lyx_mirror/src/graphics/GraphicsCache.h

// -*- C++ -*-
/* This file is part of
 * =================================================
 * 
 *          LyX, The Document Processor
 *          Copyright 1995 Matthias Ettrich.
 *          Copyright 1995-2001 The LyX Team.
 *
 *          This file Copyright 2000 Baruch Even
 * ================================================= */

#ifndef GRAPHICSCACHE_H
#define GRAPHICSCACHE_H

#ifdef __GNUG__
#pragma interface
#endif

#include <map>

#include "LString.h"
#include "GraphicsCacheItem.h"
#include <boost/utility.hpp>
#include <boost/smart_ptr.hpp>

class GraphicsCacheItem;

/** GraphicsCache is the manager of the image cache.
    It is responsible of create the GraphicsCacheItem's and maintain them.
    
    GraphicsCache is a singleton class, there should be only one instance of
    it at any moment.
*/
class GraphicsCache : boost::noncopyable {
public:
	/// Get the instance of the class.
	static GraphicsCache & getInstance();
	/// Public destructor due to compiler warnings.
	~GraphicsCache();

	typedef boost::shared_ptr<GraphicsCacheItem> shared_ptr_item;

	/// Add a file to the cache.
	shared_ptr_item addFile(string const & filename);

private:
	/// Remove a cache item if it's count has gone to zero.
	void removeFile(string const & filename);
	
	/// Private c-tor so we can control how many objects are instantiated.
	GraphicsCache() {}
	
	///
	typedef std::map<string, shared_ptr_item> CacheType;
	///
	CacheType cache;
	
	/** We need this so that an Item can tell the cache that it should be
	    deleted. (to call removeFile).
	    It also helps removing a warning gcc emits. */
	friend class GraphicsCacheItem;
};
#endif