Hacking Cairo
=============

This is a high-level guide to how the cairo distribution is organized
and how to get started hacking on it.  Make sure you read through the
file README before continuing.


Coding Style
------------

The easiest way to write code in the cairo style is to follow code close
to the place you are hacking, but if you want a written down set of
rules, see file CODING_STYLE.

Files for backends that depend on languages other than C (C++ or
Objective C for example) may use features specific to those languages.
For example, "//" comments are allowed, though discouraged, in those files.


Contact
-------

Various ways to get in touch with other cairo developers and maintainers
have been enumerated at:

	https://cairographics.org/contact/

Most of that information is also reflected in the following sections.


Mailing Lists
-------------

There are various mailing lists that are useful when developing cairo
code.  A complete list is always available at:

	https://cairographics.org/lists/

It is recommended that cairo developers subscribe to all those lists.
The cairo list by itself generates much more traffic than the others
combined, so developers and contributors should not be intimidated by
the -commit and -bugs lists.


Bug Tracking System
-------------------

We use a standard gitlab bug tracking system available at:

	https://gitlab.freedesktop.org/cairo/cairo/-/issues

See file named BUGS for detailed information on reporting bugs.  In short,
for straight bug reports, it's best to report them there such that they
are not lost or forgotten.  For discussion of new features or
complicated issues, use the mailing list.


IRC
---

It's a great idea to hang around the cairo IRC channel if you have any
interest in cairo.  We use the #cairo channel on irc.freenode.net.

Make sure you introduce yourself if your nick is not easy to match to
the name you use on the mailing list.


Version Control System
----------------------

We use /git/ for version control.  See:

	https://cairographics.org/download/

For more information on using git, see:

	https://freedesktop.org/wiki/Infrastructure/git/


Build System
------------

We use the autotools build system with cairo, but with various
customizations and advanced features.  Reading configure.in is your
best bet to understanding it, or just ask on IRC.

To bootstrap the build system run ./autogen.sh.  After that the
regular "./configure; make; make install" sequence can be used.
See file named INSTALL for more details.

There is limited support for a win32 build system.
See README.win32 and Makefile.win32 files in various directories.


ChangeLog
---------

We generate ChangeLog files automatically from the git commit log.
No manual ChangeLog writing is necessary.


Copyrights and Licensing
------------------------

The cairo library is dual-licensed under LGPL and MPL.  See the file
named COPYING for details.  The test suites are more liberal, and are
allowed to include GPL code.

When writing new code, update the file headers to add your (or your
employers) copyright line and contributor line.  If adding new files
or splitting a file, copy the file header from other files.


Source Code
-----------

The library source code and headers live in the src/ directory.
See src/README for more information.


Regression Test Suite
---------------------

Cairo has a fairly extensive regression-testing suite.  Indeed, without
these tests it would be impossible to make a cairo release without
introducing tens of regressions.  We still manage to introduce
regressions with each release even with the hundreds of tests we already
have.

The regression test suite is located under the test/ directory.
See test/README for more information.


Performance Test Suite
----------------------

There is a performance test suite located under the perf/ directory.
A collection of traces of real-world behavior are also available in the
cairo-traces repository, which can be used in isolation or hooked in
with the main performance test suite.  See perf/README for more
information.


Boilerplate
-----------

The cairo-boilerplate is a small private library used by the regression
and performance test suites.  It includes the boilerplace code needed
to initialize various backends for the test suites, as well as allow
tweaking some of the internal workings of the backends for more testing.

The boilerplate code is localted under the boilerplate/ directory.
See boilerplate/README for more information.


Documentation
-------------

Cairo uses the gtk-doc system for reference API documentation.

The reference documentation is located under doc/public.
See doc/public/README for more information.

For more documentation including frequently asked questions, tutorials,
samples, roadmap, todo list, etc visit:

	https://cairographics.org/documentation/

Some of those should gradually be moved to doc/.


Utilities
---------

We have developed several utilities useful for writing cairo or code
that uses cairo.  These tools can be found under the util/ directory.
See util/README for more information.


Releasing
---------

Now you are a cairo maintainer, so what?  See file named RELEASING.

