1 /* 2 * Copyright © 2011,2012 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 #include "hb-ot-shape-complex-indic.hh" 28 #include "hb-ot-shape-complex-vowel-constraints.hh" 29 #include "hb-ot-layout.hh" 30 31 32 /* 33 * Indic shaper. 34 */ 35 36 37 /* 38 * Indic configurations. Note that we do not want to keep every single script-specific 39 * behavior in these tables necessarily. This should mainly be used for per-script 40 * properties that are cheaper keeping here, than in the code. Ie. if, say, one and 41 * only one script has an exception, that one script can be if'ed directly in the code, 42 * instead of adding a new flag in these structs. 43 */ 44 45 enum base_position_t { 46 BASE_POS_LAST_SINHALA, 47 BASE_POS_LAST 48 }; 49 enum reph_position_t { 50 REPH_POS_AFTER_MAIN = POS_AFTER_MAIN, 51 REPH_POS_BEFORE_SUB = POS_BEFORE_SUB, 52 REPH_POS_AFTER_SUB = POS_AFTER_SUB, 53 REPH_POS_BEFORE_POST = POS_BEFORE_POST, 54 REPH_POS_AFTER_POST = POS_AFTER_POST 55 }; 56 enum reph_mode_t { 57 REPH_MODE_IMPLICIT, /* Reph formed out of initial Ra,H sequence. */ 58 REPH_MODE_EXPLICIT, /* Reph formed out of initial Ra,H,ZWJ sequence. */ 59 REPH_MODE_LOG_REPHA /* Encoded Repha character, needs reordering. */ 60 }; 61 enum blwf_mode_t { 62 BLWF_MODE_PRE_AND_POST, /* Below-forms feature applied to pre-base and post-base. */ 63 BLWF_MODE_POST_ONLY /* Below-forms feature applied to post-base only. */ 64 }; 65 struct indic_config_t 66 { 67 hb_script_t script; 68 bool has_old_spec; 69 hb_codepoint_t virama; 70 base_position_t base_pos; 71 reph_position_t reph_pos; 72 reph_mode_t reph_mode; 73 blwf_mode_t blwf_mode; 74 }; 75 76 static const indic_config_t indic_configs[] = 77 { 78 /* Default. Should be first. */ 79 {HB_SCRIPT_INVALID, false, 0,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 80 {HB_SCRIPT_DEVANAGARI,true, 0x094Du,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 81 {HB_SCRIPT_BENGALI, true, 0x09CDu,BASE_POS_LAST, REPH_POS_AFTER_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 82 {HB_SCRIPT_GURMUKHI, true, 0x0A4Du,BASE_POS_LAST, REPH_POS_BEFORE_SUB, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 83 {HB_SCRIPT_GUJARATI, true, 0x0ACDu,BASE_POS_LAST, REPH_POS_BEFORE_POST,REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 84 {HB_SCRIPT_ORIYA, true, 0x0B4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 85 {HB_SCRIPT_TAMIL, true, 0x0BCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_PRE_AND_POST}, 86 {HB_SCRIPT_TELUGU, true, 0x0C4Du,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_POST_ONLY}, 87 {HB_SCRIPT_KANNADA, true, 0x0CCDu,BASE_POS_LAST, REPH_POS_AFTER_POST, REPH_MODE_IMPLICIT, BLWF_MODE_POST_ONLY}, 88 {HB_SCRIPT_MALAYALAM, true, 0x0D4Du,BASE_POS_LAST, REPH_POS_AFTER_MAIN, REPH_MODE_LOG_REPHA,BLWF_MODE_PRE_AND_POST}, 89 {HB_SCRIPT_SINHALA, false,0x0DCAu,BASE_POS_LAST_SINHALA, 90 REPH_POS_AFTER_POST, REPH_MODE_EXPLICIT, BLWF_MODE_PRE_AND_POST}, 91 }; 92 93 94 95 /* 96 * Indic shaper. 97 */ 98 99 static const hb_ot_map_feature_t 100 indic_features[] = 101 { 102 /* 103 * Basic features. 104 * These features are applied in order, one at a time, after initial_reordering. 105 */ 106 {HB_TAG('n','u','k','t'), F_GLOBAL_MANUAL_JOINERS}, 107 {HB_TAG('a','k','h','n'), F_GLOBAL_MANUAL_JOINERS}, 108 {HB_TAG('r','p','h','f'), F_MANUAL_JOINERS}, 109 {HB_TAG('r','k','r','f'), F_GLOBAL_MANUAL_JOINERS}, 110 {HB_TAG('p','r','e','f'), F_MANUAL_JOINERS}, 111 {HB_TAG('b','l','w','f'), F_MANUAL_JOINERS}, 112 {HB_TAG('a','b','v','f'), F_MANUAL_JOINERS}, 113 {HB_TAG('h','a','l','f'), F_MANUAL_JOINERS}, 114 {HB_TAG('p','s','t','f'), F_MANUAL_JOINERS}, 115 {HB_TAG('v','a','t','u'), F_GLOBAL_MANUAL_JOINERS}, 116 {HB_TAG('c','j','c','t'), F_GLOBAL_MANUAL_JOINERS}, 117 /* 118 * Other features. 119 * These features are applied all at once, after final_reordering 120 * but before clearing syllables. 121 * Default Bengali font in Windows for example has intermixed 122 * lookups for init,pres,abvs,blws features. 123 */ 124 {HB_TAG('i','n','i','t'), F_MANUAL_JOINERS}, 125 {HB_TAG('p','r','e','s'), F_GLOBAL_MANUAL_JOINERS}, 126 {HB_TAG('a','b','v','s'), F_GLOBAL_MANUAL_JOINERS}, 127 {HB_TAG('b','l','w','s'), F_GLOBAL_MANUAL_JOINERS}, 128 {HB_TAG('p','s','t','s'), F_GLOBAL_MANUAL_JOINERS}, 129 {HB_TAG('h','a','l','n'), F_GLOBAL_MANUAL_JOINERS}, 130 /* 131 * Positioning features. 132 * We don't care about the types. 133 */ 134 {HB_TAG('d','i','s','t'), F_GLOBAL}, 135 {HB_TAG('a','b','v','m'), F_GLOBAL}, 136 {HB_TAG('b','l','w','m'), F_GLOBAL}, 137 }; 138 139 /* 140 * Must be in the same order as the indic_features array. 141 */ 142 enum { 143 _NUKT, 144 _AKHN, 145 RPHF, 146 _RKRF, 147 PREF, 148 BLWF, 149 ABVF, 150 HALF, 151 PSTF, 152 _VATU, 153 _CJCT, 154 155 INIT, 156 _PRES, 157 _ABVS, 158 _BLWS, 159 _PSTS, 160 _HALN, 161 162 _DIST, 163 _ABVM, 164 _BLWM, 165 166 INDIC_NUM_FEATURES, 167 INDIC_BASIC_FEATURES = INIT, /* Don't forget to update this! */ 168 }; 169 170 static void 171 setup_syllables (const hb_ot_shape_plan_t *plan, 172 hb_font_t *font, 173 hb_buffer_t *buffer); 174 static void 175 initial_reordering (const hb_ot_shape_plan_t *plan, 176 hb_font_t *font, 177 hb_buffer_t *buffer); 178 static void 179 final_reordering (const hb_ot_shape_plan_t *plan, 180 hb_font_t *font, 181 hb_buffer_t *buffer); 182 static void 183 clear_syllables (const hb_ot_shape_plan_t *plan, 184 hb_font_t *font, 185 hb_buffer_t *buffer); 186 187 static void 188 collect_features_indic (hb_ot_shape_planner_t *plan) 189 { 190 hb_ot_map_builder_t *map = &plan->map; 191 192 /* Do this before any lookups have been applied. */ 193 map->add_gsub_pause (setup_syllables); 194 195 map->enable_feature (HB_TAG('l','o','c','l')); 196 /* The Indic specs do not require ccmp, but we apply it here since if 197 * there is a use of it, it's typically at the beginning. */ 198 map->enable_feature (HB_TAG('c','c','m','p')); 199 200 201 unsigned int i = 0; 202 map->add_gsub_pause (initial_reordering); 203 204 for (; i < INDIC_BASIC_FEATURES; i++) { 205 map->add_feature (indic_features[i]); 206 map->add_gsub_pause (nullptr); 207 } 208 209 map->add_gsub_pause (final_reordering); 210 211 for (; i < INDIC_NUM_FEATURES; i++) 212 map->add_feature (indic_features[i]); 213 214 map->enable_feature (HB_TAG('c','a','l','t')); 215 map->enable_feature (HB_TAG('c','l','i','g')); 216 217 map->add_gsub_pause (clear_syllables); 218 } 219 220 static void 221 override_features_indic (hb_ot_shape_planner_t *plan) 222 { 223 plan->map.disable_feature (HB_TAG('l','i','g','a')); 224 } 225 226 227 struct would_substitute_feature_t 228 { 229 void init (const hb_ot_map_t *map, hb_tag_t feature_tag, bool zero_context_) 230 { 231 zero_context = zero_context_; 232 map->get_stage_lookups (0/*GSUB*/, 233 map->get_feature_stage (0/*GSUB*/, feature_tag), 234 &lookups, &count); 235 } 236 237 bool would_substitute (const hb_codepoint_t *glyphs, 238 unsigned int glyphs_count, 239 hb_face_t *face) const 240 { 241 for (unsigned int i = 0; i < count; i++) 242 if (hb_ot_layout_lookup_would_substitute_fast (face, lookups[i].index, glyphs, glyphs_count, zero_context)) 243 return true; 244 return false; 245 } 246 247 private: 248 const hb_ot_map_t::lookup_map_t *lookups; 249 unsigned int count; 250 bool zero_context; 251 }; 252 253 struct indic_shape_plan_t 254 { 255 bool load_virama_glyph (hb_font_t *font, hb_codepoint_t *pglyph) const 256 { 257 hb_codepoint_t glyph = virama_glyph.get_relaxed (); 258 if (unlikely (glyph == (hb_codepoint_t) -1)) 259 { 260 if (!config->virama || !font->get_nominal_glyph (config->virama, &glyph)) 261 glyph = 0; 262 /* Technically speaking, the spec says we should apply 'locl' to virama too. 263 * Maybe one day... */ 264 265 /* Our get_nominal_glyph() function needs a font, so we can't get the virama glyph 266 * during shape planning... Instead, overwrite it here. */ 267 virama_glyph.set_relaxed ((int) glyph); 268 } 269 270 *pglyph = glyph; 271 return glyph != 0; 272 } 273 274 const indic_config_t *config; 275 276 bool is_old_spec; 277 bool uniscribe_bug_compatible; 278 mutable hb_atomic_int_t virama_glyph; 279 280 would_substitute_feature_t rphf; 281 would_substitute_feature_t pref; 282 would_substitute_feature_t blwf; 283 would_substitute_feature_t pstf; 284 285 hb_mask_t mask_array[INDIC_NUM_FEATURES]; 286 }; 287 288 static void * 289 data_create_indic (const hb_ot_shape_plan_t *plan) 290 { 291 indic_shape_plan_t *indic_plan = (indic_shape_plan_t *) calloc (1, sizeof (indic_shape_plan_t)); 292 if (unlikely (!indic_plan)) 293 return nullptr; 294 295 indic_plan->config = &indic_configs[0]; 296 for (unsigned int i = 1; i < ARRAY_LENGTH (indic_configs); i++) 297 if (plan->props.script == indic_configs[i].script) { 298 indic_plan->config = &indic_configs[i]; 299 break; 300 } 301 302 indic_plan->is_old_spec = indic_plan->config->has_old_spec && ((plan->map.chosen_script[0] & 0x000000FFu) != '2'); 303 indic_plan->uniscribe_bug_compatible = hb_options ().uniscribe_bug_compatible; 304 indic_plan->virama_glyph.set_relaxed (-1); 305 306 /* Use zero-context would_substitute() matching for new-spec of the main 307 * Indic scripts, and scripts with one spec only, but not for old-specs. 308 * The new-spec for all dual-spec scripts says zero-context matching happens. 309 * 310 * However, testing with Malayalam shows that old and new spec both allow 311 * context. Testing with Bengali new-spec however shows that it doesn't. 312 * So, the heuristic here is the way it is. It should *only* be changed, 313 * as we discover more cases of what Windows does. DON'T TOUCH OTHERWISE. 314 */ 315 bool zero_context = !indic_plan->is_old_spec && plan->props.script != HB_SCRIPT_MALAYALAM; 316 indic_plan->rphf.init (&plan->map, HB_TAG('r','p','h','f'), zero_context); 317 indic_plan->pref.init (&plan->map, HB_TAG('p','r','e','f'), zero_context); 318 indic_plan->blwf.init (&plan->map, HB_TAG('b','l','w','f'), zero_context); 319 indic_plan->pstf.init (&plan->map, HB_TAG('p','s','t','f'), zero_context); 320 321 for (unsigned int i = 0; i < ARRAY_LENGTH (indic_plan->mask_array); i++) 322 indic_plan->mask_array[i] = (indic_features[i].flags & F_GLOBAL) ? 323 0 : plan->map.get_1_mask (indic_features[i].tag); 324 325 return indic_plan; 326 } 327 328 static void 329 data_destroy_indic (void *data) 330 { 331 free (data); 332 } 333 334 static indic_position_t 335 consonant_position_from_face (const indic_shape_plan_t *indic_plan, 336 const hb_codepoint_t consonant, 337 const hb_codepoint_t virama, 338 hb_face_t *face) 339 { 340 /* For old-spec, the order of glyphs is Consonant,Virama, 341 * whereas for new-spec, it's Virama,Consonant. However, 342 * some broken fonts (like Free Sans) simply copied lookups 343 * from old-spec to new-spec without modification. 344 * And oddly enough, Uniscribe seems to respect those lookups. 345 * Eg. in the sequence U+0924,U+094D,U+0930, Uniscribe finds 346 * base at 0. The font however, only has lookups matching 347 * 930,94D in 'blwf', not the expected 94D,930 (with new-spec 348 * table). As such, we simply match both sequences. Seems 349 * to work. */ 350 hb_codepoint_t glyphs[3] = {virama, consonant, virama}; 351 if (indic_plan->blwf.would_substitute (glyphs , 2, face) || 352 indic_plan->blwf.would_substitute (glyphs+1, 2, face)) 353 return POS_BELOW_C; 354 if (indic_plan->pstf.would_substitute (glyphs , 2, face) || 355 indic_plan->pstf.would_substitute (glyphs+1, 2, face)) 356 return POS_POST_C; 357 if (indic_plan->pref.would_substitute (glyphs , 2, face) || 358 indic_plan->pref.would_substitute (glyphs+1, 2, face)) 359 return POS_POST_C; 360 return POS_BASE_C; 361 } 362 363 364 enum syllable_type_t { 365 consonant_syllable, 366 vowel_syllable, 367 standalone_cluster, 368 symbol_cluster, 369 broken_cluster, 370 non_indic_cluster, 371 }; 372 373 #include "hb-ot-shape-complex-indic-machine.hh" 374 375 376 static void 377 setup_masks_indic (const hb_ot_shape_plan_t *plan HB_UNUSED, 378 hb_buffer_t *buffer, 379 hb_font_t *font HB_UNUSED) 380 { 381 HB_BUFFER_ALLOCATE_VAR (buffer, indic_category); 382 HB_BUFFER_ALLOCATE_VAR (buffer, indic_position); 383 384 /* We cannot setup masks here. We save information about characters 385 * and setup masks later on in a pause-callback. */ 386 387 unsigned int count = buffer->len; 388 hb_glyph_info_t *info = buffer->info; 389 for (unsigned int i = 0; i < count; i++) 390 set_indic_properties (info[i]); 391 } 392 393 static void 394 setup_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED, 395 hb_font_t *font HB_UNUSED, 396 hb_buffer_t *buffer) 397 { 398 find_syllables (buffer); 399 foreach_syllable (buffer, start, end) 400 buffer->unsafe_to_break (start, end); 401 } 402 403 static int 404 compare_indic_order (const hb_glyph_info_t *pa, const hb_glyph_info_t *pb) 405 { 406 int a = pa->indic_position(); 407 int b = pb->indic_position(); 408 409 return a < b ? -1 : a == b ? 0 : +1; 410 } 411 412 413 414 static void 415 update_consonant_positions (const hb_ot_shape_plan_t *plan, 416 hb_font_t *font, 417 hb_buffer_t *buffer) 418 { 419 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; 420 421 if (indic_plan->config->base_pos != BASE_POS_LAST) 422 return; 423 424 hb_codepoint_t virama; 425 if (indic_plan->load_virama_glyph (font, &virama)) 426 { 427 hb_face_t *face = font->face; 428 unsigned int count = buffer->len; 429 hb_glyph_info_t *info = buffer->info; 430 for (unsigned int i = 0; i < count; i++) 431 if (info[i].indic_position() == POS_BASE_C) 432 { 433 hb_codepoint_t consonant = info[i].codepoint; 434 info[i].indic_position() = consonant_position_from_face (indic_plan, consonant, virama, face); 435 } 436 } 437 } 438 439 440 /* Rules from: 441 * https://docs.microsqoft.com/en-us/typography/script-development/devanagari */ 442 443 static void 444 initial_reordering_consonant_syllable (const hb_ot_shape_plan_t *plan, 445 hb_face_t *face, 446 hb_buffer_t *buffer, 447 unsigned int start, unsigned int end) 448 { 449 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; 450 hb_glyph_info_t *info = buffer->info; 451 452 /* https://github.com/harfbuzz/harfbuzz/issues/435#issuecomment-335560167 453 * // For compatibility with legacy usage in Kannada, 454 * // Ra+h+ZWJ must behave like Ra+ZWJ+h... 455 */ 456 if (buffer->props.script == HB_SCRIPT_KANNADA && 457 start + 3 <= end && 458 is_one_of (info[start ], FLAG (OT_Ra)) && 459 is_one_of (info[start+1], FLAG (OT_H)) && 460 is_one_of (info[start+2], FLAG (OT_ZWJ))) 461 { 462 buffer->merge_clusters (start+1, start+3); 463 hb_glyph_info_t tmp = info[start+1]; 464 info[start+1] = info[start+2]; 465 info[start+2] = tmp; 466 } 467 468 /* 1. Find base consonant: 469 * 470 * The shaping engine finds the base consonant of the syllable, using the 471 * following algorithm: starting from the end of the syllable, move backwards 472 * until a consonant is found that does not have a below-base or post-base 473 * form (post-base forms have to follow below-base forms), or that is not a 474 * pre-base-reordering Ra, or arrive at the first consonant. The consonant 475 * stopped at will be the base. 476 * 477 * o If the syllable starts with Ra + Halant (in a script that has Reph) 478 * and has more than one consonant, Ra is excluded from candidates for 479 * base consonants. 480 */ 481 482 unsigned int base = end; 483 bool has_reph = false; 484 485 { 486 /* -> If the syllable starts with Ra + Halant (in a script that has Reph) 487 * and has more than one consonant, Ra is excluded from candidates for 488 * base consonants. */ 489 unsigned int limit = start; 490 if (indic_plan->mask_array[RPHF] && 491 start + 3 <= end && 492 ( 493 (indic_plan->config->reph_mode == REPH_MODE_IMPLICIT && !is_joiner (info[start + 2])) || 494 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && info[start + 2].indic_category() == OT_ZWJ) 495 )) 496 { 497 /* See if it matches the 'rphf' feature. */ 498 hb_codepoint_t glyphs[3] = {info[start].codepoint, 499 info[start + 1].codepoint, 500 indic_plan->config->reph_mode == REPH_MODE_EXPLICIT ? 501 info[start + 2].codepoint : 0}; 502 if (indic_plan->rphf.would_substitute (glyphs, 2, face) || 503 (indic_plan->config->reph_mode == REPH_MODE_EXPLICIT && 504 indic_plan->rphf.would_substitute (glyphs, 3, face))) 505 { 506 limit += 2; 507 while (limit < end && is_joiner (info[limit])) 508 limit++; 509 base = start; 510 has_reph = true; 511 } 512 } else if (indic_plan->config->reph_mode == REPH_MODE_LOG_REPHA && info[start].indic_category() == OT_Repha) 513 { 514 limit += 1; 515 while (limit < end && is_joiner (info[limit])) 516 limit++; 517 base = start; 518 has_reph = true; 519 } 520 521 switch (indic_plan->config->base_pos) 522 { 523 case BASE_POS_LAST: 524 { 525 /* -> starting from the end of the syllable, move backwards */ 526 unsigned int i = end; 527 bool seen_below = false; 528 do { 529 i--; 530 /* -> until a consonant is found */ 531 if (is_consonant (info[i])) 532 { 533 /* -> that does not have a below-base or post-base form 534 * (post-base forms have to follow below-base forms), */ 535 if (info[i].indic_position() != POS_BELOW_C && 536 (info[i].indic_position() != POS_POST_C || seen_below)) 537 { 538 base = i; 539 break; 540 } 541 if (info[i].indic_position() == POS_BELOW_C) 542 seen_below = true; 543 544 /* -> or that is not a pre-base-reordering Ra, 545 * 546 * IMPLEMENTATION NOTES: 547 * 548 * Our pre-base-reordering Ra's are marked POS_POST_C, so will be skipped 549 * by the logic above already. 550 */ 551 552 /* -> or arrive at the first consonant. The consonant stopped at will 553 * be the base. */ 554 base = i; 555 } 556 else 557 { 558 /* A ZWJ after a Halant stops the base search, and requests an explicit 559 * half form. 560 * A ZWJ before a Halant, requests a subjoined form instead, and hence 561 * search continues. This is particularly important for Bengali 562 * sequence Ra,H,Ya that should form Ya-Phalaa by subjoining Ya. */ 563 if (start < i && 564 info[i].indic_category() == OT_ZWJ && 565 info[i - 1].indic_category() == OT_H) 566 break; 567 } 568 } while (i > limit); 569 } 570 break; 571 572 case BASE_POS_LAST_SINHALA: 573 { 574 /* Sinhala base positioning is slightly different from main Indic, in that: 575 * 1. Its ZWJ behavior is different, 576 * 2. We don't need to look into the font for consonant positions. 577 */ 578 579 if (!has_reph) 580 base = limit; 581 582 /* Find the last base consonant that is not blocked by ZWJ. If there is 583 * a ZWJ right before a base consonant, that would request a subjoined form. */ 584 for (unsigned int i = limit; i < end; i++) 585 if (is_consonant (info[i])) 586 { 587 if (limit < i && info[i - 1].indic_category() == OT_ZWJ) 588 break; 589 else 590 base = i; 591 } 592 593 /* Mark all subsequent consonants as below. */ 594 for (unsigned int i = base + 1; i < end; i++) 595 if (is_consonant (info[i])) 596 info[i].indic_position() = POS_BELOW_C; 597 } 598 break; 599 } 600 601 /* -> If the syllable starts with Ra + Halant (in a script that has Reph) 602 * and has more than one consonant, Ra is excluded from candidates for 603 * base consonants. 604 * 605 * Only do this for unforced Reph. (ie. not for Ra,H,ZWJ. */ 606 if (has_reph && base == start && limit - base <= 2) { 607 /* Have no other consonant, so Reph is not formed and Ra becomes base. */ 608 has_reph = false; 609 } 610 } 611 612 613 /* 2. Decompose and reorder Matras: 614 * 615 * Each matra and any syllable modifier sign in the syllable are moved to the 616 * appropriate position relative to the consonant(s) in the syllable. The 617 * shaping engine decomposes two- or three-part matras into their constituent 618 * parts before any repositioning. Matra characters are classified by which 619 * consonant in a conjunct they have affinity for and are reordered to the 620 * following positions: 621 * 622 * o Before first half form in the syllable 623 * o After subjoined consonants 624 * o After post-form consonant 625 * o After main consonant (for above marks) 626 * 627 * IMPLEMENTATION NOTES: 628 * 629 * The normalize() routine has already decomposed matras for us, so we don't 630 * need to worry about that. 631 */ 632 633 634 /* 3. Reorder marks to canonical order: 635 * 636 * Adjacent nukta and halant or nukta and vedic sign are always repositioned 637 * if necessary, so that the nukta is first. 638 * 639 * IMPLEMENTATION NOTES: 640 * 641 * We don't need to do this: the normalize() routine already did this for us. 642 */ 643 644 645 /* Reorder characters */ 646 647 for (unsigned int i = start; i < base; i++) 648 info[i].indic_position() = MIN (POS_PRE_C, (indic_position_t) info[i].indic_position()); 649 650 if (base < end) 651 info[base].indic_position() = POS_BASE_C; 652 653 /* Mark final consonants. A final consonant is one appearing after a matra. 654 * Happens in Sinhala. */ 655 for (unsigned int i = base + 1; i < end; i++) 656 if (info[i].indic_category() == OT_M) { 657 for (unsigned int j = i + 1; j < end; j++) 658 if (is_consonant (info[j])) { 659 info[j].indic_position() = POS_FINAL_C; 660 break; 661 } 662 break; 663 } 664 665 /* Handle beginning Ra */ 666 if (has_reph) 667 info[start].indic_position() = POS_RA_TO_BECOME_REPH; 668 669 /* For old-style Indic script tags, move the first post-base Halant after 670 * last consonant. 671 * 672 * Reports suggest that in some scripts Uniscribe does this only if there 673 * is *not* a Halant after last consonant already. We know that is the 674 * case for Kannada, while it reorders unconditionally in other scripts, 675 * eg. Malayalam, Bengali, and Devanagari. We don't currently know about 676 * other scripts, so we blacklist Kannada. 677 * 678 * Kannada test case: 679 * U+0C9A,U+0CCD,U+0C9A,U+0CCD 680 * With some versions of Lohit Kannada. 681 * https://bugs.freedesktop.org/show_bug.cgi?id=59118 682 * 683 * Malayalam test case: 684 * U+0D38,U+0D4D,U+0D31,U+0D4D,U+0D31,U+0D4D 685 * With lohit-ttf-20121122/Lohit-Malayalam.ttf 686 * 687 * Bengali test case: 688 * U+0998,U+09CD,U+09AF,U+09CD 689 * With Windows XP vrinda.ttf 690 * https://github.com/harfbuzz/harfbuzz/issues/1073 691 * 692 * Devanagari test case: 693 * U+091F,U+094D,U+0930,U+094D 694 * With chandas.ttf 695 * https://github.com/harfbuzz/harfbuzz/issues/1071 696 */ 697 if (indic_plan->is_old_spec) 698 { 699 bool disallow_double_halants = buffer->props.script == HB_SCRIPT_KANNADA; 700 for (unsigned int i = base + 1; i < end; i++) 701 if (info[i].indic_category() == OT_H) 702 { 703 unsigned int j; 704 for (j = end - 1; j > i; j--) 705 if (is_consonant (info[j]) || 706 (disallow_double_halants && info[j].indic_category() == OT_H)) 707 break; 708 if (info[j].indic_category() != OT_H && j > i) { 709 /* Move Halant to after last consonant. */ 710 hb_glyph_info_t t = info[i]; 711 memmove (&info[i], &info[i + 1], (j - i) * sizeof (info[0])); 712 info[j] = t; 713 } 714 break; 715 } 716 } 717 718 /* Attach misc marks to previous char to move with them. */ 719 { 720 indic_position_t last_pos = POS_START; 721 for (unsigned int i = start; i < end; i++) 722 { 723 if ((FLAG_UNSAFE (info[i].indic_category()) & (JOINER_FLAGS | FLAG (OT_N) | FLAG (OT_RS) | FLAG (OT_H)))) 724 { 725 info[i].indic_position() = last_pos; 726 if (unlikely (info[i].indic_category() == OT_H && 727 info[i].indic_position() == POS_PRE_M)) 728 { 729 /* 730 * Uniscribe doesn't move the Halant with Left Matra. 731 * TEST: U+092B,U+093F,U+094DE 732 * We follow. This is important for the Sinhala 733 * U+0DDA split matra since it decomposes to U+0DD9,U+0DCA 734 * where U+0DD9 is a left matra and U+0DCA is the virama. 735 * We don't want to move the virama with the left matra. 736 * TEST: U+0D9A,U+0DDA 737 */ 738 for (unsigned int j = i; j > start; j--) 739 if (info[j - 1].indic_position() != POS_PRE_M) { 740 info[i].indic_position() = info[j - 1].indic_position(); 741 break; 742 } 743 } 744 } else if (info[i].indic_position() != POS_SMVD) { 745 last_pos = (indic_position_t) info[i].indic_position(); 746 } 747 } 748 } 749 /* For post-base consonants let them own anything before them 750 * since the last consonant or matra. */ 751 { 752 unsigned int last = base; 753 for (unsigned int i = base + 1; i < end; i++) 754 if (is_consonant (info[i])) 755 { 756 for (unsigned int j = last + 1; j < i; j++) 757 if (info[j].indic_position() < POS_SMVD) 758 info[j].indic_position() = info[i].indic_position(); 759 last = i; 760 } else if (info[i].indic_category() == OT_M) 761 last = i; 762 } 763 764 765 { 766 /* Use syllable() for sort accounting temporarily. */ 767 unsigned int syllable = info[start].syllable(); 768 for (unsigned int i = start; i < end; i++) 769 info[i].syllable() = i - start; 770 771 /* Sit tight, rock 'n roll! */ 772 hb_stable_sort (info + start, end - start, compare_indic_order); 773 /* Find base again */ 774 base = end; 775 for (unsigned int i = start; i < end; i++) 776 if (info[i].indic_position() == POS_BASE_C) 777 { 778 base = i; 779 break; 780 } 781 /* Things are out-of-control for post base positions, they may shuffle 782 * around like crazy. In old-spec mode, we move halants around, so in 783 * that case merge all clusters after base. Otherwise, check the sort 784 * order and merge as needed. 785 * For pre-base stuff, we handle cluster issues in final reordering. 786 * 787 * We could use buffer->sort() for this, if there was no special 788 * reordering of pre-base stuff happening later... 789 * We don't want to merge_clusters all of that, which buffer->sort() 790 * would. 791 */ 792 if (indic_plan->is_old_spec || end - start > 127) 793 buffer->merge_clusters (base, end); 794 else 795 { 796 /* Note! syllable() is a one-byte field. */ 797 for (unsigned int i = base; i < end; i++) 798 if (info[i].syllable() != 255) 799 { 800 unsigned int max = i; 801 unsigned int j = start + info[i].syllable(); 802 while (j != i) 803 { 804 max = MAX (max, j); 805 unsigned int next = start + info[j].syllable(); 806 info[j].syllable() = 255; /* So we don't process j later again. */ 807 j = next; 808 } 809 if (i != max) 810 buffer->merge_clusters (i, max + 1); 811 } 812 } 813 814 /* Put syllable back in. */ 815 for (unsigned int i = start; i < end; i++) 816 info[i].syllable() = syllable; 817 } 818 819 /* Setup masks now */ 820 821 { 822 hb_mask_t mask; 823 824 /* Reph */ 825 for (unsigned int i = start; i < end && info[i].indic_position() == POS_RA_TO_BECOME_REPH; i++) 826 info[i].mask |= indic_plan->mask_array[RPHF]; 827 828 /* Pre-base */ 829 mask = indic_plan->mask_array[HALF]; 830 if (!indic_plan->is_old_spec && 831 indic_plan->config->blwf_mode == BLWF_MODE_PRE_AND_POST) 832 mask |= indic_plan->mask_array[BLWF]; 833 for (unsigned int i = start; i < base; i++) 834 info[i].mask |= mask; 835 /* Base */ 836 mask = 0; 837 if (base < end) 838 info[base].mask |= mask; 839 /* Post-base */ 840 mask = indic_plan->mask_array[BLWF] | indic_plan->mask_array[ABVF] | indic_plan->mask_array[PSTF]; 841 for (unsigned int i = base + 1; i < end; i++) 842 info[i].mask |= mask; 843 } 844 845 if (indic_plan->is_old_spec && 846 buffer->props.script == HB_SCRIPT_DEVANAGARI) 847 { 848 /* Old-spec eye-lash Ra needs special handling. From the 849 * spec: 850 * 851 * "The feature 'below-base form' is applied to consonants 852 * having below-base forms and following the base consonant. 853 * The exception is vattu, which may appear below half forms 854 * as well as below the base glyph. The feature 'below-base 855 * form' will be applied to all such occurrences of Ra as well." 856 * 857 * Test case: U+0924,U+094D,U+0930,U+094d,U+0915 858 * with Sanskrit 2003 font. 859 * 860 * However, note that Ra,Halant,ZWJ is the correct way to 861 * request eyelash form of Ra, so we wouldbn't inhibit it 862 * in that sequence. 863 * 864 * Test case: U+0924,U+094D,U+0930,U+094d,U+200D,U+0915 865 */ 866 for (unsigned int i = start; i + 1 < base; i++) 867 if (info[i ].indic_category() == OT_Ra && 868 info[i+1].indic_category() == OT_H && 869 (i + 2 == base || 870 info[i+2].indic_category() != OT_ZWJ)) 871 { 872 info[i ].mask |= indic_plan->mask_array[BLWF]; 873 info[i+1].mask |= indic_plan->mask_array[BLWF]; 874 } 875 } 876 877 unsigned int pref_len = 2; 878 if (indic_plan->mask_array[PREF] && base + pref_len < end) 879 { 880 /* Find a Halant,Ra sequence and mark it for pre-base-reordering processing. */ 881 for (unsigned int i = base + 1; i + pref_len - 1 < end; i++) { 882 hb_codepoint_t glyphs[2]; 883 for (unsigned int j = 0; j < pref_len; j++) 884 glyphs[j] = info[i + j].codepoint; 885 if (indic_plan->pref.would_substitute (glyphs, pref_len, face)) 886 { 887 for (unsigned int j = 0; j < pref_len; j++) 888 info[i++].mask |= indic_plan->mask_array[PREF]; 889 break; 890 } 891 } 892 } 893 894 /* Apply ZWJ/ZWNJ effects */ 895 for (unsigned int i = start + 1; i < end; i++) 896 if (is_joiner (info[i])) { 897 bool non_joiner = info[i].indic_category() == OT_ZWNJ; 898 unsigned int j = i; 899 900 do { 901 j--; 902 903 /* ZWJ/ZWNJ should disable CJCT. They do that by simply 904 * being there, since we don't skip them for the CJCT 905 * feature (ie. F_MANUAL_ZWJ) */ 906 907 /* A ZWNJ disables HALF. */ 908 if (non_joiner) 909 info[j].mask &= ~indic_plan->mask_array[HALF]; 910 911 } while (j > start && !is_consonant (info[j])); 912 } 913 } 914 915 static void 916 initial_reordering_standalone_cluster (const hb_ot_shape_plan_t *plan, 917 hb_face_t *face, 918 hb_buffer_t *buffer, 919 unsigned int start, unsigned int end) 920 { 921 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; 922 923 /* We treat placeholder/dotted-circle as if they are consonants, so we 924 * should just chain. Only if not in compatibility mode that is... */ 925 926 if (indic_plan->uniscribe_bug_compatible) 927 { 928 /* For dotted-circle, this is what Uniscribe does: 929 * If dotted-circle is the last glyph, it just does nothing. 930 * Ie. It doesn't form Reph. */ 931 if (buffer->info[end - 1].indic_category() == OT_DOTTEDCIRCLE) 932 return; 933 } 934 935 initial_reordering_consonant_syllable (plan, face, buffer, start, end); 936 } 937 938 static void 939 initial_reordering_syllable (const hb_ot_shape_plan_t *plan, 940 hb_face_t *face, 941 hb_buffer_t *buffer, 942 unsigned int start, unsigned int end) 943 { 944 syllable_type_t syllable_type = (syllable_type_t) (buffer->info[start].syllable() & 0x0F); 945 switch (syllable_type) 946 { 947 case vowel_syllable: /* We made the vowels look like consonants. So let's call the consonant logic! */ 948 case consonant_syllable: 949 initial_reordering_consonant_syllable (plan, face, buffer, start, end); 950 break; 951 952 case broken_cluster: /* We already inserted dotted-circles, so just call the standalone_cluster. */ 953 case standalone_cluster: 954 initial_reordering_standalone_cluster (plan, face, buffer, start, end); 955 break; 956 957 case symbol_cluster: 958 case non_indic_cluster: 959 break; 960 } 961 } 962 963 static inline void 964 insert_dotted_circles (const hb_ot_shape_plan_t *plan HB_UNUSED, 965 hb_font_t *font, 966 hb_buffer_t *buffer) 967 { 968 /* Note: This loop is extra overhead, but should not be measurable. 969 * TODO Use a buffer scratch flag to remove the loop. */ 970 bool has_broken_syllables = false; 971 unsigned int count = buffer->len; 972 hb_glyph_info_t *info = buffer->info; 973 for (unsigned int i = 0; i < count; i++) 974 if ((info[i].syllable() & 0x0F) == broken_cluster) 975 { 976 has_broken_syllables = true; 977 break; 978 } 979 if (likely (!has_broken_syllables)) 980 return; 981 982 983 hb_codepoint_t dottedcircle_glyph; 984 if (!font->get_nominal_glyph (0x25CCu, &dottedcircle_glyph)) 985 return; 986 987 hb_glyph_info_t dottedcircle = {0}; 988 dottedcircle.codepoint = 0x25CCu; 989 set_indic_properties (dottedcircle); 990 dottedcircle.codepoint = dottedcircle_glyph; 991 992 buffer->clear_output (); 993 994 buffer->idx = 0; 995 unsigned int last_syllable = 0; 996 while (buffer->idx < buffer->len && buffer->successful) 997 { 998 unsigned int syllable = buffer->cur().syllable(); 999 syllable_type_t syllable_type = (syllable_type_t) (syllable & 0x0F); 1000 if (unlikely (last_syllable != syllable && syllable_type == broken_cluster)) 1001 { 1002 last_syllable = syllable; 1003 1004 hb_glyph_info_t ginfo = dottedcircle; 1005 ginfo.cluster = buffer->cur().cluster; 1006 ginfo.mask = buffer->cur().mask; 1007 ginfo.syllable() = buffer->cur().syllable(); 1008 /* TODO Set glyph_props? */ 1009 1010 /* Insert dottedcircle after possible Repha. */ 1011 while (buffer->idx < buffer->len && buffer->successful && 1012 last_syllable == buffer->cur().syllable() && 1013 buffer->cur().indic_category() == OT_Repha) 1014 buffer->next_glyph (); 1015 1016 buffer->output_info (ginfo); 1017 } 1018 else 1019 buffer->next_glyph (); 1020 } 1021 buffer->swap_buffers (); 1022 } 1023 1024 static void 1025 initial_reordering (const hb_ot_shape_plan_t *plan, 1026 hb_font_t *font, 1027 hb_buffer_t *buffer) 1028 { 1029 update_consonant_positions (plan, font, buffer); 1030 insert_dotted_circles (plan, font, buffer); 1031 1032 foreach_syllable (buffer, start, end) 1033 initial_reordering_syllable (plan, font->face, buffer, start, end); 1034 } 1035 1036 static void 1037 final_reordering_syllable (const hb_ot_shape_plan_t *plan, 1038 hb_buffer_t *buffer, 1039 unsigned int start, unsigned int end) 1040 { 1041 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) plan->data; 1042 hb_glyph_info_t *info = buffer->info; 1043 1044 1045 /* This function relies heavily on halant glyphs. Lots of ligation 1046 * and possibly multiple substitutions happened prior to this 1047 * phase, and that might have messed up our properties. Recover 1048 * from a particular case of that where we're fairly sure that a 1049 * class of OT_H is desired but has been lost. */ 1050 /* We don't call load_virama_glyph(), since we know it's already 1051 * loaded. */ 1052 hb_codepoint_t virama_glyph = indic_plan->virama_glyph.get_relaxed (); 1053 if (virama_glyph) 1054 { 1055 for (unsigned int i = start; i < end; i++) 1056 if (info[i].codepoint == virama_glyph && 1057 _hb_glyph_info_ligated (&info[i]) && 1058 _hb_glyph_info_multiplied (&info[i])) 1059 { 1060 /* This will make sure that this glyph passes is_halant() test. */ 1061 info[i].indic_category() = OT_H; 1062 _hb_glyph_info_clear_ligated_and_multiplied (&info[i]); 1063 } 1064 } 1065 1066 1067 /* 4. Final reordering: 1068 * 1069 * After the localized forms and basic shaping forms GSUB features have been 1070 * applied (see below), the shaping engine performs some final glyph 1071 * reordering before applying all the remaining font features to the entire 1072 * syllable. 1073 */ 1074 1075 bool try_pref = !!indic_plan->mask_array[PREF]; 1076 1077 /* Find base again */ 1078 unsigned int base; 1079 for (base = start; base < end; base++) 1080 if (info[base].indic_position() >= POS_BASE_C) 1081 { 1082 if (try_pref && base + 1 < end) 1083 { 1084 for (unsigned int i = base + 1; i < end; i++) 1085 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0) 1086 { 1087 if (!(_hb_glyph_info_substituted (&info[i]) && 1088 _hb_glyph_info_ligated_and_didnt_multiply (&info[i]))) 1089 { 1090 /* Ok, this was a 'pref' candidate but didn't form any. 1091 * Base is around here... */ 1092 base = i; 1093 while (base < end && is_halant (info[base])) 1094 base++; 1095 info[base].indic_position() = POS_BASE_C; 1096 1097 try_pref = false; 1098 } 1099 break; 1100 } 1101 } 1102 /* For Malayalam, skip over unformed below- (but NOT post-) forms. */ 1103 if (buffer->props.script == HB_SCRIPT_MALAYALAM) 1104 { 1105 for (unsigned int i = base + 1; i < end; i++) 1106 { 1107 while (i < end && is_joiner (info[i])) 1108 i++; 1109 if (i == end || !is_halant (info[i])) 1110 break; 1111 i++; /* Skip halant. */ 1112 while (i < end && is_joiner (info[i])) 1113 i++; 1114 if (i < end && is_consonant (info[i]) && info[i].indic_position() == POS_BELOW_C) 1115 { 1116 base = i; 1117 info[base].indic_position() = POS_BASE_C; 1118 } 1119 } 1120 } 1121 1122 if (start < base && info[base].indic_position() > POS_BASE_C) 1123 base--; 1124 break; 1125 } 1126 if (base == end && start < base && 1127 is_one_of (info[base - 1], FLAG (OT_ZWJ))) 1128 base--; 1129 if (base < end) 1130 while (start < base && 1131 is_one_of (info[base], (FLAG (OT_N) | FLAG (OT_H)))) 1132 base--; 1133 1134 1135 /* o Reorder matras: 1136 * 1137 * If a pre-base matra character had been reordered before applying basic 1138 * features, the glyph can be moved closer to the main consonant based on 1139 * whether half-forms had been formed. Actual position for the matra is 1140 * defined as “after last standalone halant glyph, after initial matra 1141 * position and before the main consonant”. If ZWJ or ZWNJ follow this 1142 * halant, position is moved after it. 1143 * 1144 * IMPLEMENTATION NOTES: 1145 * 1146 * It looks like the last sentence is wrong. Testing, with Windows 7 Uniscribe 1147 * and Devanagari shows that the behavior is best described as: 1148 * 1149 * "If ZWJ follows this halant, matra is NOT repositioned after this halant. 1150 * If ZWNJ follows this halant, position is moved after it." 1151 * 1152 * Test case, with Adobe Devanagari or Nirmala UI: 1153 * 1154 * U+091F,U+094D,U+200C,U+092F,U+093F 1155 * (Matra moves to the middle, after ZWNJ.) 1156 * 1157 * U+091F,U+094D,U+200D,U+092F,U+093F 1158 * (Matra does NOT move, stays to the left.) 1159 * 1160 * https://github.com/harfbuzz/harfbuzz/issues/1070 1161 */ 1162 1163 if (start + 1 < end && start < base) /* Otherwise there can't be any pre-base matra characters. */ 1164 { 1165 /* If we lost track of base, alas, position before last thingy. */ 1166 unsigned int new_pos = base == end ? base - 2 : base - 1; 1167 1168 /* Malayalam / Tamil do not have "half" forms or explicit virama forms. 1169 * The glyphs formed by 'half' are Chillus or ligated explicit viramas. 1170 * We want to position matra after them. 1171 */ 1172 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL) 1173 { 1174 search: 1175 while (new_pos > start && 1176 !(is_one_of (info[new_pos], (FLAG (OT_M) | FLAG (OT_H))))) 1177 new_pos--; 1178 1179 /* If we found no Halant we are done. 1180 * Otherwise only proceed if the Halant does 1181 * not belong to the Matra itself! */ 1182 if (is_halant (info[new_pos]) && 1183 info[new_pos].indic_position() != POS_PRE_M) 1184 { 1185 #if 0 // See comment above 1186 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */ 1187 if (new_pos + 1 < end && is_joiner (info[new_pos + 1])) 1188 new_pos++; 1189 #endif 1190 if (new_pos + 1 < end) 1191 { 1192 /* -> If ZWJ follows this halant, matra is NOT repositioned after this halant. */ 1193 if (info[new_pos + 1].indic_category() == OT_ZWJ) 1194 { 1195 /* Keep searching. */ 1196 if (new_pos > start) 1197 { 1198 new_pos--; 1199 goto search; 1200 } 1201 } 1202 /* -> If ZWNJ follows this halant, position is moved after it. */ 1203 if (info[new_pos + 1].indic_category() == OT_ZWNJ) 1204 new_pos++; 1205 } 1206 } 1207 else 1208 new_pos = start; /* No move. */ 1209 } 1210 1211 if (start < new_pos && info[new_pos].indic_position () != POS_PRE_M) 1212 { 1213 /* Now go see if there's actually any matras... */ 1214 for (unsigned int i = new_pos; i > start; i--) 1215 if (info[i - 1].indic_position () == POS_PRE_M) 1216 { 1217 unsigned int old_pos = i - 1; 1218 if (old_pos < base && base <= new_pos) /* Shouldn't actually happen. */ 1219 base--; 1220 1221 hb_glyph_info_t tmp = info[old_pos]; 1222 memmove (&info[old_pos], &info[old_pos + 1], (new_pos - old_pos) * sizeof (info[0])); 1223 info[new_pos] = tmp; 1224 1225 /* Note: this merge_clusters() is intentionally *after* the reordering. 1226 * Indic matra reordering is special and tricky... */ 1227 buffer->merge_clusters (new_pos, MIN (end, base + 1)); 1228 1229 new_pos--; 1230 } 1231 } else { 1232 for (unsigned int i = start; i < base; i++) 1233 if (info[i].indic_position () == POS_PRE_M) { 1234 buffer->merge_clusters (i, MIN (end, base + 1)); 1235 break; 1236 } 1237 } 1238 } 1239 1240 1241 /* o Reorder reph: 1242 * 1243 * Reph’s original position is always at the beginning of the syllable, 1244 * (i.e. it is not reordered at the character reordering stage). However, 1245 * it will be reordered according to the basic-forms shaping results. 1246 * Possible positions for reph, depending on the script, are; after main, 1247 * before post-base consonant forms, and after post-base consonant forms. 1248 */ 1249 1250 /* Two cases: 1251 * 1252 * - If repha is encoded as a sequence of characters (Ra,H or Ra,H,ZWJ), then 1253 * we should only move it if the sequence ligated to the repha form. 1254 * 1255 * - If repha is encoded separately and in the logical position, we should only 1256 * move it if it did NOT ligate. If it ligated, it's probably the font trying 1257 * to make it work without the reordering. 1258 */ 1259 if (start + 1 < end && 1260 info[start].indic_position() == POS_RA_TO_BECOME_REPH && 1261 ((info[start].indic_category() == OT_Repha) ^ 1262 _hb_glyph_info_ligated_and_didnt_multiply (&info[start]))) 1263 { 1264 unsigned int new_reph_pos; 1265 reph_position_t reph_pos = indic_plan->config->reph_pos; 1266 1267 /* 1. If reph should be positioned after post-base consonant forms, 1268 * proceed to step 5. 1269 */ 1270 if (reph_pos == REPH_POS_AFTER_POST) 1271 { 1272 goto reph_step_5; 1273 } 1274 1275 /* 2. If the reph repositioning class is not after post-base: target 1276 * position is after the first explicit halant glyph between the 1277 * first post-reph consonant and last main consonant. If ZWJ or ZWNJ 1278 * are following this halant, position is moved after it. If such 1279 * position is found, this is the target position. Otherwise, 1280 * proceed to the next step. 1281 * 1282 * Note: in old-implementation fonts, where classifications were 1283 * fixed in shaping engine, there was no case where reph position 1284 * will be found on this step. 1285 */ 1286 { 1287 new_reph_pos = start + 1; 1288 while (new_reph_pos < base && !is_halant (info[new_reph_pos])) 1289 new_reph_pos++; 1290 1291 if (new_reph_pos < base && is_halant (info[new_reph_pos])) 1292 { 1293 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */ 1294 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1])) 1295 new_reph_pos++; 1296 goto reph_move; 1297 } 1298 } 1299 1300 /* 3. If reph should be repositioned after the main consonant: find the 1301 * first consonant not ligated with main, or find the first 1302 * consonant that is not a potential pre-base-reordering Ra. 1303 */ 1304 if (reph_pos == REPH_POS_AFTER_MAIN) 1305 { 1306 new_reph_pos = base; 1307 while (new_reph_pos + 1 < end && info[new_reph_pos + 1].indic_position() <= POS_AFTER_MAIN) 1308 new_reph_pos++; 1309 if (new_reph_pos < end) 1310 goto reph_move; 1311 } 1312 1313 /* 4. If reph should be positioned before post-base consonant, find 1314 * first post-base classified consonant not ligated with main. If no 1315 * consonant is found, the target position should be before the 1316 * first matra, syllable modifier sign or vedic sign. 1317 */ 1318 /* This is our take on what step 4 is trying to say (and failing, BADLY). */ 1319 if (reph_pos == REPH_POS_AFTER_SUB) 1320 { 1321 new_reph_pos = base; 1322 while (new_reph_pos + 1 < end && 1323 !( FLAG_UNSAFE (info[new_reph_pos + 1].indic_position()) & (FLAG (POS_POST_C) | FLAG (POS_AFTER_POST) | FLAG (POS_SMVD)))) 1324 new_reph_pos++; 1325 if (new_reph_pos < end) 1326 goto reph_move; 1327 } 1328 1329 /* 5. If no consonant is found in steps 3 or 4, move reph to a position 1330 * immediately before the first post-base matra, syllable modifier 1331 * sign or vedic sign that has a reordering class after the intended 1332 * reph position. For example, if the reordering position for reph 1333 * is post-main, it will skip above-base matras that also have a 1334 * post-main position. 1335 */ 1336 reph_step_5: 1337 { 1338 /* Copied from step 2. */ 1339 new_reph_pos = start + 1; 1340 while (new_reph_pos < base && !is_halant (info[new_reph_pos])) 1341 new_reph_pos++; 1342 1343 if (new_reph_pos < base && is_halant (info[new_reph_pos])) 1344 { 1345 /* ->If ZWJ or ZWNJ are following this halant, position is moved after it. */ 1346 if (new_reph_pos + 1 < base && is_joiner (info[new_reph_pos + 1])) 1347 new_reph_pos++; 1348 goto reph_move; 1349 } 1350 } 1351 1352 /* 6. Otherwise, reorder reph to the end of the syllable. 1353 */ 1354 { 1355 new_reph_pos = end - 1; 1356 while (new_reph_pos > start && info[new_reph_pos].indic_position() == POS_SMVD) 1357 new_reph_pos--; 1358 1359 /* 1360 * If the Reph is to be ending up after a Matra,Halant sequence, 1361 * position it before that Halant so it can interact with the Matra. 1362 * However, if it's a plain Consonant,Halant we shouldn't do that. 1363 * Uniscribe doesn't do this. 1364 * TEST: U+0930,U+094D,U+0915,U+094B,U+094D 1365 */ 1366 if (!indic_plan->uniscribe_bug_compatible && 1367 unlikely (is_halant (info[new_reph_pos]))) { 1368 for (unsigned int i = base + 1; i < new_reph_pos; i++) 1369 if (info[i].indic_category() == OT_M) { 1370 /* Ok, got it. */ 1371 new_reph_pos--; 1372 } 1373 } 1374 goto reph_move; 1375 } 1376 1377 reph_move: 1378 { 1379 /* Move */ 1380 buffer->merge_clusters (start, new_reph_pos + 1); 1381 hb_glyph_info_t reph = info[start]; 1382 memmove (&info[start], &info[start + 1], (new_reph_pos - start) * sizeof (info[0])); 1383 info[new_reph_pos] = reph; 1384 1385 if (start < base && base <= new_reph_pos) 1386 base--; 1387 } 1388 } 1389 1390 1391 /* o Reorder pre-base-reordering consonants: 1392 * 1393 * If a pre-base-reordering consonant is found, reorder it according to 1394 * the following rules: 1395 */ 1396 1397 if (try_pref && base + 1 < end) /* Otherwise there can't be any pre-base-reordering Ra. */ 1398 { 1399 for (unsigned int i = base + 1; i < end; i++) 1400 if ((info[i].mask & indic_plan->mask_array[PREF]) != 0) 1401 { 1402 /* 1. Only reorder a glyph produced by substitution during application 1403 * of the <pref> feature. (Note that a font may shape a Ra consonant with 1404 * the feature generally but block it in certain contexts.) 1405 */ 1406 /* Note: We just check that something got substituted. We don't check that 1407 * the <pref> feature actually did it... 1408 * 1409 * Reorder pref only if it ligated. */ 1410 if (_hb_glyph_info_ligated_and_didnt_multiply (&info[i])) 1411 { 1412 /* 1413 * 2. Try to find a target position the same way as for pre-base matra. 1414 * If it is found, reorder pre-base consonant glyph. 1415 * 1416 * 3. If position is not found, reorder immediately before main 1417 * consonant. 1418 */ 1419 1420 unsigned int new_pos = base; 1421 /* Malayalam / Tamil do not have "half" forms or explicit virama forms. 1422 * The glyphs formed by 'half' are Chillus or ligated explicit viramas. 1423 * We want to position matra after them. 1424 */ 1425 if (buffer->props.script != HB_SCRIPT_MALAYALAM && buffer->props.script != HB_SCRIPT_TAMIL) 1426 { 1427 while (new_pos > start && 1428 !(is_one_of (info[new_pos - 1], FLAG(OT_M) | FLAG (OT_H)))) 1429 new_pos--; 1430 } 1431 1432 if (new_pos > start && is_halant (info[new_pos - 1])) 1433 { 1434 /* -> If ZWJ or ZWNJ follow this halant, position is moved after it. */ 1435 if (new_pos < end && is_joiner (info[new_pos])) 1436 new_pos++; 1437 } 1438 1439 { 1440 unsigned int old_pos = i; 1441 1442 buffer->merge_clusters (new_pos, old_pos + 1); 1443 hb_glyph_info_t tmp = info[old_pos]; 1444 memmove (&info[new_pos + 1], &info[new_pos], (old_pos - new_pos) * sizeof (info[0])); 1445 info[new_pos] = tmp; 1446 1447 if (new_pos <= base && base < old_pos) 1448 base++; 1449 } 1450 } 1451 1452 break; 1453 } 1454 } 1455 1456 1457 /* Apply 'init' to the Left Matra if it's a word start. */ 1458 if (info[start].indic_position () == POS_PRE_M) 1459 { 1460 if (!start || 1461 !(FLAG_UNSAFE (_hb_glyph_info_get_general_category (&info[start - 1])) & 1462 FLAG_RANGE (HB_UNICODE_GENERAL_CATEGORY_FORMAT, HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK))) 1463 info[start].mask |= indic_plan->mask_array[INIT]; 1464 else 1465 buffer->unsafe_to_break (start - 1, start + 1); 1466 } 1467 1468 1469 /* 1470 * Finish off the clusters and go home! 1471 */ 1472 if (indic_plan->uniscribe_bug_compatible) 1473 { 1474 switch ((hb_tag_t) plan->props.script) 1475 { 1476 case HB_SCRIPT_TAMIL: 1477 case HB_SCRIPT_SINHALA: 1478 break; 1479 1480 default: 1481 /* Uniscribe merges the entire syllable into a single cluster... Except for Tamil & Sinhala. 1482 * This means, half forms are submerged into the main consonant's cluster. 1483 * This is unnecessary, and makes cursor positioning harder, but that's what 1484 * Uniscribe does. */ 1485 buffer->merge_clusters (start, end); 1486 break; 1487 } 1488 } 1489 } 1490 1491 1492 static void 1493 final_reordering (const hb_ot_shape_plan_t *plan, 1494 hb_font_t *font HB_UNUSED, 1495 hb_buffer_t *buffer) 1496 { 1497 unsigned int count = buffer->len; 1498 if (unlikely (!count)) return; 1499 1500 foreach_syllable (buffer, start, end) 1501 final_reordering_syllable (plan, buffer, start, end); 1502 1503 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_category); 1504 HB_BUFFER_DEALLOCATE_VAR (buffer, indic_position); 1505 } 1506 1507 1508 static void 1509 clear_syllables (const hb_ot_shape_plan_t *plan HB_UNUSED, 1510 hb_font_t *font HB_UNUSED, 1511 hb_buffer_t *buffer) 1512 { 1513 hb_glyph_info_t *info = buffer->info; 1514 unsigned int count = buffer->len; 1515 for (unsigned int i = 0; i < count; i++) 1516 info[i].syllable() = 0; 1517 } 1518 1519 1520 static void 1521 preprocess_text_indic (const hb_ot_shape_plan_t *plan, 1522 hb_buffer_t *buffer, 1523 hb_font_t *font) 1524 { 1525 _hb_preprocess_text_vowel_constraints (plan, buffer, font); 1526 } 1527 1528 static bool 1529 decompose_indic (const hb_ot_shape_normalize_context_t *c, 1530 hb_codepoint_t ab, 1531 hb_codepoint_t *a, 1532 hb_codepoint_t *b) 1533 { 1534 switch (ab) 1535 { 1536 /* Don't decompose these. */ 1537 case 0x0931u : return false; /* DEVANAGARI LETTER RRA */ 1538 // https://github.com/harfbuzz/harfbuzz/issues/779 1539 case 0x09DCu : return false; /* BENGALI LETTER RRA */ 1540 case 0x09DDu : return false; /* BENGALI LETTER RHA */ 1541 case 0x0B94u : return false; /* TAMIL LETTER AU */ 1542 1543 1544 /* 1545 * Decompose split matras that don't have Unicode decompositions. 1546 */ 1547 1548 #if 0 1549 /* Gujarati */ 1550 /* This one has no decomposition in Unicode, but needs no decomposition either. */ 1551 /* case 0x0AC9u : return false; */ 1552 1553 /* Oriya */ 1554 case 0x0B57u : *a = no decomp, -> RIGHT; return true; 1555 #endif 1556 } 1557 1558 if ((ab == 0x0DDAu || hb_in_range<hb_codepoint_t> (ab, 0x0DDCu, 0x0DDEu))) 1559 { 1560 /* 1561 * Sinhala split matras... Let the fun begin. 1562 * 1563 * These four characters have Unicode decompositions. However, Uniscribe 1564 * decomposes them "Khmer-style", that is, it uses the character itself to 1565 * get the second half. The first half of all four decompositions is always 1566 * U+0DD9. 1567 * 1568 * Now, there are buggy fonts, namely, the widely used lklug.ttf, that are 1569 * broken with Uniscribe. But we need to support them. As such, we only 1570 * do the Uniscribe-style decomposition if the character is transformed into 1571 * its "sec.half" form by the 'pstf' feature. Otherwise, we fall back to 1572 * Unicode decomposition. 1573 * 1574 * Note that we can't unconditionally use Unicode decomposition. That would 1575 * break some other fonts, that are designed to work with Uniscribe, and 1576 * don't have positioning features for the Unicode-style decomposition. 1577 * 1578 * Argh... 1579 * 1580 * The Uniscribe behavior is now documented in the newly published Sinhala 1581 * spec in 2012: 1582 * 1583 * https://docs.microsoft.com/en-us/typography/script-development/sinhala#shaping 1584 */ 1585 1586 const indic_shape_plan_t *indic_plan = (const indic_shape_plan_t *) c->plan->data; 1587 1588 hb_codepoint_t glyph; 1589 1590 if (hb_options ().uniscribe_bug_compatible || 1591 (c->font->get_nominal_glyph (ab, &glyph) && 1592 indic_plan->pstf.would_substitute (&glyph, 1, c->font->face))) 1593 { 1594 /* Ok, safe to use Uniscribe-style decomposition. */ 1595 *a = 0x0DD9u; 1596 *b = ab; 1597 return true; 1598 } 1599 } 1600 1601 return (bool) c->unicode->decompose (ab, a, b); 1602 } 1603 1604 static bool 1605 compose_indic (const hb_ot_shape_normalize_context_t *c, 1606 hb_codepoint_t a, 1607 hb_codepoint_t b, 1608 hb_codepoint_t *ab) 1609 { 1610 /* Avoid recomposing split matras. */ 1611 if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (c->unicode->general_category (a))) 1612 return false; 1613 1614 /* Composition-exclusion exceptions that we want to recompose. */ 1615 if (a == 0x09AFu && b == 0x09BCu) { *ab = 0x09DFu; return true; } 1616 1617 return (bool) c->unicode->compose (a, b, ab); 1618 } 1619 1620 1621 const hb_ot_complex_shaper_t _hb_ot_complex_shaper_indic = 1622 { 1623 collect_features_indic, 1624 override_features_indic, 1625 data_create_indic, 1626 data_destroy_indic, 1627 preprocess_text_indic, 1628 nullptr, /* postprocess_glyphs */ 1629 HB_OT_SHAPE_NORMALIZATION_MODE_COMPOSED_DIACRITICS_NO_SHORT_CIRCUIT, 1630 decompose_indic, 1631 compose_indic, 1632 setup_masks_indic, 1633 HB_TAG_NONE, /* gpos_tag */ 1634 nullptr, /* reorder_marks */ 1635 HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE, 1636 false, /* fallback_position */ 1637 };