Interfacing Raku to Gnome GTK+

Gnome::Cairo::Pattern

Sources for drawing

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 in the form of new(:rgb()) for example.

See Also

cairo_t, cairo_surface_t

Synopsis

Declaration

unit class Gnome::Cairo::Pattern;
also is Gnome::N::TopLevelClassSupport;

Methods

new

new ( :rgb( red, green, 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. Return value: 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 clear-object() 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 status().

A translucent colored pattern is created when also an alpha value is defined.

multi method new ( :rgb( Num() $red, Num() $green, Num() $blue) )

  • $red; red color from 0 to 1

  • $green; green color from 0 to 1

  • $blue; blue color from 0 to 1

new ( )

Creates a new cairo_pattern_t as if :rgb( 1, 1, 1) is used. This is a white colored pattern.

multi method new ( )

new ( :rgba( red, green, blue, alpha) )

Creates a new cairo_pattern_t corresponding to a color with added transparency.

The caller owns the returned object and should call clear-object() 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 status().

multi method new (
  :rgba( Num() $red, Num() $green, Num() $blue, Num() $alpha)
)

  • $red; red color from 0 to 1

  • $green; green color from 0 to 1

  • $blue; blue color from 0 to 1

  • $alpha; transparency from 0 to 1 (opaque)

new ( :surface )

Create a new cairo_pattern_t for the given surface. The caller owns the returned object and should call clear-object() 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 status().

multi method new ( cairo_surface_t :$surface! )

new ( :linear( x0, y0, x1, 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 add-color-stop-rgb() or 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 set-matrix().

The caller owns the returned object and should call clear-object() 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 status().

method new ( :linear( Num() $x0, Num() $y0, Num() $x1, Num() $y1) )

  • $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

new ( :radial( cx0, cy0, radius0, cx1, cy1, 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 add-color-stop-rgb() or 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 set-matrix().

The caller owns the returned object and should call clear-object() when finished with it. To inspect the status of a pattern use status().

multi method new (
  :radial(
    Num() $cx0, Num() $cy0, Num() $radius0,
    Num() $cx1, Num() $cy1, Num() $radius1
  )
)

  • $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

new( :mesh )

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 mesh-begin-patch(), then mesh-move-to() to specify the first point in the patch (C0). Then the sides are specified with calls to mesh-curve-to() and mesh-line-to().

The four additional control points (P0, P1, P2, P3) in a patch can be specified with mesh-set-control-point(). At each corner of the patch (C0, C1, C2, C3) a color may be specified with mesh-set-corner-color-rgb() or mesh-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 mesh-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 mesh-begin-patch()/mesh-end-patch().

my Gnome::Cairo $pattern .= new(:mesh);

# Add a Coons patch
$pattern.mesh-begin-patch( $pattern);
$pattern.mesh-move-to( 0, 0);
$pattern.mesh-curve-to( 30, -30,  60,  30, 100, 0);
$pattern.mesh-curve-to( 60,  30, 130,  60, 100, 100);
$pattern.mesh-curve-to( 60,  70,  30, 130,   0, 100);
$pattern.mesh-curve-to( 30,  70, -30,  30,   0, 0);
$pattern.mesh-set-corner-color-rgb( $pattern, 0, 1, 0, 0);
$pattern.mesh-set-corner-color-rgb( 1, 0, 1, 0);
$pattern.mesh-set-corner-color-rgb( 2, 0, 0, 1);
$pattern.mesh-set-corner-color-rgb( 3, 1, 1, 0);
$pattern.mesh-end-patch;

# Add a Gouraud-shaded triangle
$pattern.mesh-begin-patch;
$pattern.mesh-move-to( 100, 100);
$pattern.mesh-line-to( 130, 130);
$pattern.mesh-line-to( 130,  70);
$pattern.mesh-set-corner-color-rgb( 0, 1, 0, 0);
$pattern.mesh-set-corner-color-rgb( 1, 0, 1, 0);
$pattern.mesh-set-corner-color-rgb( 2, 0, 0, 1);
$pattern.mesh-end-patch;

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 2. 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 pattern-set-matrix(). Return value: 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 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 pattern-status().

multi method new ( :mesh! )

add-color-stop-rgb

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 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.

method add-color-stop-rgb ( Num $offset, Num $red, Num $green, Num $blue )

  • $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

add-color-stop-rgba

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 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.

method add-color-stop-rgba ( Num $offset, Num $red, Num $green, Num $blue, Num $alpha )

  • $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

get-color-stop-count

Gets the number of color stops specified in the given gradient pattern.

method get-color-stop-count ( --> List )

List returns;

  • $count; return value for the number of color stops, or Any

  • cairo_status_t; values can be CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a gradient pattern.

get-color-stop-rgba

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 get-color-stop-count().

method get-color-stop-rgba ( Int $index --> List )
  • $index; index of the stop to return data for

The List returns;

  • $offset; return value for the offset of the stop, or Any

  • $red; return value for red component of color, or Any

  • $green; return value for green component of color, or Any

  • $blue; return value for blue component of color, or Any

  • $alpha; return value for alpha component of color, or Any

  • cairo_status_t; values can be 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

get-extend

Gets the current extend mode for a pattern. See cairo_extend_t for details on the semantics of each extend strategy.

Return value: the current extend strategy used for drawing the pattern.

method get-extend ( --> cairo_extend_t )

get-filter

Gets the current filter for a pattern. See cairo_filter_t for details on each filter.

Return value: the current filter used for resizing the pattern.

method get-filter ( --> cairo_filter_t )

get-linear-points

Gets the gradient endpoints for a linear gradient.

method get-linear-points ( --> List )

List returns;

  • $x0; return value for the x coordinate of the first point, or Any

  • $y0; return value for the y coordinate of the first point, or Any

  • $x1; return value for the x coordinate of the second point, or Any

  • $y1; return value for the y coordinate of the second point, or Any

  • cairo_status_t; values can be CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a linear gradient pattern.

get-matrix

Returns the pattern’s transformation matrix

method get-matrix ( --> cairo_matrix_t )

get-radial-circles

Gets the gradient endpoint circles for a radial gradient, each specified as a center coordinate and a radius.

method get-radial-circles ( --> List )

  • $x0; return value for the x coordinate of the center of the first circle, or Any

  • $y0; return value for the y coordinate of the center of the first circle, or Any

  • $r0; return value for the radius of the first circle, or Any

  • $x1; return value for the x coordinate of the center of the second circle, or Any

  • $y1; return value for the y coordinate of the center of the second circle, or Any

  • $r1; return value for the radius of the second circle, or Any

  • cairo_status_t; value can be CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a radial gradient pattern.

get-rgba

Gets the solid color for a solid color pattern.

method get-rgba ( --> List )

  • $red; return value for red component of color, or Any

  • $green; return value for green component of color, or Any

  • $blue; return value for blue component of color, or Any

  • $alpha; return value for alpha component of color, or Any

  • cairo_status_t; value can be CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a solid color pattern.

get-surface

Gets the surface of a surface pattern. The reference returned in surface is owned by the pattern; the caller should call surface-reference() if the surface is to be retained.

method get-surface ( --> List )

List holds;

  • Gnome::Cairo::Surface; surface of pattern, or Any

  • cairo_status_t; value can be CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if the pattern is not a surface pattern.

get-type

Get the pattern’s type. See cairo_pattern_type_t for available types. Return value: The type of pattern.

method get-type ( --> cairo_pattern_type_t )

mesh-begin-patch

Begin a patch in a mesh pattern. After calling this function, the patch shape should be defined with mesh-move-to(), mesh-line-to() and mesh-curve-to(). After defining the patch, mesh-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.

method mesh-begin-patch ( )

mesh-curve-to

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 mesh-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.

method mesh-curve-to (
  Num $x1, Num $y1, Num $x2, Num $y2, Num $x3, Num $y3
)

  • $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

mesh-end-patch

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 mesh-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.

method mesh-end-patch ( )

mesh-get-control-point

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 mesh_pattern-get-patch-count(). Valid values for point_num are from 0 to 3 and identify the control points as explained in create-mesh(). Return value: 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.

method mesh-get-control-point ( Int $patch_num, Int $point_num, Num $x, Num $y --> cairo_status_t )

  • Int $patch_num; a cairo_pattern_t

  • Int $point_num; the patch number to return data for

  • Num $x; the control point number to return data for

  • Num $y; return value for the x coordinate of the control point, or Any

mesh-get-corner-color-rgba

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 mesh-get-patch-count(). Valid values for corner_num are from 0 to 3 and identify the corners as explained in create-mesh(). Return value: 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.

method mesh-get-corner-color-rgba ( Int $patch_num, Int $corner_num, Num $red, Num $green, Num $blue, Num $alpha --> cairo_status_t )

  • Int $patch_num; a cairo_pattern_t

  • Int $corner_num; the patch number to return data for

  • Num $red; the corner number to return data for

  • Num $green; return value for red component of color, or Any

  • Num $blue; return value for green component of color, or Any

  • Num $alpha; return value for blue component of color, or Any

mesh-get-patch-count

Gets the number of patches specified in the given mesh pattern. The number only includes patches which have been finished by calling mesh-end-patch(). For example it will be 0 during the definition of the first patch.

method mesh-get-patch-count ( --> List )

Returned List holds;

  • Int; The count of patches

  • cairo_status_t; The status, CAIRO_STATUS_SUCCESS, or CAIRO_STATUS_PATTERN_TYPE_MISMATCH if pattern is not a mesh pattern.

mesh-get-path

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 mesh-get-patch-count(). Return value: 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.

method mesh-get-path ( Int $patch_num --> cairo_path_t )
  • Int $patch_num; a cairo_pattern_t

mesh-line-to

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 mesh-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.

method mesh-line-to ( Num $x, Num $y )

  • Num $x; a cairo_pattern_t

  • Num $y; the X coordinate of the end of the new line

mesh-move-to

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.

method mesh-move-to ( Num $x, Num $y )

  • Num $x; a cairo_pattern_t

  • Num $y; the X coordinate of the new position

mesh-set-control-point

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 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.

method mesh-set-control-point ( Int $point_num, Num $x, Num $y )

  • Int $point_num; a cairo_pattern_t

  • Num $x; the control point to set the position for

  • Num $y; the X coordinate of the control point

mesh-set-corner-color-rgb

Sets the color of a corner of the current patch in a mesh pattern. The color is specified in the same way as in set-source-rgb(). Valid values for corner_num are from 0 to 3 and identify the corners as explained in 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.

method mesh-set-corner-color-rgb ( Int $corner_num, Num $red, Num $green, Num $blue )

  • Int $corner_num; a cairo_pattern_t

  • Num $red; the corner to set the color for

  • Num $green; red component of color

  • Num $blue; green component of color

mesh-set-corner-color-rgba

Sets the color of a corner of the current patch in a mesh pattern. The color is specified in the same way as in set-source-rgba(). Valid values for corner_num are from 0 to 3 and identify the corners as explained in 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.

method mesh-set-corner-color-rgba ( Int $corner_num, Num $red, Num $green, Num $blue, Num $alpha )

  • Int $corner_num; a cairo_pattern_t

  • Num $red; the corner to set the color for

  • Num $green; red component of color

  • Num $blue; green component of color

  • Num $alpha; blue component of color

set-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.

method set-extend ( cairo_extend_t $extend )
  • $extend; a cairo-extend-t describing how the area outside of the pattern will be drawn

set-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 set-source-surface()). In these cases, it is convenient to use get-source() to get access to the pattern that cairo creates implicitly. For example:

  $cairo.set-source-surface( $image, $x, $y);
  $pattern.set-filter( $cairo.get-source, CAIRO_FILTER_NEAREST);

  method set-filter ( cairo_filter_t $filter )
  • $filter; a cairo-filter-t describing the filter to use for resizing the pattern

set-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 C<set-source()>.

 method set-matrix ( cairo_matrix_t $matrix )
  • $matrix; a cairo-matrix-t

status

Checks whether an error has previously occurred for this pattern.

Possible return value: CAIRO_STATUS_SUCCESS, CAIRO_STATUS_NO_MEMORY, CAIRO_STATUS_INVALID_MATRIX, CAIRO_STATUS_PATTERN_TYPE_MISMATCH, or CAIRO_STATUS_INVALID_MESH_CONSTRUCTION.

method status ( --> cairo_status_t )