/**************************************************************************** * * ftcglyph.h * * FreeType abstract glyph cache (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. * */ /* * * FTC_GCache is an _abstract_ cache object optimized to store glyph * data. It works as follows: * * - It manages FTC_GNode objects. Each one of them can hold one or more * glyph `items'. Item types are not specified in the FTC_GCache but * in classes that extend it. * * - Glyph attributes, like face ID, character size, render mode, etc., * can be grouped into abstract `glyph families'. This avoids storing * the attributes within the FTC_GCache, since it is likely that many * FTC_GNodes will belong to the same family in typical uses. * * - Each FTC_GNode is thus an FTC_Node with two additional fields: * * * gindex: A glyph index, or the first index in a glyph range. * * family: A pointer to a glyph `family'. * * - Family types are not fully specific in the FTC_Family type, but * by classes that extend it. * * Note that both FTC_ImageCache and FTC_SBitCache extend FTC_GCache. * They share an FTC_Family sub-class called FTC_BasicFamily which is * used to store the following data: face ID, pixel/point sizes, load * flags. For more details see the file `src/cache/ftcbasic.c'. * * Client applications can extend FTC_GNode with their own FTC_GNode * and FTC_Family sub-classes to implement more complex caches (e.g., * handling automatic synthesis, like obliquing & emboldening, colored * glyphs, etc.). * * See also the FTC_ICache & FTC_SCache classes in `ftcimage.h' and * `ftcsbits.h', which both extend FTC_GCache with additional * optimizations. * * A typical FTC_GCache implementation must provide at least the * following: * * - FTC_GNode sub-class, e.g. MyNode, with relevant methods: * my_node_new (must call FTC_GNode_Init) * my_node_free (must call FTC_GNode_Done) * my_node_compare (must call ftc_gnode_compare) * my_node_remove_faceid (must call ftc_gnode_unselect in case * of match) * * - FTC_Family sub-class, e.g. MyFamily, with relevant methods: * my_family_compare * my_family_init * my_family_reset (optional) * my_family_done * * - FTC_GQuery sub-class, e.g. MyQuery, to hold cache-specific query * data. * * - Constant structures for a FTC_GNodeClass. * * - MyCacheNew() can be implemented easily as a call to the convenience * function FTC_GCache_New. * * - MyCacheLookup with a call to FTC_GCache_Lookup. This function will * automatically: * * - Search for the corresponding family in the cache, or create * a new one if necessary. Put it in FTC_GQUERY(myquery).family * * - Call FTC_Cache_Lookup. * * If it returns NULL, you should create a new node, then call * ftc_cache_add as usual. */ /************************************************************************** * * Important: The functions defined in this file are only used to * implement an abstract glyph cache class. You need to * provide additional logic to implement a complete cache. * */ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /********* *********/ /********* WARNING, THIS IS BETA CODE. *********/ /********* *********/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ /*************************************************************************/ #ifndef FTCGLYPH_H_ #define FTCGLYPH_H_ #include "ftcmanag.h" FT_BEGIN_HEADER /* * We can group glyphs into `families'. Each family correspond to a * given face ID, character size, transform, etc. * * Families are implemented as MRU list nodes. They are * reference-counted. */ FTC_Family; #define FTC_FAMILY( x ) … #define FTC_FAMILY_P( x ) … FTC_GNode; #define FTC_GNODE( x ) … #define FTC_GNODE_P( x ) … FTC_GQuery; #define FTC_GQUERY( x ) … /************************************************************************** * * These functions are exported so that they can be called from * user-provided cache classes; otherwise, they are really part of the * cache sub-system internals. */ /* must be called by derived FTC_Node_InitFunc routines */ FT_LOCAL( void ) FTC_GNode_Init( FTC_GNode node, FT_UInt gindex, /* glyph index for node */ FTC_Family family ); /* call this function to clear a node's family -- this is necessary */ /* to implement the `node_remove_faceid' cache method correctly */ FT_LOCAL( void ) FTC_GNode_UnselectFamily( FTC_GNode gnode, FTC_Cache cache ); /* must be called by derived FTC_Node_DoneFunc routines */ FT_LOCAL( void ) FTC_GNode_Done( FTC_GNode node, FTC_Cache cache ); FT_LOCAL( void ) FTC_Family_Init( FTC_Family family, FTC_Cache cache ); FTC_GCache; #define FTC_GCACHE( x ) … #if 0 /* can be used as @FTC_Cache_InitFunc */ FT_LOCAL( FT_Error ) FTC_GCache_Init( FTC_GCache cache ); #endif #if 0 /* can be used as @FTC_Cache_DoneFunc */ FT_LOCAL( void ) FTC_GCache_Done( FTC_GCache cache ); #endif /* the glyph cache class adds fields for the family implementation */ FTC_GCacheClassRec; FTC_GCacheClass; #define FTC_GCACHE_CLASS( x ) … #define FTC_CACHE_GCACHE_CLASS( x ) … #define FTC_CACHE_FAMILY_CLASS( x ) … /* convenience function; use it instead of FTC_Manager_Register_Cache */ FT_LOCAL( FT_Error ) FTC_GCache_New( FTC_Manager manager, FTC_GCacheClass clazz, FTC_GCache *acache ); #ifndef FTC_INLINE FT_LOCAL( FT_Error ) FTC_GCache_Lookup( FTC_GCache cache, FT_Offset hash, FT_UInt gindex, FTC_GQuery query, FTC_Node *anode ); #endif /* */ #define FTC_FAMILY_FREE( family, cache ) … #ifdef FTC_INLINE #define FTC_GCACHE_LOOKUP_CMP( cache, famcmp, nodecmp, hash, \ gindex, query, node, error ) … /* */ #else /* !FTC_INLINE */ #define FTC_GCACHE_LOOKUP_CMP … #endif /* !FTC_INLINE */ FT_END_HEADER #endif /* FTCGLYPH_H_ */ /* END */
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