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