base/message_loop/message_pump_gtk.h

// Copyright (c) 2012 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 BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_
#define BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_

#include "base/message_loop/message_pump_glib.h"

typedef union _GdkEvent GdkEvent;
typedef struct _XDisplay Display;

namespace base {

// The documentation for this class is in message_pump_glib.h
class MessagePumpGdkObserver {
 public:
  // This method is called before processing a message.
  virtual void WillProcessEvent(GdkEvent* event) = 0;

  // This method is called after processing a message.
  virtual void DidProcessEvent(GdkEvent* event) = 0;

 protected:
  virtual ~MessagePumpGdkObserver() {}
};

// This class implements a message-pump for dispatching GTK events.
class BASE_EXPORT MessagePumpGtk : public MessagePumpGlib {
 public:
  MessagePumpGtk();
  virtual ~MessagePumpGtk();

  // Dispatch an available GdkEvent. Essentially this allows a subclass to do
  // some task before/after calling the default handler (EventDispatcher).
  void DispatchEvents(GdkEvent* event);

  // Returns default X Display.
  static Display* GetDefaultXDisplay();

  // Adds an Observer, which will start receiving notifications immediately.
  void AddObserver(MessagePumpGdkObserver* observer);

  // Removes an Observer.  It is safe to call this method while an Observer is
  // receiving a notification callback.
  void RemoveObserver(MessagePumpGdkObserver* observer);

 private:
  // Invoked from EventDispatcher. Notifies all observers we're about to
  // process an event.
  void WillProcessEvent(GdkEvent* event);

  // Invoked from EventDispatcher. Notifies all observers we processed an
  // event.
  void DidProcessEvent(GdkEvent* event);

  // Callback prior to gdk dispatching an event.
  static void EventDispatcher(GdkEvent* event, void* data);

  // List of observers.
  ObserverList<MessagePumpGdkObserver> observers_;

  DISALLOW_COPY_AND_ASSIGN(MessagePumpGtk);
};

typedef MessagePumpGtk MessagePumpForUI;

}  // namespace base

#endif  // BASE_MESSAGE_LOOP_MESSAGE_PUMP_GTK_H_