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| typedef | cairo_pattern_t |
| enum | cairo_extend_t |
| enum | cairo_filter_t |
| enum | cairo_pattern_type_t |
| enum | cairo_dither_t |
cairo_pattern_t is the paint with which cairo draws. The primary use of patterns is as the source for all cairo drawing operations, although they can also be used as masks, that is, as the brush too.
A cairo pattern is created by using one of the many constructors,
of the form
cairo_pattern_create_type()
or implicitly through
cairo_set_source_type()
functions.
void cairo_pattern_add_color_stop_rgb (cairo_pattern_t *pattern,double offset,double red,double green,double blue);
Adds an opaque color stop to a gradient pattern. The offset specifies the location along the gradient's control vector. For example, a linear gradient's control vector is from (x0,y0) to (x1,y1) while a radial gradient's control vector is from any point on the start circle to the corresponding point on the end circle.
The color is specified in the same way as in cairo_set_source_rgb().
If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend.
Note: If the pattern is not a gradient pattern, (eg. a linear or
radial pattern), then the pattern will be put into an error status
with a status of CAIRO_STATUS_PATTERN_TYPE_MISMATCH.
pattern |
||
offset |
an offset in the range [0.0 .. 1.0] |
|
red |
red component of color |
|
green |
green component of color |
|
blue |
blue component of color |
Since: 1.0
void cairo_pattern_add_color_stop_rgba (cairo_pattern_t *pattern,double offset,double red,double green,double blue,double alpha);
Adds a translucent color stop to a gradient pattern. The offset specifies the location along the gradient's control vector. For example, a linear gradient's control vector is from (x0,y0) to (x1,y1) while a radial gradient's control vector is from any point on the start circle to the corresponding point on the end circle.
The color is specified in the same way as in cairo_set_source_rgba().
If two (or more) stops are specified with identical offset values, they will be sorted according to the order in which the stops are added, (stops added earlier will compare less than stops added later). This can be useful for reliably making sharp color transitions instead of the typical blend.
Note: If the pattern is not a gradient pattern, (eg. a linear or
radial pattern), then the pattern will be put into an error status
with a status of CAIRO_STATUS_PATTERN_TYPE_MISMATCH.
pattern |
||
offset |
an offset in the range [0.0 .. 1.0] |
|
red |
red component of color |
|
green |
green component of color |
|
blue |
blue component of color |
|
alpha |
alpha component of color |
Since: 1.0
cairo_status_t cairo_pattern_get_color_stop_count (cairo_pattern_t *pattern,int *count);
Gets the number of color stops specified in the given gradient pattern.
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern
is not a gradient
pattern.
Since: 1.4
cairo_status_t cairo_pattern_get_color_stop_rgba (cairo_pattern_t *pattern,int index,double *offset,double *red,double *green,double *blue,double *alpha);
Gets the color and offset information at the given index
for a
gradient pattern. Values of index
range from 0 to n-1
where n is the number returned
by cairo_pattern_get_color_stop_count().
Note that the color and alpha values are not premultiplied.
pattern |
||
index |
index of the stop to return data for |
|
offset |
return value for the offset of the stop, or |
|
red |
return value for red component of color, or |
|
green |
return value for green component of color, or |
|
blue |
return value for blue component of color, or |
|
alpha |
return value for alpha component of color, or |
CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_INVALID_INDEX
if index
is not valid for the given pattern. If the pattern is
not a gradient pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH is
returned.
Since: 1.4
cairo_pattern_t * cairo_pattern_create_rgb (double red,double green,double blue);
Creates a new cairo_pattern_t corresponding to an opaque color. The color components are floating point numbers in the range 0 to 1. If the values passed in are outside that range, they will be clamped.
red |
red component of the color |
|
green |
green component of the color |
|
blue |
blue component of the color |
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call cairo_pattern_destroy() when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use cairo_pattern_status().
Since: 1.0
cairo_pattern_t * cairo_pattern_create_rgba (double red,double green,double blue,double alpha);
Creates a new cairo_pattern_t corresponding to a translucent color. The color components are floating point numbers in the range 0 to
If the values passed in are outside that range, they will be clamped.
The color is specified in the same way as in cairo_set_source_rgb().
red |
red component of the color |
|
green |
green component of the color |
|
blue |
blue component of the color |
|
alpha |
alpha component of the color |
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call cairo_pattern_destroy() when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use cairo_pattern_status().
Since: 1.0
cairo_status_t cairo_pattern_get_rgba (cairo_pattern_t *pattern,double *red,double *green,double *blue,double *alpha);
Gets the solid color for a solid color pattern.
Note that the color and alpha values are not premultiplied.
pattern |
||
red |
return value for red component of color, or |
|
green |
return value for green component of color, or |
|
blue |
return value for blue component of color, or |
|
alpha |
return value for alpha component of color, or |
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a solid
color pattern.
Since: 1.4
cairo_pattern_t *
cairo_pattern_create_for_surface (cairo_surface_t *surface);
Create a new cairo_pattern_t for the given surface.
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call cairo_pattern_destroy() when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use cairo_pattern_status().
Since: 1.0
cairo_status_t cairo_pattern_get_surface (cairo_pattern_t *pattern,cairo_surface_t **surface);
Gets the surface of a surface pattern. The reference returned in
surface
is owned by the pattern; the caller should call
cairo_surface_reference() if the surface is to be retained.
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a surface
pattern.
Since: 1.4
cairo_pattern_t * cairo_pattern_create_linear (double x0,double y0,double x1,double y1);
Create a new linear gradient cairo_pattern_t along the line defined
by (x0, y0) and (x1, y1). Before using the gradient pattern, a
number of color stops should be defined using
cairo_pattern_add_color_stop_rgb() or
cairo_pattern_add_color_stop_rgba().
Note: The coordinates here are in pattern space. For a new pattern,
pattern space is identical to user space, but the relationship
between the spaces can be changed with cairo_pattern_set_matrix().
x0 |
x coordinate of the start point |
|
y0 |
y coordinate of the start point |
|
x1 |
x coordinate of the end point |
|
y1 |
y coordinate of the end point |
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call cairo_pattern_destroy() when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use cairo_pattern_status().
Since: 1.0
cairo_status_t cairo_pattern_get_linear_points (cairo_pattern_t *pattern,double *x0,double *y0,double *x1,double *y1);
Gets the gradient endpoints for a linear gradient.
pattern |
||
x0 |
return value for the x coordinate of the first point, or |
|
y0 |
return value for the y coordinate of the first point, or |
|
x1 |
return value for the x coordinate of the second point, or |
|
y1 |
return value for the y coordinate of the second point, or |
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern
is not a linear
gradient pattern.
Since: 1.4
cairo_pattern_t * cairo_pattern_create_radial (double cx0,double cy0,double radius0,double cx1,double cy1,double radius1);
Creates a new radial gradient cairo_pattern_t between the two
circles defined by (cx0, cy0, radius0) and (cx1, cy1, radius1). Before using the
gradient pattern, a number of color stops should be defined using
cairo_pattern_add_color_stop_rgb() or
cairo_pattern_add_color_stop_rgba().
Note: The coordinates here are in pattern space. For a new pattern,
pattern space is identical to user space, but the relationship
between the spaces can be changed with cairo_pattern_set_matrix().
cx0 |
x coordinate for the center of the start circle |
|
cy0 |
y coordinate for the center of the start circle |
|
radius0 |
radius of the start circle |
|
cx1 |
x coordinate for the center of the end circle |
|
cy1 |
y coordinate for the center of the end circle |
|
radius1 |
radius of the end circle |
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the
returned object and should call cairo_pattern_destroy() when
finished with it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect
the status of a pattern use cairo_pattern_status().
Since: 1.0
cairo_status_t cairo_pattern_get_radial_circles (cairo_pattern_t *pattern,double *x0,double *y0,double *r0,double *x1,double *y1,double *r1);
Gets the gradient endpoint circles for a radial gradient, each specified as a center coordinate and a radius.
pattern |
||
x0 |
return value for the x coordinate of the center of the first circle, or |
|
y0 |
return value for the y coordinate of the center of the first circle, or |
|
r0 |
return value for the radius of the first circle, or |
|
x1 |
return value for the x coordinate of the center of the second circle, or |
|
y1 |
return value for the y coordinate of the center of the second circle, or |
|
r1 |
return value for the radius of the second circle, or |
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern
is not a radial
gradient pattern.
Since: 1.4
cairo_pattern_t *
cairo_pattern_create_mesh (void);
Create a new mesh pattern.
Mesh patterns are tensor-product patch meshes (type 7 shadings in PDF). Mesh patterns may also be used to create other types of shadings that are special cases of tensor-product patch meshes such as Coons patch meshes (type 6 shading in PDF) and Gouraud-shaded triangle meshes (type 4 and 5 shadings in PDF).
Mesh patterns consist of one or more tensor-product patches, which
should be defined before using the mesh pattern. Using a mesh
pattern with a partially defined patch as source or mask will put
the context in an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
A tensor-product patch is defined by 4 Bézier curves (side 0, 1, 2, 3) and by 4 additional control points (P0, P1, P2, P3) that provide further control over the patch and complete the definition of the tensor-product patch. The corner C0 is the first point of the patch.
Degenerate sides are permitted so straight lines may be used. A zero length line on one side may be used to create 3 sided patches.
C1 Side 1 C2
+---------------+
| |
| P1 P2 |
| |
Side 0 | | Side 2
| |
| |
| P0 P3 |
| |
+---------------+
C0 Side 3 C3
Each patch is constructed by first calling
cairo_mesh_pattern_begin_patch(), then cairo_mesh_pattern_move_to()
to specify the first point in the patch (C0). Then the sides are
specified with calls to cairo_mesh_pattern_curve_to() and
cairo_mesh_pattern_line_to().
The four additional control points (P0, P1, P2, P3) in a patch can
be specified with cairo_mesh_pattern_set_control_point().
At each corner of the patch (C0, C1, C2, C3) a color may be
specified with cairo_mesh_pattern_set_corner_color_rgb() or
cairo_mesh_pattern_set_corner_color_rgba(). Any corner whose color
is not explicitly specified defaults to transparent black.
A Coons patch is a special case of the tensor-product patch where the control points are implicitly defined by the sides of the patch. The default value for any control point not specified is the implicit value for a Coons patch, i.e. if no control points are specified the patch is a Coons patch.
A triangle is a special case of the tensor-product patch where the control points are implicitly defined by the sides of the patch, all the sides are lines and one of them has length 0, i.e. if the patch is specified using just 3 lines, it is a triangle. If the corners connected by the 0-length side have the same color, the patch is a Gouraud-shaded triangle.
Patches may be oriented differently to the above diagram. For example the first point could be at the top left. The diagram only shows the relationship between the sides, corners and control points. Regardless of where the first point is located, when specifying colors, corner 0 will always be the first point, corner 1 the point between side 0 and side 1 etc.
Calling cairo_mesh_pattern_end_patch() completes the current
patch. If less than 4 sides have been defined, the first missing
side is defined as a line from the current point to the first point
of the patch (C0) and the other sides are degenerate lines from C0
to C0. The corners between the added sides will all be coincident
with C0 of the patch and their color will be set to be the same as
the color of C0.
Additional patches may be added with additional calls to
cairo_mesh_pattern_begin_patch()/cairo_mesh_pattern_end_patch().
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 |
cairo_pattern_t *pattern = cairo_pattern_create_mesh (); /* Add a Coons patch */ cairo_mesh_pattern_begin_patch (pattern); cairo_mesh_pattern_move_to (pattern, 0, 0); cairo_mesh_pattern_curve_to (pattern, 30, -30, 60, 30, 100, 0); cairo_mesh_pattern_curve_to (pattern, 60, 30, 130, 60, 100, 100); cairo_mesh_pattern_curve_to (pattern, 60, 70, 30, 130, 0, 100); cairo_mesh_pattern_curve_to (pattern, 30, 70, -30, 30, 0, 0); cairo_mesh_pattern_set_corner_color_rgb (pattern, 0, 1, 0, 0); cairo_mesh_pattern_set_corner_color_rgb (pattern, 1, 0, 1, 0); cairo_mesh_pattern_set_corner_color_rgb (pattern, 2, 0, 0, 1); cairo_mesh_pattern_set_corner_color_rgb (pattern, 3, 1, 1, 0); cairo_mesh_pattern_end_patch (pattern); /* Add a Gouraud-shaded triangle */ cairo_mesh_pattern_begin_patch (pattern) cairo_mesh_pattern_move_to (pattern, 100, 100); cairo_mesh_pattern_line_to (pattern, 130, 130); cairo_mesh_pattern_line_to (pattern, 130, 70); cairo_mesh_pattern_set_corner_color_rgb (pattern, 0, 1, 0, 0); cairo_mesh_pattern_set_corner_color_rgb (pattern, 1, 0, 1, 0); cairo_mesh_pattern_set_corner_color_rgb (pattern, 2, 0, 0, 1); cairo_mesh_pattern_end_patch (pattern) |
When two patches overlap, the last one that has been added is drawn over the first one.
When a patch folds over itself, points are sorted depending on their parameter coordinates inside the patch. The v coordinate ranges from 0 to 1 when moving from side 3 to side 1; the u coordinate ranges from 0 to 1 when going from side 0 to side
Points with higher v coordinate hide points with lower v coordinate. When two points have the same v coordinate, the one with higher u coordinate is above. This means that points nearer to side 1 are above points nearer to side 3; when this is not sufficient to decide which point is above (for example when both points belong to side 1 or side 3) points nearer to side 2 are above points nearer to side 0.
For a complete definition of tensor-product patches, see the PDF specification (ISO32000), which describes the parametrization in detail.
Note: The coordinates are always in pattern space. For a new
pattern, pattern space is identical to user space, but the
relationship between the spaces can be changed with
cairo_pattern_set_matrix().
the newly created cairo_pattern_t if successful, or
an error pattern in case of no memory. The caller owns the returned
object and should call cairo_pattern_destroy() when finished with
it.
This function will always return a valid pointer, but if an error
occurred the pattern status will be set to an error. To inspect the
status of a pattern use cairo_pattern_status().
Since: 1.12
void
cairo_mesh_pattern_begin_patch (cairo_pattern_t *pattern);
Begin a patch in a mesh pattern.
After calling this function, the patch shape should be defined with
cairo_mesh_pattern_move_to(), cairo_mesh_pattern_line_to() and
cairo_mesh_pattern_curve_to().
After defining the patch, cairo_mesh_pattern_end_patch() must be
called before using pattern
as a source or mask.
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If pattern
already has a
current patch, it will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
Since: 1.12
void
cairo_mesh_pattern_end_patch (cairo_pattern_t *pattern);
Indicates the end of the current patch in a mesh pattern.
If the current patch has less than 4 sides, it is closed with a
straight line from the current point to the first point of the
patch as if cairo_mesh_pattern_line_to() was used.
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If pattern
has no current
patch or the current patch has no current point, pattern
will be
put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
Since: 1.12
void cairo_mesh_pattern_move_to (cairo_pattern_t *pattern,double x,double y);
Define the first point of the current patch in a mesh pattern.
After this call the current point will be (x
, y
).
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If pattern
has no current
patch or the current patch already has at least one side, pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
Since: 1.12
void cairo_mesh_pattern_line_to (cairo_pattern_t *pattern,double x,double y);
Adds a line to the current patch from the current point to position
(x
, y
) in pattern-space coordinates.
If there is no current point before the call to
cairo_mesh_pattern_line_to() this function will behave as
cairo_mesh_pattern_move_to(pattern
, x
, y
).
After this call the current point will be (x
, y
).
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If pattern
has no current
patch or the current patch already has 4 sides, pattern
will be
put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
pattern |
||
x |
the X coordinate of the end of the new line |
|
y |
the Y coordinate of the end of the new line |
Since: 1.12
void cairo_mesh_pattern_curve_to (cairo_pattern_t *pattern,double x1,double y1,double x2,double y2,double x3,double y3);
Adds a cubic Bézier spline to the current patch from the current
point to position (x3
, y3
) in pattern-space coordinates, using
(x1
, y1
) and (x2
, y2
) as the control points.
If the current patch has no current point before the call to
cairo_mesh_pattern_curve_to(), this function will behave as if
preceded by a call to cairo_mesh_pattern_move_to(pattern
, x1
,
y1
).
After this call the current point will be (x3
, y3
).
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If pattern
has no current
patch or the current patch already has 4 sides, pattern
will be
put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
pattern |
||
x1 |
the X coordinate of the first control point |
|
y1 |
the Y coordinate of the first control point |
|
x2 |
the X coordinate of the second control point |
|
y2 |
the Y coordinate of the second control point |
|
x3 |
the X coordinate of the end of the curve |
|
y3 |
the Y coordinate of the end of the curve |
Since: 1.12
void cairo_mesh_pattern_set_control_point (cairo_pattern_t *pattern,unsigned int point_num,double x,double y);
Set an internal control point of the current patch.
Valid values for point_num
are from 0 to 3 and identify the
control points as explained in cairo_pattern_create_mesh().
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If point_num
is not valid,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_INDEX. If pattern
has no current patch,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
pattern |
||
point_num |
the control point to set the position for |
|
x |
the X coordinate of the control point |
|
y |
the Y coordinate of the control point |
Since: 1.12
void cairo_mesh_pattern_set_corner_color_rgb (cairo_pattern_t *pattern,unsigned int corner_num,double red,double green,double blue);
Sets the color of a corner of the current patch in a mesh pattern.
The color is specified in the same way as in cairo_set_source_rgb().
Valid values for corner_num
are from 0 to 3 and identify the
corners as explained in cairo_pattern_create_mesh().
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If corner_num
is not valid,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_INDEX. If pattern
has no current patch,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
pattern |
||
corner_num |
the corner to set the color for |
|
red |
red component of color |
|
green |
green component of color |
|
blue |
blue component of color |
Since: 1.12
void cairo_mesh_pattern_set_corner_color_rgba (cairo_pattern_t *pattern,unsigned int corner_num,double red,double green,double blue,double alpha);
Sets the color of a corner of the current patch in a mesh pattern.
The color is specified in the same way as in cairo_set_source_rgba().
Valid values for corner_num
are from 0 to 3 and identify the
corners as explained in cairo_pattern_create_mesh().
Note: If pattern
is not a mesh pattern then pattern
will be put
into an error status with a status of
CAIRO_STATUS_PATTERN_TYPE_MISMATCH. If corner_num
is not valid,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_INDEX. If pattern
has no current patch,
pattern
will be put into an error status with a status of
CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
pattern |
||
corner_num |
the corner to set the color for |
|
red |
red component of color |
|
green |
green component of color |
|
blue |
blue component of color |
|
alpha |
alpha component of color |
Since: 1.12
cairo_status_t cairo_mesh_pattern_get_patch_count (cairo_pattern_t *pattern,unsigned int *count);
Gets the number of patches specified in the given mesh pattern.
The number only includes patches which have been finished by
calling cairo_mesh_pattern_end_patch(). For example it will be 0
during the definition of the first patch.
CAIRO_STATUS_SUCCESS, or
CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern
is not a mesh
pattern.
Since: 1.12
cairo_path_t * cairo_mesh_pattern_get_path (cairo_pattern_t *pattern,unsigned int patch_num);
Gets path defining the patch patch_num
for a mesh
pattern.
patch_num
can range from 0 to n-1 where n is the number returned by
cairo_mesh_pattern_get_patch_count().
the path defining the patch, or a path with status
CAIRO_STATUS_INVALID_INDEX if patch_num
or point_num
is not
valid for pattern
. If pattern
is not a mesh pattern, a path with
status CAIRO_STATUS_PATTERN_TYPE_MISMATCH is returned.
Since: 1.12
cairo_status_t cairo_mesh_pattern_get_control_point (cairo_pattern_t *pattern,unsigned int patch_num,unsigned int point_num,double *x,double *y);
Gets the control point point_num
of patch patch_num
for a mesh
pattern.
patch_num
can range from 0 to n-1 where n is the number returned by
cairo_mesh_pattern_get_patch_count().
Valid values for point_num
are from 0 to 3 and identify the
control points as explained in cairo_pattern_create_mesh().
pattern |
||
patch_num |
the patch number to return data for |
|
point_num |
the control point number to return data for |
|
x |
return value for the x coordinate of the control point, or |
|
y |
return value for the y coordinate of the control point, or |
CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_INVALID_INDEX
if patch_num
or point_num
is not valid for pattern
. If pattern
is not a mesh pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH is
returned.
Since: 1.12
cairo_status_t cairo_mesh_pattern_get_corner_color_rgba (cairo_pattern_t *pattern,unsigned int patch_num,unsigned int corner_num,double *red,double *green,double *blue,double *alpha);
Gets the color information in corner corner_num
of patch
patch_num
for a mesh pattern.
patch_num
can range from 0 to n-1 where n is the number returned by
cairo_mesh_pattern_get_patch_count().
Valid values for corner_num
are from 0 to 3 and identify the
corners as explained in cairo_pattern_create_mesh().
Note that the color and alpha values are not premultiplied.
pattern |
||
patch_num |
the patch number to return data for |
|
corner_num |
the corner number to return data for |
|
red |
return value for red component of color, or |
|
green |
return value for green component of color, or |
|
blue |
return value for blue component of color, or |
|
alpha |
return value for alpha component of color, or |
CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_INVALID_INDEX
if patch_num
or corner_num
is not valid for pattern
. If
pattern
is not a mesh pattern, CAIRO_STATUS_PATTERN_TYPE_MISMATCH
is returned.
Since: 1.12
cairo_pattern_t *
cairo_pattern_reference (cairo_pattern_t *pattern);
Increases the reference count on pattern
by one. This prevents
pattern
from being destroyed until a matching call to
cairo_pattern_destroy() is made.
Use cairo_pattern_get_reference_count() to get the number of
references to a cairo_pattern_t.
Since: 1.0
void
cairo_pattern_destroy (cairo_pattern_t *pattern);
Decreases the reference count on pattern
by one. If the result is
zero, then pattern
and all associated resources are freed. See
cairo_pattern_reference().
Since: 1.0
cairo_status_t
cairo_pattern_status (cairo_pattern_t *pattern);
Checks whether an error has previously occurred for this pattern.
CAIRO_STATUS_SUCCESS, CAIRO_STATUS_NO_MEMORY,
CAIRO_STATUS_INVALID_MATRIX, CAIRO_STATUS_PATTERN_TYPE_MISMATCH,
or CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.
Since: 1.0
void cairo_pattern_set_extend (cairo_pattern_t *pattern,cairo_extend_t extend);
Sets the mode to be used for drawing outside the area of a pattern. See cairo_extend_t for details on the semantics of each extend strategy.
The default extend mode is CAIRO_EXTEND_NONE for surface patterns
and CAIRO_EXTEND_PAD for gradient patterns.
pattern |
||
extend |
a cairo_extend_t describing how the area outside of the pattern will be drawn |
Since: 1.0
cairo_extend_t
cairo_pattern_get_extend (cairo_pattern_t *pattern);
Gets the current extend mode for a pattern. See cairo_extend_t for details on the semantics of each extend strategy.
Since: 1.0
void cairo_pattern_set_filter (cairo_pattern_t *pattern,cairo_filter_t filter);
Sets the filter to be used for resizing when using this pattern. See cairo_filter_t for details on each filter.
Note that you might want to control filtering even when you do not
have an explicit cairo_pattern_t object, (for example when using
cairo_set_source_surface()). In these cases, it is convenient to
use cairo_get_source() to get access to the pattern that cairo
creates implicitly. For example:
1 2 |
cairo_set_source_surface (cr, image, x, y); cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST); |
Since: 1.0
cairo_filter_t
cairo_pattern_get_filter (cairo_pattern_t *pattern);
Gets the current filter for a pattern. See cairo_filter_t for details on each filter.
Since: 1.0
void cairo_pattern_set_matrix (cairo_pattern_t *pattern,const cairo_matrix_t *matrix);
Sets the pattern's transformation matrix to matrix
. This matrix is
a transformation from user space to pattern space.
When a pattern is first created it always has the identity matrix for its transformation matrix, which means that pattern space is initially identical to user space.
Important: Please note that the direction of this transformation matrix is from user space to pattern space. This means that if you imagine the flow from a pattern to user space (and on to device space), then coordinates in that flow will be transformed by the inverse of the pattern matrix.
For example, if you want to make a pattern appear twice as large as it does by default the correct code to use is:
1 2 |
cairo_matrix_init_scale (&matrix, 0.5, 0.5); cairo_pattern_set_matrix (pattern, &matrix); |
Meanwhile, using values of 2.0 rather than 0.5 in the code above would cause the pattern to appear at half of its default size.
Also, please note the discussion of the user-space locking
semantics of cairo_set_source().
Since: 1.0
void cairo_pattern_get_matrix (cairo_pattern_t *pattern,cairo_matrix_t *matrix);
Stores the pattern's transformation matrix into matrix
.
Since: 1.0
cairo_pattern_type_t
cairo_pattern_get_type (cairo_pattern_t *pattern);
Get the pattern's type. See cairo_pattern_type_t for available types.
Since: 1.2
unsigned int
cairo_pattern_get_reference_count (cairo_pattern_t *pattern);
Returns the current reference count of pattern
.
Since: 1.4
cairo_status_t cairo_pattern_set_user_data (cairo_pattern_t *pattern,const cairo_user_data_key_t *key,void *user_data,cairo_destroy_func_t destroy);
Attach user data to pattern
. To remove user data from a surface,
call this function with the key that was used to set it and NULL
for data
.
pattern |
||
key |
the address of a cairo_user_data_key_t to attach the user data to |
|
user_data |
the user data to attach to the cairo_pattern_t |
|
destroy |
a cairo_destroy_func_t which will be called when the cairo_t is destroyed or when new user data is attached using the same key. |
CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY if a
slot could not be allocated for the user data.
Since: 1.4
void * cairo_pattern_get_user_data (cairo_pattern_t *pattern,const cairo_user_data_key_t *key);
Return user data previously attached to pattern
using the
specified key. If no user data has been attached with the given
key this function returns NULL.
Since: 1.4
void cairo_pattern_set_dither (cairo_pattern_t *pattern,cairo_dither_t dither);
Set the dithering mode of the rasterizer used for drawing shapes. This value is a hint, and a particular backend may or may not support a particular value. At the current time, only pixman is supported.
Since: 1.18
cairo_dither_t
cairo_pattern_get_dither (cairo_pattern_t *pattern);
Gets the current dithering mode, as set by
cairo_pattern_set_dither().
Since: 1.18
typedef struct _cairo_pattern cairo_pattern_t;
A cairo_pattern_t represents a source when drawing onto a
surface. There are different subtypes of cairo_pattern_t,
for different types of sources; for example,
cairo_pattern_create_rgb() creates a pattern for a solid
opaque color.
Other than various
cairo_pattern_create_type()
functions, some of the pattern types can be implicitly created using various
cairo_set_source_type() functions;
for example cairo_set_source_rgb().
The type of a pattern can be queried with cairo_pattern_get_type().
Memory management of cairo_pattern_t is done with
cairo_pattern_reference() and cairo_pattern_destroy().
Since: 1.0
cairo_extend_t is used to describe how pattern color/alpha will be determined for areas "outside" the pattern's natural area, (for example, outside the surface bounds or outside the gradient geometry).
Mesh patterns are not affected by the extend mode.
The default extend mode is CAIRO_EXTEND_NONE for surface patterns
and CAIRO_EXTEND_PAD for gradient patterns.
New entries may be added in future versions.
|
pixels outside of the source pattern are fully transparent (Since 1.0) |
||
|
the pattern is tiled by repeating (Since 1.0) |
||
|
the pattern is tiled by reflecting at the edges (Since 1.0; but only implemented for surface patterns since 1.6) |
||
|
pixels outside of the pattern copy the closest pixel from the source (Since 1.2; but only implemented for surface patterns since 1.6) |
Since: 1.0
cairo_filter_t is used to indicate what filtering should be
applied when reading pixel values from patterns. See
cairo_pattern_set_filter() for indicating the desired filter to be
used with a particular pattern.
|
A high-performance filter, with quality similar
to |
||
|
A reasonable-performance filter, with quality
similar to |
||
|
The highest-quality available, performance may not be suitable for interactive use. (Since 1.0) |
||
|
Nearest-neighbor filtering (Since 1.0) |
||
|
Linear interpolation in two dimensions (Since 1.0) |
||
|
This filter value is currently unimplemented, and should not be used in current code. (Since 1.0) |
Since: 1.0
cairo_pattern_type_t is used to describe the type of a given pattern.
The type of a pattern is determined by the function used to create
it. The cairo_pattern_create_rgb() and cairo_pattern_create_rgba()
functions create SOLID patterns. The remaining
cairo_pattern_create functions map to pattern types in obvious
ways.
The pattern type can be queried with cairo_pattern_get_type()
Most cairo_pattern_t functions can be called with a pattern of any
type, (though trying to change the extend or filter for a solid
pattern will have no effect). A notable exception is
cairo_pattern_add_color_stop_rgb() and
cairo_pattern_add_color_stop_rgba() which must only be called with
gradient patterns (either LINEAR or RADIAL). Otherwise the pattern
will be shutdown and put into an error state.
New entries may be added in future versions.
|
The pattern is a solid (uniform) color. It may be opaque or translucent, since 1.2. |
||
|
The pattern is a based on a surface (an image), since 1.2. |
||
|
The pattern is a linear gradient, since 1.2. |
||
|
The pattern is a radial gradient, since 1.2. |
||
|
The pattern is a mesh, since 1.12. |
||
|
The pattern is a user pattern providing raster data, since 1.12. |
Since: 1.2
Dither is an intentionally applied form of noise used to randomize quantization error, preventing large-scale patterns such as color banding in images (e.g. for gradients). Ordered dithering applies a precomputed threshold matrix to spread the errors smoothly.
cairo_dither_t is modeled on pixman dithering algorithm choice. As of Pixman 0.40, FAST corresponds to a 8x8 ordered bayer noise and GOOD and BEST use an ordered 64x64 precomputed blue noise.
|
No dithering. |
||
|
Default choice at cairo compile time. Currently NONE. |
||
|
Fastest dithering algorithm supported by the backend |
||
|
An algorithm with smoother dithering than FAST |
||
|
Best algorithm available in the backend |
Since: 1.18