Table of Contents
- Message Extraction
- Language Selection Menu
This topic explains the implementation details of internationalization and localization in the game. For documentation on how to use those features to either internationalize new game content or localize the game, see Internationalization and Localization.
The internationalization and localization implementation fo the game relies on two libraries:
- ICU is a common internationalization library that provides structures to handle locales, easily obtain the default system locale, handle date and number representations on each locale, or provide the localized names of locales to show them in a language combo box.
- tinygettext is a small library that we forked. This library provides the structures and methods that we use to load PO files in memory.
The Localization Singleton
The heart of the internationalization and localization implementation is at
L10n class implemented in this file works as a singleton, and provides many functions that can be used from anywhere in the engine C++ codebase. You can access an instance of the singleton including the
i18n/L10n.h header file and using
The singleton is initialized on engine startup, where it performs the following tasks:
- Creates a list of available locales based on the filenames of the PO files in the
l10nvirtual folder holds the combination of the files in the
binaries/data/l10nfolder, which contains the engine PO files, and the
l10nfolder of each enabled mod. See
You can obtain the list of available locales calculated here at any later time calling
g_L10n.GetSupportedLocaleCodes(). This method returns an array of strings with the locale codes found here.
g_L10n.GetSupportedLocaleDisplayNames()returns a similar vector, this one with display names instead of codes, where the name of each locale is in the language of the locale itself. The special locale "Long Strings", of code "long", is only returned if yours is a development copy (if the
config/dev.cfgfile exists in the virtual filesystem).
- Determines the current locale, first looking at the configuration value
localeand, if undefined, looking at the system locale using icu::Locale::getDefault().
Once the locale is defined, it loads the dictionary of the target locale if it is available. The dictionary is a structure from the tinygettext library that holds the list of English strings linked to translated strings (including context and plural considerations).
You can change the locale later using
g_L10n.SetLocale(). You can pass this method either a locale code as a string, such as "en_GB", or an instance of icu::Locale . The method reloads the dictionary if required.
source/gui/COList.cpp files implement the parsing of the GUI XML localization elements:
See Internationalizing GUI Files to see how to use them.
source/gui/GUIRenderer.cpp file, responsible for rendering images on the GUI, is configured to use
g_L10n.LocalizePath(), which loads localized versions of images if available.
See Localizing Images for more information.
source/i18n/scripting/JSI_L10n.cpp file publishes some of the functions that the
L10n singleton offers, as well as some custom internationalization functions based on the
Engine, as in
binaries/data/mods/public/globalscripts/l10n.js file defines the following equivalent global internationalization functions:
translate(message); translatePlural(singularMessage, pluralMessage, number); translateWithContext(context, message); translatePluralWithContext(context, singularMessage, pluralMessage, number);
Engine. whenever possible.
Object Translation Helper Function
binaries/data/mods/public/globalscripts/l10n.js file defines a function,
keys parameter is an array of strings with the names of the object properties to translate.
String Formatting Function
binaries/data/mods/public/globalscripts/sprintf.js file defines a function,
Message extractions is the process of parsing the source files searching for strings that need to be translated, and generating a translation template file (POT) from them that translators can use.
The script responsible for generating POT files is
source/tools/i18n/updateTemplates.py. This scripts goes through the
l10n folders of the sources (
l10n in mod folders) and it reads the
messages.json file there, which defines where to extract the strings from, and how to extract them.
The format of the messages.json file is a custom format. See Message Extraction for details.
The resulting POT files are generated on the same
l10n folder that contains the
messages.json file that define their configuration.
updateTemplates.py relies on the Python library pology.
Currently, the translation of the game happens in Transifex, at https://www.transifex.com/projects/p/0ad/
l10n folders of the game sources contain a hidden folder,
.tx, which contains a
config file. This config file determines where in Transifex are the PO files that must be downloaded to that specific
To download the translation files from Transifex, you can call
source/tools/i18n/pullTranslations.py, which uses those
.tx/config files and the Transifex client library to automatically download the latest PO files into their respective folders. You need to install the Transifex client library to
To use this script you need a Transifex account and have the Transifex client library installed.
Long Strings Locale
source/tools/i18n/generateLongStringTranslations.py is a special script that generates a PO file for an artificial language with code "long". This PO file consists of the longest strings (as in number of characters) of every available language for each message.
generateLongStringTranslations.py script parses the PO files in the
l10n folders of the sources, and generates the new PO file in each of those
l10n folders as well. Remember to download the real PO files before you call the script, so that the script can read the translations from them in order to find the longest strings.
Language Selection Menu
The dialog box that you open when you select Options → Language in the main menu is defined in the following files: