hb-ot-shape.cc revision 1094a294f6a44c47fc75867983f2b135a6442bab
1/* 2 * Copyright (C) 2009 Red Hat, 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 * Red Hat Author(s): Behdad Esfahbod 25 */ 26 27#include "hb-ot-shape.h" 28 29#include "hb-buffer-private.hh" 30 31#include "hb-ot-layout.h" 32 33hb_tag_t default_features[] = { 34 /* GSUB */ 35 HB_TAG('c','c','m','p'), 36 HB_TAG('l','o','c','l'), 37 HB_TAG('l','i','g','a'), 38 HB_TAG('c','l','i','g'), 39 /* GPOS */ 40 HB_TAG('k','e','r','n'), 41 HB_TAG('m','a','r','k'), 42 HB_TAG('m','k','m','k'), 43}; 44 45enum { 46 MASK_ALWAYS_ON = 1 << 0, 47 MASK_RTLM = 1 << 1 48}; 49#define MASK_BITS_USED 2 50 51struct lookup_map { 52 unsigned int index; 53 hb_mask_t mask; 54}; 55 56 57static void 58add_feature (hb_face_t *face, 59 hb_tag_t table_tag, 60 unsigned int feature_index, 61 hb_mask_t mask, 62 lookup_map *lookups, 63 unsigned int *num_lookups, 64 unsigned int room_lookups) 65{ 66 unsigned int i = room_lookups - *num_lookups; 67 lookups += *num_lookups; 68 69 unsigned int *lookup_indices = (unsigned int *) lookups; 70 71 hb_ot_layout_feature_get_lookup_indexes (face, table_tag, feature_index, 0, 72 &i, 73 lookup_indices); 74 75 *num_lookups += i; 76 77 while (i--) { 78 lookups[i].mask = mask; 79 lookups[i].index = lookup_indices[i]; 80 } 81} 82 83static hb_bool_t 84maybe_add_feature (hb_face_t *face, 85 hb_tag_t table_tag, 86 unsigned int script_index, 87 unsigned int language_index, 88 hb_tag_t feature_tag, 89 hb_mask_t mask, 90 lookup_map *lookups, 91 unsigned int *num_lookups, 92 unsigned int room_lookups) 93{ 94 unsigned int feature_index; 95 if (hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index, 96 feature_tag, 97 &feature_index)) 98 { 99 add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups); 100 return TRUE; 101 } 102 return FALSE; 103} 104 105static int 106cmp_lookups (const void *p1, const void *p2) 107{ 108 const lookup_map *a = (const lookup_map *) p1; 109 const lookup_map *b = (const lookup_map *) p2; 110 111 return a->index - b->index; 112} 113 114static void 115setup_lookups (hb_face_t *face, 116 hb_buffer_t *buffer, 117 hb_feature_t *features, 118 unsigned int num_features, 119 hb_tag_t table_tag, 120 lookup_map *lookups, 121 unsigned int *num_lookups, 122 hb_direction_t original_direction) 123{ 124 unsigned int i, j, script_index, language_index, feature_index, room_lookups; 125 126 room_lookups = *num_lookups; 127 *num_lookups = 0; 128 129 hb_ot_layout_table_choose_script (face, table_tag, 130 hb_ot_tags_from_script (buffer->script), 131 &script_index); 132 hb_ot_layout_script_find_language (face, table_tag, script_index, 133 hb_ot_tag_from_language (buffer->language), 134 &language_index); 135 136 if (hb_ot_layout_language_get_required_feature_index (face, table_tag, script_index, language_index, 137 &feature_index)) 138 add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups); 139 140 for (i = 0; i < ARRAY_LENGTH (default_features); i++) 141 maybe_add_feature (face, table_tag, script_index, language_index, default_features[i], 1, lookups, num_lookups, room_lookups); 142 143 switch (original_direction) { 144 case HB_DIRECTION_LTR: 145 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','a'), 1, lookups, num_lookups, room_lookups); 146 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','m'), 1, lookups, num_lookups, room_lookups); 147 break; 148 case HB_DIRECTION_RTL: 149 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('r','t','l','a'), 1, lookups, num_lookups, room_lookups); 150 break; 151 case HB_DIRECTION_TTB: 152 case HB_DIRECTION_BTT: 153 default: 154 break; 155 } 156 157 unsigned int next_bit = MASK_BITS_USED; 158 hb_mask_t global_mask = 0; 159 for (i = 0; i < num_features; i++) 160 { 161 hb_feature_t *feature = &features[i]; 162 if (!hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index, 163 feature->tag, 164 &feature_index)) 165 continue; 166 167 if (feature->value == 1 && feature->start == 0 && feature->end == (unsigned int) -1) { 168 add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups); 169 continue; 170 } 171 172 /* Allocate bits for the features */ 173 174 unsigned int bits_needed = _hb_bit_storage (feature->value); 175 if (!bits_needed) 176 continue; /* Feature disabled */ 177 178 if (next_bit + bits_needed > 8 * sizeof (hb_mask_t)) 179 continue; /* Oh well... */ 180 181 unsigned int mask = (1 << (next_bit + bits_needed)) - (1 << next_bit); 182 unsigned int value = feature->value << next_bit; 183 next_bit += bits_needed; 184 185 add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups); 186 187 if (feature->start == 0 && feature->end == (unsigned int) -1) 188 global_mask |= value; 189 else 190 buffer->or_masks (mask, feature->start, feature->end); 191 } 192 193 if (global_mask) 194 buffer->or_masks (global_mask, 0, (unsigned int) -1); 195 196 qsort (lookups, *num_lookups, sizeof (lookups[0]), cmp_lookups); 197 198 if (*num_lookups) 199 { 200 for (i = 1, j = 0; i < *num_lookups; i++) 201 if (lookups[i].index != lookups[j].index) 202 lookups[++j] = lookups[i]; 203 else 204 lookups[j].mask |= lookups[i].mask; 205 j++; 206 *num_lookups = j; 207 } 208} 209 210 211static hb_bool_t 212hb_ot_substitute_complex (hb_font_t *font HB_UNUSED, 213 hb_face_t *face, 214 hb_buffer_t *buffer, 215 hb_feature_t *features, 216 unsigned int num_features, 217 hb_direction_t original_direction) 218{ 219 lookup_map lookups[1000]; 220 unsigned int num_lookups = ARRAY_LENGTH (lookups); 221 unsigned int i; 222 223 if (!hb_ot_layout_has_substitution (face)) 224 return FALSE; 225 226 setup_lookups (face, buffer, features, num_features, 227 HB_OT_TAG_GSUB, 228 lookups, &num_lookups, 229 original_direction); 230 231 for (i = 0; i < num_lookups; i++) 232 hb_ot_layout_substitute_lookup (face, buffer, lookups[i].index, lookups[i].mask); 233 234 return TRUE; 235} 236 237static hb_bool_t 238hb_ot_position_complex (hb_font_t *font, 239 hb_face_t *face, 240 hb_buffer_t *buffer, 241 hb_feature_t *features, 242 unsigned int num_features, 243 hb_direction_t original_direction) 244{ 245 lookup_map lookups[1000]; 246 unsigned int num_lookups = ARRAY_LENGTH (lookups); 247 unsigned int i; 248 249 if (!hb_ot_layout_has_positioning (face)) 250 return FALSE; 251 252 setup_lookups (face, buffer, features, num_features, 253 HB_OT_TAG_GPOS, 254 lookups, &num_lookups, 255 original_direction); 256 257 for (i = 0; i < num_lookups; i++) 258 hb_ot_layout_position_lookup (font, face, buffer, lookups[i].index, lookups[i].mask); 259 260 hb_ot_layout_position_finish (font, face, buffer); 261 262 return TRUE; 263} 264 265 266/* Main shaper */ 267 268/* Prepare */ 269 270static inline hb_bool_t 271is_variation_selector (hb_codepoint_t unicode) 272{ 273 return unlikely ((unicode >= 0x180B && unicode <= 0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */ 274 (unicode >= 0xFE00 && unicode <= 0xFE0F) || /* VARIATION SELECTOR-1..16 */ 275 (unicode >= 0xE0100 && unicode <= 0xE01EF)); /* VARIATION SELECTOR-17..256 */ 276} 277 278static void 279hb_form_clusters (hb_buffer_t *buffer) 280{ 281 unsigned int count = buffer->len; 282 for (unsigned int i = 1; i < count; i++) 283 if (buffer->unicode->get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK) 284 buffer->info[i].cluster = buffer->info[i - 1].cluster; 285} 286 287static hb_direction_t 288hb_ensure_native_direction (hb_buffer_t *buffer) 289{ 290 hb_direction_t original_direction = buffer->direction; 291 292 /* TODO vertical */ 293 if (HB_DIRECTION_IS_HORIZONTAL (original_direction) && 294 original_direction != _hb_script_get_horizontal_direction (buffer->script)) 295 { 296 hb_buffer_reverse_clusters (buffer); 297 buffer->direction = HB_DIRECTION_REVERSE (buffer->direction); 298 } 299 300 return original_direction; 301} 302 303 304/* Substitute */ 305 306static void 307hb_mirror_chars (hb_buffer_t *buffer) 308{ 309 hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->get_mirroring; 310 311 if (HB_DIRECTION_IS_FORWARD (buffer->direction)) 312 return; 313 314 unsigned int count = buffer->len; 315 for (unsigned int i = 0; i < count; i++) { 316 hb_codepoint_t codepoint = get_mirroring (buffer->info[i].codepoint); 317 if (likely (codepoint == buffer->info[i].codepoint)) 318 buffer->info[i].mask |= MASK_RTLM; 319 else 320 buffer->info[i].codepoint = codepoint; 321 } 322} 323 324static void 325hb_map_glyphs (hb_font_t *font, 326 hb_face_t *face, 327 hb_buffer_t *buffer) 328{ 329 if (unlikely (!buffer->len)) 330 return; 331 332 unsigned int count = buffer->len - 1; 333 for (unsigned int i = 0; i < count; i++) { 334 if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) { 335 buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint); 336 i++; 337 } else { 338 buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0); 339 } 340 } 341 buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0); 342} 343 344static void 345hb_substitute_default (hb_font_t *font, 346 hb_face_t *face, 347 hb_buffer_t *buffer, 348 hb_feature_t *features HB_UNUSED, 349 unsigned int num_features HB_UNUSED) 350{ 351 hb_mirror_chars (buffer); 352 hb_map_glyphs (font, face, buffer); 353} 354 355static void 356hb_substitute_complex_fallback (hb_font_t *font HB_UNUSED, 357 hb_face_t *face HB_UNUSED, 358 hb_buffer_t *buffer HB_UNUSED, 359 hb_feature_t *features HB_UNUSED, 360 unsigned int num_features HB_UNUSED) 361{ 362 /* TODO Arabic */ 363} 364 365 366/* Position */ 367 368static void 369hb_position_default (hb_font_t *font, 370 hb_face_t *face, 371 hb_buffer_t *buffer, 372 hb_feature_t *features HB_UNUSED, 373 unsigned int num_features HB_UNUSED) 374{ 375 hb_buffer_clear_positions (buffer); 376 377 unsigned int count = buffer->len; 378 for (unsigned int i = 0; i < count; i++) { 379 hb_glyph_metrics_t metrics; 380 hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics); 381 buffer->pos[i].x_advance = metrics.x_advance; 382 buffer->pos[i].y_advance = metrics.y_advance; 383 } 384} 385 386static void 387hb_position_complex_fallback (hb_font_t *font HB_UNUSED, 388 hb_face_t *face HB_UNUSED, 389 hb_buffer_t *buffer HB_UNUSED, 390 hb_feature_t *features HB_UNUSED, 391 unsigned int num_features HB_UNUSED) 392{ 393 /* TODO Mark pos */ 394} 395 396static void 397hb_truetype_kern (hb_font_t *font, 398 hb_face_t *face, 399 hb_buffer_t *buffer, 400 hb_feature_t *features HB_UNUSED, 401 unsigned int num_features HB_UNUSED) 402{ 403 /* TODO Check for kern=0 */ 404 unsigned int count = buffer->len; 405 for (unsigned int i = 1; i < count; i++) { 406 hb_position_t kern, kern1, kern2; 407 kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint); 408 kern1 = kern >> 1; 409 kern2 = kern - kern1; 410 buffer->pos[i - 1].x_advance += kern1; 411 buffer->pos[i].x_advance += kern2; 412 buffer->pos[i].x_offset += kern2; 413 } 414} 415 416static void 417hb_position_complex_fallback_visual (hb_font_t *font, 418 hb_face_t *face, 419 hb_buffer_t *buffer, 420 hb_feature_t *features, 421 unsigned int num_features) 422{ 423 hb_truetype_kern (font, face, buffer, features, num_features); 424} 425 426 427/* Do it! */ 428 429void 430hb_ot_shape (hb_font_t *font, 431 hb_face_t *face, 432 hb_buffer_t *buffer, 433 hb_feature_t *features, 434 unsigned int num_features) 435{ 436 hb_direction_t original_direction; 437 hb_bool_t substitute_fallback, position_fallback; 438 439 hb_form_clusters (buffer); 440 441 /* SUBSTITUTE */ 442 443 buffer->clear_masks (); 444 445 hb_substitute_default (font, face, buffer, features, num_features); 446 447 /* We do this after substitute_default because mirroring needs to 448 * see the original direction. */ 449 original_direction = hb_ensure_native_direction (buffer); 450 451 substitute_fallback = !hb_ot_substitute_complex (font, face, buffer, features, num_features, original_direction); 452 453 if (substitute_fallback) 454 hb_substitute_complex_fallback (font, face, buffer, features, num_features); 455 456 457 /* POSITION */ 458 459 buffer->clear_masks (); 460 461 hb_position_default (font, face, buffer, features, num_features); 462 463 position_fallback = !hb_ot_position_complex (font, face, buffer, features, num_features, original_direction); 464 465 if (position_fallback) 466 hb_position_complex_fallback (font, face, buffer, features, num_features); 467 468 if (HB_DIRECTION_IS_BACKWARD (buffer->direction)) 469 hb_buffer_reverse (buffer); 470 471 if (position_fallback) 472 hb_position_complex_fallback_visual (font, face, buffer, features, num_features); 473 474 buffer->direction = original_direction; 475} 476