Cairo

NAME
SYNOPSIS
ABSTRACT
API DOCUMENTATION
SEE ALSO
AUTHORS
COPYRIGHT

NAME

Cairo - Perl interface to the cairo library

SYNOPSIS

  use Cairo;

  my $surface = Cairo::ImageSurface->create ('argb32', 100, 100);
  my $cr = Cairo::Context->create ($surface);

  $cr->rectangle (10, 10, 40, 40);
  $cr->set_source_rgb (0, 0, 0);
  $cr->fill;

  $cr->rectangle (50, 50, 40, 40);
  $cr->set_source_rgb (1, 1, 1);
  $cr->fill;

  $cr->show_page;

  $surface->write_to_png ('output.png');

ABSTRACT

Cairo provides Perl bindings for the vector graphics library cairo. It supports multiple output targets, including PNG, PDF and SVG. Cairo produces identical output on all those targets.

API DOCUMENTATION

This is a listing of the API Cairo provides. For more verbose information, refer to the cairo manual at http://cairographics.org/manual/.

Cairo::Context is the main object used when drawing with Cairo. To draw with Cairo, you create a Cairo::Context, set the target surface, and drawing options for the Cairo::Context, create shapes with methods like $cr->move_to and $cr->line_to, and then draw shapes with $cr->stroke or $cr->fill.

Cairo::Context's can be pushed to a stack via $cr->save. They may then safely be changed, without loosing the current state. Use $cr->restore to restore to the saved state.

$cr = Cairo::Context->create ($surface)

$surface: Cairo::Surface

$cr->save

$cr->restore

$status = $cr->status

$surface = $cr->get_target

$cr->push_group [1.2]

$cr->push_group_with_content ($content) [1.2]

$content: Cairo::Content

$pattern = $cr->pop_group [1.2]

$cr->pop_group_to_source [1.2]

$surface = $cr->get_group_target [1.2]

$cr->set_source_rgb ($red, $green, $blue)

$red: double
$green: double
$blue: double

$cr->set_source_rgba ($red, $green, $blue, $alpha)

$red: double
$green: double
$blue: double
$alpha: double

$cr->set_source ($source)

$source: Cairo::Pattern

$cr->set_source_surface ($surface, $x, $y)

$surface: Cairo::Surface
$x: double
$y: double

$source = $cr->get_source

$cr->set_antialias ($antialias)

$antialias: Cairo::Antialias

$antialias = $cr->get_antialias

$cr->set_dash ($offset, ...)

$offset: double
...: list of doubles

$cr->set_fill_rule ($fill_rule)

$fill_rule: Cairo::FillRule

$fill_rule = $cr->get_fill_rule

$cr->set_line_cap ($line_cap)

$line_cap: Cairo::LineCap

$line_cap = $cr->get_line_cap

$cr->set_line_join ($line_join)

$line_join: Cairo::LineJoin

$line_join = $cr->get_line_join

$cr->set_line_width ($width)

$width: double

$width = $cr->get_line_width

$cr->set_miter_limit ($limit)

$limit: double

($offset, @dashes) = $cr->get_dash [1.4]

$limit = $cr->get_miter_limit

$cr->set_operator ($op)

$op: Cairo::Operator

$op = $cr->get_operator

$cr->set_tolerance ($tolerance)

$tolerance: double

$tolerance = $cr->get_tolerance

$cr->clip

$cr->clip_preserve

($x1, $y1, $x2, $y2) = $cr->clip_extents [1.4]

@rectangles = $cr->copy_clip_rectangle_list [1.4]

$cr->reset_clip

$cr->fill

$cr->fill_preserve

($x1, $y1, $x2, $y2) = $cr->fill_extents

$bool = $cr->in_fill ($x, $y)

$x: double
$y: double

$cr->mask ($pattern)

$pattern: Cairo::Pattern

$cr->mask_surface ($surface, $surface_x, $surface_y)

$surface: Cairo::Surface
$surface_x: double
$surface_y: double

$cr->paint

$cr->paint_with_alpha ($alpha)

$alpha: double

$cr->stroke

$cr->stroke_preserve

($x1, $y1, $x2, $y2) = $cr->stroke_extents

$bool = $cr->in_stroke ($x, $y)

$x: double
$y: double

$cr->copy_page

$cr->show_page

Paths -- Creating paths and manipulating path data

  $path = [
    { type => "move-to", points => [[1, 2]] },
    { type => "line-to", points => [[3, 4]] },
    { type => "curve-to", points => [[5, 6], [7, 8], [9, 10]] },
    ...
    { type => "close-path", points => [] },
  ];

Cairo::Path is a data structure for holding a path. This data structure serves as the return value for $cr->copy_path_data and $cr->copy_path_data_flat as well the input value for $cr->append_path.

Cairo::Path is represented as an array reference that contains path elements, represented by hash references with two keys: type and points. The value for type can be either of the following:

move-to
line-to
curve-to
close-path

The value for points is an array reference which contains zero or more points. Points are represented as array references that contain two doubles: x and y. The necessary number of points depends on the type of the path element:

move-to: 1 point
line_to: 1 point
curve-to: 3 points
close-path: 0 points

The semantics and ordering of the coordinate values are consistent with $cr->move_to, $cr->line_to, $cr->curve_to, and $cr->close_path.

$path = $cr->copy_path

$path = $cr->copy_path_flat

$cr->append_path ($path)

$path: Cairo::Path

$bool = $cr->has_current_point [1.6]

($x, $y) = $cr->get_current_point

$cr->new_path

$cr->new_sub_path [1.2]

$cr->close_path

($x1, $y1, $x2, $y2) = $cr->path_extents [1.6]

$cr->arc ($xc, $yc, $radius, $angle1, $angle2)

$xc: double
$yc: double
$radius: double
$angle1: double
$angle2: double

$cr->arc_negative ($xc, $yc, $radius, $angle1, $angle2)

$xc: double
$yc: double
$radius: double
$angle1: double
$angle2: double

$cr->curve_to ($x1, $y1, $x2, $y2, $x3, $y3)

$x1: double
$y1: double
$x2: double
$y2: double
$x3: double
$y3: double

$cr->line_to ($x, $y)

$x: double
$y: double

$cr->move_to ($x, $y)

$x: double
$y: double

$cr->rectangle ($x, $y, $width, $height)

$x: double
$y: double
$width: double
$height: double

$cr->glyph_path (...)

...: list of Cairo::Glyph's

$cr->text_path ($utf8)

$utf8: string in utf8 encoding

$cr->rel_curve_to ($dx1, $dy1, $dx2, $dy2, $dx3, $dy3)

$dx1: double
$dy1: double
$dx2: double
$dy2: double
$dx3: double
$dy3: double

$cr->rel_line_to ($dx, $dy)

$dx: double
$dy: double

$cr->rel_move_to ($dx, $dy)

$dx: double
$dy: double

Patterns -- Gradients and filtered sources

$status = $pattern->status

$type = $pattern->get_type [1.2]

$pattern->set_matrix ($matrix)

$matrix: Cairo::Matrix

$matrix = $pattern->get_matrix

$pattern = Cairo::SolidPattern->create_rgb ($red, $green, $blue)

$red: double
$green: double
$blue: double

$pattern = Cairo::SolidPattern->create_rgba ($red, $green, $blue, $alpha)

$red: double
$green: double
$blue: double
$alpha: double

($r, $g, $b, $a) = $pattern->get_rgba [1.4]

$pattern = Cairo::SurfacePattern->create ($surface)

$surface: Cairo::Surface

$pattern->set_extend ($extend)

$extend: Cairo::Extend

$extend = $pattern->get_extend

$pattern->set_filter ($filter)

$filter: Cairo::Filter

$filter = $pattern->get_filter

$surface = $pattern->get_surface [1.4]

$pattern = Cairo::LinearGradient->create ($x0, $y0, $x1, $y1)

$x0: double
$y0: double
$x1: double
$y1: double

($x0, $y0, $x1, $y1) = $pattern->get_points [1.4]

$pattern = Cairo::RadialGradient->create ($cx0, $cy0, $radius0, $cx1, $cy1, $radius1)

$cx0: double
$cy0: double
$radius0: double
$cx1: double
$cy1: double
$radius1: double

($x0, $y0, $r0, $x1, $y1, $r1) = $pattern->get_circles [1.4]

$pattern->add_color_stop_rgb ($offset, $red, $green, $blue)

$offset: double
$red: double
$green: double
$blue: double

$pattern->add_color_stop_rgba ($offset, $red, $green, $blue, $alpha)

$offset: double
$red: double
$green: double
$blue: double
$alpha: double

@stops = $pattern->get_color_stops [1.4]

A color stop is represented as an array reference with five elements: offset, red, green, blue, and alpha.

Transformations -- Manipulating the current transformation matrix

Text -- Rendering text and sets of glyphs

Glyphs are represented as anonymous hash references with three keys: index, x and y. Example:

  my @glyphs = ({ index => 1, x => 2, y => 3 },
                { index => 2, x => 3, y => 4 },
                { index => 3, x => 4, y => 5 });

$cr->select_font_face ($family, $slant, $weight)

$family: string
$slant: Cairo::FontSlant
$weight: Cairo::FontWeight

$cr->set_font_size ($size)

$size: double

$cr->set_font_matrix ($matrix)

$matrix: Cairo::Matrix

$matrix = $cr->get_font_matrix

$cr->set_font_options ($options)

$options: Cairo::FontOptions

$options = $cr->get_font_options

$cr->set_scaled_font ($scaled_font) [1.2]

$scaled_font: Cairo::ScaledFont

$scaled_font = $cr->get_scaled_font [1.4]

$cr->show_text ($utf8)

$utf8: string

$cr->show_glyphs (...)

...: list of glyphs

$face = $cr->get_font_face

$extents = $cr->font_extents

$cr->set_font_face ($font_face)

$font_face: Cairo::FontFace

$cr->set_scaled_font ($scaled_font)

$scaled_font: Cairo::ScaledFont

$extents = $cr->text_extents ($utf8)

$utf8: string

$extents = $cr->glyph_extents (...)

...: list of glyphs

Fonts

FreeType Fonts -- Font support for FreeType

If your cairo library supports it, the FreeType integration allows you to load font faces from font files. You can query for this capability with Cairo::HAS_FT_FONT. To actually use this, you'll need the Font::FreeType module.

my $face = Cairo::FtFontFace->create ($ft_face, $load_flags=0)

$ft_face: Font::FreeType::Face
$load_flags: integer

This method allows you to create a Cairo::FontFace from a Font::FreeType::Face. To obtain the latter, you can for example load it from a file:

  my $file = '/usr/share/fonts/truetype/ttf-bitstream-vera/Vera.ttf';
  my $ft_face = Font::FreeType->new->face ($file);
  my $face = Cairo::FtFontFace->create ($ft_face);