doc/reference/libpurple/plugin_i18n.xml

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<chapter id="chapter-plugin-i18n">
  <title>Third Party Plugin Translation</title>

  <programlisting>
 @section Introduction
  For the purpose of this document we're going to assume that your plugin:

   - Is set up to use autotools.  It may be possible to add translation support
     without autotools, but we have no idea how.  We may not want to know, either ;)
   - Has an autogen.sh.  You may have also called this bootstrap.sh or similar.
   - Resides in a source tree that has @c configure.ac and @c Makefile.am in the
     top-level directory as well as a @c src directory in which the plugin's source
     is located.  A @c Makefile.am should also exist in the @c src directory.

  For a plugin to have translation support there are a few steps that need to
  followed:

   - In your autogen.sh, add the following after your other utility checks:
     @code
(intltoolize --version) < /dev/null > /dev/null 2>&1 || {
    echo;
    echo "You must have intltool installed to compile <YOUR PLUGIN NAME>";
    echo;
    exit;
}
     @endcode
     Then before your call to aclocal add:
     @code
intltoolize --force --copy
     @endcode
   - Now edit configure.ac and add the following:
     @code
AC_PROG_INTLTOOL

GETTEXT_PACKAGE=<YOUR PLUGIN NAME>
AC_SUBST(GETTEXT_PACKAGE)
AC_DEFINE_UNQUOTED(GETTEXT_PACKAGE, ["$GETTEXT_PACKAGE"], [Define the gettext package to be used])

ALL_LINGUAS=""
AM_GLIB_GNU_GETTEXT
     @endcode
     The position of these macros in the file don't really matter, but if you
     have issues either play around with it or feel free to ask one of the Pidgin
     developers.  Finally add 'po/Makefile.in' to you 'AC_OUTPUT' command.
   - Now create a directory named 'po'.
   - 'cd' into the 'po' directory.
   - Create/edit the file 'POTFILE.in' in your favorite editor.  Each line
     should be the name of a file that could or does have strings marked for
	 translating (we're getting to that step).  These file names should be
	 relative to the top directory of your plugin's source tree.
   - 'cd' back to the top directory of your plugin's source tree.
   - Open 'Makefile.am' and add 'po' to your 'SUBDIRS' variable.
   - While still in the top directory of your plugin's source tree,  execute
     'intltool-prepare'.  This will setup anything extra that intltool needs.
   - Fire off 'autogen.sh' and when it's completed, verify that you have a
     'po/POTFILES' (notice the lack of a .in).  If you do, everything should be
	 set on the autotools side.
   - Take a break, stretch your legs, smoke a cigarette, whatever, because
     we're done with the autotools part.
   - When you're ready, 'cd' into the directory with the source files for your
     plugin.
   - Open the file containing the PurplePluginInfo structure.
   - If you're not already, please make sure that you are including the
     'config.h' file for you plugin.  Note that 'config.h' could be whatever
	 you told autohead to use with AM_CONFIG_HEADER.  Also add the following:
	 @code
#include <glib/gi18n-lib.h>
     @endcode
	 Make sure that this include is after you include of your 'config.h',
	 otherwise you will break your build.  Also note that if you wish to
     maintain compatibility with older versions of GLib, you will need to
     include additional preprocessor directives, which we won't cover here.
   - This is where things get a bit goofy.  libpurple is going to try to
     translate our strings using the libpurple gettext package.  So we have to
     convert them before libpurple attempts to.
   - To do this, we're going to change the entries for name, summary, and
     description to NULL.
   - Next, locate your 'plugin_load' function.  Your name for this function
     may vary, but it's the third parameter to 'PURPLE_PLUGIN_INIT'.
   - Now add the following within your 'plugin_load' function:
     @code
#ifdef ENABLE_NLS
	bindtextdomain(GETTEXT_PACKAGE, LOCALEDIR);
	bind_textdomain_codeset(GETTEXT_PACKAGE, "UTF-8");
#endif /* ENABLE_NLS */

	info.name        = _("<YOUR PLUGIN NAME>");
	info.summary     = _("<YOUR PLUGIN SUMMARY>");
	info.description = _("<YOUR PLUGIN DESCRIPTION>");
     @endcode
     Note that the _() is intentional, and that it is telling intltool that
	 this string should be translated.  There is also N_() which says that a
	 string should only be marked for translation but should not be translated
	 yet.
   - Go through the rest of your code and mark all the other strings for
     translation with _().
   - When thats done, feel free to commit your work, create your po template
     (pot file) or whatever.
   - To create you po template, 'cd' to 'po' and execute:
     @code
intltool-update --pot
     @endcode
   - To add new translations to your plugin, all you have to do is add the
     language code to the 'ALL_LINGUAS' variable in your configure.ac.  Take
	 note that this list of languages should be separated by a space.  After
	 you have added the language code to 'ALL_LINGUAS', drop the xx.po file
	 into 'po', and re-'autogen.sh'.  After a full build you should now be
	 able to use the translation.

  </programlisting>
</chapter>