Module UcairoSource

Minimal Cairo bindings.

Thin bindings covering image and PDF surface creation, path drawing, text rendering, and PNG output. Designed for the Hugin rendering backend; not a general-purpose Cairo binding.

All functions raise Failure on Cairo errors and Invalid_argument on destroyed handles.

Handle types

Sourcetype t

The type for Cairo drawing contexts.

Sourcetype surface

The type for Cairo surfaces.

Enumerations

Sourcetype font_weight =
  1. | Normal
  2. | Bold
    (*

    The type for font weight.

    *)
Sourcetype line_cap =
  1. | Butt
  2. | Round
  3. | Square
    (*

    The type for line cap style.

    *)
Sourcetype line_join =
  1. | Join_miter
  2. | Join_round
  3. | Join_bevel
    (*

    The type for line join style.

    *)
Sourcetype antialias =
  1. | Antialias_default
  2. | Antialias_none
  3. | Antialias_gray
  4. | Antialias_subpixel
    (*

    The type for antialiasing mode.

    *)

Text extents

Sourcetype text_extents = {
  1. x_bearing : float;
  2. y_bearing : float;
  3. width : float;
  4. height : float;
  5. x_advance : float;
  6. y_advance : float;
}

The type for text extent measurements.

Context creation

Sourceval create : surface -> t

create surface is a new drawing context targeting surface.

State

Sourceval save : t -> unit

save t pushes the current graphics state onto the stack.

Sourceval restore : t -> unit

restore t pops the graphics state from the stack.

Transformations

Sourceval translate : t -> float -> float -> unit

translate t tx ty translates the user-space origin by (tx, ty).

Sourceval scale : t -> float -> float -> unit

scale t sx sy scales the user-space axes by (sx, sy).

Sourceval rotate : t -> float -> unit

rotate t angle rotates the user-space axes by angle radians.

Source

Sourceval set_source_rgba : t -> float -> float -> float -> float -> unit

set_source_rgba t r g b a sets the source to the given RGBA color.

Sourceval set_source_surface : t -> surface -> x:float -> y:float -> unit

set_source_surface t s ~x ~y sets s as the source, offset by (x, y).

Stroke and fill parameters

Sourceval set_line_width : t -> float -> unit

set_line_width t w sets the stroke line width.

Sourceval set_line_cap : t -> line_cap -> unit

set_line_cap t cap sets the line cap style.

Sourceval set_line_join : t -> line_join -> unit

set_line_join t join sets the line join style.

Sourceval set_dash : t -> float array -> unit

set_dash t dashes sets the dash pattern. An empty array disables dashing.

Sourceval set_antialias : t -> antialias -> unit

set_antialias t aa sets the antialiasing mode.

Font

Sourceval select_font_face : t -> string -> font_weight -> unit

select_font_face t family weight selects a toy font face. Slant is always upright.

Sourceval set_font_size : t -> float -> unit

set_font_size t size sets the font size in user-space units.

Sourceval text_extents : t -> string -> text_extents

text_extents t s is the extents of s with the current font.

Sourceval show_text : t -> string -> unit

show_text t s renders s at the current point.

Path operations

Sourceval move_to : t -> float -> float -> unit

move_to t x y begins a new sub-path at (x, y).

Sourceval line_to : t -> float -> float -> unit

line_to t x y adds a line segment to (x, y).

Sourceval arc : t -> float -> float -> r:float -> a1:float -> a2:float -> unit

arc t xc yc ~r ~a1 ~a2 adds a circular arc centered at (xc, yc) with radius r from angle a1 to a2 (in radians).

Sourceval rectangle : t -> float -> float -> w:float -> h:float -> unit

rectangle t x y ~w ~h adds a closed rectangle sub-path.

Path module

Sourcemodule Path : sig ... end

Drawing operations

Sourceval fill : t -> unit

fill t fills the current path and clears it.

Sourceval fill_preserve : t -> unit

fill_preserve t fills the current path without clearing it.

Sourceval stroke : t -> unit

stroke t strokes the current path and clears it.

Sourceval paint : t -> unit

paint t paints the current source everywhere within the current clip.

Sourceval clip : t -> unit

clip t establishes a new clip region by intersecting the current clip with the current path, then clears the path.

Surface operations

Sourcemodule Surface : sig ... end

Image surface

Sourcemodule Image : sig ... end

PDF surface

Sourcemodule Pdf : sig ... end

PNG output

Sourcemodule Png : sig ... end