Overview

Installing CFFI

cairocffi requires CFFI, which can be installed with pip but has its own dependencies that can be tricky to install.

See CFFI’s own documentation for details.

Installing cairocffi

Install with pip:

pip install cairocffi

This will automatically install CFFI.

cairocffi can also be setup to utizile XCB support via xcffib. This can also be installed automatically with pip:

pip install cairocffi[xcb]

In addition to other dependencies, this will install xcffib.

Importing

The module to import is named cairocffi in order to co-exist peacefully with Pycairo which uses cairo, but cairo is shorter and nicer to use:

import cairocffi as cairo

cairocffi will dynamically load cairo as a shared library at this point. If it fails to find it, you will see an exception like this:

OSError: library not found: 'cairo'

Make sure cairo is correctly installed and available through your system’s usual mechanisms. On Linux, the LD_LIBRARY_PATH environment variable can be used to indicate where to find shared libraries.

Installing cairo on Windows

cairocffi needs a libcairo-2.dll file in a directory that is listed in the PATH environment variable.

Alexander Shaduri’s GTK+ installer works. (Make sure to leave the Set up PATH environment variable checkbox checked.) Pycairo on Windows is sometimes compiled statically against cairo and may not provide a .dll file that cairocffi can use.

cairo versions

Cairo, pycairo, and cairocffi each have version numbers. The same cairocffi version can be used with a variety of cairo versions. For example, the Surface.set_mime_data() method is based on the cairo_surface_set_mime_data() C function, which is only available since cairo 1.10. You will get a runtime exception if you try to use it with an older cairo. You can however still use the rest of the API. There is no need for cairocffi’s versions to be tied to cairo’s versions.

Use cairo_version() to test the version number for cairo:

if cairocffi.cairo_version() > 11000:
    surface.set_mime_data('image/jpeg', jpeg_bytes)

Here are all the version numbers:

>>> print("The cairo version is %s, meaning %s."
...       % (cairocffi.cairo_version(), cairocffi.cairo_version_string())
The cairo version is 11402, meaning 1.14.02.
>>> print("The latest pycairo version this cairocffi version is compatible with is %s."
...       % cairo.version)
The latest pycairo version this cairocffi version is compatible with is 1.10.0.
>>> print("The cairocffi version is %s." % cairo.VERSION)
The cairocffi version is 0.7.2

cairocffi is tested with both cairo 1.8.2 and the latest (1.12.8 as of this writing.)

Compatibility with Pycairo

cairocffi’s Python API is compatible with Pycairo. Please file a bug if you find incompatibilities.

In your own code that uses Pycairo, you should be able to just change the imports from import cairo to import cairocffi as cairo as above. If it’s not your own code that imports Pycairo, the install_as_pycairo() function can help:

import cairocffi
cairocffi.install_as_pycairo()
import cairo
assert cairo is cairocffi

Alternatively, add a cairo.py file somewhere in your sys.path, so that it’s imported instead of pycairo:

from cairocffi import *

It is also possible to convert pycairo contexts to cairocffi.

Basic usage

For doing something useful with cairo, you need at least a surface and a context:

import cairocffi as cairo

surface = cairo.ImageSurface(cairo.FORMAT_ARGB32, 300, 200)
context = cairo.Context(surface)
with context:
    context.set_source_rgb(1, 1, 1)  # White
    context.paint()
# Restore the default source which is black.
context.move_to(90, 140)
context.rotate(-0.5)
context.set_font_size(20)
context.show_text(u'Hi from cairo!')
surface.write_to_png('example.png')

The Surface represents the target. There are various types of surface for various output backends. The Context holds internal state and is use for drawing. We’re only using solid colors here, but more complex Pattern types are also available.

All the details are in Python API reference.