base/mac/scoped_sending_event.h

   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 BASE_MAC_SCOPED_SENDING_EVENT_H_
   6 #define BASE_MAC_SCOPED_SENDING_EVENT_H_
   7
   8 #include "base/base_export.h"
   9 #include "base/basictypes.h"
  10 #include "base/message_loop/message_pump_mac.h"
  11
  12 // Nested event loops can pump IPC messages, including
  13 // script-initiated tab closes, which could release objects that the
  14 // nested event loop might message.  CrAppProtocol defines how to ask
  15 // the embedding NSApplication subclass if an event is currently being
  16 // handled, in which case such closes are deferred to the top-level
  17 // event loop.
  18 //
  19 // ScopedSendingEvent allows script-initiated event loops to work like
  20 // a nested event loop, as such events do not arrive via -sendEvent:.
  21 // CrAppControlProtocol lets ScopedSendingEvent tell the embedding
  22 // NSApplication what to return from -handlingSendEvent.
  23
  24 @protocol CrAppControlProtocol<CrAppProtocol>
  25 - (void)setHandlingSendEvent:(BOOL)handlingSendEvent;
  26 @end
  27
  28 namespace base {
  29 namespace mac {
  30
  31 class BASE_EXPORT ScopedSendingEvent {
  32  public:
  33   ScopedSendingEvent();
  34   ~ScopedSendingEvent();
  35
  36  private:
  37   // The NSApp in control at the time the constructor was run, to be
  38   // sure the |handling_| setting is restored appropriately.
  39   NSObject<CrAppControlProtocol>* app_;
  40   BOOL handling_;  // Value of -[app_ handlingSendEvent] at construction.
  41
  42   DISALLOW_COPY_AND_ASSIGN(ScopedSendingEvent);
  43 };
  44
  45 }  // namespace mac
  46 }  // namespace base
  47
  48 #endif  // BASE_MAC_SCOPED_SENDING_EVENT_H_