Extract the code for supporing extended desktop from WorkspaceWindowResizer into DragWindowResizer.

ash/wm/drag_window_resizer.cc

Index: ash/wm/drag_window_resizer.cc
diff --git a/ash/wm/drag_window_resizer.cc b/ash/wm/drag_window_resizer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..2b85f814a4d7b1264c194c81e0e9a72b4439b768
--- /dev/null
+++ b/ash/wm/drag_window_resizer.cc
@@ -0,0 +1,185 @@
+// 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_resizer.h"
+
+#include "ash/display/mouse_cursor_event_filter.h"
+#include "ash/screen_ash.h"
+#include "ash/shell.h"
+#include "ash/wm/coordinate_conversion.h"
+#include "ash/wm/cursor_manager.h"
+#include "ash/wm/drag_window_controller.h"
+#include "ash/wm/property_util.h"
+#include "ui/aura/client/aura_constants.h"
+#include "ui/aura/env.h"
+#include "ui/aura/root_window.h"
+#include "ui/aura/window.h"
+#include "ui/aura/window_delegate.h"
+#include "ui/base/hit_test.h"
+#include "ui/base/ui_base_types.h"
+#include "ui/gfx/screen.h"
+
+namespace ash {
+namespace internal {
+
+namespace {
+
+// The maximum opacity of the drag phantom window.
+const float kMaxOpacity = 0.8f;
+
+// Returns true if Ash has more than one root window.
+bool HasSecondaryRootWindow() {
+  return Shell::GetAllRootWindows().size() > 1;
+}
+
+// When there are two root windows, returns one of the root windows which is not
+// |root_window|. Returns NULL if only one root window exists.
+aura::RootWindow* GetAnotherRootWindow(aura::RootWindow* root_window) {
+  Shell::RootWindowList root_windows = Shell::GetAllRootWindows();
+  if (root_windows.size() < 2)
+    return NULL;
+  DCHECK_EQ(2U, root_windows.size());
+  if (root_windows[0] == root_window)
+    return root_windows[1];
+  return root_windows[0];
+}
+
+}
+
+DragWindowResizer::DragWindowResizer(WindowResizer* window_resizer,
+                                     const Details& details)
+    : window_resizer_(window_resizer),
+      details_(details),
+      destroyed_(NULL) {
+  // The pointer should be confined in one display during resizing a window
+  // because the window cannot span two displays at the same time anyway. The
+  // exception is window/tab dragging operation. During that operation,
+  // |mouse_warp_mode_| should be set to WARP_DRAG so that the user could move a
+  // window/tab to another display.
+  MouseCursorEventFilter* mouse_cursor_filter =
+      Shell::GetInstance()->mouse_cursor_filter();
+  mouse_cursor_filter->set_mouse_warp_mode(
+      ShouldAllowMouseWarp() ?
+      MouseCursorEventFilter::WARP_DRAG : MouseCursorEventFilter::WARP_NONE);
+  if (ShouldAllowMouseWarp()) {
+    mouse_cursor_filter->ShowSharedEdgeIndicator(
+        details.window->GetRootWindow());
+  }
+}
+
+DragWindowResizer::~DragWindowResizer() {
+  Shell* shell = Shell::GetInstance();
+  shell->mouse_cursor_filter()->set_mouse_warp_mode(
+      MouseCursorEventFilter::WARP_ALWAYS);
+  shell->mouse_cursor_filter()->HideSharedEdgeIndicator();
+
+  if (destroyed_)
+    *destroyed_ = true;
+}
+
+void DragWindowResizer::Drag(const gfx::Point& location, int event_flags) {
+  bool destroyed = false;
+  destroyed_ = &destroyed;
+  window_resizer_->Drag(location, event_flags);
+  if (destroyed)
+    return;
+  last_mouse_location_ = location;
+
+  // Show a phantom window for dragging in another root window.
+  if (HasSecondaryRootWindow()) {
+    gfx::Point location_in_screen = location;
+    wm::ConvertPointToScreen(GetTarget()->parent(), &location_in_screen);
+    const bool in_original_root =
+        wm::GetRootWindowAt(location_in_screen) == GetTarget()->GetRootWindow();
+    UpdateDragWindow(GetTarget()->bounds(), in_original_root);
+  } else {
+    drag_window_controller_.reset();
+  }
+}
+
+void DragWindowResizer::CompleteDrag(int event_flags) {
+  window_resizer_->CompleteDrag(event_flags);
+
+  GetTarget()->layer()->SetOpacity(details_.initial_opacity);
+  drag_window_controller_.reset();
+
+  // Check if the destination is another display.
+  gfx::Point last_mouse_location_in_screen = last_mouse_location_;
+  wm::ConvertPointToScreen(GetTarget()->parent(),
+                           &last_mouse_location_in_screen);
+  gfx::Screen* screen = Shell::GetScreen();
+  const gfx::Display dst_display =
+      screen->GetDisplayNearestPoint(last_mouse_location_in_screen);
+
+  if (dst_display.id() !=
+      screen->GetDisplayNearestWindow(GetTarget()->GetRootWindow()).id()) {
+    const gfx::Rect dst_bounds =
+        ScreenAsh::ConvertRectToScreen(GetTarget()->parent(),
+                                       GetTarget()->bounds());
+    GetTarget()->SetBoundsInScreen(dst_bounds, dst_display);
+  }
+}
+
+void DragWindowResizer::RevertDrag() {
+  window_resizer_->RevertDrag();
+
+  drag_window_controller_.reset();
+  GetTarget()->layer()->SetOpacity(details_.initial_opacity);
+}
+
+aura::Window* DragWindowResizer::GetTarget() {
+  return window_resizer_->GetTarget();
+}
+
+void DragWindowResizer::UpdateDragWindow(const gfx::Rect& bounds,
+                                         bool in_original_root) {
+  if (details_.window_component != HTCAPTION || !ShouldAllowMouseWarp())
+    return;
+
+  // It's available. Show a phantom window on the display if needed.
+  aura::RootWindow* another_root =
+      GetAnotherRootWindow(GetTarget()->GetRootWindow());
+  const gfx::Rect root_bounds_in_screen(another_root->GetBoundsInScreen());
+  const gfx::Rect bounds_in_screen =
+      ScreenAsh::ConvertRectToScreen(GetTarget()->parent(), bounds);
+  gfx::Rect bounds_in_another_root =
+      gfx::IntersectRects(root_bounds_in_screen, bounds_in_screen);
+  const float fraction_in_another_window =
+      (bounds_in_another_root.width() * bounds_in_another_root.height()) /
+      static_cast<float>(bounds.width() * bounds.height());
+
+  if (fraction_in_another_window > 0) {
+    if (!drag_window_controller_.get()) {
+      drag_window_controller_.reset(
+          new DragWindowController(GetTarget()));
+      // Always show the drag phantom on the |another_root| window.
+      drag_window_controller_->SetDestinationDisplay(
+          Shell::GetScreen()->GetDisplayMatching(
+              another_root->GetBoundsInScreen()));
+      drag_window_controller_->Show();
+    } else {
+      // No animation.
+      drag_window_controller_->SetBounds(bounds_in_screen);
+    }
+    const float phantom_opacity =
+      !in_original_root ? 1 : (kMaxOpacity * fraction_in_another_window);
+    const float window_opacity =
+        in_original_root ? 1 : (kMaxOpacity * (1 - fraction_in_another_window));
+    drag_window_controller_->SetOpacity(phantom_opacity);
+    GetTarget()->layer()->SetOpacity(window_opacity);
+  } else {
+    drag_window_controller_.reset();
+    GetTarget()->layer()->SetOpacity(1.0f);
+  }
+}
+
+bool DragWindowResizer::ShouldAllowMouseWarp() {
+  return (details_.window_component == HTCAPTION) &&
+      (GetTarget()->GetProperty(aura::client::kModalKey) ==
+       ui::MODAL_TYPE_NONE) &&
+      (GetTarget()->type() == aura::client::WINDOW_TYPE_NORMAL);
+}
+
+}  // namespace internal
+}  // namespace ash