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cairo_pattern_t

cairo_pattern_t — Sources for drawing

Functions

void cairo_pattern_add_color_stop_rgb ()
void cairo_pattern_add_color_stop_rgba ()
cairo_status_t cairo_pattern_get_color_stop_count ()
cairo_status_t cairo_pattern_get_color_stop_rgba ()
cairo_pattern_t * cairo_pattern_create_rgb ()
cairo_pattern_t * cairo_pattern_create_rgba ()
cairo_status_t cairo_pattern_get_rgba ()
cairo_pattern_t * cairo_pattern_create_for_surface ()
cairo_status_t cairo_pattern_get_surface ()
cairo_pattern_t * cairo_pattern_create_linear ()
cairo_status_t cairo_pattern_get_linear_points ()
cairo_pattern_t * cairo_pattern_create_radial ()
cairo_status_t cairo_pattern_get_radial_circles ()
cairo_pattern_t * cairo_pattern_create_mesh ()
void cairo_mesh_pattern_begin_patch ()
void cairo_mesh_pattern_end_patch ()
void cairo_mesh_pattern_move_to ()
void cairo_mesh_pattern_line_to ()
void cairo_mesh_pattern_curve_to ()
void cairo_mesh_pattern_set_control_point ()
void cairo_mesh_pattern_set_corner_color_rgb ()
void cairo_mesh_pattern_set_corner_color_rgba ()
cairo_status_t cairo_mesh_pattern_get_patch_count ()
cairo_path_t * cairo_mesh_pattern_get_path ()
cairo_status_t cairo_mesh_pattern_get_control_point ()
cairo_status_t cairo_mesh_pattern_get_corner_color_rgba ()
cairo_pattern_t * cairo_pattern_reference ()
void cairo_pattern_destroy ()
cairo_status_t cairo_pattern_status ()
void cairo_pattern_set_extend ()
cairo_extend_t cairo_pattern_get_extend ()
void cairo_pattern_set_filter ()
cairo_filter_t cairo_pattern_get_filter ()
void cairo_pattern_set_matrix ()
void cairo_pattern_get_matrix ()
cairo_pattern_type_t cairo_pattern_get_type ()
unsigned int cairo_pattern_get_reference_count ()
cairo_status_t cairo_pattern_set_user_data ()
void * cairo_pattern_get_user_data ()

Types and Values

Description

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.

Functions

cairo_pattern_add_color_stop_rgb ()

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.

Parameters

pattern

a cairo_pattern_t

 

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


cairo_pattern_add_color_stop_rgba ()

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.

Parameters

pattern

a cairo_pattern_t

 

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_pattern_get_color_stop_count ()

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.

Parameters

pattern

a cairo_pattern_t

 

count

return value for the number of color stops, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a gradient pattern.

Since: 1.4


cairo_pattern_get_color_stop_rgba ()

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().

Parameters

pattern

a cairo_pattern_t

 

index

index of the stop to return data for

 

offset

return value for the offset of the stop, or NULL

 

red

return value for red component of color, or NULL

 

green

return value for green component of color, or NULL

 

blue

return value for blue component of color, or NULL

 

alpha

return value for alpha component of color, or NULL

 

Returns

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_create_rgb ()

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.

Parameters

red

red component of the color

 

green

green component of the color

 

blue

blue component of the color

 

Returns

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_create_rgba ()

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

  1. If the values passed in are outside that range, they will be clamped.

Parameters

red

red component of the color

 

green

green component of the color

 

blue

blue component of the color

 

alpha

alpha component of the color

 

Returns

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_get_rgba ()

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.

Parameters

pattern

a cairo_pattern_t

 

red

return value for red component of color, or NULL

 

green

return value for green component of color, or NULL

 

blue

return value for blue component of color, or NULL

 

alpha

return value for alpha component of color, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a solid color pattern.

Since: 1.4


cairo_pattern_create_for_surface ()

cairo_pattern_t *
cairo_pattern_create_for_surface (cairo_surface_t *surface);

Create a new cairo_pattern_t for the given surface.

Parameters

surface

the surface

 

Returns

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_get_surface ()

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.

Parameters

pattern

a cairo_pattern_t

 

surface

return value for surface of pattern, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a surface pattern.

Since: 1.4


cairo_pattern_create_linear ()

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().

Parameters

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

 

Returns

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_get_linear_points ()

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.

Parameters

pattern

a cairo_pattern_t

 

x0

return value for the x coordinate of the first point, or NULL

 

y0

return value for the y coordinate of the first point, or NULL

 

x1

return value for the x coordinate of the second point, or NULL

 

y1

return value for the y coordinate of the second point, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a linear gradient pattern.

Since: 1.4


cairo_pattern_create_radial ()

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().

Parameters

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

 

Returns

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_get_radial_circles ()

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.

Parameters

pattern

a cairo_pattern_t

 

x0

return value for the x coordinate of the center of the first circle, or NULL

 

y0

return value for the y coordinate of the center of the first circle, or NULL

 

r0

return value for the radius of the first circle, or NULL

 

x1

return value for the x coordinate of the center of the second circle, or NULL

 

y1

return value for the y coordinate of the center of the second circle, or NULL

 

r1

return value for the radius of the second circle, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a radial gradient pattern.

Since: 1.4


cairo_pattern_create_mesh ()

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().

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

  1. 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().

Returns

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


cairo_mesh_pattern_begin_patch ()

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.

Parameters

pattern

a cairo_pattern_t

 

Since: 1.12


cairo_mesh_pattern_end_patch ()

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.

Parameters

pattern

a cairo_pattern_t

 

Since: 1.12


cairo_mesh_pattern_move_to ()

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.

Parameters

pattern

a cairo_pattern_t

 

x

the X coordinate of the new position

 

y

the Y coordinate of the new position

 

Since: 1.12


cairo_mesh_pattern_line_to ()

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.

Parameters

pattern

a cairo_pattern_t

 

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


cairo_mesh_pattern_curve_to ()

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.

Parameters

pattern

a cairo_pattern_t

 

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


cairo_mesh_pattern_set_control_point ()

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.

Parameters

pattern

a cairo_pattern_t

 

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


cairo_mesh_pattern_set_corner_color_rgb ()

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.

Parameters

pattern

a cairo_pattern_t

 

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


cairo_mesh_pattern_set_corner_color_rgba ()

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.

Parameters

pattern

a cairo_pattern_t

 

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_mesh_pattern_get_patch_count ()

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.

Parameters

pattern

a cairo_pattern_t

 

count

return value for the number patches, or NULL

 

Returns

CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a mesh pattern.

Since: 1.12


cairo_mesh_pattern_get_path ()

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().

Parameters

pattern

a cairo_pattern_t

 

patch_num

the patch number to return data for

 

Returns

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_mesh_pattern_get_control_point ()

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().

Parameters

pattern

a cairo_pattern_t

 

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 NULL

 

y

return value for the y coordinate of the control point, or NULL

 

Returns

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_mesh_pattern_get_corner_color_rgba ()

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().

Parameters

pattern

a cairo_pattern_t

 

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 NULL

 

green

return value for green component of color, or NULL

 

blue

return value for blue component of color, or NULL

 

alpha

return value for alpha component of color, or NULL

 

Returns

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_reference ()

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.

The number of references to a cairo_pattern_t can be get using cairo_pattern_get_reference_count().

Parameters

pattern

a cairo_pattern_t

 

Returns

the referenced cairo_pattern_t.

Since: 1.0


cairo_pattern_destroy ()

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().

Parameters

pattern

a cairo_pattern_t

 

Since: 1.0


cairo_pattern_status ()

cairo_status_t
cairo_pattern_status (cairo_pattern_t *pattern);

Checks whether an error has previously occurred for this pattern.

Parameters

pattern

a cairo_pattern_t

 

Since: 1.0


cairo_pattern_set_extend ()

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.

Parameters

pattern

a cairo_pattern_t

 

extend

a cairo_extend_t describing how the area outside of the pattern will be drawn

 

Since: 1.0


cairo_pattern_get_extend ()

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.

Parameters

pattern

a cairo_pattern_t

 

Returns

the current extend strategy used for drawing the pattern.

Since: 1.0


cairo_pattern_set_filter ()

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.

cairo_set_source_surface (cr, image, x, y);
cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_NEAREST);

Parameters

pattern

a cairo_pattern_t

 

filter

a cairo_filter_t describing the filter to use for resizing the pattern

 

Since: 1.0


cairo_pattern_get_filter ()

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.

Parameters

pattern

a cairo_pattern_t

 

Returns

the current filter used for resizing the pattern.

Since: 1.0


cairo_pattern_set_matrix ()

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:

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().

Parameters

pattern

a cairo_pattern_t

 

matrix

a cairo_matrix_t

 

Since: 1.0


cairo_pattern_get_matrix ()

void
cairo_pattern_get_matrix (cairo_pattern_t *pattern,
                          cairo_matrix_t *matrix);

Stores the pattern's transformation matrix into matrix .

Parameters

pattern

a cairo_pattern_t

 

matrix

return value for the matrix

 

Since: 1.0


cairo_pattern_get_type ()

cairo_pattern_type_t
cairo_pattern_get_type (cairo_pattern_t *pattern);

This function returns the type a pattern. See cairo_pattern_type_t for available types.

Parameters

pattern

a cairo_pattern_t

 

Returns

The type of pattern .

Since: 1.2


cairo_pattern_get_reference_count ()

unsigned int
cairo_pattern_get_reference_count (cairo_pattern_t *pattern);

Returns the current reference count of pattern .

Parameters

pattern

a cairo_pattern_t

 

Returns

the current reference count of pattern . If the object is a nil object, 0 will be returned.

Since: 1.4


cairo_pattern_set_user_data ()

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 .

Parameters

pattern

a cairo_pattern_t

 

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.

 

Returns

CAIRO_STATUS_SUCCESS or CAIRO_STATUS_NO_MEMORY if a slot could not be allocated for the user data.

Since: 1.4


cairo_pattern_get_user_data ()

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.

Parameters

pattern

a cairo_pattern_t

 

key

the address of the cairo_user_data_key_t the user data was attached to

 

Returns

the user data previously attached or NULL.

Since: 1.4

Types and Values

cairo_pattern_t

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


enum cairo_extend_t

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.

Members

CAIRO_EXTEND_NONE

pixels outside of the source pattern are fully transparent (Since 1.0)

 

CAIRO_EXTEND_REPEAT

the pattern is tiled by repeating (Since 1.0)

 

CAIRO_EXTEND_REFLECT

the pattern is tiled by reflecting at the edges (Since 1.0; but only implemented for surface patterns since 1.6)

 

CAIRO_EXTEND_PAD

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


enum cairo_filter_t

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.

Members

CAIRO_FILTER_FAST

A high-performance filter, with quality similar to CAIRO_FILTER_NEAREST (Since 1.0)

 

CAIRO_FILTER_GOOD

A reasonable-performance filter, with quality similar to CAIRO_FILTER_BILINEAR (Since 1.0)

 

CAIRO_FILTER_BEST

The highest-quality available, performance may not be suitable for interactive use. (Since 1.0)

 

CAIRO_FILTER_NEAREST

Nearest-neighbor filtering (Since 1.0)

 

CAIRO_FILTER_BILINEAR

Linear interpolation in two dimensions (Since 1.0)

 

CAIRO_FILTER_GAUSSIAN

This filter value is currently unimplemented, and should not be used in current code. (Since 1.0)

 

Since: 1.0


enum cairo_pattern_type_t

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.

Members

CAIRO_PATTERN_TYPE_SOLID

The pattern is a solid (uniform) color. It may be opaque or translucent, since 1.2.

 

CAIRO_PATTERN_TYPE_SURFACE

The pattern is a based on a surface (an image), since 1.2.

 

CAIRO_PATTERN_TYPE_LINEAR

The pattern is a linear gradient, since 1.2.

 

CAIRO_PATTERN_TYPE_RADIAL

The pattern is a radial gradient, since 1.2.

 

CAIRO_PATTERN_TYPE_MESH

The pattern is a mesh, since 1.12.

 

CAIRO_PATTERN_TYPE_RASTER_SOURCE

The pattern is a user pattern providing raster data, since 1.12.

 

Since: 1.2

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