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      1 // Copyright (c) 2011 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 CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_
      6 #define CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_
      7 
      8 #import <AppKit/AppKit.h>
      9 
     10 #include "base/memory/scoped_nsobject.h"
     11 
     12 @class CrTrackingAreaOwnerProxy;
     13 
     14 // The CrTrackingArea can be used in place of an NSTrackingArea to shut off
     15 // messaging to the |owner| at a specific point in time.
     16 @interface CrTrackingArea : NSTrackingArea {
     17  @private
     18   scoped_nsobject<CrTrackingAreaOwnerProxy> ownerProxy_;
     19 }
     20 
     21 // Designated initializer. Forwards all arguments to the superclass, but wraps
     22 // |owner| in a proxy object.
     23 //
     24 // The |proxiedOwner:| paramater has been renamed due to an incompatiblity with
     25 // the 10.5 SDK. Since that SDK version declares |-[NSTrackingArea's init...]|'s
     26 // return type to be |NSTrackingArea*| rather than |id|, a more generalized type
     27 // can't be returned by the subclass. Until the project switches to the 10.6 SDK
     28 // (where Apple changed the return type to |id|), this ugly hack must exist.
     29 // TODO(rsesek): Remove this when feasabile.
     30 - (id)initWithRect:(NSRect)rect
     31            options:(NSTrackingAreaOptions)options
     32       proxiedOwner:(id)owner  // 10.5 SDK hack. Remove at some point.
     33           userInfo:(NSDictionary*)userInfo;
     34 
     35 // Prevents any future messages from being delivered to the |owner|.
     36 - (void)clearOwner;
     37 
     38 // Watches |window| for its NSWindowWillCloseNotification and calls
     39 // |-clearOwner| when the notification is observed.
     40 - (void)clearOwnerWhenWindowWillClose:(NSWindow*)window;
     41 
     42 @end
     43 
     44 // Scoper //////////////////////////////////////////////////////////////////////
     45 
     46 // Use an instance of this class to call |-clearOwner| on the |tracking_area_|
     47 // when this goes out of scope.
     48 class ScopedCrTrackingArea {
     49  public:
     50   // Takes ownership of |tracking_area| without retaining it.
     51   explicit ScopedCrTrackingArea(CrTrackingArea* tracking_area = nil);
     52   ~ScopedCrTrackingArea();
     53 
     54   // This will call |scoped_nsobject<>::reset()| to take ownership of the new
     55   // tracking area.  Note that -clearOwner is NOT called on the existing
     56   // tracking area.
     57   void reset(CrTrackingArea* tracking_area = nil);
     58 
     59   CrTrackingArea* get() const;
     60 
     61  private:
     62   scoped_nsobject<CrTrackingArea> tracking_area_;
     63   DISALLOW_COPY_AND_ASSIGN(ScopedCrTrackingArea);
     64 };
     65 
     66 #endif  // CHROME_BROWSER_UI_COCOA_TRACKING_AREA_H_
     67