h) {
-  // Note that this does not pose a problem functionality wise - it might
-  // however pose a speed degradation if not implemented.
-  LOG(WARNING) << "NativeViewHostAura::InstallClip is not implemented yet.";
+  installed_clip_ = true;
+  clip_rect_ = gfx::Rect(x + orig_bounds_.x(),
+                         y + orig_bounds_.y(),
+                         w,
+                         h);
+  UpdateClippingWindow();
+  clipping_window_->layer()->SetMasksToBounds(true);
 }
 
 bool NativeViewHostAura::HasInstalledClip() {
@@ -76,12 +118,32 @@ bool NativeViewHostAura::HasInstalledClip() {
 }
 
 void NativeViewHostAura::UninstallClip() {
+  if (installed_clip_ == false)
+    return;
   installed_clip_ = false;
+  clipping_window_->layer()->SetMasksToBounds(false);
 }
 
 void NativeViewHostAura::ShowWidget(int x, int y, int w, int h) {
-  // TODO: need to support fast resize.
-  host_->native_view()->SetBounds(gfx::Rect(x, y, w, h));
+  if (host_->fast_resize()) {
+    gfx::Rect native_view_bounds = host_->native_view()->bounds();
+    gfx::Point native_view_origin =
+        CalculateNativeViewOrigin(clipping_window_->bounds(),
+                                  native_view_bounds);
+    orig_bounds_ = gfx::Rect(x + native_view_origin.x(),
+                             y + native_view_origin.y(),
+                             native_view_bounds.width(),
+                             native_view_bounds.height());
+
+    InstallClip(x - orig_bounds_.x(),
+                y - orig_bounds_.y(),
+                w,
+                h);
+  } else {
+    clip_rect_.Offset(x - orig_bounds_.x(), y - orig_bounds_.y());
+    orig_bounds_ = gfx::Rect(x, y, w, h);
+    UpdateClippingWindow();
+  }
   host_->native_view()->Show();
 }
 
@@ -111,4 +173,64 @@ NativeViewHostWrapper* NativeViewHostWrapper::CreateWrapper(
   return new NativeViewHostAura(host);
 }
 
+gfx::Point NativeViewHostAura::CalculateNativeViewOrigin(
+    const gfx::Rect& input_rect,
+    const gfx::Rect& native_rect) const {
+  int new_x = gfx::ToRoundedInt(host_->GetWidthScaleFactor() *
+                                (input_rect.width() -
+                                 native_rect.width()));
+  int new_y = gfx::ToRoundedInt(host_->GetHeightScaleFactor() *
+                                (input_rect.height() -
+                                 native_rect.height()));
+  return gfx::Point(new_x, new_y);
+}
+
+void NativeViewHostAura::AddClippingWindow() {
+  RemoveClippingWindow();
+  clipping_window_ = new aura::Window(NULL);
+  clipping_window_->SetTransparent(true);
+  clipping_window_->Init(ui::LAYER_NOT_DRAWN);
+  clipping_window_->layer()->set_name("NativeViewHostAuraClip");
+  clipping_window_->layer()->SetMasksToBounds(false);
+  clipping_window_observer_->SetClippingWindow(clipping_window_);
+
+  gfx::Rect bounds = host_->native_view()->bounds();
+  orig_bounds_ = bounds;
+  clipping_window_->SetBounds(bounds);
+  bounds.set_origin(gfx::Point(0, 0));
+  host_->native_view()->SetBounds(bounds);
+
+  clipping_window_->AddChild(host_->native_view());
+  clipping_window_->SetProperty(views::kHostViewKey,
+      static_cast<View*>(host_));
+  Widget::ReparentNativeView(clipping_window_,
+                             host_->GetWidget()->GetNativeView());
+  clipping_window_->Show();
+}
+
+void NativeViewHostAura::RemoveClippingWindow() {
+  if (clipping_window_) {
+    if (host_->native_view()->parent() == clipping_window_) {
+      host_->native_view()->SetBounds(clipping_window_->bounds());
+      if (clipping_window_->parent()) {
+        Widget::ReparentNativeView(host_->native_view(), NULL);
+      } else {
+        clipping_window_->RemoveChild(host_->native_view());
+      }
+    }
+    delete clipping_window_;
+  }
+}
+
+void NativeViewHostAura::UpdateClippingWindow() {
+  if (!installed_clip_)
+    clip_rect_ = orig_bounds_;
+
+  clipping_window_->SetBounds(clip_rect_);
+
+  gfx::Rect native_view_bounds = orig_bounds_;
+  native_view_bounds.Offset(-clip_rect_.x(), -clip_rect_.y());
+  host_->native_view()->SetBounds(native_view_bounds);
+}
+
 }  // namespace views