package cairo2

README.md

OCaml interface to Cairo

This is an OCaml binding for the Cairo library, a 2D graphics library with support for multiple output devices.

You can read the API of Cairo, Cairo_gtk, and Cairo_pango online.

Prerequisites

You need the development files of Cairo (see the conf-cairo package) and the OCaml package lablgtk2 (in the OPAM package lablgtk).

Compilation & Installation

The easier way to install this library — once the prerequisites are set up — is to use opam:

opam install cairo2

If you would like to compile from the sources, install Dune

opam install dune

and do:

dune build @install

or just make. You can then install it with:

dune install

Examples

You can read a version of the Cairo tutorial using this module. The code of this tutorial is available in the examples/ directory. To compile it, just do

dune build @examples

All the examples below are available (with some comments) by clicking on images in the tutorial.

Basic examples

• stroke.ml shows how to draw (stroke) a simple rectangle on a PNG surface.

• stroke.ml shows how to fill a simple rectangle on a PNG surface.

• showtext.ml illustrates how to select a font and draw some text on a PNG surface.

• paint.ml shows how to paint the current source everywhere within the current clip region.

• mask.ml shows how to apply a radial transparency mask on top of a linear gradient.

• setsourcergba.ml produces

• setsourcegradient.ml shows how to use radial and linear patterns. It generates:

• path_close.ml shows how to draw a closed path. It produces the PNG:

• textextents.ml displays graphically the various dimensions one can request about text. It generates the PNG:

• text_extents.ml exemplifies drawing consecutive UTF-8 strings in a PDF file. Some helping lines are also added to show the text extents.

• tips_ellipse.ml shows the action of dilation on the line width and how to properly draw ellipses. It generates the PNG:

• tips_letter.ml illustrates the wrong way of centering characters based on their individual extents:

  Instead, one should combine them with the font extents as shown in tips_font.ml to have:

Examples generating the images of the tutorial

• diagram.ml draw the images of the section Cairo's Drawing Model:

• draw.ml generates the various images in Drawing with Cairo, namely: