Implements AeroPeek of Windows 7..

chrome/browser/aeropeek_manager.h

+// Copyright (c) 2010 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 CHROME_BROWSER_AEROPEEK_MANAGER_H_
+#define CHROME_BROWSER_AEROPEEK_MANAGER_H_
+
+#include <list>
+
+#include "app/gfx/insets.h"
+#include "base/waitable_event.h"
+#include "chrome/browser/tabs/tab_strip_model.h"
+
+namespace gfx {
+class Size;
+}
+class TabContents;
+class AeroPeekWindow;
+class SkBitmap;
+
+// A class which defines interfaces called from AeroPeekWindow.
+// This class is used for dispatching an event received by a thumbnail window
+// and for retrieving information from Chrome.
+// An AeroPeek window receives the following events:
+// * A user clicks an AeroPeek thumbnail.
+//   We need to select a tab associated with this window.
+// * A user closes an AeroPeek thumbnail.
+//   We need to close a tab associated with this window.
+// * A user clicks a toolbar button in an AeroPeek window.
+//   We may need to dispatch this button event to a tab associated with this
+//   thumbnail window.
+//   <http://msdn.microsoft.com/en-us/library/dd378460(VS.85).aspx#thumbbars>.
+// Also, it needs the following information of the browser:
+// * The bitmap of a tab associated with this window.
+//   This bitmap is used for creating thumbnail and preview images.
+// * The rectangle of a browser frame.
+//   This rectangle is used for pasting the above bitmap to the right position
+//   and for marking the tab-content area as opaque.
+// We assume these functions are called only from a UI thread (i.e.
+// Chrome_BrowserMain).
+class AeroPeekWindowDelegate {
+ public:
+  virtual void ActivateTab(int tab_id) = 0;
+  virtual void CloseTab(int tab_id) = 0;
+  virtual void GetContentInsets(gfx::Insets* insets) = 0;
+  virtual bool GetTabThumbnail(int tab_id, SkBitmap* thumbnail) = 0;
+  virtual bool GetTabPreview(int tab_id, SkBitmap* preview) = 0;
+};
+
+// A class that implements AeroPeek of Windows 7:
+// <http://msdn.microsoft.com/en-us/library/dd378460(VS.85).aspx#thumbnails>.
+// Windows 7 can dispay a thumbnail image of each tab to its taskbar so that
+// a user can preview the contents of a tab (AeroPeek), choose a tab, close
+// a tab, etc.
+// This class implements the TabStripModelObserver interface to receive the
+// following events sent from TabStripModel and dispatch them to Windows:
+// * A tab is added.
+//   This class adds a thumbnail window for this tab to the thumbnail list
+//   of Windows.
+// * A tab is being closed.
+//   This class deletes the thumbnail window associated with this tab from the
+//   thumbnail list of Windows.
+// * A tab has been updated.
+//   This class updates the image of the thumbnail window associated with this
+//   tab.
+// Also, this class receives events sent from Windows via thumbnail windows to
+// TabStripModel:
+// * A thumbnail window is closed.
+//   Ask TabStrip to close the tab associated with this thumbnail window.
+// * A thumbnail window is selected.
+//   Ask TabStrip to activate the tab associated with this thumbnail window.
+//
+// The simplest usage of this class is:
+// 1. Create an instance of TabThumbnailManager.
+// 2. Add this instance to the observer list of a TabStrip object.
+//
+//      scoped_ptr<TabThumbnailManager> manager;
+//      manager.reset(new TabThumbnailManager(
+//          frame_->GetWindow()->GetNativeWindow(),
+//          border_left,
+//          border_top,
+//          toolbar_top));
+//      g_browser->tabstrip_model()->AddObserver(manager);
+//
+// 3. Remove this instance from the observer list of the TabStrip object when
+//    we don't need it.
+//
+//      g_browser->tabstrip_model()->RemoveObserver(manager);
+//
+class AeroPeekManager : public TabStripModelObserver,
+                        public AeroPeekWindowDelegate {
+ public:
+  explicit AeroPeekManager(HWND application_window);
+  ~AeroPeekManager();
+
+  // Sets the margins of the "user-perceived content area".
+  // (See comments of |content_insets_|).
+  void SetContentInsets(const gfx::Insets& insets);
+
+  // Returns whether or not we should enable Tab Thumbnailing and Aero Peek
+  // of Windows 7.
+  static bool Enabled();
+
+  // Overridden from TabStripModelObserver:
+  virtual void TabInsertedAt(TabContents* contents,
+                             int index,
+                             bool foreground);
+  virtual void TabClosingAt(TabContents* contents, int index);
+  virtual void TabDetachedAt(TabContents* contents, int index);
+  virtual void TabSelectedAt(TabContents* old_contents,
+                             TabContents* new_contents,
+                             int index,
+                             bool user_gesture);
+  virtual void TabMoved(TabContents* contents,
+                        int from_index,
+                        int to_index,
+                        bool pinned_state_changed);
+  virtual void TabChangedAt(TabContents* contents,
+                            int index,
+                            TabChangeType change_type);
+
+  // Overriden from TabThumbnailWindowDelegate:
+  virtual void CloseTab(int tab_id);
+  virtual void ActivateTab(int tab_id);
+  virtual void GetContentInsets(gfx::Insets* insets);
+  virtual bool GetTabThumbnail(int tab_id, SkBitmap* thumbnail);
+  virtual bool GetTabPreview(int tab_id, SkBitmap* preview);
+
+ private:
+  // Deletes the TabThumbnailWindow object associated with the specified
+  // Tab ID.
+  void DeleteAeroPeekWindow(int tab_id);
+
+  // Retrieves the AeroPeekWindow object associated with the specified
+  // Tab ID.
+  AeroPeekWindow* GetAeroPeekWindow(int tab_id) const;
+
+  // Returns a rectangle that fits into the destination rectangle and keeps
+  // the pixel-aspect ratio of the source one.
+  // (This function currently uses the longer-fit algorithm as IE8 does.)
+  void GetOutputBitmapSize(const gfx::Size& destination,
+                           const gfx::Size& source,
+                           gfx::Size* output) const;
+
+  // Returns the TabContents object associated with the specified Tab ID only
+  // if it is alive.
+  // Since Windows cannot send AeroPeek events directly to Chrome windows, we
+  // use a place-holder window to receive AeroPeek events. So, when Windows
+  // sends an AeroPeek event, the corresponding tab (and TabContents) may have
+  // been deleted by Chrome. To prevent us from accessing deleted TabContents,
+  // we need to check if the tab is still alive.
+  TabContents* GetTabContents(int tab_id) const;
+
+  // Returns the tab ID from the specified TabContents.
+  int GetTabID(TabContents* contents) const;
+
+ private:
+  // The parent window of the place-holder windows used by AeroPeek.
+  // In the case of Chrome, this window becomes a browser frame.
+  HWND application_window_;
+
+  // The list of the place-holder windows used by AeroPeek.
+  std::list<AeroPeekWindow*> tab_list_;
+
+  // The left and top borders of the frame window.
+  // When we create a preview bitmap, we use these values for preventing from
+  // over-writing the area of the browser frame.
+  int border_left_;
+  int border_top_;
+
+  // The top position of the toolbar.
+  // This value is used for setting the alpha values of the frame area so a
+  // preview image can use transparent colors only in the frame area.
+  int toolbar_top_;
+
+  // The margins of the "user-perceived content area".
+  // This value is used for pasting a tab image onto this "user-perceived
+  // content area" when creating a preview image.
+  gfx::Insets content_insets_;
+};
+
+#endif  // CHROME_BROWSER_AEROPEEK_MANAGER_H_