src/hb-ot-layout.cc

   1 /*
   2  * Copyright (C) 1998-2004  David Turner and Werner Lemberg
   3  * Copyright (C) 2006  Behdad Esfahbod
   4  * Copyright (C) 2007,2008,2009  Red Hat, Inc.
   5  *
   6  *  This is part of HarfBuzz, an OpenType Layout engine library.
   7  *
   8  * Permission is hereby granted, without written agreement and without
   9  * license or royalty fees, to use, copy, modify, and distribute this
  10  * software and its documentation for any purpose, provided that the
  11  * above copyright notice and the following two paragraphs appear in
  12  * all copies of this software.
  13  *
  14  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  15  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  16  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  17  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  18  * DAMAGE.
  19  *
  20  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  21  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  22  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  23  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  24  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  25  *
  26  * Red Hat Author(s): Behdad Esfahbod
  27  */
  28
  29 #define HB_OT_LAYOUT_CC
  30
  31 #include "hb-ot-layout.h"
  32 #include "hb-ot-layout-private.h"
  33
  34 #include "hb-ot-layout-open-private.h"
  35 #include "hb-ot-layout-gdef-private.h"
  36 #include "hb-ot-layout-gsub-private.h"
  37 #include "hb-ot-layout-gpos-private.h"
  38
  39 /* XXX */
  40 #include "harfbuzz-buffer-private.h"
  41
  42 #include <stdlib.h>
  43 #include <string.h>
  44
  45
  46 hb_ot_layout_t *
  47 hb_ot_layout_create (void)
  48 {
  49   hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
  50
  51   layout->gdef = &Null(GDEF);
  52   layout->gsub = &Null(GSUB);
  53   layout->gpos = &Null(GPOS);
  54
  55   return layout;
  56 }
  57
  58 hb_ot_layout_t *
  59 hb_ot_layout_create_for_data (const char *font_data,
  60                               int         face_index)
  61 {
  62   hb_ot_layout_t *layout;
  63
  64   if (HB_UNLIKELY (font_data == NULL))
  65     return hb_ot_layout_create ();
  66
  67   layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
  68
  69   const OpenTypeFontFile &font = OpenTypeFontFile::get_for_data (font_data);
  70   const OpenTypeFontFace &face = font.get_face (face_index);
  71
  72   layout->gdef = &GDEF::get_for_data (font.get_table_data (face.get_table_by_tag (GDEF::Tag)));
  73   layout->gsub = &GSUB::get_for_data (font.get_table_data (face.get_table_by_tag (GSUB::Tag)));
  74   layout->gpos = &GPOS::get_for_data (font.get_table_data (face.get_table_by_tag (GPOS::Tag)));
  75
  76   return layout;
  77 }
  78
  79 void
  80 hb_ot_layout_destroy (hb_ot_layout_t *layout)
  81 {
  82   free (layout);
  83 }
  84
  85 void
  86 hb_ot_layout_set_direction (hb_ot_layout_t *layout,
  87                             hb_bool_t r2l)
  88 {
  89   layout->gpos_info.r2l = !!r2l;
  90 }
  91
  92 /*
  93  * GDEF
  94  */
  95
  96 /* TODO the public class_t is a mess */
  97
  98 hb_bool_t
  99 hb_ot_layout_has_font_glyph_classes (hb_ot_layout_t *layout)
 100 {
 101   return layout->gdef->has_glyph_classes ();
 102 }
 103
 104 HB_OT_LAYOUT_INTERNAL hb_bool_t
 105 _hb_ot_layout_has_new_glyph_classes (hb_ot_layout_t *layout)
 106 {
 107   return layout->new_gdef.len > 0;
 108 }
 109
 110 HB_OT_LAYOUT_INTERNAL unsigned int
 111 _hb_ot_layout_get_glyph_property (hb_ot_layout_t *layout,
 112                                   hb_codepoint_t  glyph)
 113 {
 114   hb_ot_layout_class_t klass;
 115
 116   /* TODO old harfbuzz doesn't always parse mark attachments as it says it was
 117    * introduced without a version bump, so it may not be safe */
 118   klass = layout->gdef->get_mark_attachment_type (glyph);
 119   if (klass)
 120     return klass << 8;
 121
 122   klass = layout->gdef->get_glyph_class (glyph);
 123
 124   if (!klass && glyph < layout->new_gdef.len)
 125     klass = layout->new_gdef.klasses[glyph];
 126
 127   switch (klass) {
 128   default:
 129   case GDEF::UnclassifiedGlyph: return HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED;
 130   case GDEF::BaseGlyph:         return HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH;
 131   case GDEF::LigatureGlyph:     return HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE;
 132   case GDEF::MarkGlyph:         return HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 133   case GDEF::ComponentGlyph:    return HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT;
 134   }
 135 }
 136
 137 HB_OT_LAYOUT_INTERNAL hb_bool_t
 138 _hb_ot_layout_check_glyph_property (hb_ot_layout_t *layout,
 139                                     HB_GlyphItem    gitem,
 140                                     unsigned int    lookup_flags,
 141                                     unsigned int   *property)
 142 {
 143   hb_ot_layout_glyph_class_t basic_glyph_class;
 144   unsigned int desired_attachment_class;
 145
 146   if (gitem->gproperty == HB_BUFFER_GLYPH_PROPERTIES_UNKNOWN)
 147   {
 148     gitem->gproperty = *property = _hb_ot_layout_get_glyph_property (layout, gitem->gindex);
 149     if (gitem->gproperty == HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED)
 150       return false;
 151   }
 152
 153   *property = gitem->gproperty;
 154
 155   /* If the glyph was found in the MarkAttachmentClass table,
 156    * then that class value is the high byte of the result,
 157    * otherwise the low byte contains the basic type of the glyph
 158    * as defined by the GlyphClassDef table.
 159    */
 160   if (*property & LookupFlag::MarkAttachmentType)
 161     basic_glyph_class = HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 162   else
 163     basic_glyph_class = (hb_ot_layout_glyph_class_t) *property;
 164
 165   /* Not covered, if, for example, basic_glyph_class
 166    * is HB_GDEF_LIGATURE and lookup_flags includes LookupFlags::IgnoreLigatures
 167    */
 168   if (lookup_flags & basic_glyph_class)
 169     return false;
 170
 171   /* The high byte of lookup_flags has the meaning
 172    * "ignore marks of attachment type different than
 173    * the attachment type specified."
 174    */
 175   desired_attachment_class = lookup_flags & LookupFlag::MarkAttachmentType;
 176   if (desired_attachment_class)
 177   {
 178     if (basic_glyph_class == HB_OT_LAYOUT_GLYPH_CLASS_MARK &&
 179         *property != desired_attachment_class)
 180       return false;
 181   }
 182
 183   return true;
 184 }
 185
 186 HB_OT_LAYOUT_INTERNAL void
 187 _hb_ot_layout_set_glyph_property (hb_ot_layout_t *layout,
 188                                   hb_codepoint_t  glyph,
 189                                   unsigned int    property)
 190 {
 191   hb_ot_layout_glyph_class_t klass;
 192
 193   if (property & LookupFlag::MarkAttachmentType)
 194     klass = HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 195   else
 196     klass = (hb_ot_layout_glyph_class_t) property;
 197
 198   hb_ot_layout_set_glyph_class (layout, glyph, klass);
 199 }
 200
 201
 202 hb_ot_layout_glyph_class_t
 203 hb_ot_layout_get_glyph_class (hb_ot_layout_t *layout,
 204                               hb_codepoint_t  glyph)
 205 {
 206   unsigned int property;
 207   hb_ot_layout_class_t klass;
 208
 209   property = _hb_ot_layout_get_glyph_property (layout, glyph);
 210
 211   if (property & LookupFlag::MarkAttachmentType)
 212     return HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 213
 214   return (hb_ot_layout_glyph_class_t) property;
 215 }
 216
 217 void
 218 hb_ot_layout_set_glyph_class (hb_ot_layout_t             *layout,
 219                               hb_codepoint_t              glyph,
 220                               hb_ot_layout_glyph_class_t  klass)
 221 {
 222   /* TODO optimize this, similar to old harfbuzz code for example */
 223
 224   hb_ot_layout_class_t gdef_klass;
 225   int len = layout->new_gdef.len;
 226
 227   if (HB_UNLIKELY (glyph > 65535))
 228     return;
 229
 230   if (glyph >= len) {
 231     int new_len;
 232     unsigned char *new_klasses;
 233
 234     new_len = len == 0 ? 120 : 2 * len;
 235     if (new_len > 65535)
 236       new_len = 65535;
 237     new_klasses = (unsigned char *) realloc (layout->new_gdef.klasses, new_len * sizeof (unsigned char));
 238
 239     if (HB_UNLIKELY (!new_klasses))
 240       return;
 241
 242     memset (new_klasses + len, 0, new_len - len);
 243
 244     layout->new_gdef.klasses = new_klasses;
 245     layout->new_gdef.len = new_len;
 246   }
 247
 248   switch (klass) {
 249   default:
 250   case HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED:   gdef_klass = GDEF::UnclassifiedGlyph;   break;
 251   case HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH:     gdef_klass = GDEF::BaseGlyph;           break;
 252   case HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE:       gdef_klass = GDEF::LigatureGlyph;       break;
 253   case HB_OT_LAYOUT_GLYPH_CLASS_MARK:           gdef_klass = GDEF::MarkGlyph;           break;
 254   case HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT:      gdef_klass = GDEF::ComponentGlyph;      break;
 255   }
 256
 257   layout->new_gdef.klasses[glyph] = gdef_klass;
 258   return;
 259 }
 260
 261 void
 262 hb_ot_layout_build_glyph_classes (hb_ot_layout_t *layout,
 263                                   uint16_t        num_total_glyphs,
 264                                   hb_codepoint_t *glyphs,
 265                                   unsigned char  *klasses,
 266                                   uint16_t        count)
 267 {
 268   if (HB_UNLIKELY (!count || !glyphs || !klasses))
 269     return;
 270
 271   if (layout->new_gdef.len == 0) {
 272     layout->new_gdef.klasses = (unsigned char *) calloc (num_total_glyphs, sizeof (unsigned char));
 273     layout->new_gdef.len = count;
 274   }
 275
 276   for (unsigned int i = 0; i < count; i++)
 277     hb_ot_layout_set_glyph_class (layout, glyphs[i], (hb_ot_layout_glyph_class_t) klasses[i]);
 278 }
 279
 280 /*
 281  * GSUB/GPOS
 282  */
 283
 284 static const GSUBGPOS&
 285 get_gsubgpos_table (hb_ot_layout_t            *layout,
 286                     hb_ot_layout_table_type_t  table_type)
 287 {
 288   switch (table_type) {
 289     case HB_OT_LAYOUT_TABLE_TYPE_GSUB: return *(layout->gsub);
 290     case HB_OT_LAYOUT_TABLE_TYPE_GPOS: return *(layout->gpos);
 291     default:                           return Null(GSUBGPOS);
 292   }
 293 }
 294
 295
 296 unsigned int
 297 hb_ot_layout_table_get_script_count (hb_ot_layout_t            *layout,
 298                                      hb_ot_layout_table_type_t  table_type)
 299 {
 300   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 301
 302   return g.get_script_count ();
 303 }
 304
 305 hb_tag_t
 306 hb_ot_layout_table_get_script_tag (hb_ot_layout_t            *layout,
 307                                    hb_ot_layout_table_type_t  table_type,
 308                                    unsigned int               script_index)
 309 {
 310   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 311
 312   return g.get_script_tag (script_index);
 313 }
 314
 315 hb_bool_t
 316 hb_ot_layout_table_find_script (hb_ot_layout_t            *layout,
 317                                 hb_ot_layout_table_type_t  table_type,
 318                                 hb_tag_t                   script_tag,
 319                                 unsigned int              *script_index)
 320 {
 321   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
 322   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 323
 324   if (g.find_script_index (script_tag, script_index))
 325     return TRUE;
 326
 327   /* try finding 'DFLT' */
 328   if (g.find_script_index (HB_OT_LAYOUT_TAG_DEFAULT_SCRIPT, script_index))
 329     return FALSE;
 330
 331   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
 332   if (g.find_script_index (HB_OT_LAYOUT_TAG_DEFAULT_LANGUAGE, script_index))
 333     return FALSE;
 334
 335   if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
 336   return FALSE;
 337 }
 338
 339 unsigned int
 340 hb_ot_layout_table_get_feature_count (hb_ot_layout_t            *layout,
 341                                       hb_ot_layout_table_type_t  table_type)
 342 {
 343   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 344
 345   return g.get_feature_count ();
 346 }
 347
 348 hb_tag_t
 349 hb_ot_layout_table_get_feature_tag (hb_ot_layout_t            *layout,
 350                                     hb_ot_layout_table_type_t  table_type,
 351                                     unsigned int               feature_index)
 352 {
 353   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 354
 355   return g.get_feature_tag (feature_index);
 356 }
 357
 358 hb_bool_t
 359 hb_ot_layout_table_find_feature (hb_ot_layout_t            *layout,
 360                                  hb_ot_layout_table_type_t  table_type,
 361                                  hb_tag_t                   feature_tag,
 362                                  unsigned int              *feature_index)
 363 {
 364   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
 365   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 366
 367   if (g.find_feature_index (feature_tag, feature_index))
 368     return TRUE;
 369
 370   if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
 371   return FALSE;
 372 }
 373
 374 unsigned int
 375 hb_ot_layout_table_get_lookup_count (hb_ot_layout_t            *layout,
 376                                      hb_ot_layout_table_type_t  table_type)
 377 {
 378   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 379
 380   return g.get_lookup_count ();
 381 }
 382
 383
 384 unsigned int
 385 hb_ot_layout_script_get_language_count (hb_ot_layout_t            *layout,
 386                                         hb_ot_layout_table_type_t  table_type,
 387                                         unsigned int               script_index)
 388 {
 389   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 390
 391   return s.get_lang_sys_count ();
 392 }
 393
 394 hb_tag_t
 395 hb_ot_layout_script_get_language_tag (hb_ot_layout_t            *layout,
 396                                       hb_ot_layout_table_type_t  table_type,
 397                                       unsigned int               script_index,
 398                                       unsigned int               language_index)
 399 {
 400   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 401
 402   return s.get_lang_sys_tag (language_index);
 403 }
 404
 405 hb_bool_t
 406 hb_ot_layout_script_find_language (hb_ot_layout_t            *layout,
 407                                    hb_ot_layout_table_type_t  table_type,
 408                                    unsigned int               script_index,
 409                                    hb_tag_t                   language_tag,
 410                                    unsigned int              *language_index)
 411 {
 412   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
 413   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 414
 415   if (s.find_lang_sys_index (language_tag, language_index))
 416     return TRUE;
 417
 418   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
 419   if (s.find_lang_sys_index (HB_OT_LAYOUT_TAG_DEFAULT_LANGUAGE, language_index))
 420     return FALSE;
 421
 422   if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
 423   return FALSE;
 424 }
 425
 426 hb_bool_t
 427 hb_ot_layout_language_get_required_feature_index (hb_ot_layout_t            *layout,
 428                                                   hb_ot_layout_table_type_t  table_type,
 429                                                   unsigned int               script_index,
 430                                                   unsigned int               language_index,
 431                                                   unsigned int              *feature_index)
 432 {
 433   const LangSys &l = get_gsubgpos_table (layout, table_type).get_script (script_index).get_lang_sys (language_index);
 434
 435   if (feature_index) *feature_index = l.get_required_feature_index ();
 436
 437   return l.has_required_feature ();
 438 }
 439
 440 unsigned int
 441 hb_ot_layout_language_get_feature_count (hb_ot_layout_t            *layout,
 442                                          hb_ot_layout_table_type_t  table_type,
 443                                          unsigned int               script_index,
 444                                          unsigned int               language_index)
 445 {
 446   const LangSys &l = get_gsubgpos_table (layout, table_type).get_script (script_index).get_lang_sys (language_index);
 447
 448   return l.get_feature_count ();
 449 }
 450
 451 unsigned int
 452 hb_ot_layout_language_get_feature_index (hb_ot_layout_t            *layout,
 453                                          hb_ot_layout_table_type_t  table_type,
 454                                          unsigned int               script_index,
 455                                          unsigned int               language_index,
 456                                          unsigned int               num_feature)
 457 {
 458   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 459   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 460
 461   return l.get_feature_index (num_feature);
 462 }
 463
 464 hb_tag_t
 465 hb_ot_layout_language_get_feature_tag (hb_ot_layout_t            *layout,
 466                                        hb_ot_layout_table_type_t  table_type,
 467                                        unsigned int               script_index,
 468                                        unsigned int               language_index,
 469                                        unsigned int               num_feature)
 470 {
 471   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 472   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 473   unsigned int feature_index = l.get_feature_index (num_feature);
 474
 475   return g.get_feature_tag (feature_index);
 476 }
 477
 478
 479 hb_bool_t
 480 hb_ot_layout_language_find_feature (hb_ot_layout_t            *layout,
 481                                     hb_ot_layout_table_type_t  table_type,
 482                                     unsigned int               script_index,
 483                                     unsigned int               language_index,
 484                                     hb_tag_t                   feature_tag,
 485                                     unsigned int              *feature_index)
 486 {
 487   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
 488   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 489   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 490
 491   unsigned int num_features = l.get_feature_count ();
 492   for (unsigned int i = 0; i < num_features; i++) {
 493     unsigned int f_index = l.get_feature_index (i);
 494
 495     if (feature_tag == g.get_feature_tag (f_index)) {
 496       if (feature_index) *feature_index = f_index;
 497       return TRUE;
 498     }
 499   }
 500
 501   if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
 502   return FALSE;
 503 }
 504
 505 unsigned int
 506 hb_ot_layout_feature_get_lookup_count (hb_ot_layout_t            *layout,
 507                                        hb_ot_layout_table_type_t  table_type,
 508                                        unsigned int               feature_index)
 509 {
 510   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 511   const Feature &f = g.get_feature (feature_index);
 512
 513   return f.get_lookup_count ();
 514 }
 515
 516 unsigned int
 517 hb_ot_layout_feature_get_lookup_index (hb_ot_layout_t            *layout,
 518                                        hb_ot_layout_table_type_t  table_type,
 519                                        unsigned int               feature_index,
 520                                        unsigned int               num_lookup)
 521 {
 522   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 523   const Feature &f = g.get_feature (feature_index);
 524
 525   return f.get_lookup_index (num_lookup);
 526 }
 527
 528 /*
 529  * GSUB
 530  */
 531
 532 hb_bool_t
 533 hb_ot_layout_substitute_lookup (hb_ot_layout_t              *layout,
 534                                 hb_buffer_t                 *buffer,
 535                                 unsigned int                 lookup_index,
 536                                 hb_ot_layout_feature_mask_t  mask)
 537 {
 538   return layout->gsub->substitute_lookup (layout, buffer, lookup_index, mask);
 539 }
 540
 541 /*
 542  * GPOS
 543  */
 544
 545 hb_bool_t
 546 hb_ot_layout_position_lookup   (hb_ot_layout_t              *layout,
 547                                 hb_buffer_t                 *buffer,
 548                                 unsigned int                 lookup_index,
 549                                 hb_ot_layout_feature_mask_t  mask)
 550 {
 551   return layout->gpos->position_lookup (layout, buffer, lookup_index, mask);
 552 }
 553
 554
 555
 556 /* TODO dupped, until he old code can be removed */
 557
 558 static HB_Error
 559 hb_buffer_duplicate_out_buffer( HB_Buffer buffer )
 560 {
 561   if ( !buffer->alt_string )
 562     {
 563       HB_Error error;
 564
 565       if ( ALLOC_ARRAY( buffer->alt_string, buffer->allocated, HB_GlyphItemRec ) )
 566         return error;
 567     }
 568
 569   buffer->out_string = buffer->alt_string;
 570   memcpy( buffer->out_string, buffer->in_string, buffer->out_length * sizeof (buffer->out_string[0]) );
 571   buffer->separate_out = TRUE;
 572
 573   return HB_Err_Ok;
 574 }
 575
 576
 577
 578 HB_INTERNAL HB_Error
 579 _hb_buffer_add_output_glyph_ids( HB_Buffer  buffer,
 580                               HB_UShort  num_in,
 581                               HB_UShort  num_out,
 582                               const GlyphID *glyph_data,
 583                               HB_UShort  component,
 584                               HB_UShort  ligID )
 585 {
 586   HB_Error  error;
 587   HB_UShort i;
 588   HB_UInt properties;
 589   HB_UInt cluster;
 590
 591   error = hb_buffer_ensure( buffer, buffer->out_pos + num_out );
 592   if ( error )
 593     return error;
 594
 595   if ( !buffer->separate_out )
 596     {
 597       error = hb_buffer_duplicate_out_buffer( buffer );
 598       if ( error )
 599         return error;
 600     }
 601
 602   properties = buffer->in_string[buffer->in_pos].properties;
 603   cluster = buffer->in_string[buffer->in_pos].cluster;
 604   if ( component == 0xFFFF )
 605     component = buffer->in_string[buffer->in_pos].component;
 606   if ( ligID == 0xFFFF )
 607     ligID = buffer->in_string[buffer->in_pos].ligID;
 608
 609   for ( i = 0; i < num_out; i++ )
 610   {
 611     HB_GlyphItem item = &buffer->out_string[buffer->out_pos + i];
 612
 613     item->gindex = glyph_data[i];
 614     item->properties = properties;
 615     item->cluster = cluster;
 616     item->component = component;
 617     item->ligID = ligID;
 618     item->gproperty = HB_GLYPH_PROPERTY_UNKNOWN;
 619   }
 620
 621   buffer->in_pos  += num_in;
 622   buffer->out_pos += num_out;
 623
 624   buffer->out_length = buffer->out_pos;
 625
 626   return HB_Err_Ok;
 627 }
 628