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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #ifndef UI_WM_CORE_SHADOW_H_
      6 #define UI_WM_CORE_SHADOW_H_
      7 
      8 #include "base/basictypes.h"
      9 #include "base/memory/scoped_ptr.h"
     10 #include "ui/compositor/layer_animation_observer.h"
     11 #include "ui/gfx/rect.h"
     12 #include "ui/wm/wm_export.h"
     13 
     14 namespace ui {
     15 class Layer;
     16 }  // namespace ui
     17 
     18 namespace wm {
     19 
     20 // Simple class that draws a drop shadow around content at given bounds.
     21 class WM_EXPORT Shadow : public ui::ImplicitAnimationObserver {
     22  public:
     23   enum Style {
     24     // Active windows have more opaque shadows, shifted down to make the window
     25     // appear "higher".
     26     STYLE_ACTIVE,
     27 
     28     // Inactive windows have less opaque shadows.
     29     STYLE_INACTIVE,
     30 
     31     // Small windows like tooltips and context menus have lighter, smaller
     32     // shadows.
     33     STYLE_SMALL,
     34   };
     35 
     36   Shadow();
     37   virtual ~Shadow();
     38 
     39   void Init(Style style);
     40 
     41   // Returns |layer_.get()|. This is exposed so it can be added to the same
     42   // layer as the content and stacked below it.  SetContentBounds() should be
     43   // used to adjust the shadow's size and position (rather than applying
     44   // transformations to this layer).
     45   ui::Layer* layer() const { return layer_.get(); }
     46 
     47   const gfx::Rect& content_bounds() const { return content_bounds_; }
     48   Style style() const { return style_; }
     49 
     50   // Moves and resizes the shadow layer to frame |content_bounds|.
     51   void SetContentBounds(const gfx::Rect& content_bounds);
     52 
     53   // Sets the shadow's style, animating opacity as necessary.
     54   void SetStyle(Style style);
     55 
     56   // ui::ImplicitAnimationObserver overrides:
     57   virtual void OnImplicitAnimationsCompleted() OVERRIDE;
     58 
     59  private:
     60   // Updates the shadow images to the current |style_|.
     61   void UpdateImagesForStyle();
     62 
     63   // Updates the shadow layer bounds based on the inteior inset and the current
     64   // |content_bounds_|.
     65   void UpdateLayerBounds();
     66 
     67   // The current style, set when the transition animation starts.
     68   Style style_;
     69 
     70   // The parent layer of the shadow layer. It serves as a container accessible
     71   // from the outside to control the visibility of the shadow.
     72   scoped_ptr<ui::Layer> layer_;
     73 
     74   // The actual shadow layer corresponding to a cc::NinePatchLayer.
     75   scoped_ptr<ui::Layer> shadow_layer_;
     76 
     77   // Size of the current shadow image.
     78   gfx::Size image_size_;
     79 
     80   // Bounds of the content that the shadow encloses.
     81   gfx::Rect content_bounds_;
     82 
     83   // The interior inset of the shadow images. The content bounds of the image
     84   // grid should be set to |content_bounds_| inset by this amount.
     85   int interior_inset_;
     86 
     87   DISALLOW_COPY_AND_ASSIGN(Shadow);
     88 };
     89 
     90 }  // namespace wm
     91 
     92 #endif  // UI_WM_CORE_SHADOW_H_
     93