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Functions
Description
Regions are a simple graphical data type representing an area of integer-aligned rectangles. They are often used on raster surfaces to track areas of interest, such as change or clip areas.
Functions
cairo_region_create ()
cairo_region_t *
cairo_region_create (void);
Allocates a new empty region object.
Returns
A newly allocated cairo_region_t. Free with
cairo_region_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_region_status().
Since: 1.10
cairo_region_create_rectangle ()
cairo_region_t *
cairo_region_create_rectangle (const cairo_rectangle_int_t *rectangle);
Allocates a new region object containing rectangle
.
Returns
A newly allocated cairo_region_t. Free with
cairo_region_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_region_status().
Since: 1.10
cairo_region_create_rectangles ()
cairo_region_t * cairo_region_create_rectangles (const cairo_rectangle_int_t *rects,int count);
Allocates a new region object containing the union of all given rects
.
Returns
A newly allocated cairo_region_t. Free with
cairo_region_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_region_status().
Since: 1.10
cairo_region_copy ()
cairo_region_t *
cairo_region_copy (const cairo_region_t *original);
Allocates a new region object copying the area from original
.
Returns
A newly allocated cairo_region_t. Free with
cairo_region_destroy(). This function always returns a
valid pointer; if memory cannot be allocated, then a special
error object is returned where all operations on the object do nothing.
You can check for this with cairo_region_status().
Since: 1.10
cairo_region_reference ()
cairo_region_t *
cairo_region_reference (cairo_region_t *region);
Increases the reference count on region
by one. This prevents
region
from being destroyed until a matching call to
cairo_region_destroy() is made.
Since: 1.10
cairo_region_destroy ()
void
cairo_region_destroy (cairo_region_t *region);
Destroys a cairo_region_t object created with
cairo_region_create(), cairo_region_copy(), or
or cairo_region_create_rectangle().
Since: 1.10
cairo_region_status ()
cairo_status_t
cairo_region_status (const cairo_region_t *region);
Checks whether an error has previous occurred for this region object.
Since: 1.10
cairo_region_get_extents ()
void cairo_region_get_extents (const cairo_region_t *region,cairo_rectangle_int_t *extents);
Gets the bounding rectangle of region
as a cairo_rectangle_int_t
Since: 1.10
cairo_region_num_rectangles ()
int
cairo_region_num_rectangles (const cairo_region_t *region);
Returns the number of rectangles contained in region
.
Since: 1.10
cairo_region_get_rectangle ()
void cairo_region_get_rectangle (const cairo_region_t *region,int nth,cairo_rectangle_int_t *rectangle);
Stores the nth
rectangle from the region in rectangle
.
Parameters
region |
||
nth |
a number indicating which rectangle should be returned |
|
rectangle |
return location for a cairo_rectangle_int_t |
Since: 1.10
cairo_region_is_empty ()
cairo_bool_t
cairo_region_is_empty (const cairo_region_t *region);
Checks whether region
is empty.
Since: 1.10
cairo_region_contains_point ()
cairo_bool_t cairo_region_contains_point (const cairo_region_t *region,int x,int y);
Checks whether (x
, y
) is contained in region
.
Since: 1.10
cairo_region_contains_rectangle ()
cairo_region_overlap_t cairo_region_contains_rectangle (const cairo_region_t *region,const cairo_rectangle_int_t *rectangle);
Checks whether rectangle
is inside, outside or partially contained
in region
Returns
CAIRO_REGION_OVERLAP_IN if rectangle
is entirely inside region
,
CAIRO_REGION_OVERLAP_OUT if rectangle
is entirely outside region
, or
CAIRO_REGION_OVERLAP_PART if rectangle
is partially inside and partially outside region
.
Since: 1.10
cairo_region_equal ()
cairo_bool_t cairo_region_equal (const cairo_region_t *a,const cairo_region_t *b);
Compares whether region_a is equivalent to region_b. NULL as an argument
is equal to itself, but not to any non-NULL region.
Returns
TRUE if both regions contained the same coverage,
FALSE if it is not or any region is in an error status.
Since: 1.10
cairo_region_translate ()
void cairo_region_translate (cairo_region_t *region,int dx,int dy);
Translates region
by (dx
, dy
).
Parameters
region |
||
dx |
Amount to translate in the x direction |
|
dy |
Amount to translate in the y direction |
Since: 1.10
cairo_region_intersect ()
cairo_status_t cairo_region_intersect (cairo_region_t *dst,const cairo_region_t *other);
Computes the intersection of dst
with other
and places the result in dst
Since: 1.10
cairo_region_intersect_rectangle ()
cairo_status_t cairo_region_intersect_rectangle (cairo_region_t *dst,const cairo_rectangle_int_t *rectangle);
Computes the intersection of dst
with rectangle
and places the
result in dst
Since: 1.10
cairo_region_subtract ()
cairo_status_t cairo_region_subtract (cairo_region_t *dst,const cairo_region_t *other);
Subtracts other
from dst
and places the result in dst
Since: 1.10
cairo_region_subtract_rectangle ()
cairo_status_t cairo_region_subtract_rectangle (cairo_region_t *dst,const cairo_rectangle_int_t *rectangle);
Subtracts rectangle
from dst
and places the result in dst
Since: 1.10
cairo_region_union ()
cairo_status_t cairo_region_union (cairo_region_t *dst,const cairo_region_t *other);
Computes the union of dst
with other
and places the result in dst
Since: 1.10
cairo_region_union_rectangle ()
cairo_status_t cairo_region_union_rectangle (cairo_region_t *dst,const cairo_rectangle_int_t *rectangle);
Computes the union of dst
with rectangle
and places the result in dst
.
Since: 1.10
cairo_region_xor ()
cairo_status_t cairo_region_xor (cairo_region_t *dst,const cairo_region_t *other);
Computes the exclusive difference of dst
with other
and places the
result in dst
. That is, dst
will be set to contain all areas that
are either in dst
or in other
, but not in both.
Since: 1.10
cairo_region_xor_rectangle ()
cairo_status_t cairo_region_xor_rectangle (cairo_region_t *dst,const cairo_rectangle_int_t *rectangle);
Computes the exclusive difference of dst
with rectangle
and places the
result in dst
. That is, dst
will be set to contain all areas that are
either in dst
or in rectangle
, but not in both.
Since: 1.10
Types and Values
cairo_region_t
typedef struct _cairo_region cairo_region_t;
A cairo_region_t represents a set of integer-aligned rectangles.
It allows set-theoretical operations like cairo_region_union() and
cairo_region_intersect() to be performed on them.
Memory management of cairo_region_t is done with
cairo_region_reference() and cairo_region_destroy().
Since: 1.10
enum cairo_region_overlap_t
Used as the return value for cairo_region_contains_rectangle().
Since: 1.10