wg_message_server.h

一个小巧的嵌入式图形系统wGUI, 可以用VC编译

// wg_message_server.h
//
// CMessageServer interface
//
//
// Copyright (c) 2002 Rob Wiskow
// [e-mail]
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
//


#ifndef _WG_MESSAGE_SERVER_H_
#define _WG_MESSAGE_SERVER_H_

#include "wg_message.h"
#include <deque>
#include <map>
#include "SDL.h"
#include "SDL_thread.h"


namespace wGui
{

class CMessageClient;

//! A pair that associates message client pointers with a priority
typedef std::pair<CMessageClient*, bool> t_MessageClientActivePair;

//! Multimap of message clients ordered by priority
typedef std::multimap<unsigned char, t_MessageClientActivePair, std::greater<unsigned char> > t_MessageClientPriorityMap;

//! Map of different message types
typedef std::map<wGui::CMessage::EMessageType, t_MessageClientPriorityMap> t_MessageClientMap;


//! A server which queues and dispatches messages

//! CMessageServer is a singeton (only one instance of it is allowed to exist at any time)
//! Clients must register to get messages sent to them
//! \sa CMessage CMessageClient

class CMessageServer
{
protected:
	//! The CMessageServer class cannot be directly instantiated, it must be access through Instance()
	CMessageServer(void);

	//! Standard constructor
	virtual ~CMessageServer(void);


public:
	//! Used for marking the priority of registered message clients, where the higher priority clients will get messages first
	enum EClientPriority
	{
		PRIORITY_LAST = 0,  //!< The absolute lowest priority available
		PRIORITY_LOW = 50,  //!< Low priority
		PRIORITY_NORMAL = 100,  //!< Standard priority
		PRIORITY_HIGH = 150,  //!< High priority
		PRIORITY_FIRST = 255  //!< The absolute highest priority available
	};

	//! \return The single valid instance of the message server, or create one if it doesn't already exist
	static CMessageServer& Instance(void);

	//! Register a client to recieve messages
	//! \param pClient A pointer to the client which should recieve the messages
	//! \param eMessageType The message type the client wishes to recieve
	//! \param Priority The priority of the client for recieving the message
	void RegisterMessageClient(CMessageClient* pClient, CMessage::EMessageType eMessageType, unsigned char Priority = PRIORITY_NORMAL);

	//! Deregister a client for a certain message type
	//! \param pClient A pointer to the message client to be deregistered
	//! \param eMessageType The message type for which the client no longer should recieve messages
	void DeregisterMessageClient(CMessageClient* pClient, CMessage::EMessageType eMessageType);

	//! Deregister a client for all message types
	//! \param pClient A pointer to the message client to be deregistered
	void DeregisterMessageClient(CMessageClient* pClient);

	//! Takes the next message in the queue and dispatches it to any registered clients in priority order
	void DeliverMessage(void);

	//! Adds a message to the message queue
	//! \param pMessage A pointer to the message to be queued
	void QueueMessage(CMessage* pMessage);

	//! \return true if there's a message available in the queue
	bool MessageAvailable(void) { return m_MessageQueue.size() > 0; }


protected:
	static CMessageServer* m_pInstance;  //!< A pointer to the single instande of the message server
	std::deque<CMessage*> m_MessageQueue;  //!< The message queue
	t_MessageClientMap m_MessageClients;  //!< A map of all the registered clients
	SDL_sem* m_pSemaphore;  //!< A semaphore indicating how many messages are in the queue
};

}

#endif // _WG_MESSAGE_SERVER_H_