ui/base/cocoa/tracking_area.mm

   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 #import "ui/base/cocoa/tracking_area.h"
   6
   7 #include "base/logging.h"
   8
   9 // NSTrackingArea does not retain its |owner| so CrTrackingArea wraps the real
  10 // owner in this proxy, which can stop forwarding messages to the owner when
  11 // it is no longer |alive_|.
  12 @interface CrTrackingAreaOwnerProxy : NSObject {
  13  @private
  14   // Whether or not the owner is "alive" and should forward calls to the real
  15   // owner object.
  16   BOOL alive_;
  17
  18   // The real object for which this is a proxy. Weak.
  19   id owner_;
  20
  21   // The Class of |owner_|. When the actual object is no longer alive (and could
  22   // be zombie), this allows for introspection.
  23   Class ownerClass_;
  24 }
  25 @property(nonatomic, assign) BOOL alive;
  26 - (id)initWithOwner:(id)owner;
  27 @end
  28
  29 @implementation CrTrackingAreaOwnerProxy
  30
  31 @synthesize alive = alive_;
  32
  33 - (id)initWithOwner:(id)owner {
  34   if ((self = [super init])) {
  35     alive_ = YES;
  36     owner_ = owner;
  37     ownerClass_ = [owner class];
  38   }
  39   return self;
  40 }
  41
  42 - (void)forwardInvocation:(NSInvocation*)invocation {
  43   if (!alive_)
  44     return;
  45   [invocation invokeWithTarget:owner_];
  46 }
  47
  48 - (NSMethodSignature*)methodSignatureForSelector:(SEL)sel {
  49   // This can be called if |owner_| is not |alive_|, so use the Class to
  50   // generate the signature. |-forwardInvocation:| will block the actual call.
  51   return [ownerClass_ instanceMethodSignatureForSelector:sel];
  52 }
  53
  54 - (BOOL)respondsToSelector:(SEL)aSelector {
  55   return [ownerClass_ instancesRespondToSelector:aSelector];
  56 }
  57
  58 @end
  59
  60 // Private Interface ///////////////////////////////////////////////////////////
  61
  62 @interface CrTrackingArea (Private)
  63 - (void)windowWillClose:(NSNotification*)notif;
  64 @end
  65
  66 ////////////////////////////////////////////////////////////////////////////////
  67
  68 @implementation CrTrackingArea
  69
  70 - (id)initWithRect:(NSRect)rect
  71                         options:(NSTrackingAreaOptions)options
  72                           owner:(id)owner
  73                        userInfo:(NSDictionary*)userInfo {
  74   base::scoped_nsobject<CrTrackingAreaOwnerProxy> ownerProxy(
  75       [[CrTrackingAreaOwnerProxy alloc] initWithOwner:owner]);
  76   if ((self = [super initWithRect:rect
  77                           options:options
  78                             owner:ownerProxy.get()
  79                          userInfo:userInfo])) {
  80     ownerProxy_.swap(ownerProxy);
  81   }
  82   return self;
  83 }
  84
  85 - (void)dealloc {
  86   [self clearOwner];
  87   [[NSNotificationCenter defaultCenter] removeObserver:self];
  88   [super dealloc];
  89 }
  90
  91 - (void)clearOwner {
  92   [ownerProxy_ setAlive:NO];
  93 }
  94
  95 - (void)clearOwnerWhenWindowWillClose:(NSWindow*)window {
  96   DCHECK(window);
  97   NSNotificationCenter* center = [NSNotificationCenter defaultCenter];
  98   [center addObserver:self
  99              selector:@selector(windowWillClose:)
 100                  name:NSWindowWillCloseNotification
 101                object:window];
 102 }
 103
 104 - (void)windowWillClose:(NSNotification*)notif {
 105   [self clearOwner];
 106 }
 107
 108 @end
 109
 110 // Scoper //////////////////////////////////////////////////////////////////////
 111
 112 namespace ui {
 113
 114 ScopedCrTrackingArea::ScopedCrTrackingArea(CrTrackingArea* tracking_area)
 115     : tracking_area_(tracking_area) {
 116 }
 117
 118 ScopedCrTrackingArea::~ScopedCrTrackingArea() {
 119   [tracking_area_ clearOwner];
 120 }
 121
 122 void ScopedCrTrackingArea::reset(CrTrackingArea* tracking_area) {
 123   tracking_area_.reset(tracking_area);
 124 }
 125
 126 CrTrackingArea* ScopedCrTrackingArea::get() const {
 127   return tracking_area_.get();
 128 }
 129
 130 }  // namespace ui