Commit a4d69879 authored by Sven Neumann's avatar Sven Neumann Committed by Sven Neumann

removed lots of outdated information directed at developers and only kept

2008-09-03  Sven Neumann  <sven@gimp.org>

	* README.i18n: removed lots of outdated information directed at
	developers and only kept the most important hints for translators.


svn path=/trunk/; revision=26840
parent 2552aa2b
2008-09-03 Sven Neumann <sven@gimp.org>
* README.i18n: removed lots of outdated information directed at
developers and only kept the most important hints for translators.
2008-09-02 Sven Neumann <sven@gimp.org>
* app/plug-in/gimppluginshm.c: if INVALID_FILE_HANDLE is undefined,
......
This document exists to document the important things to care
for because of locale support. It is aimed at developers and
translators. If you are a translator, you can skip the first
sections, but you definitely want to read sections 5 - 9.
Table of Contents
This file contains some important hints for translators.
1. Why localisation?
2. How
3. Deep inside ...
4. Some magic ...
5. Tools and how to use them
6. Gimp is different
7. Adding additional textdomains
8. Tip of the Day messages
9. How to contribute
10. And more ?
The current status of the GIMP translation can be checked at
1. Why localisation?
http://l10n.gnome.org/module/gimp
Many persons from many countries start to get used to Linux.
Unfortunately not everyone is able to understand English. But
even those people sometimes like to use good and free software
without using a dictionary to get the unknown words.
So why not simply localise the software to make it available to
the mass which isn't wholly English native? Of course this also
eases the migration from PhotoX to GIMP. :))
2. How?
Translation of the GNU Image Manipulation Program is handled by the
GNOME Translation Project (see http://l10n.gnome.org/). If you want to
help, we suggest that you get in touch with the translation team of
your language (see http://l10n.gnome.org/teams/).
GNU provides a very nice package called gettext. This one offers
the possibility to translate chosen messages from the native language
of the program into that one of the users if a necessary catalog is
provided. Gettext therefore provides some easy tools to create and
maintain such catalogs and a few functions which can be called by the
program to enable automatic translation at runtime. The program gets
linked to the gettext library or glibc2 which already provides that
functionality and everything is fine.
3. Deep inside...
GIMP is different
GIMP provides header files called gimpintl.h and stdplugins-intl.h in
the libgimp directory which check whether gettext is available on the
system which GIMP is compiled on and will deactivate language support
if it's not.
If the gettext system is there it will declare 3 functions which will be
described below.
3.1 _() [more correctly: char * _( char * )]
This one is a macro for the function gettext(). You can wrap any text
with it that is allowed to be a return value of a function. If you
use it then libintl will try to translate it into the native language
of the user according to his/her environmental settings.
The gettext() function will do a lookup in the hashed catalog which
contains all the translated texts.
- If it is found a pointer to the string will be returned to the caller.
- If not, the caller will receive a pointer to the original string.
This way it is ensured that there isn't any harm caused to the program
if no useful catalog is installed.
Please note that it is important to use _() directly (and not gettext())
for simple messages because of reasons that will be mentioned below.
NOTE: I know some of the developer like short functions like _() but
for a better source understanding I suggest to use it consistently only
for text (like _("That's text!")) and not for variables (like _(text)).
Use gettext(text) instead.
3.2 N_() [more correctly: const char * ( const char * ) ]
This one is a macro for the function gettext_noop(). As you can see
and guess it doesn't really do anything in the programm i.e. it is a
dummy macro but nevertheless important. As it isn't possible to call
functions in a structure as seen here:
struct blurb
{
_("This won't work\n");
}
you have to do it in some other way. In GIMP such structures are
often used to create menus or similar things very simply. Here you
have to use the dummy to allow the generation of the template catalog
which will be described below. This one doesn't do anything but it
marks the text as important to the xgettext extractor.
The text has to be translated manually with the next function.
3.3 gettext()
This function is the same as that macro in 3.1. But there is one big
difference: The _()'s and N_()'s are the only expressions which get
parsed by the template generator.
If you have strings that should be translated but are unfortunately
in a structure you have to do that on your own which means that you
have to parse the fields with the messages in a loop and translate
the texts with this gettext() function.
Please note that it may be necessary to free or allocate memory in
this case!
4. Some magic...
As you have seen we only did the programming part until now but this
isn't all by far. To use catalogs we'll have to create them. Now
there are 3 different files which are importart:
gimp.pot:
This one is the so called template. It contains the messages which
are extracted from the sources and empty fields which have to get
filled by the author. It is used to start a new catalog or to update
the an already available one.
The Makefile will automatically call the program gettext which will
extract all messages that are wrapped by a _() or a N_() (but NOT
gettext()) and concat them to this template.
[language].po:
This file has to be an edited gimp.pot and contains the original
messages plus the translated ones. This file will be delivered
together with GIMP and is the base for the final catalog.
[language].mo:
This file is a compiled version of [language.po] which will be
automatically compiled by the Makefile system and installed in the
locale directory of the system. It contains everything that the .po
file contains except not translated messages, comments and other
overhead. For maximum speed it is also hashed to allow gettext a
faster search.
5. Tools and how to use them
As mentioned the to be translated strings are extracted directly from
the source and written to the template.
I guess many of you will now ask if it is necessary to add new
strings directly to the template or if there's a tool to achieve
that. I think I can calm down those of you who fear lots of had work
just to update the language files. There's a program called msgmerge
which will add all strings that are in the template but not in the
uncompiled catalog to it. Msgmerge does this job very nicely and also
tries to use some kind of fuzzy logic method for already translated
strings for possible reduction of translators work: If an original
string seems similar to a new one and it already has a translation,
it will be taken over to the new catalog together with a remark that
this one may not necessarily fit.
6. Gimp is different
Gimp is a complex application which has a bunch of scripts and
GIMP is a complex application which has a bunch of scripts and
plug-ins that all want to be internationalized. Therefore there is
not one catalog but many. For a full translation of GIMP's UI,
you will have to add translations for the following catalogs:
not one catalog but many. For a full translation of GIMP's UI, you
will have to add translations for the following catalogs:
po/gimp20.po -- the core
po-libgimp/gimp20-libgimp.pot -- the libgimp library
po-python/gimp20-python.pot -- the pygimp plug-ins
po-plugins/gimp20-std-plugins.pot -- the C plug-ins
po-python/gimp20-python.pot -- the pygimp plug-ins
po-script-fu/gimp20-script-fu.pot -- the script-fu scripts
po-tips/gimp20-tips.pot -- the startup tips
......@@ -172,32 +30,12 @@ this one may not necessarily fit.
gimp-perl has been moved into it's own Subversion module called
gimp-perl.
The version of GIMP you are holding in your hand uses GTK+-2.0.
GTK+-2.0 requires that all strings are UTF-8 encoded. Therefore to
make internationalisation work, po files need to be UTF-8 encoded. If
your editor doesn't support UTF-8, you need to convert it to an
encoding your editor can handle and convert it back to UTF-8 before
commiting your changes back. The gnome-i18n module in Subversion has
some scripts that help with this task, but it can also easily done
using iconv.
7. Adding additional textdomains
Third-party plug-ins (plug-ins that are not distributed with The
GIMP) can't have their messages in the gimp-std-plugins textdomain.
We have therefore provided a mechanism that allows plug-ins to
install their own message catalogs and tell GIMP to bind to that
textdomain. This is necessary so that GIMP can correctly translate
the menu paths the plug-in registers. Basically the plug-in has to
call gimp_plugin_domain_add() or gimp_domain_plugin_add_with_path()
before it registers any functions. Have a look at the script-fu
plug-in to see how this is done in detail.
8. Tip of the Day messages
GIMP Tips dialog
In addition to message catalogs Gimp provides a file with tips that
are displayed in a Tip of The Day window. This file is in XML format
and can be found in the tips directory. The english tips messages are
In addition to message catalogs GIMP provides a file with tips that
are displayed in the Tips dialog. This file is in XML format and can
be found in the tips directory. The english tips messages are
extracted from gimp-tips.xml.in so translators can use the usual
tools to create a <lang>.po file that holds the translations. All
translations are then merged into gimp-tips.xml with language
......@@ -208,27 +46,19 @@ this one may not necessarily fit.
message catalog that needs to be translated correctly. For a german
translation of the tips this would look like this:
#: app/gui/tips-parser.c:158
#: ../app/dialogs/tips-parser.c:188
msgid "tips-locale:C"
msgstr "tips-locale:de"
9. How to contribute
Any help with translations is appreciated. If you want to help,
please get in contact with the people from the GNOME Translation
Project who coordinate all translation efforts in the GNOME
Subversion tree. They have a nice web-page at
http://developer.gnome.org/projects/gtp/.
10. And more?
We hope we mentioned everything that is worth it and hope that this
document will clarify some things. If it doesn't please write us a
mail. This text of course contains errors, so if you find one tell
us...
Happy Gimping.
Daniel Egger
Sven Neumann
Localization of third-party plug-ins
Third-party plug-ins (plug-ins that are not distributed with GIMP)
can't have their messages in the gimp-std-plugins textdomain. We
have therefore provided a mechanism that allows plug-ins to install
their own message catalogs and tell GIMP to bind to that
textdomain. This is necessary so that GIMP can correctly translate
the menu paths the plug-in registers. Basically the plug-in has to
call gimp_plugin_domain_add() or gimp_domain_plugin_add_with_path()
before it registers any functions. Have a look at the script-fu
plug-in to see how this is done in detail.
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