libgd is a library used by various GNOME 3 styled applications.
However, it is not a typical library, since it doesn't guarantee
API/ABI stability, nor does it has official releases tarballs. Only
the files actually used by your project will be shipped with its
tarball. Only the necessary dependencies will be checked during
configure time and used at runtime.
Each application can configure libgd depending on its needs and will
be able to either link dynamically (privately) or statically link with
a specific development version.
Vala are also supported.
libgd originates from the GNOME Documents project (written by Cosimo
Cecchi), which was one of the first application to follow the novel
GNOME 3 application design.
Since other applications have similar needs, it makes sense to try to
reuse and improve the exisiting work. However, the design being not
frozen, and the code being not yet mattured enough and proven, it is
not possible for the developpers to guarantee API and propose the
addition to the respective projects (Gtk+, or GLib for example) right
now. Sharing the code allows to experiment, discuss and test together
before proposing it upstream.
Traditionnally, this problem is solved by copying often outdated
snippets of code around (due to no API/ABI guaratee), often not
In the past, there used to be some common aging GNOME application
libraries above Gtk+ which have been slowly deprecated in favour of
Gtk+ (gnomeui and friends).
All approaches have pros and cons. A configurable git submodule
has the following advantages:
- no direct code copying necessary because API/ABI breakage (history
is preserved etc..)
- code is shared and maintained in a common project
- you can stick to a particular upstream version, or branch off your
own version easily if needed (hopefully you find your way back upstream)
- update the submodule version when your project is ready
- the libgd options should help you to configure a library to suit
your needs, taking care of some of autofoo stuff for you
In order to use libgd, an application using autotools needs to:
1. from the top-level project directory, add the submodule:
- git submodule add git://git.gnome.org/libgd
2. in autogen.sh, it is recommended to add before autoreconf call:
- git submodule update --init --recursive
3. in top-level Makefile.am:
- add -I libgd to ACLOCAL_AMFLAGS
- add libgd to SUBDIRS, before the project src directory
4. in project configure.ac:
- add LIBGD_INIT([list-of-options]) after your project
- add libgd/Makefile to AC_CONFIG_FILES
5. from your program Makefile.am, you may now for example:
- link with $(top_builddir)/libgd/libgd.la, and include
<libgd/gd.h> (adjust your AM_CPPFLAGS as necessary)
You may be interested to look at the commit switching GNOME Boxes from
private libgd usage to the libgd submodule:
Note for example that the submodule url is "../libgd", which is a
better alternative for projects hosted on git.gnome.org. It will allow
the submodule update to reuse the address and the credentials given to
the toplevel project.
How to modify or add an API?
- add translation support
- add some form of build test
- document: options, modification process
- eventually add documentation generation
- some licensing check
- more modularity (not all in libgd.m4/Makefile.am)
- CSS styling and data: shared only with gnome-themes-standard?