1 /****************************************************************************
5 * FreeType abstract glyph cache (specification).
7 * Copyright (C) 2000-2023 by
8 * David Turner, Robert Wilhelm, and Werner Lemberg.
10 * This file is part of the FreeType project, and may only be used,
11 * modified, and distributed under the terms of the FreeType project
12 * license, LICENSE.TXT. By continuing to use, modify, or distribute
13 * this file you indicate that you have read the license and
14 * understand and accept it fully.
21 * FTC_GCache is an _abstract_ cache object optimized to store glyph
22 * data. It works as follows:
24 * - It manages FTC_GNode objects. Each one of them can hold one or more
25 * glyph `items'. Item types are not specified in the FTC_GCache but
26 * in classes that extend it.
28 * - Glyph attributes, like face ID, character size, render mode, etc.,
29 * can be grouped into abstract `glyph families'. This avoids storing
30 * the attributes within the FTC_GCache, since it is likely that many
31 * FTC_GNodes will belong to the same family in typical uses.
33 * - Each FTC_GNode is thus an FTC_Node with two additional fields:
35 * * gindex: A glyph index, or the first index in a glyph range.
36 * * family: A pointer to a glyph `family'.
38 * - Family types are not fully specific in the FTC_Family type, but
39 * by classes that extend it.
41 * Note that both FTC_ImageCache and FTC_SBitCache extend FTC_GCache.
42 * They share an FTC_Family sub-class called FTC_BasicFamily which is
43 * used to store the following data: face ID, pixel/point sizes, load
44 * flags. For more details see the file `src/cache/ftcbasic.c'.
46 * Client applications can extend FTC_GNode with their own FTC_GNode
47 * and FTC_Family sub-classes to implement more complex caches (e.g.,
48 * handling automatic synthesis, like obliquing & emboldening, colored
51 * See also the FTC_ICache & FTC_SCache classes in `ftcimage.h' and
52 * `ftcsbits.h', which both extend FTC_GCache with additional
55 * A typical FTC_GCache implementation must provide at least the
58 * - FTC_GNode sub-class, e.g. MyNode, with relevant methods:
59 * my_node_new (must call FTC_GNode_Init)
60 * my_node_free (must call FTC_GNode_Done)
61 * my_node_compare (must call ftc_gnode_compare)
62 * my_node_remove_faceid (must call ftc_gnode_unselect in case
65 * - FTC_Family sub-class, e.g. MyFamily, with relevant methods:
68 * my_family_reset (optional)
71 * - FTC_GQuery sub-class, e.g. MyQuery, to hold cache-specific query
74 * - Constant structures for a FTC_GNodeClass.
76 * - MyCacheNew() can be implemented easily as a call to the convenience
77 * function FTC_GCache_New.
79 * - MyCacheLookup with a call to FTC_GCache_Lookup. This function will
82 * - Search for the corresponding family in the cache, or create
83 * a new one if necessary. Put it in FTC_GQUERY(myquery).family
85 * - Call FTC_Cache_Lookup.
87 * If it returns NULL, you should create a new node, then call
88 * ftc_cache_add as usual.
92 /**************************************************************************
94 * Important: The functions defined in this file are only used to
95 * implement an abstract glyph cache class. You need to
96 * provide additional logic to implement a complete cache.
101 /*************************************************************************/
102 /*************************************************************************/
103 /*************************************************************************/
104 /*************************************************************************/
105 /*************************************************************************/
106 /********* *********/
107 /********* WARNING, THIS IS BETA CODE. *********/
108 /********* *********/
109 /*************************************************************************/
110 /*************************************************************************/
111 /*************************************************************************/
112 /*************************************************************************/
113 /*************************************************************************/
120 #include "ftcmanag.h"
127 * We can group glyphs into `families'. Each family correspond to a
128 * given face ID, character size, transform, etc.
130 * Families are implemented as MRU list nodes. They are
134 typedef struct FTC_FamilyRec_
136 FTC_MruNodeRec mrunode;
137 FT_UInt num_nodes; /* current number of nodes in this family */
139 FTC_MruListClass clazz;
141 } FTC_FamilyRec, *FTC_Family;
143 #define FTC_FAMILY( x ) ( (FTC_Family)(x) )
144 #define FTC_FAMILY_P( x ) ( (FTC_Family*)(x) )
147 typedef struct FTC_GNodeRec_
153 } FTC_GNodeRec, *FTC_GNode;
155 #define FTC_GNODE( x ) ( (FTC_GNode)(x) )
156 #define FTC_GNODE_P( x ) ( (FTC_GNode*)(x) )
159 typedef struct FTC_GQueryRec_
164 } FTC_GQueryRec, *FTC_GQuery;
166 #define FTC_GQUERY( x ) ( (FTC_GQuery)(x) )
169 /**************************************************************************
171 * These functions are exported so that they can be called from
172 * user-provided cache classes; otherwise, they are really part of the
173 * cache sub-system internals.
176 /* must be called by derived FTC_Node_InitFunc routines */
178 FTC_GNode_Init( FTC_GNode node,
179 FT_UInt gindex, /* glyph index for node */
182 /* call this function to clear a node's family -- this is necessary */
183 /* to implement the `node_remove_faceid' cache method correctly */
185 FTC_GNode_UnselectFamily( FTC_GNode gnode,
188 /* must be called by derived FTC_Node_DoneFunc routines */
190 FTC_GNode_Done( FTC_GNode node,
195 FTC_Family_Init( FTC_Family family,
198 typedef struct FTC_GCacheRec_
201 FTC_MruListRec families;
203 } FTC_GCacheRec, *FTC_GCache;
205 #define FTC_GCACHE( x ) ((FTC_GCache)(x))
209 /* can be used as @FTC_Cache_InitFunc */
211 FTC_GCache_Init( FTC_GCache cache );
216 /* can be used as @FTC_Cache_DoneFunc */
218 FTC_GCache_Done( FTC_GCache cache );
222 /* the glyph cache class adds fields for the family implementation */
223 typedef struct FTC_GCacheClassRec_
225 FTC_CacheClassRec clazz;
226 FTC_MruListClass family_class;
228 } FTC_GCacheClassRec;
230 typedef const FTC_GCacheClassRec* FTC_GCacheClass;
232 #define FTC_GCACHE_CLASS( x ) ((FTC_GCacheClass)(x))
234 #define FTC_CACHE_GCACHE_CLASS( x ) \
235 FTC_GCACHE_CLASS( FTC_CACHE( x )->org_class )
236 #define FTC_CACHE_FAMILY_CLASS( x ) \
237 ( (FTC_MruListClass)FTC_CACHE_GCACHE_CLASS( x )->family_class )
240 /* convenience function; use it instead of FTC_Manager_Register_Cache */
242 FTC_GCache_New( FTC_Manager manager,
243 FTC_GCacheClass clazz,
244 FTC_GCache *acache );
248 FTC_GCache_Lookup( FTC_GCache cache,
259 #define FTC_FAMILY_FREE( family, cache ) \
260 FTC_MruList_Remove( &FTC_GCACHE((cache))->families, \
261 (FTC_MruNode)(family) )
266 #define FTC_GCACHE_LOOKUP_CMP( cache, famcmp, nodecmp, hash, \
267 gindex, query, node, error ) \
269 FTC_GCache _gcache = FTC_GCACHE( cache ); \
270 FTC_GQuery _gquery = (FTC_GQuery)( query ); \
271 FTC_MruNode_CompareFunc _fcompare = (FTC_MruNode_CompareFunc)(famcmp); \
272 FTC_MruNode _mrunode; \
275 _gquery->gindex = (gindex); \
277 FTC_MRULIST_LOOKUP_CMP( &_gcache->families, _gquery, _fcompare, \
279 _gquery->family = FTC_FAMILY( _mrunode ); \
282 FTC_Family _gqfamily = _gquery->family; \
285 _gqfamily->num_nodes++; \
287 FTC_CACHE_LOOKUP_CMP( cache, nodecmp, hash, query, node, error ); \
289 if ( --_gqfamily->num_nodes == 0 ) \
290 FTC_FAMILY_FREE( _gqfamily, _gcache ); \
295 #else /* !FTC_INLINE */
297 #define FTC_GCACHE_LOOKUP_CMP( cache, famcmp, nodecmp, hash, \
298 gindex, query, node, error ) \
301 error = FTC_GCache_Lookup( FTC_GCACHE( cache ), hash, gindex, \
302 FTC_GQUERY( query ), &node ); \
306 #endif /* !FTC_INLINE */
312 #endif /* FTCGLYPH_H_ */