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_MESSAGE_LOOP_MESSAGE_PUMP_OBSERVER_H 6 #define BASE_MESSAGE_LOOP_MESSAGE_PUMP_OBSERVER_H 7 8 #include "base/base_export.h" 9 #include "base/event_types.h" 10 11 namespace base { 12 13 enum EventStatus { 14 EVENT_CONTINUE, // The event should be dispatched as normal. 15 #if defined(USE_X11) 16 EVENT_HANDLED // The event should not be processed any farther. 17 #endif 18 }; 19 20 // A MessagePumpObserver is an object that receives global 21 // notifications from the UI MessageLoop with MessagePumpWin or 22 // MessagePumpX11. 23 // 24 // NOTE: An Observer implementation should be extremely fast! 25 // 26 // For use with MessagePumpX11, please see message_pump_glib.h for more 27 // info about how this is invoked in this environment. 28 class BASE_EXPORT MessagePumpObserver { 29 public: 30 // This method is called before processing a NativeEvent. If the 31 // method returns EVENT_HANDLED, it indicates the event has already 32 // been handled, so the event is not processed any farther. If the 33 // method returns EVENT_CONTINUE, the event dispatching proceeds as 34 // normal. 35 virtual EventStatus WillProcessEvent(const NativeEvent& event) = 0; 36 37 // This method is called after processing a message. This method 38 // will not be called if WillProcessEvent returns EVENT_HANDLED. 39 virtual void DidProcessEvent(const NativeEvent& event) = 0; 40 41 protected: ~MessagePumpObserver()42 virtual ~MessagePumpObserver() {} 43 }; 44 45 } // namespace base 46 47 #endif // BASE_MESSAGE_LOOP_MESSAGE_PUMP_OBSERVER_H 48