hb-draw: HarfBuzz Manual

hb-draw

hb-draw — Glyph drawing

Functions

hb_draw_funcs_t *	hb_draw_funcs_create ()
hb_draw_funcs_t *	hb_draw_funcs_get_empty ()
hb_draw_funcs_t *	hb_draw_funcs_reference ()
void	hb_draw_funcs_destroy ()
hb_bool_t	hb_draw_funcs_set_user_data ()
void *	hb_draw_funcs_get_user_data ()
void	hb_draw_funcs_make_immutable ()
hb_bool_t	hb_draw_funcs_is_immutable ()
void	(*hb_draw_move_to_func_t) ()
void	hb_draw_funcs_set_move_to_func ()
void	(*hb_draw_line_to_func_t) ()
void	hb_draw_funcs_set_line_to_func ()
void	(*hb_draw_quadratic_to_func_t) ()
void	hb_draw_funcs_set_quadratic_to_func ()
void	(*hb_draw_cubic_to_func_t) ()
void	hb_draw_funcs_set_cubic_to_func ()
void	(*hb_draw_close_path_func_t) ()
void	hb_draw_funcs_set_close_path_func ()
void	hb_draw_move_to ()
void	hb_draw_line_to ()
void	hb_draw_quadratic_to ()
void	hb_draw_cubic_to ()
void	hb_draw_close_path ()

Types and Values

#define	HB_DRAW_STATE_DEFAULT
typedef	hb_draw_funcs_t
	hb_draw_state_t

Includes

#include <hb.h>

Description

Functions for drawing (extracting) glyph shapes.

The hb_draw_funcs_t struct can be used with hb_font_draw_glyph().

Functions

hb_draw_funcs_create ()

hb_draw_funcs_t *
hb_draw_funcs_create (void);

Creates a new draw callbacks object.

Returns

A newly allocated hb_draw_funcs_t with a reference count of 1. The initial reference count should be released with hb_draw_funcs_destroy when you are done using the hb_draw_funcs_t. This function never returns NULL. If memory cannot be allocated, a special singleton hb_draw_funcs_t object will be returned.

[transfer full]

Since: 4.0.0

hb_draw_funcs_get_empty ()

hb_draw_funcs_t *
hb_draw_funcs_get_empty (void);

Fetches the singleton empty draw-functions structure.

Returns

The empty draw-functions structure.

[transfer full]

Since: 7.0.0

hb_draw_funcs_reference ()

hb_draw_funcs_t *
hb_draw_funcs_reference (hb_draw_funcs_t *dfuncs);

Increases the reference count on dfuncs by one.

This prevents dfuncs from being destroyed until a matching call to hb_draw_funcs_destroy() is made.

[skip]

Parameters

dfuncs

draw functions

Returns

The referenced hb_draw_funcs_t.

[transfer full]

Since: 4.0.0

hb_draw_funcs_destroy ()

void
hb_draw_funcs_destroy (hb_draw_funcs_t *dfuncs);

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

[skip]

Parameters

dfuncs

draw functions

Since: 4.0.0

hb_draw_funcs_set_user_data ()

hb_bool_t
hb_draw_funcs_set_user_data (hb_draw_funcs_t *dfuncs,
                             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 draw-functions structure.

[skip]

Parameters

dfuncs	The draw-functions structure
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: 7.0.0

hb_draw_funcs_get_user_data ()

void *
hb_draw_funcs_get_user_data (const hb_draw_funcs_t *dfuncs,
                             hb_user_data_key_t *key);

Fetches the user-data associated with the specified key, attached to the specified draw-functions structure.

[skip]

Parameters

dfuncs	The draw-functions structure
key	The user-data key to query

Returns

A pointer to the user data.

[transfer none]

Since: 7.0.0

hb_draw_funcs_make_immutable ()

void
hb_draw_funcs_make_immutable (hb_draw_funcs_t *dfuncs);

Makes dfuncs object immutable.

Parameters

dfuncs

draw functions

Since: 4.0.0

hb_draw_funcs_is_immutable ()

hb_bool_t
hb_draw_funcs_is_immutable (hb_draw_funcs_t *dfuncs);

Checks whether dfuncs is immutable.

Parameters

dfuncs

draw functions

Returns

true if dfuncs is immutable, false otherwise

Since: 4.0.0

hb_draw_move_to_func_t ()

void
(*hb_draw_move_to_func_t) (hb_draw_funcs_t *dfuncs,
                           void *draw_data,
                           hb_draw_state_t *st,
                           float to_x,
                           float to_y,
                           void *user_data);

A virtual method for the hb_draw_funcs_t to perform a "move-to" draw operation.

Parameters

dfuncs	draw functions object
draw_data	The data accompanying the draw functions in `hb_font_draw_glyph()`
st	current draw state
to_x	X component of target point
to_y	Y component of target point
user_data	User data pointer passed to `hb_draw_funcs_set_move_to_func()`

Since: 4.0.0

hb_draw_funcs_set_move_to_func ()

void
hb_draw_funcs_set_move_to_func (hb_draw_funcs_t *dfuncs,
                                hb_draw_move_to_func_t func,
                                void *user_data,
                                hb_destroy_func_t destroy);

Sets move-to callback to the draw functions object.

Parameters

dfuncs	draw functions object
func	move-to callback.	[closure user_data][destroy destroy][scope notified]
user_data	Data to pass to `func`
destroy	The function to call when `user_data` is not needed anymore.	[nullable]

Since: 4.0.0

hb_draw_line_to_func_t ()

void
(*hb_draw_line_to_func_t) (hb_draw_funcs_t *dfuncs,
                           void *draw_data,
                           hb_draw_state_t *st,
                           float to_x,
                           float to_y,
                           void *user_data);

A virtual method for the hb_draw_funcs_t to perform a "line-to" draw operation.

Parameters

dfuncs	draw functions object
draw_data	The data accompanying the draw functions in `hb_font_draw_glyph()`
st	current draw state
to_x	X component of target point
to_y	Y component of target point
user_data	User data pointer passed to `hb_draw_funcs_set_line_to_func()`

Since: 4.0.0

hb_draw_funcs_set_line_to_func ()

void
hb_draw_funcs_set_line_to_func (hb_draw_funcs_t *dfuncs,
                                hb_draw_line_to_func_t func,
                                void *user_data,
                                hb_destroy_func_t destroy);

Sets line-to callback to the draw functions object.

Parameters

dfuncs	draw functions object
func	line-to callback.	[closure user_data][destroy destroy][scope notified]
user_data	Data to pass to `func`
destroy	The function to call when `user_data` is not needed anymore.	[nullable]

Since: 4.0.0

hb_draw_quadratic_to_func_t ()

void
(*hb_draw_quadratic_to_func_t) (hb_draw_funcs_t *dfuncs,
                                void *draw_data,
                                hb_draw_state_t *st,
                                float control_x,
                                float control_y,
                                float to_x,
                                float to_y,
                                void *user_data);

A virtual method for the hb_draw_funcs_t to perform a "quadratic-to" draw operation.

Parameters

dfuncs	draw functions object
draw_data	The data accompanying the draw functions in `hb_font_draw_glyph()`
st	current draw state
control_x	X component of control point
control_y	Y component of control point
to_x	X component of target point
to_y	Y component of target point
user_data	User data pointer passed to `hb_draw_funcs_set_quadratic_to_func()`

Since: 4.0.0

hb_draw_funcs_set_quadratic_to_func ()

void
hb_draw_funcs_set_quadratic_to_func (hb_draw_funcs_t *dfuncs,
                                     hb_draw_quadratic_to_func_t func,
                                     void *user_data,
                                     hb_destroy_func_t destroy);

Sets quadratic-to callback to the draw functions object.

Parameters

dfuncs	draw functions object
func	quadratic-to callback.	[closure user_data][destroy destroy][scope notified]
user_data	Data to pass to `func`
destroy	The function to call when `user_data` is not needed anymore.	[nullable]

Since: 4.0.0

hb_draw_cubic_to_func_t ()

void
(*hb_draw_cubic_to_func_t) (hb_draw_funcs_t *dfuncs,
                            void *draw_data,
                            hb_draw_state_t *st,
                            float control1_x,
                            float control1_y,
                            float control2_x,
                            float control2_y,
                            float to_x,
                            float to_y,
                            void *user_data);

A virtual method for the hb_draw_funcs_t to perform a "cubic-to" draw operation.

Parameters

dfuncs	draw functions object
draw_data	The data accompanying the draw functions in `hb_font_draw_glyph()`
st	current draw state
control1_x	X component of first control point
control1_y	Y component of first control point
control2_x	X component of second control point
control2_y	Y component of second control point
to_x	X component of target point
to_y	Y component of target point
user_data	User data pointer passed to `hb_draw_funcs_set_cubic_to_func()`

Since: 4.0.0

hb_draw_funcs_set_cubic_to_func ()

void
hb_draw_funcs_set_cubic_to_func (hb_draw_funcs_t *dfuncs,
                                 hb_draw_cubic_to_func_t func,
                                 void *user_data,
                                 hb_destroy_func_t destroy);

Sets cubic-to callback to the draw functions object.

Parameters

dfuncs	draw functions
func	cubic-to callback.	[closure user_data][destroy destroy][scope notified]
user_data	Data to pass to `func`
destroy	The function to call when `user_data` is not needed anymore.	[nullable]

Since: 4.0.0

hb_draw_close_path_func_t ()

void
(*hb_draw_close_path_func_t) (hb_draw_funcs_t *dfuncs,
                              void *draw_data,
                              hb_draw_state_t *st,
                              void *user_data);

A virtual method for the hb_draw_funcs_t to perform a "close-path" draw operation.

Parameters

dfuncs	draw functions object
draw_data	The data accompanying the draw functions in `hb_font_draw_glyph()`
st	current draw state
user_data	User data pointer passed to `hb_draw_funcs_set_close_path_func()`

Since: 4.0.0

hb_draw_funcs_set_close_path_func ()

void
hb_draw_funcs_set_close_path_func (hb_draw_funcs_t *dfuncs,
                                   hb_draw_close_path_func_t func,
                                   void *user_data,
                                   hb_destroy_func_t destroy);

Sets close-path callback to the draw functions object.

Parameters

dfuncs	draw functions object
func	close-path callback.	[closure user_data][destroy destroy][scope notified]
user_data	Data to pass to `func`
destroy	The function to call when `user_data` is not needed anymore.	[nullable]

Since: 4.0.0

hb_draw_move_to ()

void
hb_draw_move_to (hb_draw_funcs_t *dfuncs,
                 void *draw_data,
                 hb_draw_state_t *st,
                 float to_x,
                 float to_y);

Perform a "move-to" draw operation.

Parameters

dfuncs	draw functions
draw_data	associated draw data passed by the caller
st	current draw state
to_x	X component of target point
to_y	Y component of target point

Since: 4.0.0

hb_draw_line_to ()

void
hb_draw_line_to (hb_draw_funcs_t *dfuncs,
                 void *draw_data,
                 hb_draw_state_t *st,
                 float to_x,
                 float to_y);

Perform a "line-to" draw operation.

Parameters

dfuncs	draw functions
draw_data	associated draw data passed by the caller
st	current draw state
to_x	X component of target point
to_y	Y component of target point

Since: 4.0.0

hb_draw_quadratic_to ()

void
hb_draw_quadratic_to (hb_draw_funcs_t *dfuncs,
                      void *draw_data,
                      hb_draw_state_t *st,
                      float control_x,
                      float control_y,
                      float to_x,
                      float to_y);

Perform a "quadratic-to" draw operation.

Parameters

dfuncs	draw functions
draw_data	associated draw data passed by the caller
st	current draw state
control_x	X component of control point
control_y	Y component of control point
to_x	X component of target point
to_y	Y component of target point

Since: 4.0.0

hb_draw_cubic_to ()

void
hb_draw_cubic_to (hb_draw_funcs_t *dfuncs,
                  void *draw_data,
                  hb_draw_state_t *st,
                  float control1_x,
                  float control1_y,
                  float control2_x,
                  float control2_y,
                  float to_x,
                  float to_y);

Perform a "cubic-to" draw operation.

Parameters

dfuncs	draw functions
draw_data	associated draw data passed by the caller
st	current draw state
control1_x	X component of first control point
control1_y	Y component of first control point
control2_x	X component of second control point
control2_y	Y component of second control point
to_x	X component of target point
to_y	Y component of target point

Since: 4.0.0

hb_draw_close_path ()

void
hb_draw_close_path (hb_draw_funcs_t *dfuncs,
                    void *draw_data,
                    hb_draw_state_t *st);

Perform a "close-path" draw operation.

Parameters

dfuncs	draw functions
draw_data	associated draw data passed by the caller
st	current draw state

Since: 4.0.0

Types and Values

HB_DRAW_STATE_DEFAULT

#define HB_DRAW_STATE_DEFAULT {0, 0.f, 0.f, 0.f, 0.f, {0.}, {0.}, {0.}, {0.}, {0.}, {0.}, {0.}}

The default hb_draw_state_t at the start of glyph drawing.

hb_draw_funcs_t

typedef struct hb_draw_funcs_t hb_draw_funcs_t;

Glyph draw callbacks.

hb_draw_move_to_func_t, hb_draw_line_to_func_t and hb_draw_cubic_to_func_t calls are necessary to be defined but we translate hb_draw_quadratic_to_func_t calls to hb_draw_cubic_to_func_t if the callback isn't defined.

Since: 4.0.0

hb_draw_state_t

typedef struct {
  hb_bool_t path_open;

  float path_start_x;
  float path_start_y;

  float current_x;
  float current_y;
} hb_draw_state_t;

Current drawing state.

Members

hb_bool_t `path_open`;	Whether there is an open path
float `path_start_x`;	X component of the start of current path
float `path_start_y`;	Y component of the start of current path
float `current_x`;	X component of current point
float `current_y`;	Y component of current point

Since: 4.0.0