Extract the code of showing a dragging window on another display from PhantomWindowController.

ash/wm/drag_window_controller.cc

Index: ash/wm/drag_window_controller.cc
diff --git a/ash/wm/drag_window_controller.cc b/ash/wm/drag_window_controller.cc
new file mode 100644
index 0000000000000000000000000000000000000000..85e2cb449887233b53df385c0a66fb2ad3190cab
--- /dev/null
+++ b/ash/wm/drag_window_controller.cc
@@ -0,0 +1,125 @@
+// 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 "ash/wm/drag_window_controller.h"
+
+#include "ash/shell_window_ids.h"
+#include "ash/wm/window_util.h"
+#include "ui/aura/client/screen_position_client.h"
+#include "ui/aura/window.h"
+#include "ui/compositor/layer.h"
+#include "ui/compositor/scoped_layer_animation_settings.h"
+#include "ui/views/corewm/shadow_types.h"
+#include "ui/views/corewm/window_util.h"
+#include "ui/views/view.h"
+#include "ui/views/widget/widget.h"
+
+namespace ash {
+namespace internal {
+
+DragWindowController::DragWindowController(aura::Window* window)
+    : window_(window),
+      drag_widget_(NULL),
+      layer_(NULL) {
+}
+
+DragWindowController::~DragWindowController() {
+  Hide();
+}
+
+void DragWindowController::SetDestinationDisplay(
+    const gfx::Display& dst_display) {
+  dst_display_ = dst_display;
+}
+
+void DragWindowController::Show() {
+  if (!drag_widget_)
+    CreateDragWidget(window_->GetBoundsInScreen());
+  drag_widget_->Show();
+}
+
+void DragWindowController::SetBounds(const gfx::Rect& bounds) {
+  DCHECK(drag_widget_);
+  bounds_ = bounds;
+  SetBoundsInternal(bounds);
+}
+
+void DragWindowController::Hide() {
+  if (drag_widget_) {
+    drag_widget_->Close();
+    drag_widget_ = NULL;
+  }
+  if (layer_) {
+    views::corewm::DeepDeleteLayers(layer_);
+    layer_ = NULL;
+  }
+}
+
+void DragWindowController::SetOpacity(float opacity) {
+  DCHECK(drag_widget_);
+  ui::Layer* layer = drag_widget_->GetNativeWindow()->layer();
+  ui::ScopedLayerAnimationSettings scoped_setter(layer->GetAnimator());
+  layer->SetOpacity(opacity);
+}
+
+void DragWindowController::CreateDragWidget(const gfx::Rect& bounds) {
+  DCHECK(!drag_widget_);
+  drag_widget_ = new views::Widget;
+  views::Widget::InitParams params(views::Widget::InitParams::TYPE_POPUP);
+  params.transparent = true;
+  params.parent = window_->parent();
+  params.can_activate = false;
+  params.keep_on_top = true;
+  drag_widget_->set_focus_on_creation(false);
+  drag_widget_->Init(params);
+  drag_widget_->SetVisibilityChangedAnimationsEnabled(false);
+  drag_widget_->GetNativeWindow()->SetName("DragWindow");
+  drag_widget_->GetNativeWindow()->set_id(kShellWindowId_PhantomWindow);
+  // Show shadow for the dragging window.
+  SetShadowType(drag_widget_->GetNativeWindow(),
+                views::corewm::SHADOW_TYPE_RECTANGULAR);
+  SetBoundsInternal(bounds);
+  drag_widget_->StackAbove(window_);
+
+  RecreateWindowLayers();
+  aura::Window* window = drag_widget_->GetNativeWindow();
+  layer_->SetVisible(true);
+  window->layer()->Add(layer_);
+  window->layer()->StackAtTop(layer_);
+
+  // Show the widget after all the setups.
+  drag_widget_->Show();
+
+  // Fade the window in.
+  ui::Layer* widget_layer = drag_widget_->GetNativeWindow()->layer();
+  widget_layer->SetOpacity(0);
+  ui::ScopedLayerAnimationSettings scoped_setter(widget_layer->GetAnimator());
+  widget_layer->SetOpacity(1);
+}
+
+void DragWindowController::SetBoundsInternal(const gfx::Rect& bounds) {
+  aura::Window* window = drag_widget_->GetNativeWindow();
+  aura::client::ScreenPositionClient* screen_position_client =
+      aura::client::GetScreenPositionClient(window->GetRootWindow());
+  if (screen_position_client && dst_display_.is_valid())
+    screen_position_client->SetBounds(window, bounds, dst_display_);
+  else
+    drag_widget_->SetBounds(bounds);
+}
+
+void DragWindowController::RecreateWindowLayers() {
+  DCHECK(!layer_);
+  layer_ = views::corewm::RecreateWindowLayers(window_, true);
+  layer_->set_delegate(window_->layer()->delegate());
+  // Place the layer at (0, 0) of the DragWindowController's window.
+  gfx::Rect layer_bounds = layer_->bounds();
+  layer_bounds.set_origin(gfx::Point(0, 0));
+  layer_->SetBounds(layer_bounds);
+  layer_->SetVisible(false);
+  // Detach it from the current container.
+  layer_->parent()->Remove(layer_);
+}
+
+}  // namespace internal
+}  // namespace ash