hb-buffer

hb-buffer — Input and output buffers

Functions

hb_buffer_t * hb_buffer_create ()
hb_buffer_t * hb_buffer_create_similar ()
hb_buffer_t * hb_buffer_reference ()
hb_buffer_t * hb_buffer_get_empty ()
void hb_buffer_destroy ()
void hb_buffer_reset ()
void hb_buffer_clear_contents ()
hb_bool_t hb_buffer_pre_allocate ()
hb_bool_t hb_buffer_allocation_successful ()
void hb_buffer_add ()
void hb_buffer_add_codepoints ()
void hb_buffer_add_utf32 ()
void hb_buffer_add_utf16 ()
void hb_buffer_add_utf8 ()
void hb_buffer_add_latin1 ()
void hb_buffer_append ()
void hb_buffer_set_content_type ()
hb_buffer_content_type_t hb_buffer_get_content_type ()
void hb_buffer_set_direction ()
hb_direction_t hb_buffer_get_direction ()
void hb_buffer_set_script ()
hb_script_t hb_buffer_get_script ()
void hb_buffer_set_language ()
hb_language_t hb_buffer_get_language ()
void hb_buffer_set_flags ()
hb_buffer_flags_t hb_buffer_get_flags ()
void hb_buffer_set_cluster_level ()
hb_buffer_cluster_level_t hb_buffer_get_cluster_level ()
hb_bool_t hb_buffer_set_length ()
unsigned int hb_buffer_get_length ()
void hb_buffer_set_segment_properties ()
void hb_buffer_get_segment_properties ()
void hb_buffer_guess_segment_properties ()
void hb_buffer_set_unicode_funcs ()
hb_unicode_funcs_t * hb_buffer_get_unicode_funcs ()
hb_bool_t hb_buffer_set_user_data ()
void * hb_buffer_get_user_data ()
hb_glyph_info_t * hb_buffer_get_glyph_infos ()
hb_glyph_position_t * hb_buffer_get_glyph_positions ()
hb_bool_t hb_buffer_has_positions ()
hb_codepoint_t hb_buffer_get_invisible_glyph ()
void hb_buffer_set_invisible_glyph ()
hb_codepoint_t hb_buffer_get_not_found_glyph ()
void hb_buffer_set_not_found_glyph ()
void hb_buffer_set_replacement_codepoint ()
hb_codepoint_t hb_buffer_get_replacement_codepoint ()
void hb_buffer_normalize_glyphs ()
void hb_buffer_reverse ()
void hb_buffer_reverse_range ()
void hb_buffer_reverse_clusters ()
unsigned int hb_buffer_serialize ()
unsigned int hb_buffer_serialize_glyphs ()
hb_bool_t hb_buffer_deserialize_glyphs ()
unsigned int hb_buffer_serialize_unicode ()
hb_bool_t hb_buffer_deserialize_unicode ()
hb_buffer_serialize_format_t hb_buffer_serialize_format_from_string ()
const char * hb_buffer_serialize_format_to_string ()
const char ** hb_buffer_serialize_list_formats ()
hb_bool_t hb_segment_properties_equal ()
unsigned int hb_segment_properties_hash ()
void hb_segment_properties_overlay ()
hb_buffer_diff_flags_t hb_buffer_diff ()
void hb_buffer_set_message_func ()
hb_glyph_flags_t hb_glyph_info_get_glyph_flags ()
hb_bool_t (*hb_buffer_message_func_t) ()

Types and Values

Includes

#include <hb.h>

Description

Buffers serve a dual role in HarfBuzz; before shaping, they hold the input characters that are passed to hb_shape(), and after shaping they hold the output glyphs.

Functions

hb_buffer_create ()

hb_buffer_t *
hb_buffer_create (void);

Creates a new hb_buffer_t with all properties to defaults.

[Xconstructor]

Returns

A newly allocated hb_buffer_t with a reference count of 1. The initial reference count should be released with hb_buffer_destroy() when you are done using the hb_buffer_t. This function never returns NULL. If memory cannot be allocated, a special hb_buffer_t object will be returned on which hb_buffer_allocation_successful() returns false.

[transfer full]

Since: 0.9.2


hb_buffer_create_similar ()

hb_buffer_t *
hb_buffer_create_similar (const hb_buffer_t *src);

Creates a new hb_buffer_t, similar to hb_buffer_create(). The only difference is that the buffer is configured similarly to src .

Parameters

src

An hb_buffer_t

 

Returns

A newly allocated hb_buffer_t, similar to hb_buffer_create().

[transfer full]

Since: 3.3.0


hb_buffer_reference ()

hb_buffer_t *
hb_buffer_reference (hb_buffer_t *buffer);

Increases the reference count on buffer by one. This prevents buffer from being destroyed until a matching call to hb_buffer_destroy() is made.

[skip]

Parameters

buffer

An hb_buffer_t

 

Returns

The referenced hb_buffer_t.

[transfer full]

Since: 0.9.2


hb_buffer_get_empty ()

hb_buffer_t *
hb_buffer_get_empty (void);

Fetches an empty hb_buffer_t.

Returns

The empty buffer.

[transfer full]

Since: 0.9.2


hb_buffer_destroy ()

void
hb_buffer_destroy (hb_buffer_t *buffer);

Deallocate the buffer . Decreases the reference count on buffer by one. If the result is zero, then buffer and all associated resources are freed. See hb_buffer_reference().

[skip]

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.2


hb_buffer_reset ()

void
hb_buffer_reset (hb_buffer_t *buffer);

Resets the buffer to its initial status, as if it was just newly created with hb_buffer_create().

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.2


hb_buffer_clear_contents ()

void
hb_buffer_clear_contents (hb_buffer_t *buffer);

Similar to hb_buffer_reset(), but does not clear the Unicode functions and the replacement code point.

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.11


hb_buffer_pre_allocate ()

hb_bool_t
hb_buffer_pre_allocate (hb_buffer_t *buffer,
                        unsigned int size);

Pre allocates memory for buffer to fit at least size number of items.

Parameters

buffer

An hb_buffer_t

 

size

Number of items to pre allocate.

 

Returns

true if buffer memory allocation succeeded, false otherwise

Since: 0.9.2


hb_buffer_allocation_successful ()

hb_bool_t
hb_buffer_allocation_successful (hb_buffer_t *buffer);

Check if allocating memory for the buffer succeeded.

Parameters

buffer

An hb_buffer_t

 

Returns

true if buffer memory allocation succeeded, false otherwise.

Since: 0.9.2


hb_buffer_add ()

void
hb_buffer_add (hb_buffer_t *buffer,
               hb_codepoint_t codepoint,
               unsigned int cluster);

Appends a character with the Unicode value of codepoint to buffer , and gives it the initial cluster value of cluster . Clusters can be any thing the client wants, they are usually used to refer to the index of the character in the input text stream and are output in hb_glyph_info_t.cluster field.

This function does not check the validity of codepoint , it is up to the caller to ensure it is a valid Unicode code point.

Parameters

buffer

An hb_buffer_t

 

codepoint

A Unicode code point.

 

cluster

The cluster value of codepoint .

 

Since: 0.9.7


hb_buffer_add_codepoints ()

void
hb_buffer_add_codepoints (hb_buffer_t *buffer,
                          const hb_codepoint_t *text,
                          int text_length,
                          unsigned int item_offset,
                          int item_length);

Appends characters from text array to buffer . The item_offset is the position of the first character from text that will be appended, and item_length is the number of character. When shaping part of a larger text (e.g. a run of text from a paragraph), instead of passing just the substring corresponding to the run, it is preferable to pass the whole paragraph and specify the run start and length as item_offset and item_length , respectively, to give HarfBuzz the full context to be able, for example, to do cross-run Arabic shaping or properly handle combining marks at stat of run.

This function does not check the validity of text , it is up to the caller to ensure it contains a valid Unicode code points.

Parameters

buffer

a hb_buffer_t to append characters to.

 

text

an array of Unicode code points to append.

[array length=text_length]

text_length

the length of the text , or -1 if it is NULL terminated.

 

item_offset

the offset of the first code point to add to the buffer .

 

item_length

the number of code points to add to the buffer , or -1 for the end of text (assuming it is NULL terminated).

 

Since: 0.9.31


hb_buffer_add_utf32 ()

void
hb_buffer_add_utf32 (hb_buffer_t *buffer,
                     const uint32_t *text,
                     int text_length,
                     unsigned int item_offset,
                     int item_length);

See hb_buffer_add_codepoints().

Replaces invalid UTF-32 characters with the buffer replacement code point, see hb_buffer_set_replacement_codepoint().

Parameters

buffer

An hb_buffer_t

 

text

An array of UTF-32 characters to append.

[array length=text_length]

text_length

The length of the text , or -1 if it is NULL terminated

 

item_offset

The offset of the first character to add to the buffer

 

item_length

The number of characters to add to the buffer , or -1 for the end of text (assuming it is NULL terminated)

 

Since: 0.9.2


hb_buffer_add_utf16 ()

void
hb_buffer_add_utf16 (hb_buffer_t *buffer,
                     const uint16_t *text,
                     int text_length,
                     unsigned int item_offset,
                     int item_length);

See hb_buffer_add_codepoints().

Replaces invalid UTF-16 characters with the buffer replacement code point, see hb_buffer_set_replacement_codepoint().

Parameters

buffer

An hb_buffer_t

 

text

An array of UTF-16 characters to append.

[array length=text_length]

text_length

The length of the text , or -1 if it is NULL terminated

 

item_offset

The offset of the first character to add to the buffer

 

item_length

The number of characters to add to the buffer , or -1 for the end of text (assuming it is NULL terminated)

 

Since: 0.9.2


hb_buffer_add_utf8 ()

void
hb_buffer_add_utf8 (hb_buffer_t *buffer,
                    const char *text,
                    int text_length,
                    unsigned int item_offset,
                    int item_length);

See hb_buffer_add_codepoints().

Replaces invalid UTF-8 characters with the buffer replacement code point, see hb_buffer_set_replacement_codepoint().

Parameters

buffer

An hb_buffer_t

 

text

An array of UTF-8 characters to append.

[array length=text_length][element-type uint8_t]

text_length

The length of the text , or -1 if it is NULL terminated.

 

item_offset

The offset of the first character to add to the buffer .

 

item_length

The number of characters to add to the buffer , or -1 for the end of text (assuming it is NULL terminated).

 

Since: 0.9.2


hb_buffer_add_latin1 ()

void
hb_buffer_add_latin1 (hb_buffer_t *buffer,
                      const uint8_t *text,
                      int text_length,
                      unsigned int item_offset,
                      int item_length);

Similar to hb_buffer_add_codepoints(), but allows only access to first 256 Unicode code points that can fit in 8-bit strings.

Has nothing to do with non-Unicode Latin-1 encoding.

Parameters

buffer

An hb_buffer_t

 

text

an array of UTF-8 characters to append.

[array length=text_length][element-type uint8_t]

text_length

the length of the text , or -1 if it is NULL terminated

 

item_offset

the offset of the first character to add to the buffer

 

item_length

the number of characters to add to the buffer , or -1 for the end of text (assuming it is NULL terminated)

 

Since: 0.9.39


hb_buffer_append ()

void
hb_buffer_append (hb_buffer_t *buffer,
                  const hb_buffer_t *source,
                  unsigned int start,
                  unsigned int end);

Append (part of) contents of another buffer to this buffer.

Parameters

buffer

An hb_buffer_t

 

source

source hb_buffer_t

 

start

start index into source buffer to copy. Use 0 to copy from start of buffer.

 

end

end index into source buffer to copy. Use HB_FEATURE_GLOBAL_END to copy to end of buffer.

 

Since: 1.5.0


hb_buffer_set_content_type ()

void
hb_buffer_set_content_type (hb_buffer_t *buffer,
                            hb_buffer_content_type_t content_type);

Sets the type of buffer contents. Buffers are either empty, contain characters (before shaping), or contain glyphs (the result of shaping).

Parameters

buffer

An hb_buffer_t

 

content_type

The type of buffer contents to set

 

Since: 0.9.5


hb_buffer_get_content_type ()

hb_buffer_content_type_t
hb_buffer_get_content_type (hb_buffer_t *buffer);

Fetches the type of buffer contents. Buffers are either empty, contain characters (before shaping), or contain glyphs (the result of shaping).

Parameters

buffer

An hb_buffer_t

 

Returns

The type of buffer contents

Since: 0.9.5


hb_buffer_set_direction ()

void
hb_buffer_set_direction (hb_buffer_t *buffer,
                         hb_direction_t direction);

Set the text flow direction of the buffer. No shaping can happen without setting buffer direction, and it controls the visual direction for the output glyphs; for RTL direction the glyphs will be reversed. Many layout features depend on the proper setting of the direction, for example, reversing RTL text before shaping, then shaping with LTR direction is not the same as keeping the text in logical order and shaping with RTL direction.

Parameters

buffer

An hb_buffer_t

 

direction

the hb_direction_t of the buffer

 

Since: 0.9.2


hb_buffer_get_direction ()

hb_direction_t
hb_buffer_get_direction (hb_buffer_t *buffer);

See hb_buffer_set_direction()

Parameters

buffer

An hb_buffer_t

 

Returns

The direction of the buffer .

Since: 0.9.2


hb_buffer_set_script ()

void
hb_buffer_set_script (hb_buffer_t *buffer,
                      hb_script_t script);

Sets the script of buffer to script .

Script is crucial for choosing the proper shaping behaviour for scripts that require it (e.g. Arabic) and the which OpenType features defined in the font to be applied.

You can pass one of the predefined hb_script_t values, or use hb_script_from_string() or hb_script_from_iso15924_tag() to get the corresponding script from an ISO 15924 script tag.

Parameters

buffer

An hb_buffer_t

 

script

An hb_script_t to set.

 

Since: 0.9.2


hb_buffer_get_script ()

hb_script_t
hb_buffer_get_script (hb_buffer_t *buffer);

Fetches the script of buffer .

Parameters

buffer

An hb_buffer_t

 

Returns

The hb_script_t of the buffer

Since: 0.9.2


hb_buffer_set_language ()

void
hb_buffer_set_language (hb_buffer_t *buffer,
                        hb_language_t language);

Sets the language of buffer to language .

Languages are crucial for selecting which OpenType feature to apply to the buffer which can result in applying language-specific behaviour. Languages are orthogonal to the scripts, and though they are related, they are different concepts and should not be confused with each other.

Use hb_language_from_string() to convert from BCP 47 language tags to hb_language_t.

Parameters

buffer

An hb_buffer_t

 

language

An hb_language_t to set

 

Since: 0.9.2


hb_buffer_get_language ()

hb_language_t
hb_buffer_get_language (hb_buffer_t *buffer);

See hb_buffer_set_language().

Parameters

buffer

An hb_buffer_t

 

Returns

The hb_language_t of the buffer. Must not be freed by the caller.

[transfer none]

Since: 0.9.2


hb_buffer_set_flags ()

void
hb_buffer_set_flags (hb_buffer_t *buffer,
                     hb_buffer_flags_t flags);

Sets buffer flags to flags . See hb_buffer_flags_t.

Parameters

buffer

An hb_buffer_t

 

flags

The buffer flags to set

 

Since: 0.9.7


hb_buffer_get_flags ()

hb_buffer_flags_t
hb_buffer_get_flags (hb_buffer_t *buffer);

Fetches the hb_buffer_flags_t of buffer .

Parameters

buffer

An hb_buffer_t

 

Returns

The buffer flags

Since: 0.9.7


hb_buffer_set_cluster_level ()

void
hb_buffer_set_cluster_level (hb_buffer_t *buffer,
                             hb_buffer_cluster_level_t cluster_level);

Sets the cluster level of a buffer. The hb_buffer_cluster_level_t dictates one aspect of how HarfBuzz will treat non-base characters during shaping.

Parameters

buffer

An hb_buffer_t

 

cluster_level

The cluster level to set on the buffer

 

Since: 0.9.42


hb_buffer_get_cluster_level ()

hb_buffer_cluster_level_t
hb_buffer_get_cluster_level (hb_buffer_t *buffer);

Fetches the cluster level of a buffer. The hb_buffer_cluster_level_t dictates one aspect of how HarfBuzz will treat non-base characters during shaping.

Parameters

buffer

An hb_buffer_t

 

Returns

The cluster level of buffer

Since: 0.9.42


hb_buffer_set_length ()

hb_bool_t
hb_buffer_set_length (hb_buffer_t *buffer,
                      unsigned int length);

Similar to hb_buffer_pre_allocate(), but clears any new items added at the end.

Parameters

buffer

An hb_buffer_t

 

length

The new length of buffer

 

Returns

true if buffer memory allocation succeeded, false otherwise.

Since: 0.9.2


hb_buffer_get_length ()

unsigned int
hb_buffer_get_length (hb_buffer_t *buffer);

Returns the number of items in the buffer.

Parameters

buffer

An hb_buffer_t

 

Returns

The buffer length. The value valid as long as buffer has not been modified.

Since: 0.9.2


hb_buffer_set_segment_properties ()

void
hb_buffer_set_segment_properties (hb_buffer_t *buffer,
                                  const hb_segment_properties_t *props);

Sets the segment properties of the buffer, a shortcut for calling hb_buffer_set_direction(), hb_buffer_set_script() and hb_buffer_set_language() individually.

Parameters

buffer

An hb_buffer_t

 

props

An hb_segment_properties_t to use

 

Since: 0.9.7


hb_buffer_get_segment_properties ()

void
hb_buffer_get_segment_properties (hb_buffer_t *buffer,
                                  hb_segment_properties_t *props);

Sets props to the hb_segment_properties_t of buffer .

Parameters

buffer

An hb_buffer_t

 

props

The output hb_segment_properties_t.

[out]

Since: 0.9.7


hb_buffer_guess_segment_properties ()

void
hb_buffer_guess_segment_properties (hb_buffer_t *buffer);

Sets unset buffer segment properties based on buffer Unicode contents. If buffer is not empty, it must have content type HB_BUFFER_CONTENT_TYPE_UNICODE.

If buffer script is not set (ie. is HB_SCRIPT_INVALID), it will be set to the Unicode script of the first character in the buffer that has a script other than HB_SCRIPT_COMMON, HB_SCRIPT_INHERITED, and HB_SCRIPT_UNKNOWN.

Next, if buffer direction is not set (ie. is HB_DIRECTION_INVALID), it will be set to the natural horizontal direction of the buffer script as returned by hb_script_get_horizontal_direction(). If hb_script_get_horizontal_direction() returns HB_DIRECTION_INVALID, then HB_DIRECTION_LTR is used.

Finally, if buffer language is not set (ie. is HB_LANGUAGE_INVALID), it will be set to the process's default language as returned by hb_language_get_default(). This may change in the future by taking buffer script into consideration when choosing a language. Note that hb_language_get_default() is NOT threadsafe the first time it is called. See documentation for that function for details.

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.7


hb_buffer_set_unicode_funcs ()

void
hb_buffer_set_unicode_funcs (hb_buffer_t *buffer,
                             hb_unicode_funcs_t *unicode_funcs);

Sets the Unicode-functions structure of a buffer to unicode_funcs .

Parameters

buffer

An hb_buffer_t

 

unicode_funcs

The Unicode-functions structure

 

Since: 0.9.2


hb_buffer_get_unicode_funcs ()

hb_unicode_funcs_t *
hb_buffer_get_unicode_funcs (hb_buffer_t *buffer);

Fetches the Unicode-functions structure of a buffer.

Parameters

buffer

An hb_buffer_t

 

Returns

The Unicode-functions structure

Since: 0.9.2


hb_buffer_set_user_data ()

hb_bool_t
hb_buffer_set_user_data (hb_buffer_t *buffer,
                         hb_user_data_key_t *key,
                         void *data,
                         hb_destroy_func_t destroy,
                         hb_bool_t replace);

Attaches a user-data key/data pair to the specified buffer.

[skip]

Parameters

buffer

An hb_buffer_t

 

key

The user-data key

 

data

A pointer to the user data

 

destroy

A callback to call when data is not needed anymore.

[nullable]

replace

Whether to replace an existing data with the same key

 

Returns

true if success, false otherwise

Since: 0.9.2


hb_buffer_get_user_data ()

void *
hb_buffer_get_user_data (hb_buffer_t *buffer,
                         hb_user_data_key_t *key);

Fetches the user data associated with the specified key, attached to the specified buffer.

[skip]

Parameters

buffer

An hb_buffer_t

 

key

The user-data key to query

 

Returns

A pointer to the user data.

[transfer none]

Since: 0.9.2


hb_buffer_get_glyph_infos ()

hb_glyph_info_t *
hb_buffer_get_glyph_infos (hb_buffer_t *buffer,
                           unsigned int *length);

Returns buffer glyph information array. Returned pointer is valid as long as buffer contents are not modified.

Parameters

buffer

An hb_buffer_t

 

length

The output-array length.

[out]

Returns

The buffer glyph information array. The value valid as long as buffer has not been modified.

[transfer none][array length=length]

Since: 0.9.2


hb_buffer_get_glyph_positions ()

hb_glyph_position_t *
hb_buffer_get_glyph_positions (hb_buffer_t *buffer,
                               unsigned int *length);

Returns buffer glyph position array. Returned pointer is valid as long as buffer contents are not modified.

If buffer did not have positions before, the positions will be initialized to zeros, unless this function is called from within a buffer message callback (see hb_buffer_set_message_func()), in which case NULL is returned.

Parameters

buffer

An hb_buffer_t

 

length

The output length.

[out]

Returns

The buffer glyph position array. The value valid as long as buffer has not been modified.

[transfer none][array length=length]

Since: 0.9.2


hb_buffer_has_positions ()

hb_bool_t
hb_buffer_has_positions (hb_buffer_t *buffer);

Returns whether buffer has glyph position data. A buffer gains position data when hb_buffer_get_glyph_positions() is called on it, and cleared of position data when hb_buffer_clear_contents() is called.

Parameters

buffer

an hb_buffer_t.

 

Returns

true if the buffer has position array, false otherwise.

Since: 2.7.3


hb_buffer_get_invisible_glyph ()

hb_codepoint_t
hb_buffer_get_invisible_glyph (hb_buffer_t *buffer);

See hb_buffer_set_invisible_glyph().

Parameters

buffer

An hb_buffer_t

 

Returns

The buffer invisible hb_codepoint_t

Since: 2.0.0


hb_buffer_set_invisible_glyph ()

void
hb_buffer_set_invisible_glyph (hb_buffer_t *buffer,
                               hb_codepoint_t invisible);

Sets the hb_codepoint_t that replaces invisible characters in the shaping result. If set to zero (default), the glyph for the U+0020 SPACE character is used. Otherwise, this value is used verbatim.

Parameters

buffer

An hb_buffer_t

 

invisible

the invisible hb_codepoint_t

 

Since: 2.0.0


hb_buffer_get_not_found_glyph ()

hb_codepoint_t
hb_buffer_get_not_found_glyph (hb_buffer_t *buffer);

See hb_buffer_set_not_found_glyph().

Parameters

buffer

An hb_buffer_t

 

Returns

The buffer not-found hb_codepoint_t

Since: 3.1.0


hb_buffer_set_not_found_glyph ()

void
hb_buffer_set_not_found_glyph (hb_buffer_t *buffer,
                               hb_codepoint_t not_found);

Sets the hb_codepoint_t that replaces characters not found in the font during shaping.

The not-found glyph defaults to zero, sometimes knows as the ".notdef" glyph. This API allows for differentiating the two.

Parameters

buffer

An hb_buffer_t

 

not_found

the not-found hb_codepoint_t

 

Since: 3.1.0


hb_buffer_set_replacement_codepoint ()

void
hb_buffer_set_replacement_codepoint (hb_buffer_t *buffer,
                                     hb_codepoint_t replacement);

Sets the hb_codepoint_t that replaces invalid entries for a given encoding when adding text to buffer .

Default is HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT.

Parameters

buffer

An hb_buffer_t

 

replacement

the replacement hb_codepoint_t

 

Since: 0.9.31


hb_buffer_get_replacement_codepoint ()

hb_codepoint_t
hb_buffer_get_replacement_codepoint (hb_buffer_t *buffer);

Fetches the hb_codepoint_t that replaces invalid entries for a given encoding when adding text to buffer .

Parameters

buffer

An hb_buffer_t

 

Returns

The buffer replacement hb_codepoint_t

Since: 0.9.31


hb_buffer_normalize_glyphs ()

void
hb_buffer_normalize_glyphs (hb_buffer_t *buffer);

Reorders a glyph buffer to have canonical in-cluster glyph order / position. The resulting clusters should behave identical to pre-reordering clusters.

This has nothing to do with Unicode normalization.

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.2


hb_buffer_reverse ()

void
hb_buffer_reverse (hb_buffer_t *buffer);

Reverses buffer contents.

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.2


hb_buffer_reverse_range ()

void
hb_buffer_reverse_range (hb_buffer_t *buffer,
                         unsigned int start,
                         unsigned int end);

Reverses buffer contents between start and end .

Parameters

buffer

An hb_buffer_t

 

start

start index

 

end

end index

 

Since: 0.9.41


hb_buffer_reverse_clusters ()

void
hb_buffer_reverse_clusters (hb_buffer_t *buffer);

Reverses buffer clusters. That is, the buffer contents are reversed, then each cluster (consecutive items having the same cluster number) are reversed again.

Parameters

buffer

An hb_buffer_t

 

Since: 0.9.2


hb_buffer_serialize ()

unsigned int
hb_buffer_serialize (hb_buffer_t *buffer,
                     unsigned int start,
                     unsigned int end,
                     char *buf,
                     unsigned int buf_size,
                     unsigned int *buf_consumed,
                     hb_font_t *font,
                     hb_buffer_serialize_format_t format,
                     hb_buffer_serialize_flags_t flags);

Serializes buffer into a textual representation of its content, whether Unicode codepoints or glyph identifiers and positioning information. This is useful for showing the contents of the buffer, for example during debugging. See the documentation of hb_buffer_serialize_unicode() and hb_buffer_serialize_glyphs() for a description of the output format.

Parameters

buffer

an hb_buffer_t buffer.

 

start

the first item in buffer to serialize.

 

end

the last item in buffer to serialize.

 

buf

output string to write serialized buffer into.

[out][array length=buf_size][element-type uint8_t]

buf_size

the size of buf .

 

buf_consumed

if not NULL, will be set to the number of byes written into buf .

[out][optional]

font

the hb_font_t used to shape this buffer, needed to read glyph names and extents. If NULL, and empty font will be used.

[nullable]

format

the hb_buffer_serialize_format_t to use for formatting the output.

 

flags

the hb_buffer_serialize_flags_t that control what glyph properties to serialize.

 

Returns

The number of serialized items.

Since: 2.7.3


hb_buffer_serialize_glyphs ()

unsigned int
hb_buffer_serialize_glyphs (hb_buffer_t *buffer,
                            unsigned int start,
                            unsigned int end,
                            char *buf,
                            unsigned int buf_size,
                            unsigned int *buf_consumed,
                            hb_font_t *font,
                            hb_buffer_serialize_format_t format,
                            hb_buffer_serialize_flags_t flags);

Serializes buffer into a textual representation of its glyph content, useful for showing the contents of the buffer, for example during debugging. There are currently two supported serialization formats:

text

A human-readable, plain text format. The serialized glyphs will look something like:

[uni0651=0@518,0+0|uni0628=0+1897]

json

A machine-readable, structured format. The serialized glyphs will look something like:

[{"g":"uni0651","cl":0,"dx":518,"dy":0,"ax":0,"ay":0}, {"g":"uni0628","cl":0,"dx":0,"dy":0,"ax":1897,"ay":0}]

Each glyph is a JSON object, with the following properties:

Parameters

buffer

an hb_buffer_t buffer.

 

start

the first item in buffer to serialize.

 

end

the last item in buffer to serialize.

 

buf

output string to write serialized buffer into.

[out][array length=buf_size][element-type uint8_t]

buf_size

the size of buf .

 

buf_consumed

if not NULL, will be set to the number of byes written into buf .

[out][optional]

font

the hb_font_t used to shape this buffer, needed to read glyph names and extents. If NULL, and empty font will be used.

[nullable]

format

the hb_buffer_serialize_format_t to use for formatting the output.

 

flags

the hb_buffer_serialize_flags_t that control what glyph properties to serialize.

 

Returns

The number of serialized items.

Since: 0.9.7


hb_buffer_deserialize_glyphs ()

hb_bool_t
hb_buffer_deserialize_glyphs (hb_buffer_t *buffer,
                              const char *buf,
                              int buf_len,
                              const char **end_ptr,
                              hb_font_t *font,
                              hb_buffer_serialize_format_t format);

Deserializes glyphs buffer from textual representation in the format produced by hb_buffer_serialize_glyphs().

Parameters

buffer

an hb_buffer_t buffer.

 

buf

string to deserialize.

[array length=buf_len]

buf_len

the size of buf , or -1 if it is NULL-terminated

 

end_ptr

output pointer to the character after last consumed one.

[out][optional]

font

font for getting glyph IDs.

[nullable]

format

the hb_buffer_serialize_format_t of the input buf

 

Returns

true if buf is not fully consumed, false otherwise.

Since: 0.9.7


hb_buffer_serialize_unicode ()

unsigned int
hb_buffer_serialize_unicode (hb_buffer_t *buffer,
                             unsigned int start,
                             unsigned int end,
                             char *buf,
                             unsigned int buf_size,
                             unsigned int *buf_consumed,
                             hb_buffer_serialize_format_t format,
                             hb_buffer_serialize_flags_t flags);

Serializes buffer into a textual representation of its content, when the buffer contains Unicode codepoints (i.e., before shaping). This is useful for showing the contents of the buffer, for example during debugging. There are currently two supported serialization formats:

text

A human-readable, plain text format. The serialized codepoints will look something like:

 <U+0651=0|U+0628=1>

json

A machine-readable, structured format. The serialized codepoints will be a list of objects with the following properties:

For example:

[{u:1617,cl:0},{u:1576,cl:1}]

Parameters

buffer

an hb_buffer_t buffer.

 

start

the first item in buffer to serialize.

 

end

the last item in buffer to serialize.

 

buf

output string to write serialized buffer into.

[out][array length=buf_size][element-type uint8_t]

buf_size

the size of buf .

 

buf_consumed

if not NULL, will be set to the number of byes written into buf .

[out][optional]

format

the hb_buffer_serialize_format_t to use for formatting the output.

 

flags

the hb_buffer_serialize_flags_t that control what glyph properties to serialize.

 

Returns

The number of serialized items.

Since: 2.7.3


hb_buffer_deserialize_unicode ()

hb_bool_t
hb_buffer_deserialize_unicode (hb_buffer_t *buffer,
                               const char *buf,
                               int buf_len,
                               const char **end_ptr,
                               hb_buffer_serialize_format_t format);

Deserializes Unicode buffer from textual representation in the format produced by hb_buffer_serialize_unicode().

Parameters

buffer

an hb_buffer_t buffer.

 

buf

string to deserialize.

[array length=buf_len]

buf_len

the size of buf , or -1 if it is NULL-terminated

 

end_ptr

output pointer to the character after last consumed one.

[out][optional]

format

the hb_buffer_serialize_format_t of the input buf

 

Returns

true if buf is not fully consumed, false otherwise.

Since: 2.7.3


hb_buffer_serialize_format_from_string ()

hb_buffer_serialize_format_t
hb_buffer_serialize_format_from_string
                               (const char *str,
                                int len);

Parses a string into an hb_buffer_serialize_format_t. Does not check if str is a valid buffer serialization format, use hb_buffer_serialize_list_formats() to get the list of supported formats.

Parameters

str

a string to parse.

[array length=len][element-type uint8_t]

len

length of str , or -1 if string is NULL terminated

 

Returns

The parsed hb_buffer_serialize_format_t.

Since: 0.9.7


hb_buffer_serialize_format_to_string ()

const char *
hb_buffer_serialize_format_to_string (hb_buffer_serialize_format_t format);

Converts format to the string corresponding it, or NULL if it is not a valid hb_buffer_serialize_format_t.

Parameters

format

an hb_buffer_serialize_format_t to convert.

 

Returns

A NULL terminated string corresponding to format . Should not be freed.

[transfer none]

Since: 0.9.7


hb_buffer_serialize_list_formats ()

const char **
hb_buffer_serialize_list_formats (void);

Returns a list of supported buffer serialization formats.

Returns

A string array of buffer serialization formats. Should not be freed.

[transfer none]

Since: 0.9.7


hb_segment_properties_equal ()

hb_bool_t
hb_segment_properties_equal (const hb_segment_properties_t *a,
                             const hb_segment_properties_t *b);

Checks the equality of two hb_segment_properties_t's.

Parameters

a

first hb_segment_properties_t to compare.

 

b

second hb_segment_properties_t to compare.

 

Returns

true if all properties of a equal those of b , false otherwise.

Since: 0.9.7


hb_segment_properties_hash ()

unsigned int
hb_segment_properties_hash (const hb_segment_properties_t *p);

Creates a hash representing p .

Parameters

p

hb_segment_properties_t to hash.

 

Returns

A hash of p .

Since: 0.9.7


hb_segment_properties_overlay ()

void
hb_segment_properties_overlay (hb_segment_properties_t *p,
                               const hb_segment_properties_t *src);

Fills in missing fields of p from src in a considered manner.

First, if p does not have direction set, direction is copied from src .

Next, if p and src have the same direction (which can be unset), if p does not have script set, script is copied from src .

Finally, if p and src have the same direction and script (which either can be unset), if p does not have language set, language is copied from src .

Parameters

p

hb_segment_properties_t to fill in.

 

src

hb_segment_properties_t to fill in from.

 

Since: 3.3.0


hb_buffer_diff ()

hb_buffer_diff_flags_t
hb_buffer_diff (hb_buffer_t *buffer,
                hb_buffer_t *reference,
                hb_codepoint_t dottedcircle_glyph,
                unsigned int position_fuzz);

If dottedcircle_glyph is (hb_codepoint_t) -1 then HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT and HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT are never returned. This should be used by most callers if just comparing two buffers is needed.

Parameters

buffer

a buffer.

 

reference

other buffer to compare to.

 

dottedcircle_glyph

glyph id of U+25CC DOTTED CIRCLE, or (hb_codepont_t) -1.

 

position_fuzz

allowed absolute difference in position values.

 

Since: 1.5.0


hb_buffer_set_message_func ()

void
hb_buffer_set_message_func (hb_buffer_t *buffer,
                            hb_buffer_message_func_t func,
                            void *user_data,
                            hb_destroy_func_t destroy);

Sets the implementation function for hb_buffer_message_func_t.

Parameters

buffer

An hb_buffer_t

 

func

Callback function.

[closure user_data][destroy destroy][scope notified]

user_data

Data to pass to func .

[nullable]

destroy

The function to call when user_data is not needed anymore.

[nullable]

Since: 1.1.3


hb_glyph_info_get_glyph_flags ()

hb_glyph_flags_t
hb_glyph_info_get_glyph_flags (const hb_glyph_info_t *info);

Returns glyph flags encoded within a hb_glyph_info_t.

Parameters

info

a hb_glyph_info_t

 

Returns

The hb_glyph_flags_t encoded within info

Since: 1.5.0


hb_buffer_message_func_t ()

hb_bool_t
(*hb_buffer_message_func_t) (hb_buffer_t *buffer,
                             hb_font_t *font,
                             const char *message,
                             void *user_data);

A callback method for hb_buffer_t. The method gets called with the hb_buffer_t it was set on, the hb_font_t the buffer is shaped with and a message describing what step of the shaping process will be performed. Returning false from this method will skip this shaping step and move to the next one.

Parameters

buffer

An hb_buffer_t to work upon

 

font

The hb_font_t the buffer is shaped with

 

message

NULL-terminated message passed to the function

 

user_data

User data pointer passed by the caller

 

Returns

true to perform the shaping step, false to skip it.

Since: 1.1.3

Types and Values

HB_SEGMENT_PROPERTIES_DEFAULT

#define             HB_SEGMENT_PROPERTIES_DEFAULT

The default hb_segment_properties_t of of freshly created hb_buffer_t.


HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT

#define HB_BUFFER_REPLACEMENT_CODEPOINT_DEFAULT 0xFFFDu

The default code point for replacing invalid characters in a given encoding. Set to U+FFFD REPLACEMENT CHARACTER.

Since: 0.9.31


hb_buffer_t

typedef struct hb_buffer_t hb_buffer_t;

The main structure holding the input text and its properties before shaping, and output glyphs and their information after shaping.


hb_glyph_info_t

typedef struct {
  hb_codepoint_t codepoint;
  uint32_t       cluster;
} hb_glyph_info_t;

The hb_glyph_info_t is the structure that holds information about the glyphs and their relation to input text.

Members

hb_codepoint_t codepoint;

either a Unicode code point (before shaping) or a glyph index (after shaping).

 

uint32_t cluster;

the index of the character in the original text that corresponds to this hb_glyph_info_t, or whatever the client passes to hb_buffer_add(). More than one hb_glyph_info_t can have the same cluster value, if they resulted from the same character (e.g. one to many glyph substitution), and when more than one character gets merged in the same glyph (e.g. many to one glyph substitution) the hb_glyph_info_t will have the smallest cluster value of them. By default some characters are merged into the same cluster (e.g. combining marks have the same cluster as their bases) even if they are separate glyphs, hb_buffer_set_cluster_level() allow selecting more fine-grained cluster handling.

 

enum hb_glyph_flags_t

Flags for hb_glyph_info_t.

Members

HB_GLYPH_FLAG_UNSAFE_TO_BREAK

Indicates that if input text is broken at the beginning of the cluster this glyph is part of, then both sides need to be re-shaped, as the result might be different. On the flip side, it means that when this flag is not present, then it is safe to break the glyph-run at the beginning of this cluster, and the two sides will represent the exact same result one would get if breaking input text at the beginning of this cluster and shaping the two sides separately. This can be used to optimize paragraph layout, by avoiding re-shaping of each line after line-breaking.

 

HB_GLYPH_FLAG_UNSAFE_TO_CONCAT

Indicates that if input text is changed on one side of the beginning of the cluster this glyph is part of, then the shaping results for the other side might change. Note that the absence of this flag will NOT by itself mean that it IS safe to concat text. Only two pieces of text both of which clear of this flag can be concatenated safely. This can be used to optimize paragraph layout, by avoiding re-shaping of each line after line-breaking, by limiting the reshaping to a small piece around the breaking positin only, even if the breaking position carries the HB_GLYPH_FLAG_UNSAFE_TO_BREAK or when hyphenation or other text transformation happens at line-break position, in the following way: 1. Iterate back from the line-break position until the first cluster start position that is NOT unsafe-to-concat, 2. shape the segment from there till the end of line, 3. check whether the resulting glyph-run also is clear of the unsafe-to-concat at its start-of-text position; if it is, just splice it into place and the line is shaped; If not, move on to a position further back that is clear of unsafe-to-concat and retry from there, and repeat. At the start of next line a similar algorithm can be implemented. That is: 1. Iterate forward from the line-break position until the first cluster start position that is NOT unsafe-to-concat, 2. shape the segment from beginning of the line to that position, 3. check whether the resulting glyph-run also is clear of the unsafe-to-concat at its end-of-text position; if it is, just splice it into place and the beginning is shaped; If not, move on to a position further forward that is clear of unsafe-to-concat and retry up to there, and repeat. A slight complication will arise in the implementation of the algorithm above, because while our buffer API has a way to return flags for position corresponding to start-of-text, there is currently no position corresponding to end-of-text. This limitation can be alleviated by shaping more text than needed and looking for unsafe-to-concat flag within text clusters. The HB_GLYPH_FLAG_UNSAFE_TO_BREAK flag will always imply this flag. To use this flag, you must enable the buffer flag HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT during shaping, otherwise the buffer flag will not be reliably produced. Since: 4.0.0

 

HB_GLYPH_FLAG_DEFINED

All the currently defined flags.

 

Since: 1.5.0


hb_glyph_position_t

typedef struct {
  hb_position_t  x_advance;
  hb_position_t  y_advance;
  hb_position_t  x_offset;
  hb_position_t  y_offset;
} hb_glyph_position_t;

The hb_glyph_position_t is the structure that holds the positions of the glyph in both horizontal and vertical directions. All positions in hb_glyph_position_t are relative to the current point.

Members

hb_position_t x_advance;

how much the line advances after drawing this glyph when setting text in horizontal direction.

 

hb_position_t y_advance;

how much the line advances after drawing this glyph when setting text in vertical direction.

 

hb_position_t x_offset;

how much the glyph moves on the X-axis before drawing it, this should not affect how much the line advances.

 

hb_position_t y_offset;

how much the glyph moves on the Y-axis before drawing it, this should not affect how much the line advances.

 

enum hb_buffer_content_type_t

The type of hb_buffer_t contents.

Members

HB_BUFFER_CONTENT_TYPE_INVALID

Initial value for new buffer.

 

HB_BUFFER_CONTENT_TYPE_UNICODE

The buffer contains input characters (before shaping).

 

HB_BUFFER_CONTENT_TYPE_GLYPHS

The buffer contains output glyphs (after shaping).

 

enum hb_buffer_flags_t

Flags for hb_buffer_t.

Members

HB_BUFFER_FLAG_DEFAULT

the default buffer flag.

 

HB_BUFFER_FLAG_BOT

flag indicating that special handling of the beginning of text paragraph can be applied to this buffer. Should usually be set, unless you are passing to the buffer only part of the text without the full context.

 

HB_BUFFER_FLAG_EOT

flag indicating that special handling of the end of text paragraph can be applied to this buffer, similar to HB_BUFFER_FLAG_BOT .

 

HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES

flag indication that character with Default_Ignorable Unicode property should use the corresponding glyph from the font, instead of hiding them (done by replacing them with the space glyph and zeroing the advance width.) This flag takes precedence over HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES .

 

HB_BUFFER_FLAG_REMOVE_DEFAULT_IGNORABLES

flag indication that character with Default_Ignorable Unicode property should be removed from glyph string instead of hiding them (done by replacing them with the space glyph and zeroing the advance width.) HB_BUFFER_FLAG_PRESERVE_DEFAULT_IGNORABLES takes precedence over this flag. Since: 1.8.0

 

HB_BUFFER_FLAG_DO_NOT_INSERT_DOTTED_CIRCLE

flag indicating that a dotted circle should not be inserted in the rendering of incorrect character sequences (such at <0905 093E>). Since: 2.4.0

 

HB_BUFFER_FLAG_VERIFY

flag indicating that the hb_shape() call and its variants should perform various verification processes on the results of the shaping operation on the buffer. If the verification fails, then either a buffer message is sent, if a message handler is installed on the buffer, or a message is written to standard error. In either case, the shaping result might be modified to show the failed output. Since: 3.4.0

 

HB_BUFFER_FLAG_PRODUCE_UNSAFE_TO_CONCAT

flag indicating that the HB_GLYPH_FLAG_UNSAFE_TO_CONCAT glyph-flag should be produced by the shaper. By default it will not be produced since it incurs a cost. Since: 4.0.0

 

Since: 0.9.20


enum hb_buffer_cluster_level_t

Data type for holding HarfBuzz's clustering behavior options. The cluster level dictates one aspect of how HarfBuzz will treat non-base characters during shaping.

In HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES , non-base characters are merged into the cluster of the base character that precedes them.

In HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS , non-base characters are initially assigned their own cluster values, which are not merged into preceding base clusters. This allows HarfBuzz to perform additional operations like reorder sequences of adjacent marks.

HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES is the default, because it maintains backward compatibility with older versions of HarfBuzz. New client programs that do not need to maintain such backward compatibility are recommended to use HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS instead of the default.

Members

HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES

Return cluster values grouped by graphemes into monotone order.

 

HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS

Return cluster values grouped into monotone order.

 

HB_BUFFER_CLUSTER_LEVEL_CHARACTERS

Don't group cluster values.

 

HB_BUFFER_CLUSTER_LEVEL_DEFAULT

Default cluster level, equal to HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES .

 

Since: 0.9.42


hb_segment_properties_t

typedef struct {
  hb_direction_t  direction;
  hb_script_t     script;
  hb_language_t   language;
} hb_segment_properties_t;

The structure that holds various text properties of an hb_buffer_t. Can be set and retrieved using hb_buffer_set_segment_properties() and hb_buffer_get_segment_properties(), respectively.

Members

hb_direction_t direction;

the hb_direction_t of the buffer, see hb_buffer_set_direction().

 

hb_script_t script;

the hb_script_t of the buffer, see hb_buffer_set_script().

 

hb_language_t language;

the hb_language_t of the buffer, see hb_buffer_set_language().

 

enum hb_buffer_serialize_format_t

The buffer serialization and de-serialization format used in hb_buffer_serialize_glyphs() and hb_buffer_deserialize_glyphs().

Members

HB_BUFFER_SERIALIZE_FORMAT_TEXT

a human-readable, plain text format.

 

HB_BUFFER_SERIALIZE_FORMAT_JSON

a machine-readable JSON format.

 

HB_BUFFER_SERIALIZE_FORMAT_INVALID

invalid format.

 

Since: 0.9.2


enum hb_buffer_serialize_flags_t

Flags that control what glyph information are serialized in hb_buffer_serialize_glyphs().

Members

HB_BUFFER_SERIALIZE_FLAG_DEFAULT

serialize glyph names, clusters and positions.

 

HB_BUFFER_SERIALIZE_FLAG_NO_CLUSTERS

do not serialize glyph cluster.

 

HB_BUFFER_SERIALIZE_FLAG_NO_POSITIONS

do not serialize glyph position information.

 

HB_BUFFER_SERIALIZE_FLAG_NO_GLYPH_NAMES

do no serialize glyph name.

 

HB_BUFFER_SERIALIZE_FLAG_GLYPH_EXTENTS

serialize glyph extents.

 

HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS

serialize glyph flags. Since: 1.5.0

 

HB_BUFFER_SERIALIZE_FLAG_NO_ADVANCES

do not serialize glyph advances, glyph offsets will reflect absolute glyph positions. Since: 1.8.0

 

Since: 0.9.20


enum hb_buffer_diff_flags_t

Flags from comparing two hb_buffer_t's.

Buffer with different hb_buffer_content_type_t cannot be meaningfully compared in any further detail.

For buffers with differing length, the per-glyph comparison is not attempted, though we do still scan reference buffer for dotted circle and .notdef glyphs.

If the buffers have the same length, we compare them glyph-by-glyph and report which aspect(s) of the glyph info/position are different.

Members

HB_BUFFER_DIFF_FLAG_EQUAL

equal buffers.

 

HB_BUFFER_DIFF_FLAG_CONTENT_TYPE_MISMATCH

buffers with different hb_buffer_content_type_t.

 

HB_BUFFER_DIFF_FLAG_LENGTH_MISMATCH

buffers with differing length.

 

HB_BUFFER_DIFF_FLAG_NOTDEF_PRESENT

.notdef glyph is present in the reference buffer.

 

HB_BUFFER_DIFF_FLAG_DOTTED_CIRCLE_PRESENT

dotted circle glyph is present in the reference buffer.

 

HB_BUFFER_DIFF_FLAG_CODEPOINT_MISMATCH

difference in hb_glyph_info_t.codepoint

 

HB_BUFFER_DIFF_FLAG_CLUSTER_MISMATCH

difference in hb_glyph_info_t.cluster

 

HB_BUFFER_DIFF_FLAG_GLYPH_FLAGS_MISMATCH

difference in hb_glyph_flags_t.

 

HB_BUFFER_DIFF_FLAG_POSITION_MISMATCH

difference in hb_glyph_position_t.

 

Since: 1.5.0