hb-ot-shape-complex-indic.cc revision 3d25079f8d6be81b9b4b91d3a97016b8a572f571
1/* 2 * Copyright © 2011 Google, Inc. 3 * 4 * This is part of HarfBuzz, a text shaping library. 5 * 6 * Permission is hereby granted, without written agreement and without 7 * license or royalty fees, to use, copy, modify, and distribute this 8 * software and its documentation for any purpose, provided that the 9 * above copyright notice and the following two paragraphs appear in 10 * all copies of this software. 11 * 12 * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR 13 * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES 14 * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN 15 * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH 16 * DAMAGE. 17 * 18 * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, 19 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 20 * FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS 21 * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO 22 * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS. 23 * 24 * Google Author(s): Behdad Esfahbod 25 */ 26 27 28#include "hb-ot-shape-complex-indic-private.hh" 29 30static int 31compare_codepoint (const void *pa, const void *pb) 32{ 33 hb_codepoint_t a = * (hb_codepoint_t *) pa; 34 hb_codepoint_t b = * (hb_codepoint_t *) pb; 35 36 return a < b ? -1 : a == b ? 0 : +1; 37} 38 39static indic_position_t 40consonant_position (hb_codepoint_t u) 41{ 42 consonant_position_t *record; 43 44 record = (consonant_position_t *) bsearch (&u, consonant_positions, 45 ARRAY_LENGTH (consonant_positions), 46 sizeof (consonant_positions[0]), 47 compare_codepoint); 48 49 return record ? record->position : POS_BASE_C; 50} 51 52static bool 53is_ra (hb_codepoint_t u) 54{ 55 return !!bsearch (&u, ra_chars, 56 ARRAY_LENGTH (ra_chars), 57 sizeof (ra_chars[0]), 58 compare_codepoint); 59} 60 61static bool 62is_joiner (const hb_glyph_info_t &info) 63{ 64 return !!(FLAG (info.indic_category()) & (FLAG (OT_ZWJ) | FLAG (OT_ZWNJ))); 65} 66 67static bool 68is_consonant (const hb_glyph_info_t &info) 69{ 70 return !!(FLAG (info.indic_category()) & (FLAG (OT_C) | FLAG (OT_Ra))); 71} 72 73static const struct { 74 hb_tag_t tag; 75 hb_bool_t is_global; 76} indic_basic_features[] = 77{ 78 {HB_TAG('n','u','k','t'), true}, 79 {HB_TAG('a','k','h','n'), false}, 80 {HB_TAG('r','p','h','f'), false}, 81 {HB_TAG('r','k','r','f'), true}, 82 {HB_TAG('p','r','e','f'), false}, 83 {HB_TAG('b','l','w','f'), false}, 84 {HB_TAG('h','a','l','f'), false}, 85 {HB_TAG('v','a','t','u'), true}, 86 {HB_TAG('p','s','t','f'), false}, 87 {HB_TAG('c','j','c','t'), false}, 88}; 89 90/* Same order as the indic_basic_features array */ 91enum { 92 _NUKT, 93 AKHN, 94 RPHF, 95 _RKRF, 96 PREF, 97 BLWF, 98 HALF, 99 _VATU, 100 PSTF, 101 CJCT 102}; 103 104static const hb_tag_t indic_other_features[] = 105{ 106 HB_TAG('p','r','e','s'), 107 HB_TAG('a','b','v','s'), 108 HB_TAG('b','l','w','s'), 109 HB_TAG('p','s','t','s'), 110 HB_TAG('h','a','l','n'), 111 112 HB_TAG('d','i','s','t'), 113 HB_TAG('a','b','v','m'), 114 HB_TAG('b','l','w','m'), 115}; 116 117 118static void 119initial_reordering (const hb_ot_map_t *map, 120 hb_face_t *face, 121 hb_buffer_t *buffer, 122 void *user_data HB_UNUSED); 123static void 124final_reordering (const hb_ot_map_t *map, 125 hb_face_t *face, 126 hb_buffer_t *buffer, 127 void *user_data HB_UNUSED); 128 129void 130_hb_ot_shape_complex_collect_features_indic (hb_ot_map_builder_t *map, const hb_segment_properties_t *props) 131{ 132 map->add_bool_feature (HB_TAG('l','o','c','l')); 133 /* The Indic specs do not require ccmp, but we apply it here since if 134 * there is a use of it, it's typically at the beginning. */ 135 map->add_bool_feature (HB_TAG('c','c','m','p')); 136 137 map->add_gsub_pause (initial_reordering, NULL); 138 139 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_basic_features); i++) { 140 map->add_bool_feature (indic_basic_features[i].tag, indic_basic_features[i].is_global); 141 map->add_gsub_pause (NULL, NULL); 142 } 143 144 map->add_gsub_pause (final_reordering, NULL); 145 146 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_other_features); i++) { 147 map->add_bool_feature (indic_other_features[i], true); 148 map->add_gsub_pause (NULL, NULL); 149 } 150} 151 152 153hb_ot_shape_normalization_mode_t 154_hb_ot_shape_complex_normalization_preference_indic (void) 155{ 156 /* We want split matras decomposed by the common shaping logic. */ 157 return HB_OT_SHAPE_NORMALIZATION_MODE_DECOMPOSED; 158} 159 160 161void 162_hb_ot_shape_complex_setup_masks_indic (hb_ot_map_t *map, hb_buffer_t *buffer, hb_font_t *font) 163{ 164 HB_BUFFER_ALLOCATE_VAR (buffer, indic_category); 165 HB_BUFFER_ALLOCATE_VAR (buffer, indic_position); 166 HB_BUFFER_ALLOCATE_VAR (buffer, indic_syllable); 167 168 /* We cannot setup masks here. We save information about characters 169 * and setup masks later on in a pause-callback. */ 170 171 unsigned int count = buffer->len; 172 for (unsigned int i = 0; i < count; i++) 173 { 174 hb_glyph_info_t &info = buffer->info[i]; 175 unsigned int type = get_indic_categories (info.codepoint); 176 177 info.indic_category() = type & 0x0F; 178 info.indic_position() = type >> 4; 179 180 if (info.indic_category() == OT_C) { 181 info.indic_position() = consonant_position (info.codepoint); 182 if (is_ra (info.codepoint)) 183 info.indic_category() = OT_Ra; 184 } else if (info.indic_category() == OT_SM || 185 info.indic_category() == OT_VD) { 186 info.indic_position() = POS_SMVD; 187 } else if (unlikely (info.codepoint == 0x200C)) 188 info.indic_category() = OT_ZWNJ; 189 else if (unlikely (info.codepoint == 0x200D)) 190 info.indic_category() = OT_ZWJ; 191 192 if (unlikely (info.codepoint == 0x0952)) { 193 info.indic_category() = OT_A; 194 info.indic_position() = POS_SMVD; 195 } 196 } 197} 198 199static int 200compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb) 201{ 202 int a = pa->indic_position(); 203 int b = pb->indic_position(); 204 205 return a < b ? -1 : a == b ? 0 : +1; 206} 207 208static void 209initial_reordering_consonant_syllable (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array, 210 unsigned int start, unsigned int end) 211{ 212 unsigned int i; 213 hb_glyph_info_t *info = buffer->info; 214 215 /* Comments from: 216 * https://www.microsoft.com/typography/otfntdev/devanot/shaping.aspx */ 217 218 /* 1. Find base consonant: 219 * 220 * The shaping engine finds the base consonant of the syllable, using the 221 * following algorithm: starting from the end of the syllable, move backwards 222 * until a consonant is found that does not have a below-base or post-base 223 * form (post-base forms have to follow below-base forms), or that is not a 224 * pre-base reordering Ra, or arrive at the first consonant. The consonant 225 * stopped at will be the base. 226 * 227 * o If the syllable starts with Ra + Halant (in a script that has Reph) 228 * and has more than one consonant, Ra is excluded from candidates for 229 * base consonants. 230 */ 231 232 unsigned int base = end; 233 bool has_reph = false; 234 235 /* -> If the syllable starts with Ra + Halant (in a script that has Reph) 236 * and has more than one consonant, Ra is excluded from candidates for 237 * base consonants. */ 238 unsigned int limit = start; 239 if (mask_array[RPHF] && 240 start + 2 < end && 241 info[start].indic_category() == OT_Ra && 242 info[start + 1].indic_category() == OT_H) 243 { 244 limit += 2; 245 base = start; 246 has_reph = true; 247 }; 248 249 /* -> starting from the end of the syllable, move backwards */ 250 i = end; 251 do { 252 i--; 253 /* -> until a consonant is found */ 254 if (is_consonant (info[i])) 255 { 256 /* -> that does not have a below-base or post-base form 257 * (post-base forms have to follow below-base forms), */ 258 if (info[i].indic_position() != POS_BELOW_C && 259 info[i].indic_position() != POS_POST_C) 260 { 261 base = i; 262 break; 263 } 264 265 /* -> or that is not a pre-base reordering Ra, 266 * 267 * TODO 268 */ 269 270 /* -> o If the syllable starts with Ra + Halant (in a script that has Reph) 271 * and has more than one consonant, Ra is excluded from candidates for 272 * base consonants. 273 * 274 * IMPLEMENTATION NOTES: 275 * 276 * We do this by adjusting limit accordingly before entering the loop. 277 */ 278 279 /* -> or arrive at the first consonant. The consonant stopped at will 280 * be the base. */ 281 base = i; 282 } 283 else 284 if (is_joiner (info[i])) 285 break; 286 } while (i > limit); 287 if (base < start) 288 base = start; /* Just in case... */ 289 290 /* -> If the syllable starts with Ra + Halant (in a script that has Reph) 291 * and has more than one consonant, Ra is excluded from candidates for 292 * base consonants. */ 293 if (has_reph && base == start) { 294 /* Have no other consonant, so Reph is not formed and Ra becomes base. */ 295 has_reph = false; 296 } 297 298 299 300 301 /* 2. Decompose and reorder Matras: 302 * 303 * Each matra and any syllable modifier sign in the cluster are moved to the 304 * appropriate position relative to the consonant(s) in the cluster. The 305 * shaping engine decomposes two- or three-part matras into their constituent 306 * parts before any repositioning. Matra characters are classified by which 307 * consonant in a conjunct they have affinity for and are reordered to the 308 * following positions: 309 * 310 * o Before first half form in the syllable 311 * o After subjoined consonants 312 * o After post-form consonant 313 * o After main consonant (for above marks) 314 * 315 * IMPLEMENTATION NOTES: 316 * 317 * The normalize() routine has already decomposed matras for us, so we don't 318 * need to worry about that. 319 */ 320 321 322 /* 3. Reorder marks to canonical order: 323 * 324 * Adjacent nukta and halant or nukta and vedic sign are always repositioned 325 * if necessary, so that the nukta is first. 326 * 327 * IMPLEMENTATION NOTES: 328 * 329 * We don't need to do this: the normalize() routine already did this for us. 330 */ 331 332 333 /* Reorder characters */ 334 335 for (i = start; i < base; i++) 336 info[i].indic_position() = POS_PRE_C; 337 info[base].indic_position() = POS_BASE_C; 338 339 340 /* Handle beginning Ra */ 341 if (has_reph && 342 start + 3 <= end && 343 !is_joiner (info[start + 2])) 344 { 345 info[start].indic_position() = POS_REPH; 346 info[start].mask = mask_array[RPHF]; 347 } 348 349 /* For old-style Indic script tags, move the first post-base Halant after 350 * last consonant. */ 351 if ((map->get_chosen_script (0) & 0x000000FF) != '2') { 352 /* We should only do this for Indic scripts which have a version two I guess. */ 353 for (i = base + 1; i < end; i++) 354 if (info[i].indic_category() == OT_H) { 355 unsigned int j; 356 for (j = end - 1; j > i; j--) 357 if ((FLAG (info[j].indic_category()) & (FLAG (OT_C) | FLAG (OT_Ra)))) 358 break; 359 if (j > i) { 360 /* Move Halant to after last consonant. */ 361 hb_glyph_info_t t = info[i]; 362 memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0])); 363 info[j] = t; 364 } 365 break; 366 } 367 } 368 369 /* Attach ZWJ, ZWNJ, nukta, and halant to previous char to move with them. */ 370 for (i = start + 1; i < end; i++) 371 if ((FLAG (info[i].indic_category()) & 372 (FLAG (OT_ZWNJ) | FLAG (OT_ZWJ) | FLAG (OT_N) | FLAG (OT_H)))) 373 info[i].indic_position() = info[i - 1].indic_position(); 374 375 /* We do bubble-sort, skip malicious clusters attempts */ 376 if (end - start < 64) 377 { 378 /* Sit tight, rock 'n roll! */ 379 hb_bubble_sort (info + start, end - start, compare_indic_order); 380 /* Find base again */ 381 base = end; 382 for (i = start; i < end; i++) 383 if (info[i].indic_position() == POS_BASE_C) { 384 base = i; 385 break; 386 } 387 } 388 389 /* Setup masks now */ 390 391 { 392 hb_mask_t mask; 393 394 /* Pre-base */ 395 mask = mask_array[HALF] | mask_array[AKHN] | mask_array[CJCT]; 396 for (i = start; i < base; i++) 397 info[i].mask |= mask; 398 /* Base */ 399 mask = mask_array[AKHN] | mask_array[CJCT]; 400 info[base].mask |= mask; 401 /* Post-base */ 402 mask = mask_array[BLWF] | mask_array[PSTF] | mask_array[CJCT]; 403 for (i = base + 1; i < end; i++) 404 info[i].mask |= mask; 405 } 406 407 /* Apply ZWJ/ZWNJ effects */ 408 for (i = start + 1; i < end; i++) 409 if (is_joiner (info[i])) { 410 bool non_joiner = info[i].indic_category() == OT_ZWNJ; 411 unsigned int j = i; 412 413 do { 414 j--; 415 416 /* Reading the Unicode and OpenType specs, I think the following line 417 * is correct, but this is not what the test suite expects currently. 418 * The test suite has been drinking, not me... But disable while 419 * investigating. 420 */ 421 //info[j].mask &= !mask_array[CJCT]; 422 if (non_joiner) 423 info[j].mask &= !mask_array[HALF]; 424 425 } while (j > start && !is_consonant (info[j])); 426 } 427} 428 429 430static void 431initial_reordering_vowel_syllable (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array, 432 unsigned int start, unsigned int end) 433{ 434 /* TODO 435 * Not clear to me how this should work. Do the matras move to before the 436 * independent vowel? No idea. 437 */ 438} 439 440static void 441initial_reordering_standalone_cluster (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array, 442 unsigned int start, unsigned int end) 443{ 444 /* TODO 445 * Easiest thing to do here is to convert the NBSP to consonant and 446 * call initial_reordering_consonant_syllable. 447 */ 448} 449 450static void 451initial_reordering_non_indic (const hb_ot_map_t *map, hb_buffer_t *buffer, hb_mask_t *mask_array, 452 unsigned int start, unsigned int end) 453{ 454 /* Nothing to do right now. If we ever switch to using the output 455 * buffer in the reordering process, we'd need to next_glyph() here. */ 456} 457 458#include "hb-ot-shape-complex-indic-machine.hh" 459 460static void 461initial_reordering (const hb_ot_map_t *map, 462 hb_face_t *face, 463 hb_buffer_t *buffer, 464 void *user_data HB_UNUSED) 465{ 466 hb_mask_t mask_array[ARRAY_LENGTH (indic_basic_features)] = {0}; 467 unsigned int num_masks = ARRAY_LENGTH (indic_basic_features); 468 for (unsigned int i = 0; i < num_masks; i++) 469 mask_array[i] = map->get_1_mask (indic_basic_features[i].tag); 470 471 find_syllables (map, buffer, mask_array); 472} 473 474static void 475final_reordering_syllable (hb_buffer_t *buffer, 476 unsigned int start, unsigned int end) 477{ 478 /* 4. Final reordering: 479 * 480 * After the localized forms and basic shaping forms GSUB features have been 481 * applied (see below), the shaping engine performs some final glyph 482 * reordering before applying all the remaining font features to the entire 483 * cluster. 484 * 485 * o Reorder matras: 486 * 487 * If a pre-base matra character had been reordered before applying basic 488 * features, the glyph can be moved closer to the main consonant based on 489 * whether half-forms had been formed. Actual position for the matra is 490 * defined as “after last standalone halant glyph, after initial matra 491 * position and before the main consonant”. If ZWJ or ZWNJ follow this 492 * halant, position is moved after it. 493 * 494 * o Reorder reph: 495 * 496 * Reph’s original position is always at the beginning of the syllable, 497 * (i.e. it is not reordered at the character reordering stage). However, 498 * it will be reordered according to the basic-forms shaping results. 499 * Possible positions for reph, depending on the script, are; after main, 500 * before post-base consonant forms, and after post-base consonant forms. 501 * 502 * 1. If reph should be positioned after post-base consonant forms, 503 * proceed to step 5. 504 * 505 * 2. If the reph repositioning class is not after post-base: target 506 * position is after the first explicit halant glyph between the 507 * first post-reph consonant and last main consonant. If ZWJ or ZWNJ 508 * are following this halant, position is moved after it. If such 509 * position is found, this is the target position. Otherwise, 510 * proceed to the next step. 511 * 512 * Note: in old-implementation fonts, where classifications were 513 * fixed in shaping engine, there was no case where reph position 514 * will be found on this step. 515 * 516 * 3. If reph should be repositioned after the main consonant: from the 517 * first consonant not ligated with main, or find the first 518 * consonant that is not a potential pre-base reordering Ra. 519 * 520 * 521 * 4. If reph should be positioned before post-base consonant, find 522 * first post-base classified consonant not ligated with main. If no 523 * consonant is found, the target position should be before the 524 * first matra, syllable modifier sign or vedic sign. 525 * 526 * 5. If no consonant is found in steps 3 or 4, move reph to a position 527 * immediately before the first post-base matra, syllable modifier 528 * sign or vedic sign that has a reordering class after the intended 529 * reph position. For example, if the reordering position for reph 530 * is post-main, it will skip above-base matras that also have a 531 * post-main position. 532 * 533 * 6. Otherwise, reorder reph to the end of the syllable. 534 * 535 * o Reorder pre-base reordering consonants: 536 * 537 * If a pre-base reordering consonant is found, reorder it according to 538 * the following rules: 539 * 540 * 1. Only reorder a glyph produced by substitution during application 541 * of the feature. (Note that a font may shape a Ra consonant with 542 * the feature generally but block it in certain contexts.) 543 * 544 * 2. Try to find a target position the same way as for pre-base matra. 545 * If it is found, reorder pre-base consonant glyph. 546 * 547 * 3. If position is not found, reorder immediately before main 548 * consonant. 549 */ 550 551 /* TODO */ 552 buffer->merge_clusters (start, end); 553} 554 555 556static void 557final_reordering (const hb_ot_map_t *map, 558 hb_face_t *face, 559 hb_buffer_t *buffer, 560 void *user_data HB_UNUSED) 561{ 562 unsigned int count = buffer->len; 563 if (!count) return; 564 565 hb_glyph_info_t *info = buffer->info; 566 unsigned int last = 0; 567 unsigned int last_syllable = info[0].indic_syllable(); 568 for (unsigned int i = 1; i < count; i++) 569 if (last_syllable != info[i].indic_syllable()) { 570 final_reordering_syllable (buffer, last, i); 571 last = i; 572 last_syllable = info[last].indic_syllable(); 573 } 574 final_reordering_syllable (buffer, last, count); 575 576 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_syllable); 577 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category); 578 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position); 579} 580 581 582 583