src/hb-ot-shape.cc

   1 /*
   2  * Copyright © 2009,2010  Red Hat, Inc.
   3  * Copyright © 2010,2011,2012  Google, Inc.
   4  *
   5  *  This is part of HarfBuzz, a text shaping library.
   6  *
   7  * Permission is hereby granted, without written agreement and without
   8  * license or royalty fees, to use, copy, modify, and distribute this
   9  * software and its documentation for any purpose, provided that the
  10  * above copyright notice and the following two paragraphs appear in
  11  * all copies of this software.
  12  *
  13  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  14  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  15  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  16  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  17  * DAMAGE.
  18  *
  19  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  20  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  21  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  22  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  23  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  24  *
  25  * Red Hat Author(s): Behdad Esfahbod
  26  * Google Author(s): Behdad Esfahbod
  27  */
  28
  29 #define HB_SHAPER ot
  30 #define hb_ot_shaper_face_data_t hb_ot_layout_t
  31 #define hb_ot_shaper_shape_plan_data_t hb_ot_shape_plan_t
  32 #include "hb-shaper-impl-private.hh"
  33
  34 #include "hb-ot-shape-private.hh"
  35 #include "hb-ot-shape-complex-private.hh"
  36 #include "hb-ot-shape-fallback-private.hh"
  37 #include "hb-ot-shape-normalize-private.hh"
  38
  39 #include "hb-ot-layout-private.hh"
  40 #include "hb-unicode-private.hh"
  41 #include "hb-set-private.hh"
  42
  43
  44 static hb_tag_t common_features[] = {
  45   HB_TAG('c','c','m','p'),
  46   HB_TAG('l','o','c','l'),
  47   HB_TAG('m','a','r','k'),
  48   HB_TAG('m','k','m','k'),
  49   HB_TAG('r','l','i','g'),
  50 };
  51
  52
  53 static hb_tag_t horizontal_features[] = {
  54   HB_TAG('c','a','l','t'),
  55   HB_TAG('c','l','i','g'),
  56   HB_TAG('c','u','r','s'),
  57   HB_TAG('k','e','r','n'),
  58   HB_TAG('l','i','g','a'),
  59   HB_TAG('r','c','l','t'),
  60 };
  61
  62 static hb_tag_t vertical_features[] = {
  63   HB_TAG('v','e','r','t'),
  64 };
  65
  66
  67
  68 static void
  69 hb_ot_shape_collect_features (hb_ot_shape_planner_t          *planner,
  70                               const hb_segment_properties_t  *props,
  71                               const hb_feature_t             *user_features,
  72                               unsigned int                    num_user_features)
  73 {
  74   hb_ot_map_builder_t *map = &planner->map;
  75
  76   switch (props->direction) {
  77     case HB_DIRECTION_LTR:
  78       map->add_global_bool_feature (HB_TAG ('l','t','r','a'));
  79       map->add_global_bool_feature (HB_TAG ('l','t','r','m'));
  80       break;
  81     case HB_DIRECTION_RTL:
  82       map->add_global_bool_feature (HB_TAG ('r','t','l','a'));
  83       map->add_feature (HB_TAG ('r','t','l','m'), 1, F_NONE);
  84       break;
  85     case HB_DIRECTION_TTB:
  86     case HB_DIRECTION_BTT:
  87     case HB_DIRECTION_INVALID:
  88     default:
  89       break;
  90   }
  91
  92   map->add_feature (HB_TAG ('f','r','a','c'), 1, F_NONE);
  93   map->add_feature (HB_TAG ('n','u','m','r'), 1, F_NONE);
  94   map->add_feature (HB_TAG ('d','n','o','m'), 1, F_NONE);
  95
  96   if (planner->shaper->collect_features)
  97     planner->shaper->collect_features (planner);
  98
  99   for (unsigned int i = 0; i < ARRAY_LENGTH (common_features); i++)
 100     map->add_global_bool_feature (common_features[i]);
 101
 102   if (HB_DIRECTION_IS_HORIZONTAL (props->direction))
 103     for (unsigned int i = 0; i < ARRAY_LENGTH (horizontal_features); i++)
 104       map->add_feature (horizontal_features[i], 1, F_GLOBAL |
 105                         (horizontal_features[i] == HB_TAG('k','e','r','n') ?
 106                          F_HAS_FALLBACK : F_NONE));
 107   else
 108     for (unsigned int i = 0; i < ARRAY_LENGTH (vertical_features); i++)
 109       map->add_feature (vertical_features[i], 1, F_GLOBAL |
 110                         (vertical_features[i] == HB_TAG('v','k','r','n') ?
 111                          F_HAS_FALLBACK : F_NONE));
 112
 113   if (planner->shaper->override_features)
 114     planner->shaper->override_features (planner);
 115
 116   for (unsigned int i = 0; i < num_user_features; i++) {
 117     const hb_feature_t *feature = &user_features[i];
 118     map->add_feature (feature->tag, feature->value,
 119                       (feature->start == 0 && feature->end == (unsigned int) -1) ?
 120                        F_GLOBAL : F_NONE);
 121   }
 122 }
 123
 124
 125 /*
 126  * shaper face data
 127  */
 128
 129 hb_ot_shaper_face_data_t *
 130 _hb_ot_shaper_face_data_create (hb_face_t *face)
 131 {
 132   return _hb_ot_layout_create (face);
 133 }
 134
 135 void
 136 _hb_ot_shaper_face_data_destroy (hb_ot_shaper_face_data_t *data)
 137 {
 138   _hb_ot_layout_destroy (data);
 139 }
 140
 141
 142 /*
 143  * shaper font data
 144  */
 145
 146 struct hb_ot_shaper_font_data_t {};
 147
 148 hb_ot_shaper_font_data_t *
 149 _hb_ot_shaper_font_data_create (hb_font_t *font)
 150 {
 151   return (hb_ot_shaper_font_data_t *) HB_SHAPER_DATA_SUCCEEDED;
 152 }
 153
 154 void
 155 _hb_ot_shaper_font_data_destroy (hb_ot_shaper_font_data_t *data)
 156 {
 157 }
 158
 159
 160 /*
 161  * shaper shape_plan data
 162  */
 163
 164 hb_ot_shaper_shape_plan_data_t *
 165 _hb_ot_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan,
 166                                       const hb_feature_t *user_features,
 167                                       unsigned int        num_user_features)
 168 {
 169   hb_ot_shape_plan_t *plan = (hb_ot_shape_plan_t *) calloc (1, sizeof (hb_ot_shape_plan_t));
 170   if (unlikely (!plan))
 171     return NULL;
 172
 173   hb_ot_shape_planner_t planner (shape_plan);
 174
 175   planner.shaper = hb_ot_shape_complex_categorize (&planner);
 176
 177   hb_ot_shape_collect_features (&planner, &shape_plan->props, user_features, num_user_features);
 178
 179   planner.compile (*plan);
 180
 181   if (plan->shaper->data_create) {
 182     plan->data = plan->shaper->data_create (plan);
 183     if (unlikely (!plan->data))
 184       return NULL;
 185   }
 186
 187   return plan;
 188 }
 189
 190 void
 191 _hb_ot_shaper_shape_plan_data_destroy (hb_ot_shaper_shape_plan_data_t *plan)
 192 {
 193   if (plan->shaper->data_destroy)
 194     plan->shaper->data_destroy (const_cast<void *> (plan->data));
 195
 196   plan->finish ();
 197
 198   free (plan);
 199 }
 200
 201
 202 /*
 203  * shaper
 204  */
 205
 206 struct hb_ot_shape_context_t
 207 {
 208   hb_ot_shape_plan_t *plan;
 209   hb_font_t *font;
 210   hb_face_t *face;
 211   hb_buffer_t  *buffer;
 212   const hb_feature_t *user_features;
 213   unsigned int        num_user_features;
 214
 215   /* Transient stuff */
 216   hb_direction_t target_direction;
 217 };
 218
 219
 220
 221 /* Main shaper */
 222
 223
 224 /* Prepare */
 225
 226 static void
 227 hb_set_unicode_props (hb_buffer_t *buffer)
 228 {
 229   unsigned int count = buffer->len;
 230   hb_glyph_info_t *info = buffer->info;
 231   for (unsigned int i = 0; i < count; i++)
 232     _hb_glyph_info_set_unicode_props (&info[i], buffer->unicode);
 233 }
 234
 235 static void
 236 hb_insert_dotted_circle (hb_buffer_t *buffer, hb_font_t *font)
 237 {
 238   if (!(buffer->flags & HB_BUFFER_FLAG_BOT) ||
 239       buffer->context_len[0] ||
 240       _hb_glyph_info_get_general_category (&buffer->info[0]) !=
 241       HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 242     return;
 243
 244   if (!font->has_glyph (0x25CCu))
 245     return;
 246
 247   hb_glyph_info_t dottedcircle = {0};
 248   dottedcircle.codepoint = 0x25CCu;
 249   _hb_glyph_info_set_unicode_props (&dottedcircle, buffer->unicode);
 250
 251   buffer->clear_output ();
 252
 253   buffer->idx = 0;
 254   hb_glyph_info_t info = dottedcircle;
 255   info.cluster = buffer->cur().cluster;
 256   info.mask = buffer->cur().mask;
 257   buffer->output_info (info);
 258   while (buffer->idx < buffer->len)
 259     buffer->next_glyph ();
 260
 261   buffer->swap_buffers ();
 262 }
 263
 264 static void
 265 hb_form_clusters (hb_buffer_t *buffer)
 266 {
 267   unsigned int count = buffer->len;
 268   hb_glyph_info_t *info = buffer->info;
 269   for (unsigned int i = 1; i < count; i++)
 270     if (HB_UNICODE_GENERAL_CATEGORY_IS_MARK (_hb_glyph_info_get_general_category (&info[i])))
 271       buffer->merge_clusters (i - 1, i + 1);
 272 }
 273
 274 static void
 275 hb_ensure_native_direction (hb_buffer_t *buffer)
 276 {
 277   hb_direction_t direction = buffer->props.direction;
 278
 279   /* TODO vertical:
 280    * The only BTT vertical script is Ogham, but it's not clear to me whether OpenType
 281    * Ogham fonts are supposed to be implemented BTT or not.  Need to research that
 282    * first. */
 283   if ((HB_DIRECTION_IS_HORIZONTAL (direction) && direction != hb_script_get_horizontal_direction (buffer->props.script)) ||
 284       (HB_DIRECTION_IS_VERTICAL   (direction) && direction != HB_DIRECTION_TTB))
 285   {
 286     hb_buffer_reverse_clusters (buffer);
 287     buffer->props.direction = HB_DIRECTION_REVERSE (buffer->props.direction);
 288   }
 289 }
 290
 291
 292 /* Substitute */
 293
 294 static inline void
 295 hb_ot_mirror_chars (hb_ot_shape_context_t *c)
 296 {
 297   if (HB_DIRECTION_IS_FORWARD (c->target_direction))
 298     return;
 299
 300   hb_buffer_t *buffer = c->buffer;
 301   hb_unicode_funcs_t *unicode = buffer->unicode;
 302   hb_mask_t rtlm_mask = c->plan->rtlm_mask;
 303
 304   unsigned int count = buffer->len;
 305   hb_glyph_info_t *info = buffer->info;
 306   for (unsigned int i = 0; i < count; i++) {
 307     hb_codepoint_t codepoint = unicode->mirroring (info[i].codepoint);
 308     if (likely (codepoint == info[i].codepoint))
 309       info[i].mask |= rtlm_mask;
 310     else
 311       info[i].codepoint = codepoint;
 312   }
 313 }
 314
 315 static inline void
 316 hb_ot_shape_setup_masks_fraction (hb_ot_shape_context_t *c)
 317 {
 318   if (!c->plan->has_frac)
 319     return;
 320
 321   hb_buffer_t *buffer = c->buffer;
 322
 323   /* TODO look in pre/post context text also. */
 324   unsigned int count = buffer->len;
 325   hb_glyph_info_t *info = buffer->info;
 326   for (unsigned int i = 0; i < count; i++)
 327   {
 328     if (info[i].codepoint == 0x2044u) /* FRACTION SLASH */
 329     {
 330       unsigned int start = i, end = i + 1;
 331       while (start &&
 332              _hb_glyph_info_get_general_category (&info[start - 1]) ==
 333              HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER)
 334         start--;
 335       while (end < count &&
 336              _hb_glyph_info_get_general_category (&info[end]) ==
 337              HB_UNICODE_GENERAL_CATEGORY_DECIMAL_NUMBER)
 338         end++;
 339
 340       for (unsigned int j = start; j < i; j++)
 341         info[j].mask |= c->plan->numr_mask | c->plan->frac_mask;
 342       info[i].mask |= c->plan->frac_mask;
 343       for (unsigned int j = i + 1; j < end; j++)
 344         info[j].mask |= c->plan->frac_mask | c->plan->dnom_mask;
 345
 346       i = end - 1;
 347     }
 348   }
 349 }
 350
 351 static inline void
 352 hb_ot_shape_initialize_masks (hb_ot_shape_context_t *c)
 353 {
 354   hb_ot_map_t *map = &c->plan->map;
 355   hb_buffer_t *buffer = c->buffer;
 356
 357   hb_mask_t global_mask = map->get_global_mask ();
 358   buffer->reset_masks (global_mask);
 359 }
 360
 361 static inline void
 362 hb_ot_shape_setup_masks (hb_ot_shape_context_t *c)
 363 {
 364   hb_ot_map_t *map = &c->plan->map;
 365   hb_buffer_t *buffer = c->buffer;
 366
 367   hb_ot_shape_setup_masks_fraction (c);
 368
 369   if (c->plan->shaper->setup_masks)
 370     c->plan->shaper->setup_masks (c->plan, buffer, c->font);
 371
 372   for (unsigned int i = 0; i < c->num_user_features; i++)
 373   {
 374     const hb_feature_t *feature = &c->user_features[i];
 375     if (!(feature->start == 0 && feature->end == (unsigned int)-1)) {
 376       unsigned int shift;
 377       hb_mask_t mask = map->get_mask (feature->tag, &shift);
 378       buffer->set_masks (feature->value << shift, mask, feature->start, feature->end);
 379     }
 380   }
 381 }
 382
 383 static inline void
 384 hb_ot_map_glyphs_fast (hb_buffer_t  *buffer)
 385 {
 386   /* Normalization process sets up glyph_index(), we just copy it. */
 387   unsigned int count = buffer->len;
 388   hb_glyph_info_t *info = buffer->info;
 389   for (unsigned int i = 0; i < count; i++)
 390     info[i].codepoint = info[i].glyph_index();
 391 }
 392
 393 static inline void
 394 hb_synthesize_glyph_classes (hb_ot_shape_context_t *c)
 395 {
 396   unsigned int count = c->buffer->len;
 397   hb_glyph_info_t *info = c->buffer->info;
 398   for (unsigned int i = 0; i < count; i++)
 399   {
 400     hb_ot_layout_glyph_class_mask_t klass;
 401
 402     /* Never mark default-ignorables as marks.
 403      * They won't get in the way of lookups anyway,
 404      * but having them as mark will cause them to be skipped
 405      * over if the lookup-flag says so, but at least for the
 406      * Mongolian variation selectors, looks like Uniscribe
 407      * marks them as non-mark.  Some Mongolian fonts without
 408      * GDEF rely on this.  Another notable character that
 409      * this applies to is COMBINING GRAPHEME JOINER. */
 410     klass = (_hb_glyph_info_get_general_category (&info[i]) !=
 411              HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK ||
 412              _hb_glyph_info_is_default_ignorable (&info[i])) ?
 413             HB_OT_LAYOUT_GLYPH_PROPS_BASE_GLYPH :
 414             HB_OT_LAYOUT_GLYPH_PROPS_MARK;
 415     _hb_glyph_info_set_glyph_props (&info[i], klass);
 416   }
 417 }
 418
 419 static inline void
 420 hb_ot_substitute_default (hb_ot_shape_context_t *c)
 421 {
 422   hb_buffer_t *buffer = c->buffer;
 423
 424   if (c->plan->shaper->preprocess_text)
 425     c->plan->shaper->preprocess_text (c->plan, buffer, c->font);
 426
 427   hb_ot_shape_initialize_masks (c);
 428
 429   hb_ot_mirror_chars (c);
 430
 431   HB_BUFFER_ALLOCATE_VAR (buffer, glyph_index);
 432
 433   _hb_ot_shape_normalize (c->plan, buffer, c->font);
 434
 435   hb_ot_shape_setup_masks (c);
 436
 437   /* This is unfortunate to go here, but necessary... */
 438   if (!hb_ot_layout_has_positioning (c->face))
 439     _hb_ot_shape_fallback_position_recategorize_marks (c->plan, c->font, buffer);
 440
 441   hb_ot_map_glyphs_fast (buffer);
 442
 443   HB_BUFFER_DEALLOCATE_VAR (buffer, glyph_index);
 444 }
 445
 446 static inline void
 447 hb_ot_substitute_complex (hb_ot_shape_context_t *c)
 448 {
 449   hb_buffer_t *buffer = c->buffer;
 450
 451   _hb_buffer_allocate_gsubgpos_vars (buffer);
 452   hb_ot_layout_substitute_start (c->font, buffer);
 453
 454   if (!hb_ot_layout_has_glyph_classes (c->face))
 455     hb_synthesize_glyph_classes (c);
 456
 457   c->plan->substitute (c->font, buffer);
 458
 459   hb_ot_layout_substitute_finish (c->font, buffer);
 460
 461   return;
 462 }
 463
 464 static inline void
 465 hb_ot_substitute (hb_ot_shape_context_t *c)
 466 {
 467   hb_ot_substitute_default (c);
 468   hb_ot_substitute_complex (c);
 469 }
 470
 471 /* Position */
 472
 473 static inline void
 474 adjust_mark_offsets (hb_glyph_position_t *pos)
 475 {
 476   pos->x_offset -= pos->x_advance;
 477   pos->y_offset -= pos->y_advance;
 478 }
 479
 480 static inline void
 481 zero_mark_width (hb_glyph_position_t *pos)
 482 {
 483   pos->x_advance = 0;
 484   pos->y_advance = 0;
 485 }
 486
 487 static inline void
 488 zero_mark_widths_by_unicode (hb_buffer_t *buffer, bool adjust_offsets)
 489 {
 490   unsigned int count = buffer->len;
 491   hb_glyph_info_t *info = buffer->info;
 492   for (unsigned int i = 0; i < count; i++)
 493     if (_hb_glyph_info_get_general_category (&info[i]) == HB_UNICODE_GENERAL_CATEGORY_NON_SPACING_MARK)
 494     {
 495       if (adjust_offsets)
 496         adjust_mark_offsets (&buffer->pos[i]);
 497       zero_mark_width (&buffer->pos[i]);
 498     }
 499 }
 500
 501 static inline void
 502 zero_mark_widths_by_gdef (hb_buffer_t *buffer, bool adjust_offsets)
 503 {
 504   unsigned int count = buffer->len;
 505   hb_glyph_info_t *info = buffer->info;
 506   for (unsigned int i = 0; i < count; i++)
 507     if (_hb_glyph_info_is_mark (&info[i]))
 508     {
 509       if (adjust_offsets)
 510         adjust_mark_offsets (&buffer->pos[i]);
 511       zero_mark_width (&buffer->pos[i]);
 512     }
 513 }
 514
 515 static inline void
 516 hb_ot_position_default (hb_ot_shape_context_t *c)
 517 {
 518   hb_direction_t direction = c->buffer->props.direction;
 519   unsigned int count = c->buffer->len;
 520   hb_glyph_info_t *info = c->buffer->info;
 521   hb_glyph_position_t *pos = c->buffer->pos;
 522   for (unsigned int i = 0; i < count; i++)
 523   {
 524     c->font->get_glyph_advance_for_direction (info[i].codepoint,
 525                                               direction,
 526                                               &pos[i].x_advance,
 527                                               &pos[i].y_advance);
 528     c->font->subtract_glyph_origin_for_direction (info[i].codepoint,
 529                                                   direction,
 530                                                   &pos[i].x_offset,
 531                                                   &pos[i].y_offset);
 532
 533   }
 534 }
 535
 536 static inline bool
 537 hb_ot_position_complex (hb_ot_shape_context_t *c)
 538 {
 539   bool ret = false;
 540   unsigned int count = c->buffer->len;
 541   bool has_positioning = hb_ot_layout_has_positioning (c->face);
 542   /* If the font has no GPOS, AND, no fallback positioning will
 543    * happen, AND, direction is forward, then when zeroing mark
 544    * widths, we shift the mark with it, such that the mark
 545    * is positioned hanging over the previous glyph.  When
 546    * direction is backward we don't shift and it will end up
 547    * hanging over the next glyph after the final reordering.
 548    * If fallback positinoing happens or GPOS is present, we don't
 549    * care.
 550    */
 551   bool adjust_offsets_when_zeroing = !(has_positioning || c->plan->shaper->fallback_position ||
 552                                        HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction));
 553
 554   switch (c->plan->shaper->zero_width_marks)
 555   {
 556     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY:
 557       zero_mark_widths_by_gdef (c->buffer, adjust_offsets_when_zeroing);
 558       break;
 559
 560     /* Not currently used for any shaper:
 561     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_EARLY:
 562       zero_mark_widths_by_unicode (c->buffer, adjust_offsets_when_zeroing);
 563       break;
 564     */
 565
 566     default:
 567     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE:
 568     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_LATE:
 569     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE:
 570       break;
 571   }
 572
 573   if (has_positioning)
 574   {
 575     hb_glyph_info_t *info = c->buffer->info;
 576     hb_glyph_position_t *pos = c->buffer->pos;
 577
 578     /* Change glyph origin to what GPOS expects, apply GPOS, change it back. */
 579
 580     for (unsigned int i = 0; i < count; i++) {
 581       c->font->add_glyph_origin_for_direction (info[i].codepoint,
 582                                                HB_DIRECTION_LTR,
 583                                                &pos[i].x_offset,
 584                                                &pos[i].y_offset);
 585     }
 586
 587     c->plan->position (c->font, c->buffer);
 588
 589     for (unsigned int i = 0; i < count; i++) {
 590       c->font->subtract_glyph_origin_for_direction (info[i].codepoint,
 591                                                     HB_DIRECTION_LTR,
 592                                                     &pos[i].x_offset,
 593                                                     &pos[i].y_offset);
 594     }
 595
 596     ret = true;
 597   }
 598
 599   switch (c->plan->shaper->zero_width_marks)
 600   {
 601     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_LATE:
 602       zero_mark_widths_by_unicode (c->buffer, adjust_offsets_when_zeroing);
 603       break;
 604
 605     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_LATE:
 606       zero_mark_widths_by_gdef (c->buffer, adjust_offsets_when_zeroing);
 607       break;
 608
 609     default:
 610     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_NONE:
 611     //case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_UNICODE_EARLY:
 612     case HB_OT_SHAPE_ZERO_WIDTH_MARKS_BY_GDEF_EARLY:
 613       break;
 614   }
 615
 616   return ret;
 617 }
 618
 619 static inline void
 620 hb_ot_position (hb_ot_shape_context_t *c)
 621 {
 622   hb_ot_layout_position_start (c->font, c->buffer);
 623
 624   hb_ot_position_default (c);
 625
 626   hb_bool_t fallback = !hb_ot_position_complex (c);
 627
 628   hb_ot_layout_position_finish (c->font, c->buffer);
 629
 630   if (fallback && c->plan->shaper->fallback_position)
 631     _hb_ot_shape_fallback_position (c->plan, c->font, c->buffer);
 632
 633   if (HB_DIRECTION_IS_BACKWARD (c->buffer->props.direction))
 634     hb_buffer_reverse (c->buffer);
 635
 636   /* Visual fallback goes here. */
 637
 638   if (fallback)
 639     _hb_ot_shape_fallback_kern (c->plan, c->font, c->buffer);
 640
 641   _hb_buffer_deallocate_gsubgpos_vars (c->buffer);
 642 }
 643
 644
 645 /* Post-process */
 646
 647 static void
 648 hb_ot_hide_default_ignorables (hb_ot_shape_context_t *c)
 649 {
 650   if (c->buffer->flags & HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES)
 651     return;
 652
 653   hb_codepoint_t space;
 654   enum {
 655     SPACE_DONT_KNOW,
 656     SPACE_AVAILABLE,
 657     SPACE_UNAVAILABLE
 658   } space_status = SPACE_DONT_KNOW;
 659
 660   unsigned int count = c->buffer->len;
 661   hb_glyph_info_t *info = c->buffer->info;
 662   hb_glyph_position_t *pos = c->buffer->pos;
 663   unsigned int j = 0;
 664   for (unsigned int i = 0; i < count; i++)
 665   {
 666     if (unlikely (!_hb_glyph_info_ligated (&info[i]) &&
 667                   _hb_glyph_info_is_default_ignorable (&info[i])))
 668     {
 669       if (space_status == SPACE_DONT_KNOW)
 670         space_status = c->font->get_glyph (' ', 0, &space) ? SPACE_AVAILABLE : SPACE_UNAVAILABLE;
 671
 672       if (space_status == SPACE_AVAILABLE)
 673       {
 674         info[i].codepoint = space;
 675         pos[i].x_advance = 0;
 676         pos[i].y_advance = 0;
 677       }
 678       else
 679         continue; /* Delete it. */
 680     }
 681     if (j != i)
 682     {
 683       info[j] = info[i];
 684       pos[j] = pos[i];
 685     }
 686     j++;
 687   }
 688   c->buffer->len = j;
 689 }
 690
 691
 692 /* Pull it all together! */
 693
 694 static void
 695 hb_ot_shape_internal (hb_ot_shape_context_t *c)
 696 {
 697   c->buffer->deallocate_var_all ();
 698
 699   /* Save the original direction, we use it later. */
 700   c->target_direction = c->buffer->props.direction;
 701
 702   _hb_buffer_allocate_unicode_vars (c->buffer);
 703
 704   c->buffer->clear_output ();
 705
 706   hb_set_unicode_props (c->buffer);
 707   hb_insert_dotted_circle (c->buffer, c->font);
 708   hb_form_clusters (c->buffer);
 709
 710   hb_ensure_native_direction (c->buffer);
 711
 712   hb_ot_substitute (c);
 713   hb_ot_position (c);
 714
 715   hb_ot_hide_default_ignorables (c);
 716
 717   _hb_buffer_deallocate_unicode_vars (c->buffer);
 718
 719   c->buffer->props.direction = c->target_direction;
 720
 721   c->buffer->deallocate_var_all ();
 722 }
 723
 724
 725 hb_bool_t
 726 _hb_ot_shape (hb_shape_plan_t    *shape_plan,
 727               hb_font_t          *font,
 728               hb_buffer_t        *buffer,
 729               const hb_feature_t *features,
 730               unsigned int        num_features)
 731 {
 732   hb_ot_shape_context_t c = {HB_SHAPER_DATA_GET (shape_plan), font, font->face, buffer, features, num_features};
 733   hb_ot_shape_internal (&c);
 734
 735   return true;
 736 }
 737
 738
 739 void
 740 hb_ot_shape_plan_collect_lookups (hb_shape_plan_t *shape_plan,
 741                                   hb_tag_t         table_tag,
 742                                   hb_set_t        *lookup_indexes /* OUT */)
 743 {
 744   /* XXX Does the first part always succeed? */
 745   HB_SHAPER_DATA_GET (shape_plan)->collect_lookups (table_tag, lookup_indexes);
 746 }
 747
 748
 749 /* TODO Move this to hb-ot-shape-normalize, make it do decompose, and make it public. */
 750 static void
 751 add_char (hb_font_t          *font,
 752           hb_unicode_funcs_t *unicode,
 753           hb_bool_t           mirror,
 754           hb_codepoint_t      u,
 755           hb_set_t           *glyphs)
 756 {
 757   hb_codepoint_t glyph;
 758   if (font->get_glyph (u, 0, &glyph))
 759     glyphs->add (glyph);
 760   if (mirror)
 761   {
 762     hb_codepoint_t m = unicode->mirroring (u);
 763     if (m != u && font->get_glyph (m, 0, &glyph))
 764       glyphs->add (glyph);
 765   }
 766 }
 767
 768
 769 void
 770 hb_ot_shape_glyphs_closure (hb_font_t          *font,
 771                             hb_buffer_t        *buffer,
 772                             const hb_feature_t *features,
 773                             unsigned int        num_features,
 774                             hb_set_t           *glyphs)
 775 {
 776   hb_ot_shape_plan_t plan;
 777
 778   const char *shapers[] = {"ot", NULL};
 779   hb_shape_plan_t *shape_plan = hb_shape_plan_create_cached (font->face, &buffer->props,
 780                                                              features, num_features, shapers);
 781
 782   bool mirror = hb_script_get_horizontal_direction (buffer->props.script) == HB_DIRECTION_RTL;
 783
 784   unsigned int count = buffer->len;
 785   hb_glyph_info_t *info = buffer->info;
 786   for (unsigned int i = 0; i < count; i++)
 787     add_char (font, buffer->unicode, mirror, info[i].codepoint, glyphs);
 788
 789   hb_set_t lookups;
 790   lookups.init ();
 791   hb_ot_shape_plan_collect_lookups (shape_plan, HB_OT_TAG_GSUB, &lookups);
 792
 793   /* And find transitive closure. */
 794   hb_set_t copy;
 795   copy.init ();
 796   do {
 797     copy.set (glyphs);
 798     for (hb_codepoint_t lookup_index = -1; hb_set_next (&lookups, &lookup_index);)
 799       hb_ot_layout_lookup_substitute_closure (font->face, lookup_index, glyphs);
 800   } while (!copy.is_equal (glyphs));
 801
 802   hb_shape_plan_destroy (shape_plan);
 803 }