Chapter 11. Localization

This chapter describes how to use Mozilla's internationalization (I18N) and localization (L10N) technologies to make applications usable by people around the world. Because the Mozilla community (and the Internet community in general), is global, it is vital to be able to cross language barriers by localizing your application and making it available to a wider audience.

In this chapter, you are given step-by-step instructions on how to change the visible text for your application in the XUL interface and how to handle nonstatic strings that arise from dynamic string handling in other areas of your application code.

While the basic technologies that are used are not new, Mozilla is innovating in areas such as Unicode support and quick access language pack installs. The information in this chapter about the internationalization ( and localization ( projects will give you a solid foundation for what is possible in your own application.

11.1. Localization Basics

Before learning how to localize your Mozilla application, it's useful to run through some of the high-level goals and features of the Mozilla internationalization and localization projects. First, here are some definitions:

Locale in the context of this chapter is related specifically to the display of text in the user interface. The focus will be on UI localization of XUL files and strings contained in JavaScript and C++ files, as well as the methods employed for localization.

Here are some main features of the Mozilla internationalization capabilities, which are relevant to the user front end application level:

Recalling the architecture of the XPFE toolkit described in Chapter 2, the locale component can be easily plugged in and out of the application that you are working on without impacting any other components. This functionality is ideal, for instance, for people with linguistic skills and less experience with technical issues to become involved in a Mozilla-related project.

11.1.3. UI Aesthetics and Principles

To put locale in context, this section looks at some issues you may encounter when localizing your Mozilla application. Some are universal principles and others are unique to the environment. This reference is by no means exhaustive, but it contains some scenarios and tips the authors came across in their experience with locale in Mozilla. Space management

One of the guiding principles in UI design is for your interface to not get too crowded. Although estimates are not specific, it is wise to leave about 30 percent expansion space in your window and dialogs. To achieve this flexibility, you have to ensure that the XUL window has ample space in the first place for all the widgets to fit.

More specifically, the application needs to have space for widgets to expand or contract without detracting from the overall look and feel. Intuitive use of the XUL box model (refer to Chapter 3 for more information) and correct choice of widgets goes a long way in achieving this goal.

The factors that can cause this space to be filled include using languages/character sets that are more verbose than the one that was there originally, and the users changing their font size settings. Some safeguards that have been built into Mozilla already handle this problem. Much of it is done in CSS, but other methods are available. The section "Language Quirks," later in this chapter, outlines one of these methods.