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hb-ot-layout

hb-ot-layout — OpenType Layout

Functions

hb_language_t hb_ot_tag_to_language ()
hb_script_t hb_ot_tag_to_script ()
void hb_ot_tags_from_script_and_language ()
void hb_ot_tags_to_script_and_language ()
void hb_ot_layout_collect_lookups ()
void hb_ot_layout_collect_features ()
unsigned int hb_ot_layout_feature_get_characters ()
unsigned int hb_ot_layout_feature_get_lookups ()
hb_bool_t hb_ot_layout_feature_get_name_ids ()
unsigned int hb_ot_layout_feature_with_variations_get_lookups ()
unsigned int hb_ot_layout_get_attach_points ()
hb_bool_t hb_ot_layout_get_baseline ()
hb_ot_layout_glyph_class_t hb_ot_layout_get_glyph_class ()
void hb_ot_layout_get_glyphs_in_class ()
unsigned int hb_ot_layout_get_ligature_carets ()
hb_bool_t hb_ot_layout_get_size_params ()
hb_bool_t (*hb_ot_layout_glyph_sequence_func_t) ()
hb_bool_t hb_ot_layout_has_glyph_classes ()
hb_bool_t hb_ot_layout_has_positioning ()
hb_bool_t hb_ot_layout_has_substitution ()
hb_bool_t hb_ot_layout_language_find_feature ()
unsigned int hb_ot_layout_language_get_feature_indexes ()
unsigned int hb_ot_layout_language_get_feature_tags ()
hb_bool_t hb_ot_layout_language_get_required_feature ()
void hb_ot_layout_lookup_collect_glyphs ()
void hb_ot_layout_lookup_substitute_closure ()
void hb_ot_layout_lookups_substitute_closure ()
hb_bool_t hb_ot_layout_lookup_would_substitute ()
unsigned int hb_ot_layout_script_get_language_tags ()
hb_bool_t hb_ot_layout_script_select_language ()
hb_bool_t hb_ot_layout_table_find_feature_variations ()
unsigned int hb_ot_layout_table_get_feature_tags ()
unsigned int hb_ot_layout_table_get_script_tags ()
unsigned int hb_ot_layout_table_get_lookup_count ()
hb_bool_t hb_ot_layout_table_select_script ()
void hb_ot_shape_plan_collect_lookups ()
hb_bool_t hb_ot_layout_language_get_required_feature_index ()

Object Hierarchy

    GEnum
    ├── hb_ot_layout_baseline_tag_t
    ╰── hb_ot_layout_glyph_class_t

Includes

#include <hb-ot.h>

Description

Functions for querying OpenType Layout features in the font face.

Functions

hb_ot_tag_to_language ()

hb_language_t
hb_ot_tag_to_language (hb_tag_t tag);

Returns

.

[transfer none]

Since: 0.9.2


hb_ot_tag_to_script ()

hb_script_t
hb_ot_tag_to_script (hb_tag_t tag);

hb_ot_tags_from_script_and_language ()

void
hb_ot_tags_from_script_and_language (hb_script_t script,
                                     hb_language_t language,
                                     unsigned int *script_count,
                                     hb_tag_t *script_tags,
                                     unsigned int *language_count,
                                     hb_tag_t *language_tags);

Converts an hb_script_t and an hb_language_t to script and language tags.

Parameters

script

an hb_script_t to convert.

 

language

an hb_language_t to convert.

 

script_count

maximum number of script tags to retrieve (IN) and actual number of script tags retrieved (OUT).

[allow-none]

script_tags

array of size at least script_count to store the script tag results.

[out][allow-none]

language_count

maximum number of language tags to retrieve (IN) and actual number of language tags retrieved (OUT).

[allow-none]

language_tags

array of size at least language_count to store the language tag results.

[out][allow-none]

Since: 2.0.0


hb_ot_tags_to_script_and_language ()

void
hb_ot_tags_to_script_and_language (hb_tag_t script_tag,
                                   hb_tag_t language_tag,
                                   hb_script_t *script,
                                   hb_language_t *language);

Converts a script tag and a language tag to an hb_script_t and an hb_language_t.

Parameters

script_tag

a script tag

 

language_tag

a language tag

 

script

the hb_script_t corresponding to script_tag (OUT).

[allow-none]

language

the hb_language_t corresponding to script_tag and language_tag (OUT).

[allow-none]

Since: 2.0.0


hb_ot_layout_collect_lookups ()

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);

Fetches a list of all feature-lookup indexes in the specified face's GSUB table or GPOS table, underneath the specified scripts, languages, and features. If no list of scripts is provided, all scripts will be queried. If no list of languages is provided, all languages will be queried. If no list of features is provided, all features will be queried.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

scripts

The array of scripts to collect lookups for

 

languages

The array of languages to collect lookups for

 

features

The array of features to collect lookups for

 

lookup_indexes

The array of lookup indexes found for the query.

[out]

Since: 0.9.8


hb_ot_layout_collect_features ()

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);

Fetches a list of all feature indexes in the specified face's GSUB table or GPOS table, underneath the specified scripts, languages, and features. If no list of scripts is provided, all scripts will be queried. If no list of languages is provided, all languages will be queried. If no list of features is provided, all features will be queried.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

scripts

The array of scripts to collect features for

 

languages

The array of languages to collect features for

 

features

The array of features to collect

 

feature_indexes

The array of feature indexes found for the query.

[out]

Since: 1.8.5


hb_ot_layout_feature_get_characters ()

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,
                                     hb_codepoint_t *characters);

Fetches a list of the characters defined as having a variant under the specified "Character Variant" ("cvXX") feature tag.

Note: If the char_count output value is equal to its input value, then there is a chance there were more characters defined under the feature tag than were returned. This function can be called with incrementally larger start_offset until the char_count output value is lower than its input value, or the size of the characters array can be increased.

Parameters

face

hb_face_t to work upon

 

table_tag

table tag to query, "GSUB" or "GPOS".

 

feature_index

index of feature to query.

 

start_offset

offset of the first character to retrieve

 

char_count

Input = the maximum number of characters to return; Output = the actual number of characters returned (may be zero).

[inout][allow-none]

characters

A buffer pointer. The Unicode codepoints of the characters for which this feature provides glyph variants.

[out caller-allocates][array length=char_count]

Returns

Number of total sample characters in the cvXX feature.

Since: 2.0.0


hb_ot_layout_feature_get_lookups ()

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,
                                  unsigned int *lookup_indexes);

Fetches a list of all lookups enumerated for the specified feature, in the specified face's GSUB table or GPOS table. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

feature_index

The index of the requested feature

 

start_offset

offset of the first lookup to retrieve

 

lookup_count

Input = the maximum number of lookups to return; Output = the actual number of lookups returned (may be zero).

[inout][allow-none]

lookup_indexes

The array of lookup indexes found for the query.

[out][array length=lookup_count]

Since: 0.9.7


hb_ot_layout_feature_get_name_ids ()

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,
                                   hb_ot_name_id_t *tooltip_id,
                                   hb_ot_name_id_t *sample_id,
                                   unsigned int *num_named_parameters,
                                   hb_ot_name_id_t *first_param_id);

Fetches name indices from feature parameters for "Stylistic Set" ('ssXX') or "Character Variant" ('cvXX') features.

Parameters

face

hb_face_t to work upon

 

table_tag

table tag to query, "GSUB" or "GPOS".

 

feature_index

index of feature to query.

 

label_id

The ‘name’ table name ID that specifies a string for a user-interface label for this feature. (May be NULL.).

[out][allow-none]

tooltip_id

The ‘name’ table name ID that specifies a string that an application can use for tooltip text for this feature. (May be NULL.).

[out][allow-none]

sample_id

The ‘name’ table name ID that specifies sample text that illustrates the effect of this feature. (May be NULL.).

[out][allow-none]

num_named_parameters

Number of named parameters. (May be zero.).

[out][allow-none]

first_param_id

The first ‘name’ table name ID used to specify strings for user-interface labels for the feature parameters. (Must be zero if numParameters is zero.).

[out][allow-none]

Returns

true if data found, false otherwise

Since: 2.0.0


hb_ot_layout_feature_with_variations_get_lookups ()

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,
                                unsigned int *lookup_indexes);

Fetches a list of all lookups enumerated for the specified feature, in the specified face's GSUB table or GPOS table, enabled at the specified variations index. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

feature_index

The index of the feature to query

 

variations_index

The index of the feature variation to query

 

start_offset

offset of the first lookup to retrieve

 

lookup_count

Input = the maximum number of lookups to return; Output = the actual number of lookups returned (may be zero).

[inout][allow-none]

lookup_indexes

The array of lookups found for the query.

[out][array length=lookup_count]

hb_ot_layout_get_attach_points ()

unsigned int
hb_ot_layout_get_attach_points (hb_face_t *face,
                                hb_codepoint_t glyph,
                                unsigned int start_offset,
                                unsigned int *point_count,
                                unsigned int *point_array);

Fetches a list of all attachment points for the specified glyph in the GDEF table of the face. The list returned will begin at the offset provided.

Useful if the client program wishes to cache the list.

Parameters

face

The hb_face_t to work on

 

glyph

The hb_codepoint_t code point to query

 

start_offset

offset of the first attachment point to retrieve

 

point_count

Input = the maximum number of attachment points to return; Output = the actual number of attachment points returned (may be zero).

[inout][allow-none]

point_array

The array of attachment points found for the query.

[out][array length=point_count]

hb_ot_layout_get_baseline ()

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);

Fetches a baseline value from the face.

Parameters

font

a font

 

baseline_tag

a baseline tag

 

direction

text direction.

 

script_tag

script tag.

 

language_tag

language tag.

 

coord

baseline value if found.

[out]

Returns

if found baseline value in the the font.

Since: 2.6.0


hb_ot_layout_get_glyph_class ()

hb_ot_layout_glyph_class_t
hb_ot_layout_get_glyph_class (hb_face_t *face,
                              hb_codepoint_t glyph);

Fetches the GDEF class of the requested glyph in the specified face.

Parameters

face

The hb_face_t to work on

 

glyph

The hb_codepoint_t code point to query

 

Returns

The hb_ot_layout_glyph_class_t glyph class of the given code point in the GDEF table of the face.

Since: 0.9.7


hb_ot_layout_get_glyphs_in_class ()

void
hb_ot_layout_get_glyphs_in_class (hb_face_t *face,
                                  hb_ot_layout_glyph_class_t klass,
                                  hb_set_t *glyphs);

Retrieves the set of all glyphs from the face that belong to the requested glyph class in the face's GDEF table.

Parameters

face

The hb_face_t to work on

 

klass

The hb_ot_layout_glyph_class_t GDEF class to retrieve

 

glyphs

The hb_set_t set of all glyphs belonging to the requested class.

[out]

Since: 0.9.7


hb_ot_layout_get_ligature_carets ()

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,
                                  hb_position_t *caret_array);

Fetches a list of the caret positions defined for a ligature glyph in the GDEF table of the font. The list returned will begin at the offset provided.

Parameters

font

The hb_font_t to work on

 

direction

The hb_direction_t text direction to use

 

glyph

The hb_codepoint_t code point to query

 

start_offset

offset of the first caret position to retrieve

 

caret_count

Input = the maximum number of caret positions to return; Output = the actual number of caret positions returned (may be zero).

[inout][allow-none]

caret_array

The array of caret positions found for the query.

[out][array length=caret_count]

hb_ot_layout_get_size_params ()

hb_bool_t
hb_ot_layout_get_size_params (hb_face_t *face,
                              unsigned int *design_size,
                              unsigned int *subfamily_id,
                              hb_ot_name_id_t *subfamily_name_id,
                              unsigned int *range_start,
                              unsigned int *range_end);

Fetches optical-size feature data (i.e., the size feature from GPOS). Note that the subfamily_id and the subfamily name string (accessible via the subfamily_name_id) as used here are defined as pertaining only to fonts within a font family that differ specifically in their respective size ranges; other ways to differentiate fonts within a subfamily are not covered by the size feature.

For more information on this distinction, see the size documentation at https://docs.microsoft.com/en-us/typography/opentype/spec/features_pttag-39size39

Parameters

face

hb_face_t to work upon

 

design_size

The design size of the face.

[out]

subfamily_id

The identifier of the face within the font subfamily.

[out]

subfamily_name_id

The ‘name’ table name ID of the face within the font subfamily.

[out]

range_start

The minimum size of the recommended size range for the face.

[out]

range_end

The maximum size of the recommended size range for the face.

[out]

Returns

true if data found, false otherwise

Since: 0.9.10


hb_ot_layout_glyph_sequence_func_t ()

hb_bool_t
(*hb_ot_layout_glyph_sequence_func_t) (hb_font_t *font,
                                       hb_tag_t table_tag,
                                       unsigned int lookup_index,
                                       const hb_ot_layout_glyph_sequence_t *sequence,
                                       void *user_data);

hb_ot_layout_has_glyph_classes ()

hb_bool_t
hb_ot_layout_has_glyph_classes (hb_face_t *face);

Tests whether a face has any glyph classes defined in its GDEF table.

Parameters

face

hb_face_t to work upon

 

Returns

true if data found, false otherwise


hb_ot_layout_has_positioning ()

hb_bool_t
hb_ot_layout_has_positioning (hb_face_t *face);

Parameters

face

hb_face_t to work upon

 

Returns

true if the face has GPOS data, false otherwise


hb_ot_layout_has_substitution ()

hb_bool_t
hb_ot_layout_has_substitution (hb_face_t *face);

Tests whether the specified face includes any GSUB substitutions.

Parameters

face

hb_face_t to work upon

 

Returns

true if data found, false otherwise


hb_ot_layout_language_find_feature ()

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);

Fetches the index of a given feature tag in the specified face's GSUB table or GPOS table, underneath the specified script and language.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_index

The index of the requested language tag

 

feature_tag

hb_tag_t of the feature tag requested

 

feature_index

The index of the requested feature.

[out]

Returns

true if the feature is found, false otherwise


hb_ot_layout_language_get_feature_indexes ()

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,
                                unsigned int *feature_indexes);

Fetches a list of all features in the specified face's GSUB table or GPOS table, underneath the specified script and language. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_index

The index of the requested language tag

 

start_offset

offset of the first feature tag to retrieve

 

feature_count

Input = the maximum number of feature tags to return; Output: the actual number of feature tags returned (may be zero).

[inout][allow-none]

feature_indexes

The array of feature indexes found for the query.

[out][array length=feature_count]

hb_ot_layout_language_get_feature_tags ()

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,
                                hb_tag_t *feature_tags);

Fetches a list of all features in the specified face's GSUB table or GPOS table, underneath the specified script and language. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_index

The index of the requested language tag

 

start_offset

offset of the first feature tag to retrieve

 

feature_count

Input = the maximum number of feature tags to return; Output = the actual number of feature tags returned (may be zero).

[inout][allow-none]

feature_tags

The array of hb_tag_t feature tags found for the query.

[out][array length=feature_count]

hb_ot_layout_language_get_required_feature ()

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,
                                hb_tag_t *feature_tag);

Fetches the tag of a requested feature index in the given face's GSUB or GPOS table, underneath the specified script and language.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_index

The index of the requested language tag

 

feature_index

The index of the requested feature

 

feature_tag

The hb_tag_t of the requested feature.

[out]

Returns

true if the feature is found, false otherwise

Since: 0.9.30


hb_ot_layout_lookup_collect_glyphs ()

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,
                                    hb_set_t *glyphs_input,
                                    hb_set_t *glyphs_after,
                                    hb_set_t *glyphs_output);

Fetches a list of all glyphs affected by the specified lookup in the specified face's GSUB table or GPOS table.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

lookup_index

The index of the feature lookup to query

 

glyphs_before

Array of glyphs preceding the substitution range.

[out]

glyphs_input

Array of input glyphs that would be substituted by the lookup.

[out]

glyphs_after

Array of glyphs following the substition range.

[out]

glyphs_output

Array of glyphs that would be the substitued output of the lookup.

[out]

Since: 0.9.7


hb_ot_layout_lookup_substitute_closure ()

void
hb_ot_layout_lookup_substitute_closure
                               (hb_face_t *face,
                                unsigned int lookup_index,
                                hb_set_t *glyphs);

Compute the transitive closure of glyphs needed for a specified lookup.

Parameters

face

hb_face_t to work upon

 

lookup_index

index of the feature lookup to query

 

glyphs

Array of glyphs comprising the transitive closure of the lookup.

[out]

Since: 0.9.7


hb_ot_layout_lookups_substitute_closure ()

void
hb_ot_layout_lookups_substitute_closure
                               (hb_face_t *face,
                                const hb_set_t *lookups,
                                hb_set_t *glyphs);

Compute the transitive closure of glyphs needed for all of the provided lookups.

Parameters

face

hb_face_t to work upon

 

lookups

The set of lookups to query

 

glyphs

Array of glyphs comprising the transitive closure of the lookups.

[out]

Since: 1.8.1


hb_ot_layout_lookup_would_substitute ()

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);

Tests whether a specified lookup in the specified face would trigger a substitution on the given glyph sequence.

Parameters

face

hb_face_t to work upon

 

lookup_index

The index of the lookup to query

 

glyphs

The sequence of glyphs to query for substitution

 

glyphs_length

The length of the glyph sequence

 

zero_context

hb_bool_t indicating whether substitutions should be context-free

 

Returns

true if a substitution would be triggered, false otherwise

Since: 0.9.7


hb_ot_layout_script_get_language_tags ()

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,
                                       hb_tag_t *language_tags);

Fetches a list of language tags in the given face's GSUB or GPOS table, underneath the specified script index. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

start_offset

offset of the first language tag to retrieve

 

language_count

Input = the maximum number of language tags to return; Output = the actual number of language tags returned (may be zero).

[inout][allow-none]

language_tags

Array of language tags found in the table.

[out][array length=language_count]

hb_ot_layout_script_select_language ()

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);

Fetches the index of a given language tag in the specified face's GSUB table or GPOS table, underneath the specified script index.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_count

The number of languages in the specified script

 

language_tags

The array of language tags

 

language_index

The index of the requested language.

[out]

Returns

true if the language tag is found, false otherwise

Since: 2.0.0


hb_ot_layout_table_find_feature_variations ()

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);

Fetches a list of feature variations in the specified face's GSUB table or GPOS table, at the specified variation coordinates.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

coords

The variation coordinates to query

 

num_coords

The number of variation coorinates

 

variations_index

The array of feature variations found for the query.

[out]

hb_ot_layout_table_get_feature_tags ()

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,
                                     hb_tag_t *feature_tags);

Fetches a list of all feature tags in the given face's GSUB or GPOS table.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

start_offset

offset of the first feature tag to retrieve

 

feature_count

Input = the maximum number of feature tags to return; Output = the actual number of feature tags returned (may be zero).

[inout][allow-none]

feature_tags

Array of feature tags found in the table.

[out][array length=feature_count]

hb_ot_layout_table_get_script_tags ()

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,
                                    hb_tag_t *script_tags);

Fetches a list of all scripts enumerated in the specified face's GSUB table or GPOS table. The list returned will begin at the offset provided.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

start_offset

offset of the first script tag to retrieve

 

script_count

Input = the maximum number of script tags to return; Output = the actual number of script tags returned (may be zero).

[inout][allow-none]

script_tags

The array of hb_tag_t script tags found for the query.

[out][array length=script_count]

hb_ot_layout_table_get_lookup_count ()

unsigned int
hb_ot_layout_table_get_lookup_count (hb_face_t *face,
                                     hb_tag_t table_tag);

Fetches the total number of lookups enumerated in the specified face's GSUB table or GPOS table.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

Since: 0.9.22


hb_ot_layout_table_select_script ()

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,
                                  hb_tag_t *chosen_script);

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_count

Number of script tags in the array

 

script_tags

Array of hb_tag_t script tags

 

script_index

The index of the requested script.

[out]

chosen_script

hb_tag_t of the requested script.

[out]

Since: 2.0.0


hb_ot_shape_plan_collect_lookups ()

void
hb_ot_shape_plan_collect_lookups (hb_shape_plan_t *shape_plan,
                                  hb_tag_t table_tag,
                                  hb_set_t *lookup_indexes);

Since: 0.9.7


hb_ot_layout_language_get_required_feature_index ()

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);

Fetches the index of a requested feature in the given face's GSUB or GPOS table, underneath the specified script and language.

Parameters

face

hb_face_t to work upon

 

table_tag

HB_OT_TAG_GSUB or HB_OT_TAG_GPOS

 

script_index

The index of the requested script tag

 

language_index

The index of the requested language tag

 

feature_index

The index of the requested feature.

[out]

Returns

true if the feature is found, false otherwise

Types and Values

HB_OT_MAX_TAGS_PER_LANGUAGE

#define HB_OT_MAX_TAGS_PER_LANGUAGE 3u

Since: 2.0.0


HB_OT_MAX_TAGS_PER_SCRIPT

#define HB_OT_MAX_TAGS_PER_SCRIPT 3u

Since: 2.0.0


HB_OT_TAG_DEFAULT_LANGUAGE

#define HB_OT_TAG_DEFAULT_LANGUAGE HB_TAG ('d', 'f', 'l', 't')

HB_OT_TAG_DEFAULT_SCRIPT

#define HB_OT_TAG_DEFAULT_SCRIPT HB_TAG ('D', 'F', 'L', 'T')

HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX

#define HB_OT_LAYOUT_DEFAULT_LANGUAGE_INDEX 0xFFFFu

HB_OT_LAYOUT_NO_FEATURE_INDEX

#define HB_OT_LAYOUT_NO_FEATURE_INDEX		0xFFFFu

HB_OT_LAYOUT_NO_SCRIPT_INDEX

#define HB_OT_LAYOUT_NO_SCRIPT_INDEX		0xFFFFu

HB_OT_LAYOUT_NO_VARIATIONS_INDEX

#define HB_OT_LAYOUT_NO_VARIATIONS_INDEX 0xFFFFFFFFu

HB_OT_TAG_BASE

#define HB_OT_TAG_BASE HB_TAG('B','A','S','E')

HB_OT_TAG_GDEF

#define HB_OT_TAG_GDEF HB_TAG('G','D','E','F')

HB_OT_TAG_GPOS

#define HB_OT_TAG_GPOS HB_TAG('G','P','O','S')

HB_OT_TAG_GSUB

#define HB_OT_TAG_GSUB HB_TAG('G','S','U','B')

HB_OT_TAG_JSTF

#define HB_OT_TAG_JSTF HB_TAG('J','S','T','F')

enum hb_ot_layout_baseline_tag_t

Baseline tags from https://docs.microsoft.com/en-us/typography/opentype/spec/baselinetags

Members

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_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, 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.

 

_HB_OT_LAYOUT_BASELINE_TAG_MAX_VALUE

   

Since: 2.6.0


enum hb_ot_layout_glyph_class_t

The GDEF classes defined for glyphs.

Members

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

 
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