/****************************************************************************
*
* ftcmanag.h
*
* FreeType Cache Manager (specification).
*
* Copyright (C) 2000-2023 by
* David Turner, Robert Wilhelm, and Werner Lemberg.
*
* This file is part of the FreeType project, and may only be used,
* modified, and distributed under the terms of the FreeType project
* license, LICENSE.TXT. By continuing to use, modify, or distribute
* this file you indicate that you have read the license and
* understand and accept it fully.
*
*/
/**************************************************************************
*
* A cache manager is in charge of the following:
*
* - Maintain a mapping between generic FTC_FaceIDs and live FT_Face
* objects. The mapping itself is performed through a user-provided
* callback. However, the manager maintains a small cache of FT_Face
* and FT_Size objects in order to speed up things considerably.
*
* - Manage one or more cache objects. Each cache is in charge of
* holding a varying number of `cache nodes'. Each cache node
* represents a minimal amount of individually accessible cached
* data. For example, a cache node can be an FT_Glyph image
* containing a vector outline, or some glyph metrics, or anything
* else.
*
* Each cache node has a certain size in bytes that is added to the
* total amount of `cache memory' within the manager.
*
* All cache nodes are located in a global LRU list, where the oldest
* node is at the tail of the list.
*
* Each node belongs to a single cache, and includes a reference
* count to avoid destroying it (due to caching).
*
*/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/********* *********/
/********* WARNING, THIS IS BETA CODE. *********/
/********* *********/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
/*************************************************************************/
#ifndef FTCMANAG_H_
#define FTCMANAG_H_
#include <freetype/ftcache.h>
#include "ftcmru.h"
#include "ftccache.h"
FT_BEGIN_HEADER
/**************************************************************************
*
* @Section:
* cache_subsystem
*
*/
#define FTC_MAX_FACES_DEFAULT 2
#define FTC_MAX_SIZES_DEFAULT 4
#define FTC_MAX_BYTES_DEFAULT 200000L /* ~200kByte by default */
/* maximum number of caches registered in a single manager */
#define FTC_MAX_CACHES 16
typedef struct FTC_ManagerRec_
{
FT_Library library;
FT_Memory memory;
FTC_Node nodes_list;
FT_Offset max_weight;
FT_Offset cur_weight;
FT_UInt num_nodes;
FTC_Cache caches[FTC_MAX_CACHES];
FT_UInt num_caches;
FTC_MruListRec faces;
FTC_MruListRec sizes;
FT_Pointer request_data;
FTC_Face_Requester request_face;
} FTC_ManagerRec;
/**************************************************************************
*
* @Function:
* FTC_Manager_Compress
*
* @Description:
* This function is used to check the state of the cache manager if
* its `num_bytes' field is greater than its `max_bytes' field. It
* will flush as many old cache nodes as possible (ignoring cache
* nodes with a non-zero reference count).
*
* @InOut:
* manager ::
* A handle to the cache manager.
*
* @Note:
* Client applications should not call this function directly. It is
* normally invoked by specific cache implementations.
*
* The reason this function is exported is to allow client-specific
* cache classes.
*/
FT_LOCAL( void )
FTC_Manager_Compress( FTC_Manager manager );
/* try to flush `count' old nodes from the cache; return the number
* of really flushed nodes
*/
FT_LOCAL( FT_UInt )
FTC_Manager_FlushN( FTC_Manager manager,
FT_UInt count );
/* this must be used internally for the moment */
FT_LOCAL( FT_Error )
FTC_Manager_RegisterCache( FTC_Manager manager,
FTC_CacheClass clazz,
FTC_Cache *acache );
/* */
#define FTC_SCALER_COMPARE( a, b ) \
( (a)->face_id == (b)->face_id && \
(a)->width == (b)->width && \
(a)->height == (b)->height && \
((a)->pixel != 0) == ((b)->pixel != 0) && \
( (a)->pixel || \
( (a)->x_res == (b)->x_res && \
(a)->y_res == (b)->y_res ) ) )
#define FTC_SCALER_HASH( q ) \
( FTC_FACE_ID_HASH( (q)->face_id ) + \
(q)->width + (q)->height*7 + \
( (q)->pixel ? 0 : ( (q)->x_res*33 ^ (q)->y_res*61 ) ) )
/* */
FT_END_HEADER
#endif /* FTCMANAG_H_ */
/* END */
