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 /* XXX */
  32 #include "hb-buffer-private.h"
  33
  34 #include "hb-ot-layout.h"
  35 #include "hb-ot-layout-private.h"
  36
  37 #include "hb-ot-layout-open-private.h"
  38 #include "hb-ot-layout-gdef-private.h"
  39 #include "hb-ot-layout-gsub-private.h"
  40 #include "hb-ot-layout-gpos-private.h"
  41
  42
  43 #include <stdlib.h>
  44 #include <string.h>
  45
  46
  47 hb_ot_layout_t *
  48 hb_ot_layout_create (void)
  49 {
  50   hb_ot_layout_t *layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
  51
  52   layout->gdef = &Null(GDEF);
  53   layout->gsub = &Null(GSUB);
  54   layout->gpos = &Null(GPOS);
  55
  56   return layout;
  57 }
  58
  59 hb_ot_layout_t *
  60 hb_ot_layout_create_for_data (const char *font_data,
  61                               int         face_index)
  62 {
  63   hb_ot_layout_t *layout;
  64
  65   if (HB_UNLIKELY (font_data == NULL))
  66     return hb_ot_layout_create ();
  67
  68   layout = (hb_ot_layout_t *) calloc (1, sizeof (hb_ot_layout_t));
  69
  70   const OpenTypeFontFile &font = OpenTypeFontFile::get_for_data (font_data);
  71   const OpenTypeFontFace &face = font.get_face (face_index);
  72
  73   layout->gdef = &GDEF::get_for_data (font.get_table_data (face.get_table_by_tag (GDEF::Tag)));
  74   layout->gsub = &GSUB::get_for_data (font.get_table_data (face.get_table_by_tag (GSUB::Tag)));
  75   layout->gpos = &GPOS::get_for_data (font.get_table_data (face.get_table_by_tag (GPOS::Tag)));
  76
  77   return layout;
  78 }
  79
  80 void
  81 hb_ot_layout_destroy (hb_ot_layout_t *layout)
  82 {
  83   free (layout);
  84 }
  85
  86 void
  87 hb_ot_layout_set_direction (hb_ot_layout_t *layout,
  88                             hb_bool_t r2l)
  89 {
  90   layout->gpos_info.r2l = !!r2l;
  91 }
  92
  93 void
  94 hb_ot_layout_set_hinting (hb_ot_layout_t *layout,
  95                           hb_bool_t hinted)
  96 {
  97   layout->gpos_info.dvi = !hinted;
  98 }
  99
 100 void
 101 hb_ot_layout_set_scale (hb_ot_layout_t *layout,
 102                         hb_16dot16_t x_scale, hb_16dot16_t y_scale)
 103 {
 104   layout->gpos_info.x_scale = x_scale;
 105   layout->gpos_info.y_scale = y_scale;
 106 }
 107
 108 void
 109 hb_ot_layout_set_ppem (hb_ot_layout_t *layout,
 110                        unsigned int x_ppem, unsigned int y_ppem)
 111 {
 112   layout->gpos_info.x_ppem = x_ppem;
 113   layout->gpos_info.y_ppem = y_ppem;
 114 }
 115
 116
 117 /*
 118  * GDEF
 119  */
 120
 121 /* TODO the public class_t is a mess */
 122
 123 hb_bool_t
 124 hb_ot_layout_has_font_glyph_classes (hb_ot_layout_t *layout)
 125 {
 126   return layout->gdef->has_glyph_classes ();
 127 }
 128
 129 HB_INTERNAL hb_bool_t
 130 _hb_ot_layout_has_new_glyph_classes (hb_ot_layout_t *layout)
 131 {
 132   return layout->new_gdef.len > 0;
 133 }
 134
 135 HB_INTERNAL unsigned int
 136 _hb_ot_layout_get_glyph_property (hb_ot_layout_t *layout,
 137                                   hb_codepoint_t  glyph)
 138 {
 139   hb_ot_layout_class_t klass;
 140
 141   /* TODO old harfbuzz doesn't always parse mark attachments as it says it was
 142    * introduced without a version bump, so it may not be safe */
 143   klass = layout->gdef->get_mark_attachment_type (layout, glyph);
 144   if (klass)
 145     return klass << 8;
 146
 147   klass = layout->gdef->get_glyph_class (layout, glyph);
 148
 149   if (!klass && glyph < layout->new_gdef.len)
 150     klass = layout->new_gdef.klasses[glyph];
 151
 152   switch (klass) {
 153   default:
 154   case GDEF::UnclassifiedGlyph: return HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED;
 155   case GDEF::BaseGlyph:         return HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH;
 156   case GDEF::LigatureGlyph:     return HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE;
 157   case GDEF::MarkGlyph:         return HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 158   case GDEF::ComponentGlyph:    return HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT;
 159   }
 160 }
 161
 162 HB_INTERNAL hb_bool_t
 163 _hb_ot_layout_check_glyph_property (hb_ot_layout_t  *layout,
 164                                     hb_glyph_info_t *ginfo,
 165                                     unsigned int     lookup_flags,
 166                                     unsigned int    *property)
 167 {
 168   hb_ot_layout_glyph_class_t basic_glyph_class;
 169   unsigned int desired_attachment_class;
 170
 171   if (ginfo->gproperty == HB_BUFFER_GLYPH_PROPERTIES_UNKNOWN)
 172   {
 173     ginfo->gproperty = *property = _hb_ot_layout_get_glyph_property (layout, ginfo->gindex);
 174     if (ginfo->gproperty == HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED)
 175       return false;
 176   }
 177
 178   *property = ginfo->gproperty;
 179
 180   /* If the glyph was found in the MarkAttachmentClass table,
 181    * then that class value is the high byte of the result,
 182    * otherwise the low byte contains the basic type of the glyph
 183    * as defined by the GlyphClassDef table.
 184    */
 185   if (*property & LookupFlag::MarkAttachmentType)
 186     basic_glyph_class = HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 187   else
 188     basic_glyph_class = (hb_ot_layout_glyph_class_t) *property;
 189
 190   /* Not covered, if, for example, basic_glyph_class
 191    * is HB_GDEF_LIGATURE and lookup_flags includes LookupFlags::IgnoreLigatures
 192    */
 193   if (lookup_flags & basic_glyph_class)
 194     return false;
 195
 196   /* The high byte of lookup_flags has the meaning
 197    * "ignore marks of attachment type different than
 198    * the attachment type specified."
 199    */
 200   desired_attachment_class = lookup_flags & LookupFlag::MarkAttachmentType;
 201   if (desired_attachment_class)
 202   {
 203     if (basic_glyph_class == HB_OT_LAYOUT_GLYPH_CLASS_MARK &&
 204         *property != desired_attachment_class)
 205       return false;
 206   }
 207
 208   return true;
 209 }
 210
 211 HB_INTERNAL void
 212 _hb_ot_layout_set_glyph_property (hb_ot_layout_t *layout,
 213                                   hb_codepoint_t  glyph,
 214                                   unsigned int    property)
 215 {
 216   hb_ot_layout_glyph_class_t klass;
 217
 218   if (property & LookupFlag::MarkAttachmentType)
 219     klass = HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 220   else
 221     klass = (hb_ot_layout_glyph_class_t) property;
 222
 223   hb_ot_layout_set_glyph_class (layout, glyph, klass);
 224 }
 225
 226
 227 hb_ot_layout_glyph_class_t
 228 hb_ot_layout_get_glyph_class (hb_ot_layout_t *layout,
 229                               hb_codepoint_t  glyph)
 230 {
 231   unsigned int property;
 232   hb_ot_layout_class_t klass;
 233
 234   property = _hb_ot_layout_get_glyph_property (layout, glyph);
 235
 236   if (property & LookupFlag::MarkAttachmentType)
 237     return HB_OT_LAYOUT_GLYPH_CLASS_MARK;
 238
 239   return (hb_ot_layout_glyph_class_t) property;
 240 }
 241
 242 void
 243 hb_ot_layout_set_glyph_class (hb_ot_layout_t             *layout,
 244                               hb_codepoint_t              glyph,
 245                               hb_ot_layout_glyph_class_t  klass)
 246 {
 247   /* TODO optimize this, similar to old harfbuzz code for example */
 248
 249   hb_ot_layout_class_t gdef_klass;
 250   int len = layout->new_gdef.len;
 251
 252   if (HB_UNLIKELY (glyph > 65535))
 253     return;
 254
 255   if (glyph >= len) {
 256     int new_len;
 257     unsigned char *new_klasses;
 258
 259     new_len = len == 0 ? 120 : 2 * len;
 260     if (new_len > 65535)
 261       new_len = 65535;
 262     new_klasses = (unsigned char *) realloc (layout->new_gdef.klasses, new_len * sizeof (unsigned char));
 263
 264     if (HB_UNLIKELY (!new_klasses))
 265       return;
 266
 267     memset (new_klasses + len, 0, new_len - len);
 268
 269     layout->new_gdef.klasses = new_klasses;
 270     layout->new_gdef.len = new_len;
 271   }
 272
 273   switch (klass) {
 274   default:
 275   case HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED:   gdef_klass = GDEF::UnclassifiedGlyph;   break;
 276   case HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH:     gdef_klass = GDEF::BaseGlyph;           break;
 277   case HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE:       gdef_klass = GDEF::LigatureGlyph;       break;
 278   case HB_OT_LAYOUT_GLYPH_CLASS_MARK:           gdef_klass = GDEF::MarkGlyph;           break;
 279   case HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT:      gdef_klass = GDEF::ComponentGlyph;      break;
 280   }
 281
 282   layout->new_gdef.klasses[glyph] = gdef_klass;
 283   return;
 284 }
 285
 286 void
 287 hb_ot_layout_build_glyph_classes (hb_ot_layout_t *layout,
 288                                   uint16_t        num_total_glyphs,
 289                                   hb_codepoint_t *glyphs,
 290                                   unsigned char  *klasses,
 291                                   uint16_t        count)
 292 {
 293   if (HB_UNLIKELY (!count || !glyphs || !klasses))
 294     return;
 295
 296   if (layout->new_gdef.len == 0) {
 297     layout->new_gdef.klasses = (unsigned char *) calloc (num_total_glyphs, sizeof (unsigned char));
 298     layout->new_gdef.len = count;
 299   }
 300
 301   for (unsigned int i = 0; i < count; i++)
 302     hb_ot_layout_set_glyph_class (layout, glyphs[i], (hb_ot_layout_glyph_class_t) klasses[i]);
 303 }
 304
 305 hb_bool_t
 306 hb_ot_layout_get_attach_points (hb_ot_layout_t *layout,
 307                                 hb_codepoint_t  glyph,
 308                                 unsigned int   *point_count /* IN/OUT */,
 309                                 unsigned int   *point_array /* OUT */)
 310 {
 311   return layout->gdef->get_attach_points (layout, glyph, point_count, point_array);
 312 }
 313
 314 hb_bool_t
 315 hb_ot_layout_get_lig_carets (hb_ot_layout_t *layout,
 316                              hb_codepoint_t  glyph,
 317                              unsigned int   *caret_count /* IN/OUT */,
 318                              int            *caret_array /* OUT */)
 319 {
 320   return layout->gdef->get_lig_carets (layout, glyph, caret_count, caret_array);
 321 }
 322
 323 /*
 324  * GSUB/GPOS
 325  */
 326
 327 static const GSUBGPOS&
 328 get_gsubgpos_table (hb_ot_layout_t            *layout,
 329                     hb_ot_layout_table_type_t  table_type)
 330 {
 331   switch (table_type) {
 332     case HB_OT_LAYOUT_TABLE_TYPE_GSUB: return *(layout->gsub);
 333     case HB_OT_LAYOUT_TABLE_TYPE_GPOS: return *(layout->gpos);
 334     default:                           return Null(GSUBGPOS);
 335   }
 336 }
 337
 338
 339 unsigned int
 340 hb_ot_layout_table_get_script_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_script_count ();
 346 }
 347
 348 hb_tag_t
 349 hb_ot_layout_table_get_script_tag (hb_ot_layout_t            *layout,
 350                                    hb_ot_layout_table_type_t  table_type,
 351                                    unsigned int               script_index)
 352 {
 353   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 354
 355   return g.get_script_tag (script_index);
 356 }
 357
 358 hb_bool_t
 359 hb_ot_layout_table_find_script (hb_ot_layout_t            *layout,
 360                                 hb_ot_layout_table_type_t  table_type,
 361                                 hb_tag_t                   script_tag,
 362                                 unsigned int              *script_index)
 363 {
 364   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_SCRIPT_INDEX);
 365   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 366
 367   if (g.find_script_index (script_tag, script_index))
 368     return TRUE;
 369
 370   /* try finding 'DFLT' */
 371   if (g.find_script_index (HB_OT_LAYOUT_TAG_DEFAULT_SCRIPT, script_index))
 372     return FALSE;
 373
 374   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
 375   if (g.find_script_index (HB_OT_LAYOUT_TAG_DEFAULT_LANGUAGE, script_index))
 376     return FALSE;
 377
 378   if (script_index) *script_index = HB_OT_LAYOUT_NO_SCRIPT_INDEX;
 379   return FALSE;
 380 }
 381
 382 unsigned int
 383 hb_ot_layout_table_get_feature_count (hb_ot_layout_t            *layout,
 384                                       hb_ot_layout_table_type_t  table_type)
 385 {
 386   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 387
 388   return g.get_feature_count ();
 389 }
 390
 391 hb_tag_t
 392 hb_ot_layout_table_get_feature_tag (hb_ot_layout_t            *layout,
 393                                     hb_ot_layout_table_type_t  table_type,
 394                                     unsigned int               feature_index)
 395 {
 396   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 397
 398   return g.get_feature_tag (feature_index);
 399 }
 400
 401 hb_bool_t
 402 hb_ot_layout_table_find_feature (hb_ot_layout_t            *layout,
 403                                  hb_ot_layout_table_type_t  table_type,
 404                                  hb_tag_t                   feature_tag,
 405                                  unsigned int              *feature_index)
 406 {
 407   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
 408   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 409
 410   if (g.find_feature_index (feature_tag, feature_index))
 411     return TRUE;
 412
 413   if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
 414   return FALSE;
 415 }
 416
 417 unsigned int
 418 hb_ot_layout_table_get_lookup_count (hb_ot_layout_t            *layout,
 419                                      hb_ot_layout_table_type_t  table_type)
 420 {
 421   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 422
 423   return g.get_lookup_count ();
 424 }
 425
 426
 427 unsigned int
 428 hb_ot_layout_script_get_language_count (hb_ot_layout_t            *layout,
 429                                         hb_ot_layout_table_type_t  table_type,
 430                                         unsigned int               script_index)
 431 {
 432   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 433
 434   return s.get_lang_sys_count ();
 435 }
 436
 437 hb_tag_t
 438 hb_ot_layout_script_get_language_tag (hb_ot_layout_t            *layout,
 439                                       hb_ot_layout_table_type_t  table_type,
 440                                       unsigned int               script_index,
 441                                       unsigned int               language_index)
 442 {
 443   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 444
 445   return s.get_lang_sys_tag (language_index);
 446 }
 447
 448 hb_bool_t
 449 hb_ot_layout_script_find_language (hb_ot_layout_t            *layout,
 450                                    hb_ot_layout_table_type_t  table_type,
 451                                    unsigned int               script_index,
 452                                    hb_tag_t                   language_tag,
 453                                    unsigned int              *language_index)
 454 {
 455   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX);
 456   const Script &s = get_gsubgpos_table (layout, table_type).get_script (script_index);
 457
 458   if (s.find_lang_sys_index (language_tag, language_index))
 459     return TRUE;
 460
 461   /* try with 'dflt'; MS site has had typos and many fonts use it now :( */
 462   if (s.find_lang_sys_index (HB_OT_LAYOUT_TAG_DEFAULT_LANGUAGE, language_index))
 463     return FALSE;
 464
 465   if (language_index) *language_index = HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX;
 466   return FALSE;
 467 }
 468
 469 hb_bool_t
 470 hb_ot_layout_language_get_required_feature_index (hb_ot_layout_t            *layout,
 471                                                   hb_ot_layout_table_type_t  table_type,
 472                                                   unsigned int               script_index,
 473                                                   unsigned int               language_index,
 474                                                   unsigned int              *feature_index)
 475 {
 476   const LangSys &l = get_gsubgpos_table (layout, table_type).get_script (script_index).get_lang_sys (language_index);
 477
 478   if (feature_index) *feature_index = l.get_required_feature_index ();
 479
 480   return l.has_required_feature ();
 481 }
 482
 483 unsigned int
 484 hb_ot_layout_language_get_feature_count (hb_ot_layout_t            *layout,
 485                                          hb_ot_layout_table_type_t  table_type,
 486                                          unsigned int               script_index,
 487                                          unsigned int               language_index)
 488 {
 489   const LangSys &l = get_gsubgpos_table (layout, table_type).get_script (script_index).get_lang_sys (language_index);
 490
 491   return l.get_feature_count ();
 492 }
 493
 494 unsigned int
 495 hb_ot_layout_language_get_feature_index (hb_ot_layout_t            *layout,
 496                                          hb_ot_layout_table_type_t  table_type,
 497                                          unsigned int               script_index,
 498                                          unsigned int               language_index,
 499                                          unsigned int               num_feature)
 500 {
 501   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 502   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 503
 504   return l.get_feature_index (num_feature);
 505 }
 506
 507 hb_tag_t
 508 hb_ot_layout_language_get_feature_tag (hb_ot_layout_t            *layout,
 509                                        hb_ot_layout_table_type_t  table_type,
 510                                        unsigned int               script_index,
 511                                        unsigned int               language_index,
 512                                        unsigned int               num_feature)
 513 {
 514   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 515   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 516   unsigned int feature_index = l.get_feature_index (num_feature);
 517
 518   return g.get_feature_tag (feature_index);
 519 }
 520
 521
 522 hb_bool_t
 523 hb_ot_layout_language_find_feature (hb_ot_layout_t            *layout,
 524                                     hb_ot_layout_table_type_t  table_type,
 525                                     unsigned int               script_index,
 526                                     unsigned int               language_index,
 527                                     hb_tag_t                   feature_tag,
 528                                     unsigned int              *feature_index)
 529 {
 530   ASSERT_STATIC (NO_INDEX == HB_OT_LAYOUT_NO_FEATURE_INDEX);
 531   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 532   const LangSys &l = g.get_script (script_index).get_lang_sys (language_index);
 533
 534   unsigned int num_features = l.get_feature_count ();
 535   for (unsigned int i = 0; i < num_features; i++) {
 536     unsigned int f_index = l.get_feature_index (i);
 537
 538     if (feature_tag == g.get_feature_tag (f_index)) {
 539       if (feature_index) *feature_index = f_index;
 540       return TRUE;
 541     }
 542   }
 543
 544   if (feature_index) *feature_index = HB_OT_LAYOUT_NO_FEATURE_INDEX;
 545   return FALSE;
 546 }
 547
 548 unsigned int
 549 hb_ot_layout_feature_get_lookup_count (hb_ot_layout_t            *layout,
 550                                        hb_ot_layout_table_type_t  table_type,
 551                                        unsigned int               feature_index)
 552 {
 553   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 554   const Feature &f = g.get_feature (feature_index);
 555
 556   return f.get_lookup_count ();
 557 }
 558
 559 unsigned int
 560 hb_ot_layout_feature_get_lookup_index (hb_ot_layout_t            *layout,
 561                                        hb_ot_layout_table_type_t  table_type,
 562                                        unsigned int               feature_index,
 563                                        unsigned int               num_lookup)
 564 {
 565   const GSUBGPOS &g = get_gsubgpos_table (layout, table_type);
 566   const Feature &f = g.get_feature (feature_index);
 567
 568   return f.get_lookup_index (num_lookup);
 569 }
 570
 571 /*
 572  * GSUB
 573  */
 574
 575 hb_bool_t
 576 hb_ot_layout_substitute_lookup (hb_ot_layout_t              *layout,
 577                                 hb_buffer_t                 *buffer,
 578                                 unsigned int                 lookup_index,
 579                                 hb_ot_layout_feature_mask_t  mask)
 580 {
 581   return layout->gsub->substitute_lookup (layout, buffer, lookup_index, mask);
 582 }
 583
 584 /*
 585  * GPOS
 586  */
 587
 588 hb_bool_t
 589 hb_ot_layout_position_lookup   (hb_ot_layout_t              *layout,
 590                                 hb_buffer_t                 *buffer,
 591                                 unsigned int                 lookup_index,
 592                                 hb_ot_layout_feature_mask_t  mask)
 593 {
 594   return layout->gpos->position_lookup (layout, buffer, lookup_index, mask);
 595 }