1 /***************************************************************************/ 2 /* */ 3 /* ftautoh.h */ 4 /* */ 5 /* FreeType API for controlling the auto-hinter (specification only). */ 6 /* */ 7 /* Copyright 2012-2015 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 __FTAUTOH_H__ 20 #define __FTAUTOH_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 * 37 * @section: 38 * auto_hinter 39 * 40 * @title: 41 * The auto-hinter 42 * 43 * @abstract: 44 * Controlling the auto-hinting module. 45 * 46 * @description: 47 * While FreeType's auto-hinter doesn't expose API functions by itself, 48 * it is possible to control its behaviour with @FT_Property_Set and 49 * @FT_Property_Get. The following lists the available properties 50 * together with the necessary macros and structures. 51 * 52 * Note that the auto-hinter's module name is `autofitter' for 53 * historical reasons. 54 * 55 */ 56 57 58 /************************************************************************** 59 * 60 * @property: 61 * glyph-to-script-map 62 * 63 * @description: 64 * *Experimental* *only* 65 * 66 * The auto-hinter provides various script modules to hint glyphs. 67 * Examples of supported scripts are Latin or CJK. Before a glyph is 68 * auto-hinted, the Unicode character map of the font gets examined, and 69 * the script is then determined based on Unicode character ranges, see 70 * below. 71 * 72 * OpenType fonts, however, often provide much more glyphs than 73 * character codes (small caps, superscripts, ligatures, swashes, etc.), 74 * to be controlled by so-called `features'. Handling OpenType features 75 * can be quite complicated and thus needs a separate library on top of 76 * FreeType. 77 * 78 * The mapping between glyph indices and scripts (in the auto-hinter 79 * sense, see the @FT_AUTOHINTER_SCRIPT_XXX values) is stored as an 80 * array with `num_glyphs' elements, as found in the font's @FT_Face 81 * structure. The `glyph-to-script-map' property returns a pointer to 82 * this array, which can be modified as needed. Note that the 83 * modification should happen before the first glyph gets processed by 84 * the auto-hinter so that the global analysis of the font shapes 85 * actually uses the modified mapping. 86 * 87 * The following example code demonstrates how to access it (omitting 88 * the error handling). 89 * 90 * { 91 * FT_Library library; 92 * FT_Face face; 93 * FT_Prop_GlyphToScriptMap prop; 94 * 95 * 96 * FT_Init_FreeType( &library ); 97 * FT_New_Face( library, "foo.ttf", 0, &face ); 98 * 99 * prop.face = face; 100 * 101 * FT_Property_Get( library, "autofitter", 102 * "glyph-to-script-map", &prop ); 103 * 104 * // adjust `prop.map' as needed right here 105 * 106 * FT_Load_Glyph( face, ..., FT_LOAD_FORCE_AUTOHINT ); 107 * } 108 * 109 */ 110 111 112 /************************************************************************** 113 * 114 * @enum: 115 * FT_AUTOHINTER_SCRIPT_XXX 116 * 117 * @description: 118 * *Experimental* *only* 119 * 120 * A list of constants used for the @glyph-to-script-map property to 121 * specify the script submodule the auto-hinter should use for hinting a 122 * particular glyph. 123 * 124 * @values: 125 * FT_AUTOHINTER_SCRIPT_NONE :: 126 * Don't auto-hint this glyph. 127 * 128 * FT_AUTOHINTER_SCRIPT_LATIN :: 129 * Apply the latin auto-hinter. For the auto-hinter, `latin' is a 130 * very broad term, including Cyrillic and Greek also since characters 131 * from those scripts share the same design constraints. 132 * 133 * By default, characters from the following Unicode ranges are 134 * assigned to this submodule. 135 * 136 * { 137 * U+0020 - U+007F // Basic Latin (no control characters) 138 * U+00A0 - U+00FF // Latin-1 Supplement (no control characters) 139 * U+0100 - U+017F // Latin Extended-A 140 * U+0180 - U+024F // Latin Extended-B 141 * U+0250 - U+02AF // IPA Extensions 142 * U+02B0 - U+02FF // Spacing Modifier Letters 143 * U+0300 - U+036F // Combining Diacritical Marks 144 * U+0370 - U+03FF // Greek and Coptic 145 * U+0400 - U+04FF // Cyrillic 146 * U+0500 - U+052F // Cyrillic Supplement 147 * U+1D00 - U+1D7F // Phonetic Extensions 148 * U+1D80 - U+1DBF // Phonetic Extensions Supplement 149 * U+1DC0 - U+1DFF // Combining Diacritical Marks Supplement 150 * U+1E00 - U+1EFF // Latin Extended Additional 151 * U+1F00 - U+1FFF // Greek Extended 152 * U+2000 - U+206F // General Punctuation 153 * U+2070 - U+209F // Superscripts and Subscripts 154 * U+20A0 - U+20CF // Currency Symbols 155 * U+2150 - U+218F // Number Forms 156 * U+2460 - U+24FF // Enclosed Alphanumerics 157 * U+2C60 - U+2C7F // Latin Extended-C 158 * U+2DE0 - U+2DFF // Cyrillic Extended-A 159 * U+2E00 - U+2E7F // Supplemental Punctuation 160 * U+A640 - U+A69F // Cyrillic Extended-B 161 * U+A720 - U+A7FF // Latin Extended-D 162 * U+FB00 - U+FB06 // Alphab. Present. Forms (Latin Ligatures) 163 * U+1D400 - U+1D7FF // Mathematical Alphanumeric Symbols 164 * U+1F100 - U+1F1FF // Enclosed Alphanumeric Supplement 165 * } 166 * 167 * FT_AUTOHINTER_SCRIPT_CJK :: 168 * Apply the CJK auto-hinter, covering Chinese, Japanese, Korean, old 169 * Vietnamese, and some other scripts. 170 * 171 * By default, characters from the following Unicode ranges are 172 * assigned to this submodule. 173 * 174 * { 175 * U+1100 - U+11FF // Hangul Jamo 176 * U+2E80 - U+2EFF // CJK Radicals Supplement 177 * U+2F00 - U+2FDF // Kangxi Radicals 178 * U+2FF0 - U+2FFF // Ideographic Description Characters 179 * U+3000 - U+303F // CJK Symbols and Punctuation 180 * U+3040 - U+309F // Hiragana 181 * U+30A0 - U+30FF // Katakana 182 * U+3100 - U+312F // Bopomofo 183 * U+3130 - U+318F // Hangul Compatibility Jamo 184 * U+3190 - U+319F // Kanbun 185 * U+31A0 - U+31BF // Bopomofo Extended 186 * U+31C0 - U+31EF // CJK Strokes 187 * U+31F0 - U+31FF // Katakana Phonetic Extensions 188 * U+3200 - U+32FF // Enclosed CJK Letters and Months 189 * U+3300 - U+33FF // CJK Compatibility 190 * U+3400 - U+4DBF // CJK Unified Ideographs Extension A 191 * U+4DC0 - U+4DFF // Yijing Hexagram Symbols 192 * U+4E00 - U+9FFF // CJK Unified Ideographs 193 * U+A960 - U+A97F // Hangul Jamo Extended-A 194 * U+AC00 - U+D7AF // Hangul Syllables 195 * U+D7B0 - U+D7FF // Hangul Jamo Extended-B 196 * U+F900 - U+FAFF // CJK Compatibility Ideographs 197 * U+FE10 - U+FE1F // Vertical forms 198 * U+FE30 - U+FE4F // CJK Compatibility Forms 199 * U+FF00 - U+FFEF // Halfwidth and Fullwidth Forms 200 * U+1B000 - U+1B0FF // Kana Supplement 201 * U+1D300 - U+1D35F // Tai Xuan Hing Symbols 202 * U+1F200 - U+1F2FF // Enclosed Ideographic Supplement 203 * U+20000 - U+2A6DF // CJK Unified Ideographs Extension B 204 * U+2A700 - U+2B73F // CJK Unified Ideographs Extension C 205 * U+2B740 - U+2B81F // CJK Unified Ideographs Extension D 206 * U+2F800 - U+2FA1F // CJK Compatibility Ideographs Supplement 207 * } 208 * 209 * FT_AUTOHINTER_SCRIPT_INDIC :: 210 * Apply the indic auto-hinter, covering all major scripts from the 211 * Indian sub-continent and some other related scripts like Thai, Lao, 212 * or Tibetan. 213 * 214 * By default, characters from the following Unicode ranges are 215 * assigned to this submodule. 216 * 217 * { 218 * U+0900 - U+0DFF // Indic Range 219 * U+0F00 - U+0FFF // Tibetan 220 * U+1900 - U+194F // Limbu 221 * U+1B80 - U+1BBF // Sundanese 222 * U+1C80 - U+1CDF // Meetei Mayak 223 * U+A800 - U+A82F // Syloti Nagri 224 * U+11800 - U+118DF // Sharada 225 * } 226 * 227 * Note that currently Indic support is rudimentary only, missing blue 228 * zone support. 229 * 230 */ 231 #define FT_AUTOHINTER_SCRIPT_NONE 0 232 #define FT_AUTOHINTER_SCRIPT_LATIN 1 233 #define FT_AUTOHINTER_SCRIPT_CJK 2 234 #define FT_AUTOHINTER_SCRIPT_INDIC 3 235 236 237 /************************************************************************** 238 * 239 * @struct: 240 * FT_Prop_GlyphToScriptMap 241 * 242 * @description: 243 * *Experimental* *only* 244 * 245 * The data exchange structure for the @glyph-to-script-map property. 246 * 247 */ 248 typedef struct FT_Prop_GlyphToScriptMap_ 249 { 250 FT_Face face; 251 FT_Byte* map; 252 253 } FT_Prop_GlyphToScriptMap; 254 255 256 /************************************************************************** 257 * 258 * @property: 259 * fallback-script 260 * 261 * @description: 262 * *Experimental* *only* 263 * 264 * If no auto-hinter script module can be assigned to a glyph, a 265 * fallback script gets assigned to it (see also the 266 * @glyph-to-script-map property). By default, this is 267 * @FT_AUTOHINTER_SCRIPT_CJK. Using the `fallback-script' property, 268 * this fallback value can be changed. 269 * 270 * { 271 * FT_Library library; 272 * FT_UInt fallback_script = FT_AUTOHINTER_SCRIPT_NONE; 273 * 274 * 275 * FT_Init_FreeType( &library ); 276 * 277 * FT_Property_Set( library, "autofitter", 278 * "fallback-script", &fallback_script ); 279 * } 280 * 281 * @note: 282 * This property can be used with @FT_Property_Get also. 283 * 284 * It's important to use the right timing for changing this value: The 285 * creation of the glyph-to-script map that eventually uses the 286 * fallback script value gets triggered either by setting or reading a 287 * face-specific property like @glyph-to-script-map, or by auto-hinting 288 * any glyph from that face. In particular, if you have already created 289 * an @FT_Face structure but not loaded any glyph (using the 290 * auto-hinter), a change of the fallback script will affect this face. 291 * 292 */ 293 294 295 /************************************************************************** 296 * 297 * @property: 298 * default-script 299 * 300 * @description: 301 * *Experimental* *only* 302 * 303 * If FreeType gets compiled with FT_CONFIG_OPTION_USE_HARFBUZZ to make 304 * the HarfBuzz library access OpenType features for getting better 305 * glyph coverages, this property sets the (auto-fitter) script to be 306 * used for the default (OpenType) script data of a font's GSUB table. 307 * Features for the default script are intended for all scripts not 308 * explicitly handled in GSUB; an example is a `dlig' feature, 309 * containing the combination of the characters `T', `E', and `L' to 310 * form a `TEL' ligature. 311 * 312 * By default, this is @FT_AUTOHINTER_SCRIPT_LATIN. Using the 313 * `default-script' property, this default value can be changed. 314 * 315 * { 316 * FT_Library library; 317 * FT_UInt default_script = FT_AUTOHINTER_SCRIPT_NONE; 318 * 319 * 320 * FT_Init_FreeType( &library ); 321 * 322 * FT_Property_Set( library, "autofitter", 323 * "default-script", &default_script ); 324 * } 325 * 326 * @note: 327 * This property can be used with @FT_Property_Get also. 328 * 329 * It's important to use the right timing for changing this value: The 330 * creation of the glyph-to-script map that eventually uses the 331 * default script value gets triggered either by setting or reading a 332 * face-specific property like @glyph-to-script-map, or by auto-hinting 333 * any glyph from that face. In particular, if you have already created 334 * an @FT_Face structure but not loaded any glyph (using the 335 * auto-hinter), a change of the default script will affect this face. 336 * 337 */ 338 339 340 /************************************************************************** 341 * 342 * @property: 343 * increase-x-height 344 * 345 * @description: 346 * For ppem values in the range 6~<= ppem <= `increase-x-height', round 347 * up the font's x~height much more often than normally. If the value 348 * is set to~0, which is the default, this feature is switched off. Use 349 * this property to improve the legibility of small font sizes if 350 * necessary. 351 * 352 * { 353 * FT_Library library; 354 * FT_Face face; 355 * FT_Prop_IncreaseXHeight prop; 356 * 357 * 358 * FT_Init_FreeType( &library ); 359 * FT_New_Face( library, "foo.ttf", 0, &face ); 360 * FT_Set_Char_Size( face, 10 * 64, 0, 72, 0 ); 361 * 362 * prop.face = face; 363 * prop.limit = 14; 364 * 365 * FT_Property_Set( library, "autofitter", 366 * "increase-x-height", &prop ); 367 * } 368 * 369 * @note: 370 * This property can be used with @FT_Property_Get also. 371 * 372 * Set this value right after calling @FT_Set_Char_Size, but before 373 * loading any glyph (using the auto-hinter). 374 * 375 */ 376 377 378 /************************************************************************** 379 * 380 * @struct: 381 * FT_Prop_IncreaseXHeight 382 * 383 * @description: 384 * The data exchange structure for the @increase-x-height property. 385 * 386 */ 387 typedef struct FT_Prop_IncreaseXHeight_ 388 { 389 FT_Face face; 390 FT_UInt limit; 391 392 } FT_Prop_IncreaseXHeight; 393 394 395 /************************************************************************** 396 * 397 * @property: 398 * warping 399 * 400 * @description: 401 * *Experimental* *only* 402 * 403 * If FreeType gets compiled with option AF_CONFIG_OPTION_USE_WARPER to 404 * activate the warp hinting code in the auto-hinter, this property 405 * switches warping on and off. 406 * 407 * Warping only works in `light' auto-hinting mode. The idea of the 408 * code is to slightly scale and shift a glyph along the non-hinted 409 * dimension (which is usually the horizontal axis) so that as much of 410 * its segments are aligned (more or less) to the grid. To find out a 411 * glyph's optimal scaling and shifting value, various parameter 412 * combinations are tried and scored. 413 * 414 * By default, warping is off. The example below shows how to switch on 415 * warping (omitting the error handling). 416 * 417 * { 418 * FT_Library library; 419 * FT_Bool warping = 1; 420 * 421 * 422 * FT_Init_FreeType( &library ); 423 * 424 * FT_Property_Set( library, "autofitter", 425 * "warping", &warping ); 426 * } 427 * 428 * @note: 429 * This property can be used with @FT_Property_Get also. 430 * 431 * The warping code can also change advance widths. Have a look at the 432 * `lsb_delta' and `rsb_delta' fields in the @FT_GlyphSlotRec structure 433 * for details on improving inter-glyph distances while rendering. 434 * 435 * Since warping is a global property of the auto-hinter it is best to 436 * change its value before rendering any face. Otherwise, you should 437 * reload all faces that get auto-hinted in `light' hinting mode. 438 * 439 */ 440 441 442 /* */ 443 444 445 FT_END_HEADER 446 447 #endif /* __FTAUTOH_H__ */ 448 449 450 /* END */ 451
