While dragging a window, show a semi-transparent aura window instead of the standard gray phantom wi

ash/wm/workspace/phantom_window_controller.h

 // 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.
 
 #ifndef ASH_WM_WORKSPACE_PHANTOM_WINDOW_CONTROLLER_H_
 #define ASH_WM_WORKSPACE_PHANTOM_WINDOW_CONTROLLER_H_
 
 #include "ash/ash_export.h"
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/animation/animation_delegate.h"
+#include "ui/gfx/display.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 class Window;
+class RootWindow;
 }
 
 namespace ui {
 class SlideAnimation;
 }
 
 namespace views {
 class Widget;
 }
 
 namespace ash {
 namespace internal {
 
 // PhantomWindowController is responsible for showing a phantom representation
 // of a window. It's used used during dragging a window to show a snap location.
 class ASH_EXPORT PhantomWindowController : public ui::AnimationDelegate {
  public:
-  explicit PhantomWindowController(aura::Window* window);
+  enum Style {
+    STYLE_SHADOW,  // for window snapping.
+    STYLE_WINDOW,  // for window dragging.
+  };
+
+  PhantomWindowController(aura::Window* window,
+                          aura::RootWindow* root_window,
+                          Style style);
   virtual ~PhantomWindowController();
 
   // Bounds last passed to Show().
   const gfx::Rect& bounds() const { return bounds_; }
 
   // Shows the phantom window at the specified location (coordinates of the
   // parent). This does not immediately show the window.
   void Show(const gfx::Rect& bounds);
 
   // This is used to set bounds for the phantom window immediately. This should
   // be called only when the phantom window is already visible.
   void SetBounds(const gfx::Rect& bounds);
 
   // Hides the phantom.
   void Hide();
 
   // Returns true if the phantom is showing.
   bool IsShowing() const;
 
   // If set, the phantom window is stacked below this window, otherwise it
   // is stacked above the window passed to the constructor.
   void set_phantom_below_window(aura::Window* phantom_below_window) {
     phantom_below_window_ = phantom_below_window;
   }
 
+  Style style() const {
+    return style_;
+  }
+
+  // Sets/gets the opacity of the phantom window.
+  void SetOpacity(float opacity);
+  float GetOpacity() const;
+
   // ui::AnimationDelegate overrides:
   virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE;
 
  private:
   // Creates and shows the |phantom_widget_| at |bounds|.
   void CreatePhantomWidget(const gfx::Rect& bounds);
 
+  // Sets bounds of the phantom window. The window is shown on |dst_display_|
+  // if its id() is valid. Otherwise, a display nearest to |bounds| is chosen.
+  void SetBoundsInternal(const gfx::Rect& bounds);
+
   // Window the phantom is placed beneath.
   aura::Window* window_;
 
+  // The display where the phantom is placed. When dst_display_.id() is -1, a
+  // display nearest to the current |bounds_| is automatically used.
+  gfx::Display dst_display_;
+
   // If set, the phantom window should get stacked below this window.
   aura::Window* phantom_below_window_;
 
   // Initially the bounds of |window_|. Each time Show() is invoked
   // |start_bounds_| is then reset to the bounds of |phantom_widget_| and
   // |bounds_| is set to the value passed into Show(). The animation animates
   // between these two values.
   gfx::Rect start_bounds_;
   gfx::Rect bounds_;
 
   views::Widget* phantom_widget_;
 
   // Used to transition the bounds.
   scoped_ptr<ui::SlideAnimation> animation_;
 
+  // The style of the phantom window.
+  Style style_;
+
   DISALLOW_COPY_AND_ASSIGN(PhantomWindowController);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_PHANTOM_WINDOW_CONTROLLER_H_