ftcmanag.h (5734B)
1 /**************************************************************************** 2 * 3 * ftcmanag.h 4 * 5 * FreeType Cache Manager (specification). 6 * 7 * Copyright (C) 2000-2025 by 8 * David Turner, Robert Wilhelm, and Werner Lemberg. 9 * 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. 15 * 16 */ 17 18 19 /************************************************************************** 20 * 21 * A cache manager is in charge of the following: 22 * 23 * - Maintain a mapping between generic FTC_FaceIDs and live FT_Face 24 * objects. The mapping itself is performed through a user-provided 25 * callback. However, the manager maintains a small cache of FT_Face 26 * and FT_Size objects in order to speed up things considerably. 27 * 28 * - Manage one or more cache objects. Each cache is in charge of 29 * holding a varying number of `cache nodes'. Each cache node 30 * represents a minimal amount of individually accessible cached 31 * data. For example, a cache node can be an FT_Glyph image 32 * containing a vector outline, or some glyph metrics, or anything 33 * else. 34 * 35 * Each cache node has a certain size in bytes that is added to the 36 * total amount of `cache memory' within the manager. 37 * 38 * All cache nodes are located in a global LRU list, where the oldest 39 * node is at the tail of the list. 40 * 41 * Each node belongs to a single cache, and includes a reference 42 * count to avoid destroying it (due to caching). 43 * 44 */ 45 46 47 /*************************************************************************/ 48 /*************************************************************************/ 49 /*************************************************************************/ 50 /*************************************************************************/ 51 /*************************************************************************/ 52 /********* *********/ 53 /********* WARNING, THIS IS BETA CODE. *********/ 54 /********* *********/ 55 /*************************************************************************/ 56 /*************************************************************************/ 57 /*************************************************************************/ 58 /*************************************************************************/ 59 /*************************************************************************/ 60 61 62 #ifndef FTCMANAG_H_ 63 #define FTCMANAG_H_ 64 65 66 #include <freetype/ftcache.h> 67 #include "ftcmru.h" 68 #include "ftccache.h" 69 70 71 FT_BEGIN_HEADER 72 73 74 /************************************************************************** 75 * 76 * @Section: 77 * cache_subsystem 78 * 79 */ 80 81 82 #define FTC_MAX_FACES_DEFAULT 2 83 #define FTC_MAX_SIZES_DEFAULT 4 84 #define FTC_MAX_BYTES_DEFAULT 200000L /* ~200kByte by default */ 85 86 /* maximum number of caches registered in a single manager */ 87 #define FTC_MAX_CACHES 16 88 89 90 typedef struct FTC_ManagerRec_ 91 { 92 FT_Library library; 93 FT_Memory memory; 94 95 FTC_Node nodes_list; 96 FT_Offset max_weight; 97 FT_Offset cur_weight; 98 FT_UInt num_nodes; 99 100 FTC_Cache caches[FTC_MAX_CACHES]; 101 FT_UInt num_caches; 102 103 FTC_MruListRec faces; 104 FTC_MruListRec sizes; 105 106 FT_Pointer request_data; 107 FTC_Face_Requester request_face; 108 109 } FTC_ManagerRec; 110 111 112 /************************************************************************** 113 * 114 * @Function: 115 * FTC_Manager_Compress 116 * 117 * @Description: 118 * This function is used to check the state of the cache manager if 119 * its `num_bytes' field is greater than its `max_bytes' field. It 120 * will flush as many old cache nodes as possible (ignoring cache 121 * nodes with a non-zero reference count). 122 * 123 * @InOut: 124 * manager :: 125 * A handle to the cache manager. 126 * 127 * @Note: 128 * Client applications should not call this function directly. It is 129 * normally invoked by specific cache implementations. 130 * 131 * The reason this function is exported is to allow client-specific 132 * cache classes. 133 */ 134 FT_LOCAL( void ) 135 FTC_Manager_Compress( FTC_Manager manager ); 136 137 138 /* try to flush `count' old nodes from the cache; return the number 139 * of really flushed nodes 140 */ 141 FT_LOCAL( FT_UInt ) 142 FTC_Manager_FlushN( FTC_Manager manager, 143 FT_UInt count ); 144 145 146 /* this must be used internally for the moment */ 147 FT_LOCAL( FT_Error ) 148 FTC_Manager_RegisterCache( FTC_Manager manager, 149 FTC_CacheClass clazz, 150 FTC_Cache *acache ); 151 152 /* */ 153 154 #define FTC_SCALER_COMPARE( a, b ) \ 155 ( (a)->face_id == (b)->face_id && \ 156 (a)->width == (b)->width && \ 157 (a)->height == (b)->height && \ 158 ((a)->pixel != 0) == ((b)->pixel != 0) && \ 159 ( (a)->pixel || \ 160 ( (a)->x_res == (b)->x_res && \ 161 (a)->y_res == (b)->y_res ) ) ) 162 163 #define FTC_SCALER_HASH( q ) \ 164 ( FTC_FACE_ID_HASH( (q)->face_id ) + \ 165 (q)->width + (q)->height*7 + \ 166 ( (q)->pixel ? 0 : ( (q)->x_res*33 ^ (q)->y_res*61 ) ) ) 167 168 /* */ 169 170 FT_END_HEADER 171 172 #endif /* FTCMANAG_H_ */ 173 174 175 /* END */