Ardour User Interface Translation How-To

Ardour's user interface can be translated into many languages. For this the
application uses gettext engine. It works like this: there is a plain text
editable PO file for every language that contains a number of sequences like: a
line in English, a line in target language and a reference to a line in source
code where original text in English comes from. The build system then creates a
binary version of each PO file with MO file extension and places it in a system
directory where running instance of Ardour will pick and use it.

Ardour has two main PO files to translate: for user interface and for Ardour's
library. Some messages from the library are actually passed to user interface
(various warnings, for example), so ideally you have to translate both. For
example, Russian translations are located here:

gtk2_ardour/po/ru.po
libs/ardour/po/ru.po

There are few supplementation translations that can be found here (again,
showing the case for Russian):

libs/gtkmm2ext/po/ru.po

Every PO file's name is a two-character code, e.g. 'de' for German, 'es' for
Spanish and so on. However it's fairly common to have localizations for local
versions of a language, e.g. 'pt_BR' would stand for Brazilian Portuguese, and
'es_MX' would stand for Mexican Spanish. Please refer to ISO language code
table for details.

Here is the best workflow for existing translations.

1. Build Ardour  using './waf' command (this step is actually optional).
2a. If there is no existing translation for your language, run './waf i18n_pot'
which will generate a POT (.pot) file for each of the directories shown
above. For each directory you plan to translate, rename the POT file to end in .po and then
continue with step 3.
2b. If there is an existing translation for your language, run './waf
i18n_pot' which will bring it up to date (along with all other PO files)
3. Open the relevant PO file in you PO editor of choice (see below).
4. Open Ardour, find something untranslated, locate this phrase in PO file, translate.
5. Repeat previous step several times, save the PO file.
6. Run './waf i18n_mo' to regenerate binary MO files and 'sudo ./waf install' to install them.
7. Restart Ardour to see what your translation looks like and whether it needs fixes, e.g. has to be shorter.

Note that as of Ardour 3 beta 1 the translations are only installed when you
run './waf i18n' after './waf' and before 'sudo ./waf install'.

When you are done, save the file and submit it to the tracker.

There are some more things you need to know.

1. Where does a phrase come from?

Often when you go through translation hunting for untranslated messages, you
stumble upon things you have no idea where they come from. To assist you there
most advanced PO editors have means to tell you which source code file it comes
from, or, in some cases, even show the context in source code. Ardour has
pretty much meaningful names for source code files, so it should help. If it
doesn't, please ask on IRC for help.

2. Variables

You will often meet things like "%1" or "%2" in the translation files. This is
a variable that should be left intact. Here is an example:

"Cannot load XML for session from %1"

When Ardour runs, this "%1" will be substituted with "Ardour" so that the whole
phrase will be "Cannot load XML for session from Ardour". If Mixbus (an
commercial Ardour's spin-off) runs, this will be "Cannot load XML for session
from Mixbus" instead. You get the idea. So just place this variable in your
translation in a way that makes the phrase sound natural in your language and
make sure you know where the phrase comes from (see above) so that you know how
to translate it correctly.

3. Plural forms

English has two plural forms, but many other languages have three and even four
plural forms. Some parts of Ardour's code respect that, but some not (check for
existing bug reports). A PO editor usually simplifies translating every plural
form by putting every plural form into a dedicated tab.

Not every PO editor can calculate the equation for the plural forms in your
language, but you can look it up in headers of PO files from some application
such a GIMP or Inkscape. Here is an example for Russian:

http://git.gnome.org/browse/gimp/plain/po/ru.po

"Plural-Forms: nplurals=3; plural=(n%10==1 && n%100!=11 ? 0 : n%10>=2 && n"
"%10<=4 && (n%100<10 || n%100>=20) ? 1 : 2); 10<=4 && (n%100<10 || n"
"%100>=20) ? 1 : 2);\n"

4. PO editors

It's really up to you which PO editor you choose. These ones are most popular:

poEdit. It works on Linux, Mac and Windows. The user interface is fairly simple. 

Lokalize. Part of KDE desktop environment. It's a fairly advanced translation tool.

GTranslator. Usually considered as GNOME translation tool, but has very few
actual GNOME dependencies. Feature-wise it's somewhere between poEdit and
Lokalize.
