Files
libopenshot/include/Cache.h
2011-10-11 08:44:27 -05:00

64 lines
1.6 KiB
C++

#ifndef OPENSHOT_CACHE_H
#define OPENSHOT_CACHE_H
/**
* \file
* \brief Header file for Cache class
* \author Copyright (c) 2011 Jonathan Thomas
*/
#include <map>
#include <queue>
#include "Frame.h"
#include "Exceptions.h"
/// This namespace is the default namespace for all code in the openshot library.
namespace openshot {
/**
* \brief This class is a cache manager for Frame objects. It is used by FileReaders (such as FFmpegReader) to cache
* recently accessed frames.
*
* Due to the high cost of decoding streams, once a frame is decoded, converted to RGB, and a Frame object is created,
* it critical to keep these Frames cached for performance reasons.
*/
class Cache {
private:
int max_frames; ///< This is the max number of frames to cache
map<int, Frame> frames; ///< This map holds the frame number and Frame objects
queue<int> frame_numbers; ///< This queue holds a sequential list of cached Frame numbers
/// Clean up cached frames that exceed the number in our max_frames variable
void CleanUp();
public:
/// Default constructor, max frames to cache is 20
Cache();
/// Constructor that sets the max frames to cache
Cache(int max_frames);
/// Add a Frame to the cache
void Add(int frame_number, Frame frame);
/// Check for the existance of a frame in the cache
bool Exists(int frame_number);
/// Get a frame from the cache
Frame GetFrame(int frame_number);
/// Clear the cache of all frames
void Clear();
/// Display the list of cache and clear the cache (mainly for debugging reasons)
void DisplayAndClear();
/// Count the frames in the queue
int Count();
};
}
#endif