kc3-lang/harfbuzz/src/hb-ot-layout.h

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• Hash : 4a26e289
  Author :
  Date : 2025-09-30T15:31:04
  

  Add `hb_ot_layout_lookup_collect_glyph_alternates()` (#5367)
  
  * [map] Massage operator << overloads
  
  * [ot-layout] Add +hb_ot_layout_lookup_collect_glyph_alternates
  
  To collect all glyph mapping from SingleSubst or AlternateSubst
  lookups in one call.  Needed by FreeType autohinter for performance.
  
  New API:
  +hb_ot_layout_lookup_collect_glyph_alternates()
  
  * [layout] Change hb_ot_layout_lookup_collect_glyph_alternates() API
  
  https://github.com/harfbuzz/harfbuzz/pull/5367#discussion_r2149019638

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• src/hb-ot-layout.h

• /*
   * Copyright © 2007,2008,2009  Red Hat, Inc.
   *
   *  This is part of HarfBuzz, a text shaping library.
   *
   * Permission is hereby granted, without written agreement and without
   * license or royalty fees, to use, copy, modify, and distribute this
   * software and its documentation for any purpose, provided that the
   * above copyright notice and the following two paragraphs appear in
   * all copies of this software.
   *
   * IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
   * DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
   * ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
   * IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
   * DAMAGE.
   *
   * THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
   * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
   * FITNESS FOR A PARTICULAR PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS
   * ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
   * PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
   *
   * Red Hat Author(s): Behdad Esfahbod
   */
  
  #if !defined(HB_OT_H_IN) && !defined(HB_NO_SINGLE_HEADER_ERROR)
  #error "Include <hb-ot.h> instead."
  #endif
  
  #ifndef HB_OT_LAYOUT_H
  #define HB_OT_LAYOUT_H
  
  #include "hb.h"
  
  #include "hb-ot-name.h"
  
  HB_BEGIN_DECLS
  
  
  /**
   * HB_OT_TAG_BASE:
   *
   * OpenType [Baseline Table](https://docs.microsoft.com/en-us/typography/opentype/spec/base).
   */
  #define HB_OT_TAG_BASE HB_TAG('B','A','S','E')
  /**
   * HB_OT_TAG_GDEF:
   *
   * OpenType [Glyph Definition Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gdef).
   */
  #define HB_OT_TAG_GDEF HB_TAG('G','D','E','F')
  /**
   * HB_OT_TAG_GSUB:
   *
   * OpenType [Glyph Substitution Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gsub).
   */
  #define HB_OT_TAG_GSUB HB_TAG('G','S','U','B')
  /**
   * HB_OT_TAG_GPOS:
   *
   * OpenType [Glyph Positioning Table](https://docs.microsoft.com/en-us/typography/opentype/spec/gpos).
   */
  #define HB_OT_TAG_GPOS HB_TAG('G','P','O','S')
  /**
   * HB_OT_TAG_JSTF:
   *
   * OpenType [Justification Table](https://docs.microsoft.com/en-us/typography/opentype/spec/jstf).
   */
  #define HB_OT_TAG_JSTF HB_TAG('J','S','T','F')
  
  
  /*
   * Script & Language tags.
   */
  
  /**
   * HB_OT_TAG_DEFAULT_SCRIPT:
   *
   * OpenType script tag, `DFLT`, for features that are not script-specific.
   *
   */
  #define HB_OT_TAG_DEFAULT_SCRIPT	HB_TAG ('D', 'F', 'L', 'T')
  /**
   * HB_OT_TAG_DEFAULT_LANGUAGE:
   *
   * OpenType language tag, `dflt`. Not a valid language tag, but some fonts
   * mistakenly use it.
   */
  #define HB_OT_TAG_DEFAULT_LANGUAGE	HB_TAG ('d', 'f', 'l', 't')
  
  /**
   * HB_OT_MAX_TAGS_PER_SCRIPT:
   *
   * Maximum number of OpenType tags that can correspond to a give #hb_script_t.
   *
   * Since: 2.0.0
   **/
  #define HB_OT_MAX_TAGS_PER_SCRIPT	3u
  /**
   * HB_OT_MAX_TAGS_PER_LANGUAGE:
   *
   * Maximum number of OpenType tags that can correspond to a give #hb_language_t.
   *
   * Since: 2.0.0
   **/
  #define HB_OT_MAX_TAGS_PER_LANGUAGE	3u
  
  HB_EXTERN void
  hb_ot_tags_from_script_and_language (hb_script_t   script,
  				     hb_language_t language,
  				     unsigned int *script_count /* IN/OUT */,
  				     hb_tag_t     *script_tags /* OUT */,
  				     unsigned int *language_count /* IN/OUT */,
  				     hb_tag_t     *language_tags /* OUT */);
  
  HB_EXTERN hb_script_t
  hb_ot_tag_to_script (hb_tag_t tag);
  
  HB_EXTERN hb_language_t
  hb_ot_tag_to_language (hb_tag_t tag);
  
  HB_EXTERN void
  hb_ot_tags_to_script_and_language (hb_tag_t       script_tag,
  				   hb_tag_t       language_tag,
  				   hb_script_t   *script /* OUT */,
  				   hb_language_t *language /* OUT */);
  
  
  /*
   * GDEF
   */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_has_glyph_classes (hb_face_t *face);
  
  /**
   * hb_ot_layout_glyph_class_t:
   * @HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED: Glyphs not matching the other classifications
   * @HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH: Spacing, single characters, capable of accepting marks
   * @HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE: Glyphs that represent ligation of multiple characters
   * @HB_OT_LAYOUT_GLYPH_CLASS_MARK: Non-spacing, combining glyphs that represent marks
   * @HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT: Spacing glyphs that represent part of a single character
   *
   * The GDEF classes defined for glyphs.
   *
   **/
  typedef enum {
    HB_OT_LAYOUT_GLYPH_CLASS_UNCLASSIFIED	= 0,
    HB_OT_LAYOUT_GLYPH_CLASS_BASE_GLYPH	= 1,
    HB_OT_LAYOUT_GLYPH_CLASS_LIGATURE	= 2,
    HB_OT_LAYOUT_GLYPH_CLASS_MARK		= 3,
    HB_OT_LAYOUT_GLYPH_CLASS_COMPONENT	= 4
  } hb_ot_layout_glyph_class_t;
  
  HB_EXTERN hb_ot_layout_glyph_class_t
  hb_ot_layout_get_glyph_class (hb_face_t      *face,
  			      hb_codepoint_t  glyph);
  
  HB_EXTERN void
  hb_ot_layout_get_glyphs_in_class (hb_face_t                  *face,
  				  hb_ot_layout_glyph_class_t  klass,
  				  hb_set_t                   *glyphs /* OUT */);
  
  /* Not that useful.  Provides list of attach points for a glyph that a
   * client may want to cache */
  HB_EXTERN unsigned int
  hb_ot_layout_get_attach_points (hb_face_t      *face,
  				hb_codepoint_t  glyph,
  				unsigned int    start_offset,
  				unsigned int   *point_count /* IN/OUT */,
  				unsigned int   *point_array /* OUT */);
  
  /* Ligature caret positions */
  HB_EXTERN unsigned int
  hb_ot_layout_get_ligature_carets (hb_font_t      *font,
  				  hb_direction_t  direction,
  				  hb_codepoint_t  glyph,
  				  unsigned int    start_offset,
  				  unsigned int   *caret_count /* IN/OUT */,
  				  hb_position_t  *caret_array /* OUT */);
  
  
  /*
   * GSUB/GPOS feature query and enumeration interface
   */
  
  /**
   * HB_OT_LAYOUT_NO_SCRIPT_INDEX:
   *
   * Special value for script index indicating unsupported script.
   */
  #define HB_OT_LAYOUT_NO_SCRIPT_INDEX		0xFFFFu
  /**
   * HB_OT_LAYOUT_NO_FEATURE_INDEX:
   *
   * Special value for feature index indicating unsupported feature.
   */
  #define HB_OT_LAYOUT_NO_FEATURE_INDEX		0xFFFFu
  /**
   * HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX:
   *
   * Special value for language index indicating default or unsupported language.
   */
  #define HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX	0xFFFFu
  /**
   * HB_OT_LAYOUT_NO_VARIATIONS_INDEX:
   *
   * Special value for variations index indicating unsupported variation.
   */
  #define HB_OT_LAYOUT_NO_VARIATIONS_INDEX	0xFFFFFFFFu
  
  HB_EXTERN unsigned int
  hb_ot_layout_table_get_script_tags (hb_face_t    *face,
  				    hb_tag_t      table_tag,
  				    unsigned int  start_offset,
  				    unsigned int *script_count /* IN/OUT */,
  				    hb_tag_t     *script_tags /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_table_find_script (hb_face_t    *face,
  				hb_tag_t      table_tag,
  				hb_tag_t      script_tag,
  				unsigned int *script_index /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_table_select_script (hb_face_t      *face,
  				  hb_tag_t        table_tag,
  				  unsigned int    script_count,
  				  const hb_tag_t *script_tags,
  				  unsigned int   *script_index /* OUT */,
  				  hb_tag_t       *chosen_script /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_table_get_feature_tags (hb_face_t    *face,
  				     hb_tag_t      table_tag,
  				     unsigned int  start_offset,
  				     unsigned int *feature_count /* IN/OUT */,
  				     hb_tag_t     *feature_tags /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_script_get_language_tags (hb_face_t    *face,
  				       hb_tag_t      table_tag,
  				       unsigned int  script_index,
  				       unsigned int  start_offset,
  				       unsigned int *language_count /* IN/OUT */,
  				       hb_tag_t     *language_tags /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_script_select_language (hb_face_t      *face,
  				     hb_tag_t        table_tag,
  				     unsigned int    script_index,
  				     unsigned int    language_count,
  				     const hb_tag_t *language_tags,
  				     unsigned int   *language_index /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_script_select_language2 (hb_face_t      *face,
  				     hb_tag_t        table_tag,
  				     unsigned int    script_index,
  				     unsigned int    language_count,
  				     const hb_tag_t *language_tags,
  				     unsigned int   *language_index /* OUT */,
  				     hb_tag_t       *chosen_language /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_language_get_required_feature_index (hb_face_t    *face,
  						  hb_tag_t      table_tag,
  						  unsigned int  script_index,
  						  unsigned int  language_index,
  						  unsigned int *feature_index /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_language_get_required_feature (hb_face_t    *face,
  					    hb_tag_t      table_tag,
  					    unsigned int  script_index,
  					    unsigned int  language_index,
  					    unsigned int *feature_index /* OUT */,
  					    hb_tag_t     *feature_tag /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_language_get_feature_indexes (hb_face_t    *face,
  					   hb_tag_t      table_tag,
  					   unsigned int  script_index,
  					   unsigned int  language_index,
  					   unsigned int  start_offset,
  					   unsigned int *feature_count /* IN/OUT */,
  					   unsigned int *feature_indexes /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_language_get_feature_tags (hb_face_t    *face,
  					hb_tag_t      table_tag,
  					unsigned int  script_index,
  					unsigned int  language_index,
  					unsigned int  start_offset,
  					unsigned int *feature_count /* IN/OUT */,
  					hb_tag_t     *feature_tags /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_language_find_feature (hb_face_t    *face,
  				    hb_tag_t      table_tag,
  				    unsigned int  script_index,
  				    unsigned int  language_index,
  				    hb_tag_t      feature_tag,
  				    unsigned int *feature_index /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_feature_get_lookups (hb_face_t    *face,
  				  hb_tag_t      table_tag,
  				  unsigned int  feature_index,
  				  unsigned int  start_offset,
  				  unsigned int *lookup_count /* IN/OUT */,
  				  unsigned int *lookup_indexes /* OUT */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_table_get_lookup_count (hb_face_t    *face,
  				     hb_tag_t      table_tag);
  
  HB_EXTERN void
  hb_ot_layout_collect_features (hb_face_t      *face,
  			       hb_tag_t        table_tag,
  			       const hb_tag_t *scripts,
  			       const hb_tag_t *languages,
  			       const hb_tag_t *features,
  			       hb_set_t       *feature_indexes /* OUT */);
  
  HB_EXTERN void
  hb_ot_layout_collect_features_map (hb_face_t      *face,
  				   hb_tag_t        table_tag,
  				   unsigned        script_index,
  				   unsigned        language_index,
  				   hb_map_t       *feature_map /* OUT */);
  
  HB_EXTERN void
  hb_ot_layout_collect_lookups (hb_face_t      *face,
  			      hb_tag_t        table_tag,
  			      const hb_tag_t *scripts,
  			      const hb_tag_t *languages,
  			      const hb_tag_t *features,
  			      hb_set_t       *lookup_indexes /* OUT */);
  
  HB_EXTERN void
  hb_ot_layout_lookup_collect_glyphs (hb_face_t    *face,
  				    hb_tag_t      table_tag,
  				    unsigned int  lookup_index,
  				    hb_set_t     *glyphs_before, /* OUT.  May be NULL */
  				    hb_set_t     *glyphs_input,  /* OUT.  May be NULL */
  				    hb_set_t     *glyphs_after,  /* OUT.  May be NULL */
  				    hb_set_t     *glyphs_output  /* OUT.  May be NULL */);
  
  
  /* Variations support */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_table_find_feature_variations (hb_face_t    *face,
  					    hb_tag_t      table_tag,
  					    const int    *coords,
  					    unsigned int  num_coords,
  					    unsigned int *variations_index /* out */);
  
  HB_EXTERN unsigned int
  hb_ot_layout_feature_with_variations_get_lookups (hb_face_t    *face,
  						  hb_tag_t      table_tag,
  						  unsigned int  feature_index,
  						  unsigned int  variations_index,
  						  unsigned int  start_offset,
  						  unsigned int *lookup_count /* IN/OUT */,
  						  unsigned int *lookup_indexes /* OUT */);
  
  
  /*
   * GSUB
   */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_has_substitution (hb_face_t *face);
  
  HB_EXTERN unsigned
  hb_ot_layout_lookup_get_glyph_alternates (hb_face_t      *face,
  					  unsigned        lookup_index,
  					  hb_codepoint_t  glyph,
  					  unsigned        start_offset,
  					  unsigned       *alternate_count /* IN/OUT */,
  					  hb_codepoint_t *alternate_glyphs /* OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_lookup_collect_glyph_alternates (hb_face_t *face,
  					      unsigned   lookup_index,
  					      hb_map_t  *alternate_count /* IN/OUT */,
  					      hb_map_t  *alternate_glyphs /* IN/OUT */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_lookup_would_substitute (hb_face_t            *face,
  				      unsigned int          lookup_index,
  				      const hb_codepoint_t *glyphs,
  				      unsigned int          glyphs_length,
  				      hb_bool_t             zero_context);
  
  HB_EXTERN void
  hb_ot_layout_lookup_substitute_closure (hb_face_t    *face,
  					unsigned int  lookup_index,
  					hb_set_t     *glyphs
  					/*TODO , hb_bool_t  inclusive */);
  
  HB_EXTERN void
  hb_ot_layout_lookups_substitute_closure (hb_face_t      *face,
  					 const hb_set_t *lookups,
  					 hb_set_t       *glyphs);
  
  
  /*
   * GPOS
   */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_has_positioning (hb_face_t *face);
  
  /* Optical 'size' feature info.  Returns true if found.
   * https://docs.microsoft.com/en-us/typography/opentype/spec/features_pt#size */
  HB_EXTERN hb_bool_t
  hb_ot_layout_get_size_params (hb_face_t       *face,
  			      unsigned int    *design_size,       /* OUT.  May be NULL */
  			      unsigned int    *subfamily_id,      /* OUT.  May be NULL */
  			      hb_ot_name_id_t *subfamily_name_id, /* OUT.  May be NULL */
  			      unsigned int    *range_start,       /* OUT.  May be NULL */
  			      unsigned int    *range_end          /* OUT.  May be NULL */);
  
  HB_EXTERN hb_position_t
  hb_ot_layout_lookup_get_optical_bound (hb_font_t      *font,
  				       unsigned        lookup_index,
  				       hb_direction_t  direction,
  				       hb_codepoint_t  glyph);
  
  
  /*
   * GSUB/GPOS
   */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_feature_get_name_ids (hb_face_t       *face,
  				   hb_tag_t         table_tag,
  				   unsigned int     feature_index,
  				   hb_ot_name_id_t *label_id             /* OUT.  May be NULL */,
  				   hb_ot_name_id_t *tooltip_id           /* OUT.  May be NULL */,
  				   hb_ot_name_id_t *sample_id            /* OUT.  May be NULL */,
  				   unsigned int    *num_named_parameters /* OUT.  May be NULL */,
  				   hb_ot_name_id_t *first_param_id       /* OUT.  May be NULL */);
  
  
  HB_EXTERN unsigned int
  hb_ot_layout_feature_get_characters (hb_face_t      *face,
  				     hb_tag_t        table_tag,
  				     unsigned int    feature_index,
  				     unsigned int    start_offset,
  				     unsigned int   *char_count    /* IN/OUT.  May be NULL */,
  				     hb_codepoint_t *characters    /* OUT.     May be NULL */);
  
  
  /*
   * BASE
   */
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_get_font_extents (hb_font_t         *font,
  			       hb_direction_t     direction,
  			       hb_tag_t           script_tag,
  			       hb_tag_t           language_tag,
  			       hb_font_extents_t *extents);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_get_font_extents2 (hb_font_t         *font,
  				hb_direction_t     direction,
  				hb_script_t        script,
  				hb_language_t      language,
  				hb_font_extents_t *extents);
  
  /**
   * hb_ot_layout_baseline_tag_t:
   * @HB_OT_LAYOUT_BASELINE_TAG_ROMAN: The baseline used by alphabetic scripts such as Latin, Cyrillic and Greek.
   * In vertical writing mode, the alphabetic baseline for characters rotated 90 degrees clockwise.
   * (This would not apply to alphabetic characters that remain upright in vertical writing mode, since these
   * characters are not rotated.)
   * @HB_OT_LAYOUT_BASELINE_TAG_HANGING: The hanging baseline. In horizontal direction, this is the horizontal
   * line from which syllables seem, to hang in Tibetan and other similar scripts. In vertical writing mode,
   * for Tibetan (or some other similar script) characters rotated 90 degrees clockwise.
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT: Ideographic character face bottom or left edge,
   * if the direction is horizontal or vertical, respectively.
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_TOP_OR_RIGHT: Ideographic character face top or right edge,
   * if the direction is horizontal or vertical, respectively.
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_CENTRAL: The center of the ideographic character face. Since: 4.0.0
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_BOTTOM_OR_LEFT: Ideographic em-box bottom or left edge,
   * if the direction is horizontal or vertical, respectively.
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT: Ideographic em-box top or right edge baseline,
   * @HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_CENTRAL: The center of the ideographic em-box. Since: 4.0.0
   * if the direction is horizontal or vertical, respectively.
   * @HB_OT_LAYOUT_BASELINE_TAG_MATH: The baseline about which mathematical characters are centered.
   * In vertical writing mode when mathematical characters rotated 90 degrees clockwise, are centered.
   *
   * Baseline tags from [Baseline Tags](https://docs.microsoft.com/en-us/typography/opentype/spec/baselinetags) registry.
   *
   * Since: 2.6.0
   */
  typedef enum {
    HB_OT_LAYOUT_BASELINE_TAG_ROMAN			= HB_TAG ('r','o','m','n'),
    HB_OT_LAYOUT_BASELINE_TAG_HANGING			= HB_TAG ('h','a','n','g'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_BOTTOM_OR_LEFT	= HB_TAG ('i','c','f','b'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_TOP_OR_RIGHT	= HB_TAG ('i','c','f','t'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_FACE_CENTRAL		= HB_TAG ('I','c','f','c'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_BOTTOM_OR_LEFT	= HB_TAG ('i','d','e','o'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_TOP_OR_RIGHT	= HB_TAG ('i','d','t','p'),
    HB_OT_LAYOUT_BASELINE_TAG_IDEO_EMBOX_CENTRAL		= HB_TAG ('I','d','c','e'),
    HB_OT_LAYOUT_BASELINE_TAG_MATH			= HB_TAG ('m','a','t','h'),
  
    /*< private >*/
    _HB_OT_LAYOUT_BASELINE_TAG_MAX_VALUE = HB_TAG_MAX_SIGNED /*< skip >*/
  } hb_ot_layout_baseline_tag_t;
  
  HB_EXTERN hb_ot_layout_baseline_tag_t
  hb_ot_layout_get_horizontal_baseline_tag_for_script (hb_script_t script);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_get_baseline (hb_font_t                   *font,
  			   hb_ot_layout_baseline_tag_t  baseline_tag,
  			   hb_direction_t               direction,
  			   hb_tag_t                     script_tag,
  			   hb_tag_t                     language_tag,
  			   hb_position_t               *coord        /* OUT.  May be NULL. */);
  
  HB_EXTERN hb_bool_t
  hb_ot_layout_get_baseline2 (hb_font_t                   *font,
  			    hb_ot_layout_baseline_tag_t  baseline_tag,
  			    hb_direction_t               direction,
  			    hb_script_t                  script,
  			    hb_language_t                language,
  			    hb_position_t               *coord        /* OUT.  May be NULL. */);
  
  HB_EXTERN void
  hb_ot_layout_get_baseline_with_fallback (hb_font_t                   *font,
  					 hb_ot_layout_baseline_tag_t  baseline_tag,
  					 hb_direction_t               direction,
  					 hb_tag_t                     script_tag,
  					 hb_tag_t                     language_tag,
  					 hb_position_t               *coord        /* OUT */);
  
  HB_EXTERN void
  hb_ot_layout_get_baseline_with_fallback2 (hb_font_t                   *font,
  					  hb_ot_layout_baseline_tag_t  baseline_tag,
  					  hb_direction_t               direction,
  					  hb_script_t                  script,
  					  hb_language_t                language,
  					  hb_position_t               *coord        /* OUT */);
  
  HB_END_DECLS
  
  #endif /* HB_OT_LAYOUT_H */
  

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