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| 1 /***************************************************************************/ | |
| 2 /* */ | |
| 3 /* ftincrem.h */ | |
| 4 /* */ | |
| 5 /* FreeType incremental loading (specification). */ | |
| 6 /* */ | |
| 7 /* Copyright 2002, 2003, 2006-2008, 2010, 2014 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 #ifndef __FTINCREM_H__ | |
| 20 #define __FTINCREM_H__ | |
| 21 | |
| 22 #include <ft2build.h> | |
| 23 #include FT_FREETYPE_H | |
| 24 | |
| 25 #ifdef FREETYPE_H | |
| 26 #error "freetype.h of FreeType 1 has been loaded!" | |
| 27 #error "Please fix the directory search order for header files" | |
| 28 #error "so that freetype.h of FreeType 2 is found first." | |
| 29 #endif | |
| 30 | |
| 31 | |
| 32 FT_BEGIN_HEADER | |
| 33 | |
| 34 /*************************************************************************** | |
| 35 * | |
| 36 * @section: | |
| 37 * incremental | |
| 38 * | |
| 39 * @title: | |
| 40 * Incremental Loading | |
| 41 * | |
| 42 * @abstract: | |
| 43 * Custom Glyph Loading. | |
| 44 * | |
| 45 * @description: | |
| 46 * This section contains various functions used to perform so-called | |
| 47 * `incremental' glyph loading. This is a mode where all glyphs loaded | |
| 48 * from a given @FT_Face are provided by the client application. | |
| 49 * | |
| 50 * Apart from that, all other tables are loaded normally from the font | |
| 51 * file. This mode is useful when FreeType is used within another | |
| 52 * engine, e.g., a PostScript Imaging Processor. | |
| 53 * | |
| 54 * To enable this mode, you must use @FT_Open_Face, passing an | |
| 55 * @FT_Parameter with the @FT_PARAM_TAG_INCREMENTAL tag and an | |
| 56 * @FT_Incremental_Interface value. See the comments for | |
| 57 * @FT_Incremental_InterfaceRec for an example. | |
| 58 * | |
| 59 */ | |
| 60 | |
| 61 | |
| 62 /*************************************************************************** | |
| 63 * | |
| 64 * @type: | |
| 65 * FT_Incremental | |
| 66 * | |
| 67 * @description: | |
| 68 * An opaque type describing a user-provided object used to implement | |
| 69 * `incremental' glyph loading within FreeType. This is used to support | |
| 70 * embedded fonts in certain environments (e.g., PostScript interpreters), | |
| 71 * where the glyph data isn't in the font file, or must be overridden by | |
| 72 * different values. | |
| 73 * | |
| 74 * @note: | |
| 75 * It is up to client applications to create and implement @FT_Incremental | |
| 76 * objects, as long as they provide implementations for the methods | |
| 77 * @FT_Incremental_GetGlyphDataFunc, @FT_Incremental_FreeGlyphDataFunc | |
| 78 * and @FT_Incremental_GetGlyphMetricsFunc. | |
| 79 * | |
| 80 * See the description of @FT_Incremental_InterfaceRec to understand how | |
| 81 * to use incremental objects with FreeType. | |
| 82 * | |
| 83 */ | |
| 84 typedef struct FT_IncrementalRec_* FT_Incremental; | |
| 85 | |
| 86 | |
| 87 /*************************************************************************** | |
| 88 * | |
| 89 * @struct: | |
| 90 * FT_Incremental_MetricsRec | |
| 91 * | |
| 92 * @description: | |
| 93 * A small structure used to contain the basic glyph metrics returned | |
| 94 * by the @FT_Incremental_GetGlyphMetricsFunc method. | |
| 95 * | |
| 96 * @fields: | |
| 97 * bearing_x :: | |
| 98 * Left bearing, in font units. | |
| 99 * | |
| 100 * bearing_y :: | |
| 101 * Top bearing, in font units. | |
| 102 * | |
| 103 * advance :: | |
| 104 * Horizontal component of glyph advance, in font units. | |
| 105 * | |
| 106 * advance_v :: | |
| 107 * Vertical component of glyph advance, in font units. | |
| 108 * | |
| 109 * @note: | |
| 110 * These correspond to horizontal or vertical metrics depending on the | |
| 111 * value of the `vertical' argument to the function | |
| 112 * @FT_Incremental_GetGlyphMetricsFunc. | |
| 113 * | |
| 114 */ | |
| 115 typedef struct FT_Incremental_MetricsRec_ | |
| 116 { | |
| 117 FT_Long bearing_x; | |
| 118 FT_Long bearing_y; | |
| 119 FT_Long advance; | |
| 120 FT_Long advance_v; /* since 2.3.12 */ | |
| 121 | |
| 122 } FT_Incremental_MetricsRec; | |
| 123 | |
| 124 | |
| 125 /*************************************************************************** | |
| 126 * | |
| 127 * @struct: | |
| 128 * FT_Incremental_Metrics | |
| 129 * | |
| 130 * @description: | |
| 131 * A handle to an @FT_Incremental_MetricsRec structure. | |
| 132 * | |
| 133 */ | |
| 134 typedef struct FT_Incremental_MetricsRec_* FT_Incremental_Metrics; | |
| 135 | |
| 136 | |
| 137 /*************************************************************************** | |
| 138 * | |
| 139 * @type: | |
| 140 * FT_Incremental_GetGlyphDataFunc | |
| 141 * | |
| 142 * @description: | |
| 143 * A function called by FreeType to access a given glyph's data bytes | |
| 144 * during @FT_Load_Glyph or @FT_Load_Char if incremental loading is | |
| 145 * enabled. | |
| 146 * | |
| 147 * Note that the format of the glyph's data bytes depends on the font | |
| 148 * file format. For TrueType, it must correspond to the raw bytes within | |
| 149 * the `glyf' table. For PostScript formats, it must correspond to the | |
| 150 * *unencrypted* charstring bytes, without any `lenIV' header. It is | |
| 151 * undefined for any other format. | |
| 152 * | |
| 153 * @input: | |
| 154 * incremental :: | |
| 155 * Handle to an opaque @FT_Incremental handle provided by the client | |
| 156 * application. | |
| 157 * | |
| 158 * glyph_index :: | |
| 159 * Index of relevant glyph. | |
| 160 * | |
| 161 * @output: | |
| 162 * adata :: | |
| 163 * A structure describing the returned glyph data bytes (which will be | |
| 164 * accessed as a read-only byte block). | |
| 165 * | |
| 166 * @return: | |
| 167 * FreeType error code. 0~means success. | |
| 168 * | |
| 169 * @note: | |
| 170 * If this function returns successfully the method | |
| 171 * @FT_Incremental_FreeGlyphDataFunc will be called later to release | |
| 172 * the data bytes. | |
| 173 * | |
| 174 * Nested calls to @FT_Incremental_GetGlyphDataFunc can happen for | |
| 175 * compound glyphs. | |
| 176 * | |
| 177 */ | |
| 178 typedef FT_Error | |
| 179 (*FT_Incremental_GetGlyphDataFunc)( FT_Incremental incremental, | |
| 180 FT_UInt glyph_index, | |
| 181 FT_Data* adata ); | |
| 182 | |
| 183 | |
| 184 /*************************************************************************** | |
| 185 * | |
| 186 * @type: | |
| 187 * FT_Incremental_FreeGlyphDataFunc | |
| 188 * | |
| 189 * @description: | |
| 190 * A function used to release the glyph data bytes returned by a | |
| 191 * successful call to @FT_Incremental_GetGlyphDataFunc. | |
| 192 * | |
| 193 * @input: | |
| 194 * incremental :: | |
| 195 * A handle to an opaque @FT_Incremental handle provided by the client | |
| 196 * application. | |
| 197 * | |
| 198 * data :: | |
| 199 * A structure describing the glyph data bytes (which will be accessed | |
| 200 * as a read-only byte block). | |
| 201 * | |
| 202 */ | |
| 203 typedef void | |
| 204 (*FT_Incremental_FreeGlyphDataFunc)( FT_Incremental incremental, | |
| 205 FT_Data* data ); | |
| 206 | |
| 207 | |
| 208 /*************************************************************************** | |
| 209 * | |
| 210 * @type: | |
| 211 * FT_Incremental_GetGlyphMetricsFunc | |
| 212 * | |
| 213 * @description: | |
| 214 * A function used to retrieve the basic metrics of a given glyph index | |
| 215 * before accessing its data. This is necessary because, in certain | |
| 216 * formats like TrueType, the metrics are stored in a different place from | |
| 217 * the glyph images proper. | |
| 218 * | |
| 219 * @input: | |
| 220 * incremental :: | |
| 221 * A handle to an opaque @FT_Incremental handle provided by the client | |
| 222 * application. | |
| 223 * | |
| 224 * glyph_index :: | |
| 225 * Index of relevant glyph. | |
| 226 * | |
| 227 * vertical :: | |
| 228 * If true, return vertical metrics. | |
| 229 * | |
| 230 * ametrics :: | |
| 231 * This parameter is used for both input and output. | |
| 232 * The original glyph metrics, if any, in font units. If metrics are | |
| 233 * not available all the values must be set to zero. | |
| 234 * | |
| 235 * @output: | |
| 236 * ametrics :: | |
| 237 * The replacement glyph metrics in font units. | |
| 238 * | |
| 239 */ | |
| 240 typedef FT_Error | |
| 241 (*FT_Incremental_GetGlyphMetricsFunc) | |
| 242 ( FT_Incremental incremental, | |
| 243 FT_UInt glyph_index, | |
| 244 FT_Bool vertical, | |
| 245 FT_Incremental_MetricsRec *ametrics ); | |
| 246 | |
| 247 | |
| 248 /************************************************************************** | |
| 249 * | |
| 250 * @struct: | |
| 251 * FT_Incremental_FuncsRec | |
| 252 * | |
| 253 * @description: | |
| 254 * A table of functions for accessing fonts that load data | |
| 255 * incrementally. Used in @FT_Incremental_InterfaceRec. | |
| 256 * | |
| 257 * @fields: | |
| 258 * get_glyph_data :: | |
| 259 * The function to get glyph data. Must not be null. | |
| 260 * | |
| 261 * free_glyph_data :: | |
| 262 * The function to release glyph data. Must not be null. | |
| 263 * | |
| 264 * get_glyph_metrics :: | |
| 265 * The function to get glyph metrics. May be null if the font does | |
| 266 * not provide overriding glyph metrics. | |
| 267 * | |
| 268 */ | |
| 269 typedef struct FT_Incremental_FuncsRec_ | |
| 270 { | |
| 271 FT_Incremental_GetGlyphDataFunc get_glyph_data; | |
| 272 FT_Incremental_FreeGlyphDataFunc free_glyph_data; | |
| 273 FT_Incremental_GetGlyphMetricsFunc get_glyph_metrics; | |
| 274 | |
| 275 } FT_Incremental_FuncsRec; | |
| 276 | |
| 277 | |
| 278 /*************************************************************************** | |
| 279 * | |
| 280 * @struct: | |
| 281 * FT_Incremental_InterfaceRec | |
| 282 * | |
| 283 * @description: | |
| 284 * A structure to be used with @FT_Open_Face to indicate that the user | |
| 285 * wants to support incremental glyph loading. You should use it with | |
| 286 * @FT_PARAM_TAG_INCREMENTAL as in the following example: | |
| 287 * | |
| 288 * { | |
| 289 * FT_Incremental_InterfaceRec inc_int; | |
| 290 * FT_Parameter parameter; | |
| 291 * FT_Open_Args open_args; | |
| 292 * | |
| 293 * | |
| 294 * // set up incremental descriptor | |
| 295 * inc_int.funcs = my_funcs; | |
| 296 * inc_int.object = my_object; | |
| 297 * | |
| 298 * // set up optional parameter | |
| 299 * parameter.tag = FT_PARAM_TAG_INCREMENTAL; | |
| 300 * parameter.data = &inc_int; | |
| 301 * | |
| 302 * // set up FT_Open_Args structure | |
| 303 * open_args.flags = FT_OPEN_PATHNAME | FT_OPEN_PARAMS; | |
| 304 * open_args.pathname = my_font_pathname; | |
| 305 * open_args.num_params = 1; | |
| 306 * open_args.params = ¶meter; // we use one optional argument | |
| 307 * | |
| 308 * // open the font | |
| 309 * error = FT_Open_Face( library, &open_args, index, &face ); | |
| 310 * ... | |
| 311 * } | |
| 312 * | |
| 313 */ | |
| 314 typedef struct FT_Incremental_InterfaceRec_ | |
| 315 { | |
| 316 const FT_Incremental_FuncsRec* funcs; | |
| 317 FT_Incremental object; | |
| 318 | |
| 319 } FT_Incremental_InterfaceRec; | |
| 320 | |
| 321 | |
| 322 /*************************************************************************** | |
| 323 * | |
| 324 * @type: | |
| 325 * FT_Incremental_Interface | |
| 326 * | |
| 327 * @description: | |
| 328 * A pointer to an @FT_Incremental_InterfaceRec structure. | |
| 329 * | |
| 330 */ | |
| 331 typedef FT_Incremental_InterfaceRec* FT_Incremental_Interface; | |
| 332 | |
| 333 | |
| 334 /*************************************************************************** | |
| 335 * | |
| 336 * @constant: | |
| 337 * FT_PARAM_TAG_INCREMENTAL | |
| 338 * | |
| 339 * @description: | |
| 340 * A constant used as the tag of @FT_Parameter structures to indicate | |
| 341 * an incremental loading object to be used by FreeType. | |
| 342 * | |
| 343 */ | |
| 344 #define FT_PARAM_TAG_INCREMENTAL FT_MAKE_TAG( 'i', 'n', 'c', 'r' ) | |
| 345 | |
| 346 /* */ | |
| 347 | |
| 348 | |
| 349 FT_END_HEADER | |
| 350 | |
| 351 #endif /* __FTINCREM_H__ */ | |
| 352 | |
| 353 | |
| 354 /* END */ | |
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