src/hb-ot-layout.h

   1 /*
   2  * Copyright © 2007,2008,2009  Red Hat, Inc.
   3  *
   4  *  This is part of HarfBuzz, a text shaping library.
   5  *
   6  * Permission is hereby granted, without written agreement and without
   7  * license or royalty fees, to use, copy, modify, and distribute this
   8  * software and its documentation for any purpose, provided that the
   9  * above copyright notice and the following two paragraphs appear in
  10  * all copies of this software.
  11  *
  12  * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
  13  * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
  14  * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
  15  * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
  16  * DAMAGE.
  17  *
  18  * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
  19  * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
  20  * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
  21  * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
  22  * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
  23  *
  24  * Red Hat Author(s): Behdad Esfahbod
  25  */
  26
  27 #if !defined(HB_OT_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
  28 #error "Include <hb-ot.h> instead."
  29 #endif
  30
  31 #ifndef HB_OT_LAYOUT_H
  32 #define HB_OT_LAYOUT_H
  33
  34 #include "hb.h"
  35
  36 #include "hb-ot-name.h"
  37
  38 HB_BEGIN_DECLS
  39
  40
  41 /**
  42  * HB_OT_TAG_BASE:
  43  *
  44  * OpenType [Baseline Table](https://docs.microsoft.com/en-us/typography/opentype/spec/base).
  45  */
  46 #define HB_OT_TAG_BASE HB_TAG('B','A','S','E')
  47 /**
  48  * HB_OT_TAG_GDEF:
  49  *
  50  * OpenType [Glyph Definition Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gdef).
  51  */
  52 #define HB_OT_TAG_GDEF HB_TAG('G','D','E','F')
  53 /**
  54  * HB_OT_TAG_GSUB:
  55  *
  56  * OpenType [Glyph Substitution Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gsub).
  57  */
  58 #define HB_OT_TAG_GSUB HB_TAG('G','S','U','B')
  59 /**
  60  * HB_OT_TAG_GPOS:
  61  *
  62  * OpenType [Glyph Positioning Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gpos).
  63  */
  64 #define HB_OT_TAG_GPOS HB_TAG('G','P','O','S')
  65 /**
  66  * HB_OT_TAG_JSTF:
  67  *
  68  * OpenType [Justification Table](https://docs.microsoft.com/en-us/typography/opentype/spec/jstf).
  69  */
  70 #define HB_OT_TAG_JSTF HB_TAG('J','S','T','F')
  71
  72
  73 /*
  74  * Script & Language tags.
  75  */
  76
  77 /**
  78  * HB_OT_TAG_DEFAULT_SCRIPT:
  79  *
  80  * OpenType script tag, `DFLT`, for features that are not script-specific.
  81  *
  82  */
  83 #define HB_OT_TAG_DEFAULT_SCRIPT        HB_TAG ('D', 'F', 'L', 'T')
  84 /**
  85  * HB_OT_TAG_DEFAULT_LANGUAGE:
  86  *
  87  * OpenType language tag, `dflt`. Not a valid language tag, but some fonts
  88  * mistakenly use it.
  89  */
  90 #define HB_OT_TAG_DEFAULT_LANGUAGE      HB_TAG ('d', 'f', 'l', 't')
  91
  92 /**
  93  * HB_OT_MAX_TAGS_PER_SCRIPT:
  94  *
  95  * Maximum number of OpenType tags that can correspond to a give #hb_script_t.
  96  *
  97  * Since: 2.0.0
  98  **/
  99 #define HB_OT_MAX_TAGS_PER_SCRIPT       3u
 100 /**
 101  * HB_OT_MAX_TAGS_PER_LANGUAGE:
 102  *
 103  * Maximum number of OpenType tags that can correspond to a give #hb_language_t.
 104  *
 105  * Since: 2.0.0
 106  **/
 107 #define HB_OT_MAX_TAGS_PER_LANGUAGE     3u
 108
 109 HB_EXTERN void
 110 hb_ot_tags_from_script_and_language (hb_script_t   script,
 111                                      hb_language_t language,
 112                                      unsigned int *script_count /* IN/OUT */,
 113                                      hb_tag_t     *script_tags /* OUT */,
 114                                      unsigned int *language_count /* IN/OUT */,
 115                                      hb_tag_t     *language_tags /* OUT */);
 116
 117 HB_EXTERN hb_script_t
 118 hb_ot_tag_to_script (hb_tag_t tag);
 119
 120 HB_EXTERN hb_language_t
 121 hb_ot_tag_to_language (hb_tag_t tag);
 122
 123 HB_EXTERN void
 124 hb_ot_tags_to_script_and_language (hb_tag_t       script_tag,
 125                                    hb_tag_t       language_tag,
 126                                    hb_script_t   *script /* OUT */,
 127                                    hb_language_t *language /* OUT */);
 128
 129
 130 /*
 131  * GDEF
 132  */
 133
 134 HB_EXTERN hb_bool_t
 135 hb_ot_layout_has_glyph_classes (hb_face_t *face);
 136
 137 /**
 138  * hb_ot_layout_glyph_class_t:
 139  * @HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED: Glyphs not matching the other classifications
 140  * @HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH: Spacing, single characters, capable of accepting marks
 141  * @HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE: Glyphs that represent ligation of multiple characters
 142  * @HB_OT_LAYOUT_GLYPH_CLASS_MARK: Non-spacing, combining glyphs that represent marks
 143  * @HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT: Spacing glyphs that represent part of a single character
 144  *
 145  * The GDEF classes defined for glyphs.
 146  *
 147  **/
 148 typedef enum {
 149   HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED = 0,
 150   HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH   = 1,
 151   HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE     = 2,
 152   HB_OT_LAYOUT_GLYPH_CLASS_MARK         = 3,
 153   HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT    = 4
 154 } hb_ot_layout_glyph_class_t;
 155
 156 HB_EXTERN hb_ot_layout_glyph_class_t
 157 hb_ot_layout_get_glyph_class (hb_face_t      *face,
 158                               hb_codepoint_t  glyph);
 159
 160 HB_EXTERN void
 161 hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
 162                                   hb_ot_layout_glyph_class_t  klass,
 163                                   hb_set_t                   *glyphs /* OUT */);
 164
 165 /* Not that useful.  Provides list of attach points for a glyph that a
 166  * client may want to cache */
 167 HB_EXTERN unsigned int
 168 hb_ot_layout_get_attach_points (hb_face_t      *face,
 169                                 hb_codepoint_t  glyph,
 170                                 unsigned int    start_offset,
 171                                 unsigned int   *point_count /* IN/OUT */,
 172                                 unsigned int   *point_array /* OUT */);
 173
 174 /* Ligature caret positions */
 175 HB_EXTERN unsigned int
 176 hb_ot_layout_get_ligature_carets (hb_font_t      *font,
 177                                   hb_direction_t  direction,
 178                                   hb_codepoint_t  glyph,
 179                                   unsigned int    start_offset,
 180                                   unsigned int   *caret_count /* IN/OUT */,
 181                                   hb_position_t  *caret_array /* OUT */);
 182
 183
 184 /*
 185  * GSUB/GPOS feature query and enumeration interface
 186  */
 187
 188 /**
 189  * HB_OT_LAYOUT_NO_SCRIPT_INDEX:
 190  *
 191  * Special value for script index indicating unsupported script.
 192  */
 193 #define HB_OT_LAYOUT_NO_SCRIPT_INDEX            0xFFFFu
 194 /**
 195  * HB_OT_LAYOUT_NO_FEATURE_INDEX:
 196  *
 197  * Special value for feature index indicating unsupported feature.
 198  */
 199 #define HB_OT_LAYOUT_NO_FEATURE_INDEX           0xFFFFu
 200 /**
 201  * HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX:
 202  *
 203  * Special value for language index indicating default or unsupported language.
 204  */
 205 #define HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX     0xFFFFu
 206 /**
 207  * HB_OT_LAYOUT_NO_VARIATIONS_INDEX:
 208  *
 209  * Special value for variations index indicating unsupported variation.
 210  */
 211 #define HB_OT_LAYOUT_NO_VARIATIONS_INDEX        0xFFFFFFFFu
 212
 213 HB_EXTERN unsigned int
 214 hb_ot_layout_table_get_script_tags (hb_face_t    *face,
 215                                     hb_tag_t      table_tag,
 216                                     unsigned int  start_offset,
 217                                     unsigned int *script_count /* IN/OUT */,
 218                                     hb_tag_t     *script_tags /* OUT */);
 219
 220 HB_EXTERN hb_bool_t
 221 hb_ot_layout_table_find_script (hb_face_t    *face,
 222                                 hb_tag_t      table_tag,
 223                                 hb_tag_t      script_tag,
 224                                 unsigned int *script_index /* OUT */);
 225
 226 HB_EXTERN hb_bool_t
 227 hb_ot_layout_table_select_script (hb_face_t      *face,
 228                                   hb_tag_t        table_tag,
 229                                   unsigned int    script_count,
 230                                   const hb_tag_t *script_tags,
 231                                   unsigned int   *script_index /* OUT */,
 232                                   hb_tag_t       *chosen_script /* OUT */);
 233
 234 HB_EXTERN unsigned int
 235 hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
 236                                      hb_tag_t      table_tag,
 237                                      unsigned int  start_offset,
 238                                      unsigned int *feature_count /* IN/OUT */,
 239                                      hb_tag_t     *feature_tags /* OUT */);
 240
 241 HB_EXTERN unsigned int
 242 hb_ot_layout_script_get_language_tags (hb_face_t    *face,
 243                                        hb_tag_t      table_tag,
 244                                        unsigned int  script_index,
 245                                        unsigned int  start_offset,
 246                                        unsigned int *language_count /* IN/OUT */,
 247                                        hb_tag_t     *language_tags /* OUT */);
 248
 249 HB_EXTERN hb_bool_t
 250 hb_ot_layout_script_select_language (hb_face_t      *face,
 251                                      hb_tag_t        table_tag,
 252                                      unsigned int    script_index,
 253                                      unsigned int    language_count,
 254                                      const hb_tag_t *language_tags,
 255                                      unsigned int   *language_index /* OUT */);
 256
 257 HB_EXTERN hb_bool_t
 258 hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
 259                                                   hb_tag_t      table_tag,
 260                                                   unsigned int  script_index,
 261                                                   unsigned int  language_index,
 262                                                   unsigned int *feature_index /* OUT */);
 263
 264 HB_EXTERN hb_bool_t
 265 hb_ot_layout_language_get_required_feature (hb_face_t    *face,
 266                                             hb_tag_t      table_tag,
 267                                             unsigned int  script_index,
 268                                             unsigned int  language_index,
 269                                             unsigned int *feature_index /* OUT */,
 270                                             hb_tag_t     *feature_tag /* OUT */);
 271
 272 HB_EXTERN unsigned int
 273 hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
 274                                            hb_tag_t      table_tag,
 275                                            unsigned int  script_index,
 276                                            unsigned int  language_index,
 277                                            unsigned int  start_offset,
 278                                            unsigned int *feature_count /* IN/OUT */,
 279                                            unsigned int *feature_indexes /* OUT */);
 280
 281 HB_EXTERN unsigned int
 282 hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
 283                                         hb_tag_t      table_tag,
 284                                         unsigned int  script_index,
 285                                         unsigned int  language_index,
 286                                         unsigned int  start_offset,
 287                                         unsigned int *feature_count /* IN/OUT */,
 288                                         hb_tag_t     *feature_tags /* OUT */);
 289
 290 HB_EXTERN hb_bool_t
 291 hb_ot_layout_language_find_feature (hb_face_t    *face,
 292                                     hb_tag_t      table_tag,
 293                                     unsigned int  script_index,
 294                                     unsigned int  language_index,
 295                                     hb_tag_t      feature_tag,
 296                                     unsigned int *feature_index /* OUT */);
 297
 298 HB_EXTERN unsigned int
 299 hb_ot_layout_feature_get_lookups (hb_face_t    *face,
 300                                   hb_tag_t      table_tag,
 301                                   unsigned int  feature_index,
 302                                   unsigned int  start_offset,
 303                                   unsigned int *lookup_count /* IN/OUT */,
 304                                   unsigned int *lookup_indexes /* OUT */);
 305
 306 HB_EXTERN unsigned int
 307 hb_ot_layout_table_get_lookup_count (hb_face_t    *face,
 308                                      hb_tag_t      table_tag);
 309
 310 HB_EXTERN void
 311 hb_ot_layout_collect_features (hb_face_t      *face,
 312                                hb_tag_t        table_tag,
 313                                const hb_tag_t *scripts,
 314                                const hb_tag_t *languages,
 315                                const hb_tag_t *features,
 316                                hb_set_t       *feature_indexes /* OUT */);
 317
 318 HB_EXTERN void
 319 hb_ot_layout_collect_lookups (hb_face_t      *face,
 320                               hb_tag_t        table_tag,
 321                               const hb_tag_t *scripts,
 322                               const hb_tag_t *languages,
 323                               const hb_tag_t *features,
 324                               hb_set_t       *lookup_indexes /* OUT */);
 325
 326 HB_EXTERN void
 327 hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
 328                                     hb_tag_t      table_tag,
 329                                     unsigned int  lookup_index,
 330                                     hb_set_t     *glyphs_before, /* OUT.  May be NULL */
 331                                     hb_set_t     *glyphs_input,  /* OUT.  May be NULL */
 332                                     hb_set_t     *glyphs_after,  /* OUT.  May be NULL */
 333                                     hb_set_t     *glyphs_output  /* OUT.  May be NULL */);
 334
 335 #ifdef HB_NOT_IMPLEMENTED
 336 typedef struct
 337 {
 338   const hb_codepoint_t *before,
 339   unsigned int          before_length,
 340   const hb_codepoint_t *input,
 341   unsigned int          input_length,
 342   const hb_codepoint_t *after,
 343   unsigned int          after_length,
 344 } hb_ot_layout_glyph_sequence_t;
 345
 346 typedef hb_bool_t
 347 (*hb_ot_layout_glyph_sequence_func_t) (hb_font_t    *font,
 348                                        hb_tag_t      table_tag,
 349                                        unsigned int  lookup_index,
 350                                        const hb_ot_layout_glyph_sequence_t *sequence,
 351                                        void         *user_data);
 352
 353 HB_EXTERN void
 354 Xhb_ot_layout_lookup_enumerate_sequences (hb_face_t    *face,
 355                                          hb_tag_t      table_tag,
 356                                          unsigned int  lookup_index,
 357                                          hb_ot_layout_glyph_sequence_func_t callback,
 358                                          void         *user_data);
 359 #endif
 360
 361 /* Variations support */
 362
 363 HB_EXTERN hb_bool_t
 364 hb_ot_layout_table_find_feature_variations (hb_face_t    *face,
 365                                             hb_tag_t      table_tag,
 366                                             const int    *coords,
 367                                             unsigned int  num_coords,
 368                                             unsigned int *variations_index /* out */);
 369
 370 HB_EXTERN unsigned int
 371 hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
 372                                                   hb_tag_t      table_tag,
 373                                                   unsigned int  feature_index,
 374                                                   unsigned int  variations_index,
 375                                                   unsigned int  start_offset,
 376                                                   unsigned int *lookup_count /* IN/OUT */,
 377                                                   unsigned int *lookup_indexes /* OUT */);
 378
 379
 380 /*
 381  * GSUB
 382  */
 383
 384 HB_EXTERN hb_bool_t
 385 hb_ot_layout_has_substitution (hb_face_t *face);
 386
 387 HB_EXTERN unsigned
 388 hb_ot_layout_lookup_get_glyph_alternates (hb_face_t      *face,
 389                                           unsigned        lookup_index,
 390                                           hb_codepoint_t  glyph,
 391                                           unsigned        start_offset,
 392                                           unsigned       *alternate_count /* IN/OUT */,
 393                                           hb_codepoint_t *alternate_glyphs /* OUT */);
 394
 395 HB_EXTERN hb_bool_t
 396 hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
 397                                       unsigned int          lookup_index,
 398                                       const hb_codepoint_t *glyphs,
 399                                       unsigned int          glyphs_length,
 400                                       hb_bool_t             zero_context);
 401
 402 HB_EXTERN void
 403 hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
 404                                         unsigned int  lookup_index,
 405                                         hb_set_t     *glyphs
 406                                         /*TODO , hb_bool_t  inclusive */);
 407
 408 HB_EXTERN void
 409 hb_ot_layout_lookups_substitute_closure (hb_face_t      *face,
 410                                          const hb_set_t *lookups,
 411                                          hb_set_t       *glyphs);
 412
 413
 414 #ifdef HB_NOT_IMPLEMENTED
 415 /* Note: You better have GDEF when using this API, or marks won't do much. */
 416 HB_EXTERN hb_bool_t
 417 Xhb_ot_layout_lookup_substitute (hb_font_t            *font,
 418                                 unsigned int          lookup_index,
 419                                 const hb_ot_layout_glyph_sequence_t *sequence,
 420                                 unsigned int          out_size,
 421                                 hb_codepoint_t       *glyphs_out,   /* OUT */
 422                                 unsigned int         *clusters_out, /* OUT */
 423                                 unsigned int         *out_length    /* OUT */);
 424 #endif
 425
 426
 427 /*
 428  * GPOS
 429  */
 430
 431 HB_EXTERN hb_bool_t
 432 hb_ot_layout_has_positioning (hb_face_t *face);
 433
 434 #ifdef HB_NOT_IMPLEMENTED
 435 /* Note: You better have GDEF when using this API, or marks won't do much. */
 436 HB_EXTERN hb_bool_t
 437 Xhb_ot_layout_lookup_position (hb_font_t            *font,
 438                               unsigned int          lookup_index,
 439                               const hb_ot_layout_glyph_sequence_t *sequence,
 440                               hb_glyph_position_t  *positions /* IN / OUT */);
 441 #endif
 442
 443 /* Optical 'size' feature info.  Returns true if found.
 444  * https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#size */
 445 HB_EXTERN hb_bool_t
 446 hb_ot_layout_get_size_params (hb_face_t       *face,
 447                               unsigned int    *design_size,       /* OUT.  May be NULL */
 448                               unsigned int    *subfamily_id,      /* OUT.  May be NULL */
 449                               hb_ot_name_id_t *subfamily_name_id, /* OUT.  May be NULL */
 450                               unsigned int    *range_start,       /* OUT.  May be NULL */
 451                               unsigned int    *range_end          /* OUT.  May be NULL */);
 452
 453
 454 HB_EXTERN hb_bool_t
 455 hb_ot_layout_feature_get_name_ids (hb_face_t       *face,
 456                                    hb_tag_t         table_tag,
 457                                    unsigned int     feature_index,
 458                                    hb_ot_name_id_t *label_id             /* OUT.  May be NULL */,
 459                                    hb_ot_name_id_t *tooltip_id           /* OUT.  May be NULL */,
 460                                    hb_ot_name_id_t *sample_id            /* OUT.  May be NULL */,
 461                                    unsigned int    *num_named_parameters /* OUT.  May be NULL */,
 462                                    hb_ot_name_id_t *first_param_id       /* OUT.  May be NULL */);
 463
 464
 465 HB_EXTERN unsigned int
 466 hb_ot_layout_feature_get_characters (hb_face_t      *face,
 467                                      hb_tag_t        table_tag,
 468                                      unsigned int    feature_index,
 469                                      unsigned int    start_offset,
 470                                      unsigned int   *char_count    /* IN/OUT.  May be NULL */,
 471                                      hb_codepoint_t *characters    /* OUT.     May be NULL */);
 472
 473 /*
 474  * BASE
 475  */
 476
 477 /**
 478  * hb_ot_layout_baseline_tag_t:
 479  * @HB_OT_LAYOUT_BASELINE_TAG_ROMAN: The baseline used by alphabetic scripts such as Latin, Cyrillic and Greek.
 480  * In vertical writing mode, the alphabetic baseline for characters rotated 90 degrees clockwise.
 481  * (This would not apply to alphabetic characters that remain upright in vertical writing mode, since these
 482  * characters are not rotated.)
 483  * @HB_OT_LAYOUT_BASELINE_TAG_HANGING: The hanging baseline. In horizontal direction, this is the horizontal
 484  * line from which syllables seem, to hang in Tibetan and other similar scripts. In vertical writing mode,
 485  * for Tibetan (or some other similar script) characters rotated 90 degrees clockwise.
 486  * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT: Ideographic character face bottom or left edge,
 487  * if the direction is horizontal or vertical, respectively.
 488  * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_TOP_OR_RIGHT: Ideographic character face top or right edge,
 489  * if the direction is horizontal or vertical, respectively.
 490  * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_BOTTOM_OR_LEFT: Ideographic em-box bottom or left edge,
 491  * if the direction is horizontal or vertical, respectively.
 492  * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT: Ideographic em-box top or right edge baseline,
 493  * if the direction is horizontal or vertical, respectively.
 494  * @HB_OT_LAYOUT_BASELINE_TAG_MATH: The baseline about which mathematical characters are centered.
 495  * In vertical writing mode when mathematical characters rotated 90 degrees clockwise, are centered.
 496  *
 497  * Baseline tags from [Baseline Tags](https://docs.microsoft.com/en-us/typography/opentype/spec/baselinetags) registry.
 498  *
 499  * Since: 2.6.0
 500  */
 501 typedef enum {
 502   HB_OT_LAYOUT_BASELINE_TAG_ROMAN                       = HB_TAG ('r','o','m','n'),
 503   HB_OT_LAYOUT_BASELINE_TAG_HANGING                     = HB_TAG ('h','a','n','g'),
 504   HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT    = HB_TAG ('i','c','f','b'),
 505   HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_TOP_OR_RIGHT      = HB_TAG ('i','c','f','t'),
 506   HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_BOTTOM_OR_LEFT   = HB_TAG ('i','d','e','o'),
 507   HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT     = HB_TAG ('i','d','t','p'),
 508   HB_OT_LAYOUT_BASELINE_TAG_MATH                        = HB_TAG ('m','a','t','h'),
 509
 510   /*< private >*/
 511   _HB_OT_LAYOUT_BASELINE_TAG_MAX_VALUE = HB_TAG_MAX_SIGNED /*< skip >*/
 512 } hb_ot_layout_baseline_tag_t;
 513
 514 HB_EXTERN hb_bool_t
 515 hb_ot_layout_get_baseline (hb_font_t                   *font,
 516                            hb_ot_layout_baseline_tag_t  baseline_tag,
 517                            hb_direction_t               direction,
 518                            hb_tag_t                     script_tag,
 519                            hb_tag_t                     language_tag,
 520                            hb_position_t               *coord        /* OUT.  May be NULL. */);
 521
 522 HB_END_DECLS
 523
 524 #endif /* HB_OT_LAYOUT_H */