weston/doc/sphinx/toc/libweston.rst
Pekka Paalanen 9dccfd1ef3 doc: output management sequence diagrams
When we were designing the libweston output API, I wrote a design document
as a Phabricator wiki page. Phabricator is no longer accessible so that
information needs to be migrated to a new place. Here I am converting most of
it into libweston Sphinx documentation, particularly pulling in the sequence
diagrams I drew. This should help people understand how libweston output
configuration works.

The diagrams are committed as both MSC source files and rendered PNG files. I
did not bother tinkering with the build to run mscgen automatically and then
with the CI images to install the tool.

The Sphinx configuration need numref explicitly enabled so that figures are
automatically numbered and can be referenced by their number rather than their
whole caption text(!).

The document structure is changed a little better flowing with Output
Management being the overview page and the Heads and Outputs being the API
pages.

First I wrote the struct weston_output and weston_head descriptions in Doxygen
comments in libweston.h, but then in the API page that text would have been
buried somewhere towards the end of the page. So I put that text in ReST
instead where it comes as first on the pages as it should. The doc for the
structs only contain a link to the top of the page. Yes, the comment style in
libweston.h is a little broken. If I left the asterisk there it would show up
as a bullet point in Sphinx. OTOH putting everything from \rst in a single line
did not produce anything.

Because Sphinx cannot look in two places, the images need to be copied into the
build dir too.

mscgen: http://www.mcternan.me.uk/mscgen/

Fixes: https://gitlab.freedesktop.org/wayland/weston/issues/25

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>
2020-01-27 12:14:14 +00:00

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Libweston
=========
.. toctree::
:maxdepth: 2
:caption: Contents:
libweston/compositor.rst
libweston/output-management.rst
libweston/log.rst
`Libweston` is an effort to separate the re-usable parts of Weston into a
library. `Libweston` provides most of the boring and tedious bits of correctly
implementing core Wayland protocols and interfacing with input and output
systems, so that people who just want to write a new "Wayland window manager"
(WM) or a small desktop environment (DE) can focus on the WM part.
Libweston was first introduced in Weston 1.12, and is expected to continue
evolving through many Weston releases before it achieves a stable API and
feature completeness.
`Libweston`'s primary purpose is exporting an API for creating Wayland
compositors. Libweston's secondary purpose is to export the weston_config API
so that third party plugins and helper programs can read :file:`weston.ini` if
they want to. However, these two scopes are orthogonal and independent. At no
point will the compositor functionality use or depend on the weston_config
functionality.
Further work
------------
In current form, `libweston` is an amalgam of various APIs mashed together and
currently it needs a large clean-up and re-organization and possibly, a split
into class-specific files. The documentation only provide the public
API and not the private API used inside `libweston` or other functionality
required in the core internals of the library.
With that in mind we see the following steps needed to achieve that:
- migrate everything that should not reside in the public API (for instance,
the doxygen **\\internal** command is a clear indication that that symbol
should not be present in the public API) to private headers.
- if needed be, create class-specific files, like **input** and **output**
which should tackle specific functionality, and allows to write the
documentation parts much easier, and provides clarity for `libweston`
users when they'd read it.