hb-shape: HarfBuzz Manual

hb-shape

hb-shape — Conversion of text strings into positioned glyphs

Functions

void	hb_shape ()
hb_bool_t	hb_shape_full ()
hb_bool_t	hb_shape_justify ()
const char **	hb_shape_list_shapers ()

Includes

#include <hb.h>

Description

Shaping is the central operation of HarfBuzz. Shaping operates on buffers, which are sequences of Unicode characters that use the same font and have the same text direction, script, and language. After shaping the buffer contains the output glyphs and their positions.

Functions

hb_shape ()

void
hb_shape (hb_font_t *font,
          hb_buffer_t *buffer,
          const hb_feature_t *features,
          unsigned int num_features);

Shapes buffer using font turning its Unicode characters content to positioned glyphs. If features is not NULL, it will be used to control the features applied during shaping. If two features have the same tag but overlapping ranges the value of the feature with the higher index takes precedence.

Parameters

font	an hb_font_t to use for shaping
buffer	an hb_buffer_t to shape
features	an array of user specified hb_feature_t or `NULL`.	[array length=num_features][nullable]
num_features	the length of `features` array

Since: 0.9.2

hb_shape_full ()

hb_bool_t
hb_shape_full (hb_font_t *font,
               hb_buffer_t *buffer,
               const hb_feature_t *features,
               unsigned int num_features,
               const char * const *shaper_list);

See hb_shape() for details. If shaper_list is not NULL, the specified shapers will be used in the given order, otherwise the default shapers list will be used.

Parameters

font	an hb_font_t to use for shaping
buffer	an hb_buffer_t to shape
features	an array of user specified hb_feature_t or `NULL`.	[array length=num_features][nullable]
num_features	the length of `features` array
shaper_list	a `NULL`-terminated array of shapers to use or `NULL`.	[array zero-terminated=1][nullable]

Returns

false if all shapers failed, true otherwise

Since: 0.9.2

hb_shape_justify ()

hb_bool_t
hb_shape_justify (hb_font_t *font,
                  hb_buffer_t *buffer,
                  const hb_feature_t *features,
                  unsigned int num_features,
                  const char * const *shaper_list,
                  float min_target_advance,
                  float max_target_advance,
                  float *advance,
                  hb_tag_t *var_tag,
                  float *var_value);

See hb_shape_full() for basic details. If shaper_list is not NULL, the specified shapers will be used in the given order, otherwise the default shapers list will be used.

In addition, justify the shaping results such that the shaping results reach the target advance width/height, depending on the buffer direction.

If the advance of the buffer shaped with hb_shape_full() is already known, put that in *advance. Otherwise set *advance to zero.

This API is currently experimental and will probably change in the future.

Parameters

font	a mutable hb_font_t to use for shaping
buffer	an hb_buffer_t to shape
features	an array of user specified hb_feature_t or `NULL`.	[array length=num_features][nullable]
num_features	the length of `features` array
shaper_list	a `NULL`-terminated array of shapers to use or `NULL`.	[array zero-terminated=1][nullable]
min_target_advance	Minimum advance width/height to aim for.
max_target_advance	Maximum advance width/height to aim for.
advance	Input/output advance width/height of the buffer.	[inout]
var_tag	Variation-axis tag used for justification.	[out]
var_value	Variation-axis value used to reach target justification.	[out]

Returns

false if all shapers failed, true otherwise

XSince: EXPERIMENTAL

hb_shape_list_shapers ()

const char **
hb_shape_list_shapers (void);

Retrieves the list of shapers supported by HarfBuzz.

Returns

an array of constant strings.

[transfer none][array zero-terminated=1]

Since: 0.9.2