PIKApp/devel-docs/HACKING.md

Building from git and contributing

While packagers are expected to compile PIKA from tarballs (same for personal usage), developers who wish to contribute patches should compile from the git repository.

The procedure is basically the same (such as described in the INSTALL file, which you will notice doesn't exist in the repository; you can find INSTALL.in instead, whose base text is the same before substitution by the build configuration step). Yet it has a few extra steps.

Git

PIKA is available from GNOME Git. You can use the following commands to get PIKA from the the git server:

$ git clone https://gitlab.gnome.org/GNOME/pika.git

You can read more on using GNOME's git service at these URLs:

https://wiki.gnome.org/Git
https://www.kernel.org/pub/software/scm/git/docs/

The development branches of PIKA closely follow the development branches of babl and GEGL which are considered part of the project. Therefore you will also have to clone and build these repositories:

$ git clone https://gitlab.gnome.org/GNOME/babl.git
$ git clone https://gitlab.gnome.org/GNOME/gegl.git

As for other requirements as listed in the INSTALL file, if you use a development-oriented Linux distribution (Debian Testing or Fedora for instance), you will often be able to install all of them from your package manager. On Windows, the MSYS2 project is great for keeping up with libraries too. On macOS, it is unfortunately much more of a hurdle and you should probably look at instructions in our pika-macos-build repository which is how we build PIKA for macOS.

We also know that PIKA is built on various *BSD, proprietary Unixes, even on GNU-Hurd and less known systems such as Haiku OS but we don't have much details to help you there. Yet we still welcome patches to improve situation on any platform.

In any case, if you use a system providing too old packages, you might be forced to build from source (tarballs or repositories) the various dependencies list in INSTALL.

Additional Requirements

Our autotools build system requires the following packages (or newer versions) installed when building from git (unlike building from tarball):

* GNU autoconf 2.54 or over
    - ftp://ftp.gnu.org/gnu/autoconf/
* GNU automake 1.13 or over
    - ftp://ftp.gnu.org/gnu/automake/
* GNU libtool 1.5 or over
    - ftp://ftp.gnu.org/gnu/libtool/

Alternatively a build with meson 0.53.0 or over is possible but it is not complete yet, hence not usable for packaging (yet usable for development).

For some specific build rules, you will also need:

* xsltproc
    - ftp://ftp.gnome.org/pub/GNOME/sources/libxslt/1.1/

In any cases, you will require this tool for dependency retrieval:

* pkg-config 0.16.0 (or preferably a newer version)
    - https://www.freedesktop.org/software/pkgconfig/

These are only the additional requirements if you want to compile from the git repository. The file INSTALL lists the various libraries we depend on.

Additional Compilation Steps

If you are accessing PIKA via git, then you will need to take more steps to get it to compile. You can do all these steps at once by running:

pika/trunk$ ./autogen.sh

Basically this does the following for you:

pika/trunk$ aclocal-1.9; libtoolize; automake-1.9 -a;
pika/trunk$ autoconf;

The above commands create the "configure" script. Now you can run the configure script in pika/trunk to create all the Makefiles.

Before running autogen.sh or configure, make sure you have libtool in your path. Also make sure glib-2.0.m4 glib-gettext.m4, gtk-3.0.m4 and pkg.m4 are either installed in the same $prefix/share/aclocal relative to your automake/aclocal installation or call autogen.sh as follows:

$ ACLOCAL_FLAGS="-I $prefix/share/aclocal" ./autogen.sh

Note that autogen.sh runs configure for you. If you wish to pass options like --prefix=/usr to configure you can give those options to autogen.sh and they will be passed on to configure.

If AUTOGEN_CONFIGURE_ARGS is set, these options will also be passed to the configure script. If for example you want to enable the build of the PIKA API reference manuals, you can set AUTOGEN_CONFIGURE_ARGS to "--enable-gi-docgen".

If you want to use libraries from a non-standard prefix, you should set PKG_CONFIG_PATH appropriately. Some libraries do not use pkgconfig, see the output of ./configure --help for information on what environment variables to set to point the compiler and linker to the correct path. Note that you need to do this even if you are installing PIKA itself into the same prefix as the library.

Patches

The best way to submit patches is to provide files created with git-format-patch. The recommended command for a patch against the master branch is:

$ git format-patch origin/master

It is recommended that you file a bug report in our tracker and either create a merge request or attach your patch to the report as a plain text file, not compressed.

Please follow the guidelines for coding style and other requirements listed in CODING_STYLE.md. When you will contribute your first patches, you will notice that we care very much about clean and tidy code, which helps for understanding. Hence we care about coding style and consistency!

Auto-generated Files

Please notice that some files in the source are generated from other sources. All those files have a short notice about being generated somewhere at the top. Among them are the files ending in pdb.[ch] in the libpika/ directory and the files ending in cmds.c in the app/pdb/ subdirectory. Those are generated from the respective .pdb files in pdb/groups.

Other files are:

• plug-ins/common/Makefile.am generated by running plug-ins/common/mkgen.pl.
• icons/Color/Makefile.am and icons/Symbolic/Makefile.am generated by tools/generate-icon-makefiles.py
• AUTHORS from authors.xml