hb-ot-shape.cc revision 15c7379c16dbb9ee8ed1c0333ca7492532ce8423
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 33/* XXX vertical */ 34hb_tag_t default_features[] = { 35 HB_TAG('c','a','l','t'), 36 HB_TAG('c','c','m','p'), 37 HB_TAG('c','l','i','g'), 38 HB_TAG('c','s','w','h'), 39 HB_TAG('c','u','r','s'), 40 HB_TAG('k','e','r','n'), 41 HB_TAG('l','i','g','a'), 42 HB_TAG('l','o','c','l'), 43 HB_TAG('m','a','r','k'), 44 HB_TAG('m','k','m','k'), 45 HB_TAG('r','l','i','g') 46}; 47 48enum { 49 MASK_ALWAYS_ON = 1 << 0, 50 MASK_RTLM = 1 << 1 51}; 52#define MASK_BITS_USED 2 53 54struct lookup_map { 55 unsigned int index; 56 hb_mask_t mask; 57}; 58 59 60static void 61add_feature (hb_face_t *face, 62 hb_tag_t table_tag, 63 unsigned int feature_index, 64 hb_mask_t mask, 65 lookup_map *lookups, 66 unsigned int *num_lookups, 67 unsigned int room_lookups) 68{ 69 unsigned int i = room_lookups - *num_lookups; 70 lookups += *num_lookups; 71 72 unsigned int *lookup_indices = (unsigned int *) lookups; 73 74 hb_ot_layout_feature_get_lookup_indexes (face, table_tag, feature_index, 0, 75 &i, 76 lookup_indices); 77 78 *num_lookups += i; 79 80 while (i--) { 81 lookups[i].mask = mask; 82 lookups[i].index = lookup_indices[i]; 83 } 84} 85 86static hb_bool_t 87maybe_add_feature (hb_face_t *face, 88 hb_tag_t table_tag, 89 unsigned int script_index, 90 unsigned int language_index, 91 hb_tag_t feature_tag, 92 hb_mask_t mask, 93 lookup_map *lookups, 94 unsigned int *num_lookups, 95 unsigned int room_lookups) 96{ 97 unsigned int feature_index; 98 if (hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index, 99 feature_tag, 100 &feature_index)) 101 { 102 add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups); 103 return TRUE; 104 } 105 return FALSE; 106} 107 108static int 109cmp_lookups (const void *p1, const void *p2) 110{ 111 const lookup_map *a = (const lookup_map *) p1; 112 const lookup_map *b = (const lookup_map *) p2; 113 114 return a->index - b->index; 115} 116 117static void 118setup_lookups (hb_face_t *face, 119 hb_buffer_t *buffer, 120 hb_feature_t *features, 121 unsigned int num_features, 122 hb_tag_t table_tag, 123 lookup_map *lookups, 124 unsigned int *num_lookups, 125 hb_direction_t original_direction) 126{ 127 unsigned int i, j, script_index, language_index, feature_index, room_lookups; 128 129 room_lookups = *num_lookups; 130 *num_lookups = 0; 131 132 hb_ot_layout_table_choose_script (face, table_tag, 133 hb_ot_tags_from_script (buffer->script), 134 &script_index); 135 hb_ot_layout_script_find_language (face, table_tag, script_index, 136 hb_ot_tag_from_language (buffer->language), 137 &language_index); 138 139 if (hb_ot_layout_language_get_required_feature_index (face, table_tag, script_index, language_index, 140 &feature_index)) 141 add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups); 142 143 for (i = 0; i < ARRAY_LENGTH (default_features); i++) 144 maybe_add_feature (face, table_tag, script_index, language_index, default_features[i], 1, lookups, num_lookups, room_lookups); 145 146 switch (original_direction) { 147 case HB_DIRECTION_LTR: 148 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','a'), 1, lookups, num_lookups, room_lookups); 149 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('l','t','r','m'), 1, lookups, num_lookups, room_lookups); 150 break; 151 case HB_DIRECTION_RTL: 152 maybe_add_feature (face, table_tag, script_index, language_index, HB_TAG ('r','t','l','a'), 1, lookups, num_lookups, room_lookups); 153 break; 154 case HB_DIRECTION_TTB: 155 case HB_DIRECTION_BTT: 156 default: 157 break; 158 } 159 160 unsigned int next_bit = MASK_BITS_USED; 161 hb_mask_t global_mask = 0; 162 for (i = 0; i < num_features; i++) 163 { 164 hb_feature_t *feature = &features[i]; 165 if (!hb_ot_layout_language_find_feature (face, table_tag, script_index, language_index, 166 feature->tag, 167 &feature_index)) 168 continue; 169 170 if (feature->value == 1 && feature->start == 0 && feature->end == (unsigned int) -1) { 171 add_feature (face, table_tag, feature_index, 1, lookups, num_lookups, room_lookups); 172 continue; 173 } 174 175 /* Allocate bits for the features */ 176 177 unsigned int bits_needed = _hb_bit_storage (feature->value); 178 if (!bits_needed) 179 continue; /* Feature disabled */ 180 181 if (next_bit + bits_needed > 8 * sizeof (hb_mask_t)) 182 continue; /* Oh well... */ 183 184 unsigned int mask = (1 << (next_bit + bits_needed)) - (1 << next_bit); 185 unsigned int value = feature->value << next_bit; 186 next_bit += bits_needed; 187 188 add_feature (face, table_tag, feature_index, mask, lookups, num_lookups, room_lookups); 189 190 if (feature->start == 0 && feature->end == (unsigned int) -1) 191 global_mask |= value; 192 else 193 buffer->or_masks (mask, feature->start, feature->end); 194 } 195 196 if (global_mask) 197 buffer->or_masks (global_mask, 0, (unsigned int) -1); 198 199 qsort (lookups, *num_lookups, sizeof (lookups[0]), cmp_lookups); 200 201 if (*num_lookups) 202 { 203 for (i = 1, j = 0; i < *num_lookups; i++) 204 if (lookups[i].index != lookups[j].index) 205 lookups[++j] = lookups[i]; 206 else 207 lookups[j].mask |= lookups[i].mask; 208 j++; 209 *num_lookups = j; 210 } 211} 212 213 214static hb_bool_t 215hb_ot_substitute_complex (hb_font_t *font HB_UNUSED, 216 hb_face_t *face, 217 hb_buffer_t *buffer, 218 hb_feature_t *features, 219 unsigned int num_features, 220 hb_direction_t original_direction) 221{ 222 lookup_map lookups[1000]; 223 unsigned int num_lookups = ARRAY_LENGTH (lookups); 224 unsigned int i; 225 226 if (!hb_ot_layout_has_substitution (face)) 227 return FALSE; 228 229 setup_lookups (face, buffer, features, num_features, 230 HB_OT_TAG_GSUB, 231 lookups, &num_lookups, 232 original_direction); 233 234 for (i = 0; i < num_lookups; i++) 235 hb_ot_layout_substitute_lookup (face, buffer, lookups[i].index, lookups[i].mask); 236 237 return TRUE; 238} 239 240static hb_bool_t 241hb_ot_position_complex (hb_font_t *font, 242 hb_face_t *face, 243 hb_buffer_t *buffer, 244 hb_feature_t *features, 245 unsigned int num_features, 246 hb_direction_t original_direction) 247{ 248 lookup_map lookups[1000]; 249 unsigned int num_lookups = ARRAY_LENGTH (lookups); 250 unsigned int i; 251 252 if (!hb_ot_layout_has_positioning (face)) 253 return FALSE; 254 255 setup_lookups (face, buffer, features, num_features, 256 HB_OT_TAG_GPOS, 257 lookups, &num_lookups, 258 original_direction); 259 260 for (i = 0; i < num_lookups; i++) 261 hb_ot_layout_position_lookup (font, face, buffer, lookups[i].index, lookups[i].mask); 262 263 hb_ot_layout_position_finish (font, face, buffer); 264 265 return TRUE; 266} 267 268 269/* Main shaper */ 270 271/* Prepare */ 272 273static inline hb_bool_t 274is_variation_selector (hb_codepoint_t unicode) 275{ 276 return unlikely ((unicode >= 0x180B && unicode <= 0x180D) || /* MONGOLIAN FREE VARIATION SELECTOR ONE..THREE */ 277 (unicode >= 0xFE00 && unicode <= 0xFE0F) || /* VARIATION SELECTOR-1..16 */ 278 (unicode >= 0xE0100 && unicode <= 0xE01EF)); /* VARIATION SELECTOR-17..256 */ 279} 280 281static void 282hb_form_clusters (hb_buffer_t *buffer) 283{ 284 unsigned int count = buffer->len; 285 for (unsigned int i = 1; i < count; i++) 286 if (buffer->unicode->v.get_general_category (buffer->info[i].codepoint) == HB_CATEGORY_NON_SPACING_MARK) 287 buffer->info[i].cluster = buffer->info[i - 1].cluster; 288} 289 290static hb_direction_t 291hb_ensure_native_direction (hb_buffer_t *buffer) 292{ 293 hb_direction_t original_direction = buffer->direction; 294 295 /* TODO vertical */ 296 if (HB_DIRECTION_IS_HORIZONTAL (original_direction) && 297 original_direction != _hb_script_get_horizontal_direction (buffer->script)) 298 { 299 hb_buffer_reverse_clusters (buffer); 300 buffer->direction = HB_DIRECTION_REVERSE (buffer->direction); 301 } 302 303 return original_direction; 304} 305 306 307/* Substitute */ 308 309static void 310hb_mirror_chars (hb_buffer_t *buffer) 311{ 312 hb_unicode_get_mirroring_func_t get_mirroring = buffer->unicode->v.get_mirroring; 313 314 if (HB_DIRECTION_IS_FORWARD (buffer->direction)) 315 return; 316 317 unsigned int count = buffer->len; 318 for (unsigned int i = 0; i < count; i++) { 319 hb_codepoint_t codepoint = get_mirroring (buffer->info[i].codepoint); 320 if (likely (codepoint == buffer->info[i].codepoint)) 321 buffer->info[i].mask |= MASK_RTLM; 322 else 323 buffer->info[i].codepoint = codepoint; 324 } 325} 326 327static void 328hb_map_glyphs (hb_font_t *font, 329 hb_face_t *face, 330 hb_buffer_t *buffer) 331{ 332 if (unlikely (!buffer->len)) 333 return; 334 335 unsigned int count = buffer->len - 1; 336 for (unsigned int i = 0; i < count; i++) { 337 if (unlikely (is_variation_selector (buffer->info[i + 1].codepoint))) { 338 buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, buffer->info[i + 1].codepoint); 339 i++; 340 } else { 341 buffer->info[i].codepoint = hb_font_get_glyph (font, face, buffer->info[i].codepoint, 0); 342 } 343 } 344 buffer->info[count].codepoint = hb_font_get_glyph (font, face, buffer->info[count].codepoint, 0); 345} 346 347static void 348hb_substitute_default (hb_font_t *font, 349 hb_face_t *face, 350 hb_buffer_t *buffer, 351 hb_feature_t *features HB_UNUSED, 352 unsigned int num_features HB_UNUSED) 353{ 354 hb_map_glyphs (font, face, buffer); 355} 356 357static void 358hb_substitute_complex_fallback (hb_font_t *font HB_UNUSED, 359 hb_face_t *face HB_UNUSED, 360 hb_buffer_t *buffer HB_UNUSED, 361 hb_feature_t *features HB_UNUSED, 362 unsigned int num_features HB_UNUSED) 363{ 364 /* TODO Arabic */ 365} 366 367 368/* Position */ 369 370static void 371hb_position_default (hb_font_t *font, 372 hb_face_t *face, 373 hb_buffer_t *buffer, 374 hb_feature_t *features HB_UNUSED, 375 unsigned int num_features HB_UNUSED) 376{ 377 hb_buffer_clear_positions (buffer); 378 379 unsigned int count = buffer->len; 380 for (unsigned int i = 0; i < count; i++) { 381 hb_glyph_metrics_t metrics; 382 hb_font_get_glyph_metrics (font, face, buffer->info[i].codepoint, &metrics); 383 buffer->pos[i].x_advance = metrics.x_advance; 384 buffer->pos[i].y_advance = metrics.y_advance; 385 } 386} 387 388static void 389hb_position_complex_fallback (hb_font_t *font HB_UNUSED, 390 hb_face_t *face HB_UNUSED, 391 hb_buffer_t *buffer HB_UNUSED, 392 hb_feature_t *features HB_UNUSED, 393 unsigned int num_features HB_UNUSED) 394{ 395 /* TODO Mark pos */ 396} 397 398static void 399hb_truetype_kern (hb_font_t *font, 400 hb_face_t *face, 401 hb_buffer_t *buffer, 402 hb_feature_t *features HB_UNUSED, 403 unsigned int num_features HB_UNUSED) 404{ 405 /* TODO Check for kern=0 */ 406 unsigned int count = buffer->len; 407 for (unsigned int i = 1; i < count; i++) { 408 hb_position_t kern, kern1, kern2; 409 kern = hb_font_get_kerning (font, face, buffer->info[i - 1].codepoint, buffer->info[i].codepoint); 410 kern1 = kern >> 1; 411 kern2 = kern - kern1; 412 buffer->pos[i - 1].x_advance += kern1; 413 buffer->pos[i].x_advance += kern2; 414 buffer->pos[i].x_offset += kern2; 415 } 416} 417 418static void 419hb_position_complex_fallback_visual (hb_font_t *font, 420 hb_face_t *face, 421 hb_buffer_t *buffer, 422 hb_feature_t *features, 423 unsigned int num_features) 424{ 425 hb_truetype_kern (font, face, buffer, features, num_features); 426} 427 428 429/* Do it! */ 430 431void 432hb_ot_shape (hb_font_t *font, 433 hb_face_t *face, 434 hb_buffer_t *buffer, 435 hb_feature_t *features, 436 unsigned int num_features) 437{ 438 hb_direction_t original_direction; 439 hb_bool_t substitute_fallback, position_fallback; 440 441 hb_form_clusters (buffer); 442 443 /* SUBSTITUTE */ 444 445 buffer->clear_masks (); 446 447 /* Mirroring needs to see the original direction */ 448 hb_mirror_chars (buffer); 449 450 original_direction = hb_ensure_native_direction (buffer); 451 452 hb_substitute_default (font, face, buffer, features, num_features); 453 454 substitute_fallback = !hb_ot_substitute_complex (font, face, buffer, features, num_features, original_direction); 455 456 if (substitute_fallback) 457 hb_substitute_complex_fallback (font, face, buffer, features, num_features); 458 459 460 /* POSITION */ 461 462 buffer->clear_masks (); 463 464 hb_position_default (font, face, buffer, features, num_features); 465 466 position_fallback = !hb_ot_position_complex (font, face, buffer, features, num_features, original_direction); 467 468 if (position_fallback) 469 hb_position_complex_fallback (font, face, buffer, features, num_features); 470 471 if (HB_DIRECTION_IS_BACKWARD (buffer->direction)) 472 hb_buffer_reverse (buffer); 473 474 if (position_fallback) 475 hb_position_complex_fallback_visual (font, face, buffer, features, num_features); 476 477 buffer->direction = original_direction; 478} 479