aura: Draw drop shadows under browsers and menus.

ui/aura_shell/shadow_controller.h

+// Copyright (c) 2011 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 UI_AURA_SHELL_SHADOW_CONTROLLER_H_
+#define UI_AURA_SHELL_SHADOW_CONTROLLER_H_
+#pragma once
+
+#include <map>
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "base/memory/linked_ptr.h"
+#include "ui/aura/desktop_observer.h"
+#include "ui/aura/window_observer.h"
+
+namespace aura {
+class Window;
+}
+namespace gfx {
+class Rect;
+}
+
+namespace aura_shell {
+namespace internal {
+
+class Shadow;
+
+// ShadowController observes changes to windows and creates and updates drop
+// shadows as needed.
+class ShadowController : public aura::DesktopObserver,
+                         public aura::WindowObserver {
+public:
+  class TestApi {
+   public:
+    explicit TestApi(ShadowController* controller) : controller_(controller) {}
+    ~TestApi() {}
+
+    Shadow* GetShadowForWindow(aura::Window* window) {
+      return controller_->GetShadowForWindow(window);
+    }
+
+   private:
+    ShadowController* controller_;  // not owned
+
+    DISALLOW_COPY_AND_ASSIGN(TestApi);
+  };
+
+  explicit ShadowController();
+  virtual ~ShadowController();
+
+  // aura::DesktopObserver override:
+  virtual void OnWindowInitialized(aura::Window* window) OVERRIDE;
+
+  // aura::WindowObserver overrides:
+  virtual void OnWindowParentChanged(
+      aura::Window* window, aura::Window* parent) OVERRIDE;
+  virtual void OnPropertyChanged(
+      aura::Window* window, const char* name, void* old) OVERRIDE;
+  virtual void OnWindowVisibilityChanged(
+      aura::Window* window, bool visible) OVERRIDE;
+  virtual void OnWindowBoundsChanged(
+      aura::Window* window, const gfx::Rect& bounds) OVERRIDE;
+  virtual void OnWindowStackingChanged(aura::Window* window) OVERRIDE;
+  virtual void OnWindowDestroyed(aura::Window* window) OVERRIDE;
+
+ private:
+  typedef std::map<aura::Window*, linked_ptr<Shadow> > WindowShadowMap;
+
+  // Checks if |window| is visible and contains a property requesting a shadow.
+  bool ShouldShowShadowForWindow(aura::Window* window) const;
+
+  // Returns |window|'s shadow from |window_shadows_|, or NULL if no shadow
+  // exists.
+  Shadow* GetShadowForWindow(aura::Window* window);
+
+  // Shows or hides |window|'s shadow as needed (creating the shadow if
+  // necessary).
+  void HandlePossibleShadowVisibilityChange(aura::Window* window);
+
+  // Creates a new shadow for |window| and stores it in |window_shadows_|.  The
+  // shadow's visibility, bounds, and stacking are initialized appropriately.
+  void CreateShadowForWindow(aura::Window* window);
+
+  // Stacks |shadow|'s layer directly beneath |window|'s layer.
+  void StackShadowBelowWindow(Shadow* shadow, aura::Window* window);
+
+  WindowShadowMap window_shadows_;
+
+  DISALLOW_COPY_AND_ASSIGN(ShadowController);
+};
+
+}  // namepsace aura_shell
+}  // namepsace internal
+
+#endif  // UI_AURA_SHELL_SHADOW_CONTROLLER_H_