Implement features in NativeViewHostAura for scroll end effect

ui/views/controls/native/native_view_host_aura.cc

 // 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.
 
 #include "ui/views/controls/native/native_view_host_aura.h"
 
 #include "base/logging.h"
 #include "ui/aura/focus_manager.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 {
 
 NativeViewHostAura::NativeViewHostAura(NativeViewHost* host)
     : host_(host),
-      installed_clip_(false) {
+      installed_clip_(false),
+      clipping_window_(NULL) {
+  clipping_window_.SetTransparent(true);
+  clipping_window_.Init(ui::LAYER_NOT_DRAWN);
+  clipping_window_.set_owned_by_parent(false);
+  clipping_window_.layer()->set_name("NativeViewHostAuraClip");
+  clipping_window_.layer()->SetMasksToBounds(false);
 }
 
 NativeViewHostAura::~NativeViewHostAura() {
   if (host_->native_view()) {
     host_->native_view()->ClearProperty(views::kHostViewKey);
     host_->native_view()->RemoveObserver(this);
+    RemoveClippingWindow();
   }
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // NativeViewHostAura, NativeViewHostWrapper implementation:
-void NativeViewHostAura::NativeViewWillAttach() {
+void NativeViewHostAura::AttachNativeView() {
   host_->native_view()->AddObserver(this);
   host_->native_view()->SetProperty(views::kHostViewKey,
       static_cast<View*>(host_));
+  AddClippingWindow();
 }
 
 void NativeViewHostAura::NativeViewDetaching(bool destroyed) {
   if (!destroyed) {
+    RemoveClippingWindow();
     host_->native_view()->ClearProperty(views::kHostViewKey);
     host_->native_view()->RemoveObserver(this);
     host_->native_view()->Hide();
     if (host_->native_view()->parent())
       Widget::ReparentNativeView(host_->native_view(), NULL);
+  } else {
+    clipping_window_.Hide();
+    if (clipping_window_.parent())
+      clipping_window_.parent()->RemoveChild(&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());
+  if (host_->native_view()->parent() !=  host_->GetWidget()->GetNativeView())
+    AddClippingWindow();
+
   if (host_->IsDrawn())
     host_->native_view()->Show();
   else
     host_->native_view()->Hide();
   host_->Layout();
 }
 
 void NativeViewHostAura::RemovedFromWidget() {
   if (host_->native_view()) {
     host_->native_view()->Hide();
+    RemoveClippingWindow();
     if (host_->native_view()->parent())
       host_->native_view()->parent()->RemoveChild(host_->native_view());
   }
 }
 
 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_.origin().x(),
+                         y + orig_bounds_.origin().y(),
+                         w,
+                         h);
+  UpdateClippingWindow();
+  clipping_window_.layer()->SetMasksToBounds(true);
 }
 
 bool NativeViewHostAura::HasInstalledClip() {
   return installed_clip_;
 }
 
 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()) {
+    UninstallClip();
+    InstallClip(x - orig_bounds_.origin().x(),
+                y - orig_bounds_.origin().y(),
+                w,
+                h);
+  } else {
+    clip_rect_.Offset(x - orig_bounds_.origin().x(),
+                      y - orig_bounds_.origin().y());
+    orig_bounds_ = gfx::Rect(x, y, w, h);
+    UpdateClippingWindow();
+  }
   host_->native_view()->Show();
 }
 
 void NativeViewHostAura::HideWidget() {
   host_->native_view()->Hide();
 }
 
 void NativeViewHostAura::SetFocus() {
   aura::Window* window = host_->native_view();
   aura::client::FocusClient* client = aura::client::GetFocusClient(window);
   if (client)
     client->FocusWindow(window);
 }
 
 gfx::NativeViewAccessible NativeViewHostAura::GetNativeViewAccessible() {
   return NULL;
 }
 
 void NativeViewHostAura::OnWindowDestroyed(aura::Window* window) {
   DCHECK(window == host_->native_view());
   host_->NativeViewDestroyed();
 }
 
 // static
 NativeViewHostWrapper* NativeViewHostWrapper::CreateWrapper(
     NativeViewHost* host) {
   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() {
+  gfx::Rect bounds = host_->native_view()->bounds();
+  orig_bounds_ = bounds;
+
+  if (host_->GetWidget()->GetNativeView()) {
+    Widget::ReparentNativeView(&clipping_window_,
+                               host_->GetWidget()->GetNativeView());
+  }
+  Widget::ReparentNativeView(host_->native_view(),
+                             &clipping_window_);
+
+  clipping_window_.SetBounds(bounds);
+  bounds.set_origin(gfx::Point(0, 0));
+  host_->native_view()->SetBounds(bounds);
+  clipping_window_.Show();
+}
+
+void NativeViewHostAura::RemoveClippingWindow() {
+  if (host_->native_view()->parent() == &clipping_window_) {
+    if (host_->GetWidget()->GetNativeView()) {
+      Widget::ReparentNativeView(host_->native_view(),
+                                 host_->GetWidget()->GetNativeView());
+    } else {
+      clipping_window_.RemoveChild(host_->native_view());
+    }
+    host_->native_view()->SetBounds(clipping_window_.bounds());
+  }
+  clipping_window_.Hide();
+  if (clipping_window_.parent())
+    clipping_window_.parent()->RemoveChild(&clipping_window_);
+}
+
+void NativeViewHostAura::UpdateClippingWindow() {
+  if (installed_clip_) {
+    clipping_window_.SetBounds(clip_rect_);
+    gfx::Rect native_view_bounds = host_->native_view()->bounds();
+    gfx::Point native_view_origin =
+        CalculateNativeViewOrigin(clipping_window_.bounds(),
+                                  native_view_bounds);
+
+    native_view_bounds.set_origin(native_view_origin);
+    host_->native_view()->SetBounds(native_view_bounds);
+  } else {
+    clip_rect_ = orig_bounds_;
+    clipping_window_.SetBounds(orig_bounds_);
+    host_->native_view()->SetBounds(gfx::Rect(orig_bounds_.size()));
+  }
+}
+
 }  // namespace views