1 // afblue.dat 2 // 3 // Auto-fitter data for blue strings. 4 // 5 // Copyright 2013, 2014 by 6 // David Turner, Robert Wilhelm, and Werner Lemberg. 7 // 8 // This file is part of the FreeType project, and may only be used, 9 // modified, and distributed under the terms of the FreeType project 10 // license, LICENSE.TXT. By continuing to use, modify, or distribute 11 // this file you indicate that you have read the license and 12 // understand and accept it fully. 13 14 15 // This file contains data specific to blue zones. It gets processed by 16 // a script to simulate `jagged arrays', with enumeration values holding 17 // offsets into the arrays. 18 // 19 // The format of the file is rather simple: A section starts with three 20 // labels separated by whitespace and followed by a colon (everything in a 21 // single line); the first label gives the name of the enumeration template, 22 // the second the name of the array template, and the third the name of the 23 // `maximum' template, holding the size of the largest array element. The 24 // script then fills the corresponding templates (indicated by `@' 25 // characters around the name). 26 // 27 // A section contains one or more data records. Each data record consists 28 // of two or more lines. The first line holds the enumeration name, and the 29 // remaining lines the corresponding array data. 30 // 31 // There are two possible representations for array data. 32 // 33 // - A string of characters in UTF-8 encoding enclosed in double quotes, 34 // using C syntax. There can be only one string per line, thus the 35 // starting and ending double quote must be the first and last character 36 // in the line, respectively, ignoring whitespace before and after the 37 // string. Space characters within the string are ignored too. If there 38 // are multiple strings (in multiple lines), they are concatenated to a 39 // single string. In the output, a string gets represented as a series of 40 // singles bytes, followed by a zero byte. The enumeration values simply 41 // hold byte offsets to the start of the corresponding strings. 42 // 43 // - Data blocks enclosed in balanced braces, which get copied verbatim and 44 // which can span multiple lines. The opening brace of a block must be 45 // the first character of a line (ignoring whitespace), and the closing 46 // brace the last (ignoring whitespace also). The script appends a comma 47 // character after each block and counts the number of blocks to set the 48 // enumeration values. 49 // 50 // A section can contain either strings only or data blocks only. 51 // 52 // A comment line starts with `//'; it gets removed. A preprocessor 53 // directive line (using the standard syntax of `cpp') starts with `#' and 54 // gets copied verbatim to both the enumeration and the array. Whitespace 55 // outside of a string is insignificant. 56 // 57 // Preprocessor directives are ignored while the script computes maximum 58 // values; this essentially means that the maximum values can easily be too 59 // large. Given that the purpose of those values is to create local 60 // fixed-size arrays at compile time for further processing of the blue zone 61 // data, this isn't a problem. Note the the final zero byte of a string is 62 // not counted. Note also that the count holds the number of UTF-8 encoded 63 // characters, not bytes. 64 65 66 // The blue zone string data, to be used in the blue stringsets below. 67 68 AF_BLUE_STRING_ENUM AF_BLUE_STRINGS_ARRAY AF_BLUE_STRING_MAX_LEN: 69 70 AF_BLUE_STRING_CYRILLIC_CAPITAL_TOP 71 "" 72 AF_BLUE_STRING_CYRILLIC_CAPITAL_BOTTOM 73 "" 74 AF_BLUE_STRING_CYRILLIC_SMALL 75 "" 76 AF_BLUE_STRING_CYRILLIC_SMALL_DESCENDER 77 "" 78 79 // we separate the letters with spaces to avoid ligatures; 80 // this is just for convenience to simplify reading 81 AF_BLUE_STRING_DEVANAGARI_BASE 82 " " 83 AF_BLUE_STRING_DEVANAGARI_TOP 84 " " 85 // note that some fonts have extreme variation in the height of the 86 // round head elements; for this reason we also define the `base' 87 // blue zone, which must be always present 88 AF_BLUE_STRING_DEVANAGARI_HEAD 89 " " 90 AF_BLUE_STRING_DEVANAGARI_BOTTOM 91 " " 92 93 AF_BLUE_STRING_GREEK_CAPITAL_TOP 94 "" 95 AF_BLUE_STRING_GREEK_CAPITAL_BOTTOM 96 "" 97 AF_BLUE_STRING_GREEK_SMALL_BETA_TOP 98 "" 99 AF_BLUE_STRING_GREEK_SMALL 100 "" 101 AF_BLUE_STRING_GREEK_SMALL_DESCENDER 102 "" 103 104 AF_BLUE_STRING_HEBREW_TOP 105 "" 106 AF_BLUE_STRING_HEBREW_BOTTOM 107 "" 108 AF_BLUE_STRING_HEBREW_DESCENDER 109 "" 110 111 AF_BLUE_STRING_LATIN_CAPITAL_TOP 112 "THEZOCQS" 113 AF_BLUE_STRING_LATIN_CAPITAL_BOTTOM 114 "HEZLOCUS" 115 AF_BLUE_STRING_LATIN_SMALL_F_TOP 116 "fijkdbh" 117 AF_BLUE_STRING_LATIN_SMALL 118 "xzroesc" 119 AF_BLUE_STRING_LATIN_SMALL_DESCENDER 120 "pqgjy" 121 122 #ifdef AF_CONFIG_OPTION_CJK 123 124 AF_BLUE_STRING_CJK_TOP 125 "" 126 "" 127 "" 128 " |" 129 "" 130 "" 131 "" 132 "" 133 AF_BLUE_STRING_CJK_BOTTOM 134 "" 135 "" 136 "" 137 " |" 138 "" 139 "" 140 "" 141 "" 142 143 #ifdef AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT 144 145 AF_BLUE_STRING_CJK_LEFT 146 "" 147 "" 148 "" 149 " |" 150 "" 151 "" 152 "" 153 "" 154 AF_BLUE_STRING_CJK_RIGHT 155 "" 156 "" 157 "" 158 " |" 159 "" 160 "" 161 "" 162 "" 163 164 #endif /* AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT */ 165 166 #endif /* AF_CONFIG_OPTION_CJK */ 167 168 169 // The blue zone stringsets, as used in the script styles, cf. `afstyles.h'. 170 // 171 // The AF_BLUE_PROPERTY_XXX flags are defined in `afblue.h'; here some 172 // explanations. 173 // 174 // A blue zone in general is defined by a reference and an overshoot line. 175 // During the hinting process, all coordinate values between those two lines 176 // are set equal to the reference value, provided that the blue zone is not 177 // wider than 0.75 pixels (otherwise the blue zone gets ignored). All 178 // entries must have `AF_BLUE_STRING_MAX' as the final line. 179 // 180 // During the glyph analysis, edges are sorted from bottom to top, and then 181 // sequentially checked, edge by edge, against the blue zones in the order 182 // given below. 183 // 184 // 185 // latin auto-hinter 186 // ----------------- 187 // 188 // Characters in a blue string are automatically classified as having a flat 189 // (reference) or a round (overshoot) extremum. The blue zone is then set 190 // up by the mean values of all flat extrema and all round extrema, 191 // respectively. Only horizontal blue zones (i.e., adjusting vertical 192 // coordinate values) are supported. 193 // 194 // For the latin auto-hinter, the overshoot should be larger than the 195 // reference for top zones, and vice versa for bottom zones. 196 // 197 // LATIN_TOP 198 // Take the maximum flat and round coordinate values of the blue string 199 // characters for computing the blue zone's reference and overshoot 200 // values. 201 // 202 // If not set, take the minimum values. 203 // 204 // LATIN_NEUTRAL 205 // Ignore round extrema and define the blue zone with flat values only. 206 // Both top and bottom of contours can match. This is useful for 207 // scripts like Devanagari where vowel signs attach to the base 208 // character and are implemented as components of composite glyphs. 209 // 210 // If not set, both round and flat extrema are taken into account. 211 // Additionally, only the top or the bottom of a contour can match, 212 // depending on the LATIN_TOP flag. 213 // 214 // Neutral blue zones should always follow non-neutral blue zones. 215 // 216 // LATIN_X_HEIGHT 217 // Scale all glyphs vertically from the corresponding script to make the 218 // reference line of this blue zone align on the grid. The scaling 219 // takes place before all other blue zones get aligned to the grid. 220 // Only one blue character string of a script style can have this flag. 221 // 222 // LATIN_LONG 223 // Apply an additional constraint for blue zone values: Don't 224 // necessarily use the extremum as-is but a segment of the topmost (or 225 // bottommost) contour that is longer than a heuristic threshold, and 226 // which is not too far away vertically from the real extremum. This 227 // ensures that small bumps in the outline are ignored (for example, the 228 // `vertical serifs' found in many Hebrew glyph designs). 229 // 230 // The segment must be at least EM/25 font units long, and the distance 231 // to the extremum must be smaller than EM/4. 232 // 233 // 234 // cjk auto-hinter 235 // --------------- 236 // 237 // Characters in a blue string are *not* automatically classified. Instead, 238 // first come the characters used for the overshoot value, then the 239 // character `|', then the characters used for the reference value. The 240 // blue zone is then set up by the mean values of all reference values and 241 // all overshoot values, respectively. Both horizontal and vertical blue 242 // zones (i.e., adjusting vertical and horizontal coordinate values, 243 // respectively) are supported. 244 // 245 // For the cjk auto-hinter, the overshoot should be smaller than the 246 // reference for top zones, and vice versa for bottom zones. 247 // 248 // CJK_TOP 249 // Take the maximum flat and round coordinate values of the blue string 250 // characters. If not set, take the minimum values. 251 // 252 // CJK_RIGHT 253 // A synonym for CJK_TOP. If CJK_HORIZ is set, this flag indicates the 254 // right blue zone, taking horizontal maximum values. 255 // 256 // CJK_HORIZ 257 // Define a blue zone for horizontal hinting (i.e., vertical blue 258 // zones). If not set, this is a blue zone for vertical hinting. 259 260 261 AF_BLUE_STRINGSET_ENUM AF_BLUE_STRINGSETS_ARRAY AF_BLUE_STRINGSET_MAX_LEN: 262 263 AF_BLUE_STRINGSET_CYRL 264 { AF_BLUE_STRING_CYRILLIC_CAPITAL_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 265 { AF_BLUE_STRING_CYRILLIC_CAPITAL_BOTTOM, 0 } 266 { AF_BLUE_STRING_CYRILLIC_SMALL, AF_BLUE_PROPERTY_LATIN_TOP | 267 AF_BLUE_PROPERTY_LATIN_X_HEIGHT } 268 { AF_BLUE_STRING_CYRILLIC_SMALL, 0 } 269 { AF_BLUE_STRING_CYRILLIC_SMALL_DESCENDER, 0 } 270 { AF_BLUE_STRING_MAX, 0 } 271 272 AF_BLUE_STRINGSET_DEVA 273 { AF_BLUE_STRING_DEVANAGARI_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 274 { AF_BLUE_STRING_DEVANAGARI_HEAD, AF_BLUE_PROPERTY_LATIN_TOP } 275 { AF_BLUE_STRING_DEVANAGARI_BASE, AF_BLUE_PROPERTY_LATIN_TOP | 276 AF_BLUE_PROPERTY_LATIN_NEUTRAL | 277 AF_BLUE_PROPERTY_LATIN_X_HEIGHT } 278 { AF_BLUE_STRING_DEVANAGARI_BASE, 0 } 279 { AF_BLUE_STRING_DEVANAGARI_BOTTOM, 0 } 280 { AF_BLUE_STRING_MAX, 0 } 281 282 AF_BLUE_STRINGSET_GREK 283 { AF_BLUE_STRING_GREEK_CAPITAL_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 284 { AF_BLUE_STRING_GREEK_CAPITAL_BOTTOM, 0 } 285 { AF_BLUE_STRING_GREEK_SMALL_BETA_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 286 { AF_BLUE_STRING_GREEK_SMALL, AF_BLUE_PROPERTY_LATIN_TOP | 287 AF_BLUE_PROPERTY_LATIN_X_HEIGHT } 288 { AF_BLUE_STRING_GREEK_SMALL, 0 } 289 { AF_BLUE_STRING_GREEK_SMALL_DESCENDER, 0 } 290 { AF_BLUE_STRING_MAX, 0 } 291 292 AF_BLUE_STRINGSET_HEBR 293 { AF_BLUE_STRING_HEBREW_TOP, AF_BLUE_PROPERTY_LATIN_TOP | 294 AF_BLUE_PROPERTY_LATIN_LONG } 295 { AF_BLUE_STRING_HEBREW_BOTTOM, 0 } 296 { AF_BLUE_STRING_HEBREW_DESCENDER, 0 } 297 { AF_BLUE_STRING_MAX, 0 } 298 299 AF_BLUE_STRINGSET_LATN 300 { AF_BLUE_STRING_LATIN_CAPITAL_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 301 { AF_BLUE_STRING_LATIN_CAPITAL_BOTTOM, 0 } 302 { AF_BLUE_STRING_LATIN_SMALL_F_TOP, AF_BLUE_PROPERTY_LATIN_TOP } 303 { AF_BLUE_STRING_LATIN_SMALL, AF_BLUE_PROPERTY_LATIN_TOP | 304 AF_BLUE_PROPERTY_LATIN_X_HEIGHT } 305 { AF_BLUE_STRING_LATIN_SMALL, 0 } 306 { AF_BLUE_STRING_LATIN_SMALL_DESCENDER, 0 } 307 { AF_BLUE_STRING_MAX, 0 } 308 309 #ifdef AF_CONFIG_OPTION_CJK 310 311 AF_BLUE_STRINGSET_HANI 312 { AF_BLUE_STRING_CJK_TOP, AF_BLUE_PROPERTY_CJK_TOP } 313 { AF_BLUE_STRING_CJK_BOTTOM, 0 } 314 #ifdef AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT 315 { AF_BLUE_STRING_CJK_LEFT, AF_BLUE_PROPERTY_CJK_HORIZ } 316 { AF_BLUE_STRING_CJK_RIGHT, AF_BLUE_PROPERTY_CJK_HORIZ | 317 AF_BLUE_PROPERTY_CJK_RIGHT } 318 #endif /* AF_CONFIG_OPTION_CJK_BLUE_HANI_VERT */ 319 { AF_BLUE_STRING_MAX, 0 } 320 321 #endif /* AF_CONFIG_OPTION_CJK */ 322 323 324 // END 325
