Version 35 (modified by michael, 9 years ago) (diff)

Mentioned ticket:4503

Translating VirtualBox (I18N)

This document describes how users without a strong technical background in software engineering can contribute translations to other languages. The process is very straightforward and based on the easy to use  Qt Linguist tool which is a part of the Qt toolkit for C++ version 4.

If you are just wanting to point out a mistake or any other issue with one of the existing translations, you should add a comment onto the end of ticket:4503. Translators are encouraged to subscribe to that ticket by adding a short comment onto it themselves so that they will be notified about updates to the ticket.

Translation is possible for all languages, including languages with non-latin alphabets. The process requires you to perform an initial translation which you then have to keep up to date as VirtualBox evolves. The original language is English which -- together with German -- is handled by the VirtualBox team. The Qt Linguist tool will also assist you in finding where your translation has to be updated for a new release of VirtualBox.

Language file naming and location

All language files in VirtualBox are named according to the following rule:


where <component> is the name of the component and <lang> is the language identifier. Possible values for the <component> part are:

VirtualBox VirtualBox GUI front-end
qt Qt library itself (built-in dialogs and other resources like key names)

The language identifier has the form of <language>[_<TERRITORY>], where <language> is a two-letter language code as defined by  ISO 639, and optional <TERRITORY> is a two-letter territory (country) code as defined by  ISO 3166. See the examples of language file names at the end of this section.

Binary language files used at runtime are located in the nls subdirectory of the directory that contains the component's executable, and have the .qm extension. Source translation files are located in the nls subdirectory of the component's source tree and have the .ts extension.

At runtime, VirtualBox selects a binary language file for the given language identifier xx_YY in the following order (the first match wins):

  1. <component>_xx_YY.qm
  2. <component>_xx.qm
  3. [built-in English translation]

The language identifier is initially chosen according to the current user's locale setting.

Here are some examples of language file names:

  • qt_de.qm (Qt translation, Deutsch language, all territories)
  • VirtualBox_ru.qm (VirtualBox GUI translation, Russian language, all territories)
  • VirtualBox_zh_TW.qm (VirtualBox GUI translation, Chinese language, Taiwan)


There are two prerequisities to create a new or update an existing translation:

  1.  subversion tool, to get and update .ts source files from the SVN repository that contains the VirtualBox OSE source code. In order to install subversion, download the latest version from the  Tigris web site.
  1.  Qt Linguist tool, to edit .ts files. In order to get Qt Linguist, download the latest 4.x.x version of the Open Source Edition of the Qt toolkit for C++ for your platform from the  Nokia web site. Alternatively, you can try to download the toolkit sources and compile them yourself to get a Qt Linguist application. Please note that we will not accept translation files processed by Qt Linguist version 3 (part of Qt Toolkit 3.x.x) because the format of language files is incompatible with Qt4.

Note that the full VirtualBox source code is not necessary to perform a translation or to test it. See below for detailed instructions.

Preparing a translation to a new language

This section describes how to start a translation of VirtualBox to a new language.

  1. Define a language identifier for your language according to the rule described above. If translations to your language vary depending on the country, use the _<TERRITORY> suffix, otherwise omit it (i.e. no need to apply the suffix if it represents the only possible country). Let's say that your language code is my_MY for the purpose of this description.
  1. Check that your language is not yet supported by visiting the directory in the source tree.
  1. Add a comment to ticket:2018 that you are going to maintain the translation to your language to inform other people that may also want to participate. Before adding such a comment, check that nobody else has already started the translation to the same language.
  1. Go to some directory on your local hard drive and download the NLS subdirectories containing .ts files from the VirtualBox source tree by typing the following command in the command line window (terminal) of your host OS (assumes that subversion has been properly installed so that the svn executable can be found by the host OS):
    svn co VirtualBox_nls
    This will create the VirtualBox_nls/ subdirectory on your local drive containing all .ts files for the VirutalBox GUI component and for Qt4 itself.
  1. Go to VirtualBox_nls/ and copy the translation templates for each component to new files corresponding to your language. Taking the example from step 1, you will need to copy VirtualBox_xx_YY.ts to VirtualBox_my_MY.ts and qt_xx_YY.ts to qt_my_MY.ts.
  1. Start Qt Linguist, open and translate new files you got in step 5. Note that you should always keep the .ts files you translate inside the VirtualBox_nls/ directory and not move them anywhere else.
  1. Make sure all the fields in a special context named @@@ in the file VirtualBox_my_MY.ts are properly translated (see below).
  1. Make sure you followed the Translation hints while translating.
  1. Check your translation at runtime by referring to the Testing the translation section below.
  1. Submit your translation as described in the Submitting the translation section.

Special context @@@

A special context named @@@ contains translatable items necessary to identify the given translation file, so you must ensure they are properly translated. This context is currently present only in the VirtualBox_my_MY.ts file. There are five items in this context:

  1. Native language name (the original value is English). Translate it to a common, human-readable name of the language of your translation, as written in the language itself. For example, for Russian, it will be Русский. Please note that the <language> part in the name of the .ts file must match the language specified here.
  1. Native language country name (the original value is --). If the language of your translation is the same regardless of the territory (country) of speaking, then translate it to an empty string. If you are translating to a particular variant of your language, translate this item to a common, human-readable name of the territory (country) where this variant is used, as written in the language itself. Please note that the <TERRITORY> part in the name of the .ts file must match the language specified here.
  1. Language name, in English (the original value is English). The same as 1, but a common English spelling of the language name.
  1. Language country name, in English (the original value is --). The same as 2, but a common English spelling of the territory (country).
  1. Comma-separated list of translators (the original value is Oracle Corporation). This item used is to specify a list of authors who worked on this translation. Please use the Latin alphabet here, to make it readable by everyone.

Every item in this special context has a self-descriptive comment field, so it will not be difficult to locate them in your translation file even if the order there differs from the order they are listed here.

Picking up recent changes to the translation files

Existing .ts files are periodically synchronized with the source code by the GUI maintainer at Oracle, either a few weeks before a new product release, or after a big number of language-related changes in the user interface (UI). This synchronization is performed to add new (untranslated) strings used in the UI to .ts files which then need to be translated by contributors. See ticket:2018 for more information about the synchronization process.

In order to get the latest changes to the existing .ts that appear as a result of the described synchronization, as well as all other modifications made by Oracle developers or other contributors, you will need to do the following steps. These steps imply that you already performed step 5 of the section Preparing a translation to a new language above and have a copy of the NLS subdirectory in the VirtualBox_nls/ directory of your local hard drive.

  1. Go to the VirtualBox_nls/ directory and type the following command in the command line window (terminal) of your host OS:
    svn update
    This will pull out recent changes from the VirtualBox SVN (if any) and merge them with the local copy of the .ts file for your language (which, according to step 6 from Preparing a translation to a new language you keep right there).
  1. In some rare cases there may be conflicts between the latest SVN version of the .ts file and your local version. You will have to resolve these conflicts manually (please see the  subversion manual for details).

Updating the translation made by someone else

If you want to continue the translation made by someone else, please perform the following steps:

  1. Define a language identifier for your language according to the rule described above. If translations to your language vary depending on the country, use the _<TERRITORY> suffix, otherwise omit it (i.e. no need to apply the suffix if it represents the only possible country). Let's say that your language code is my_MY for the purpose of this description.
  1. Look through comments to ticket:2018 to find out who is currently maintaining the translation to your language. Contact these people in order to coordinate your work and avoid conflicts.
  1. Download the NLS subdirectory from the VirtualBox SVN repository as described in step 5 of the Preparing a translation to a new language section.
  1. Follow other steps starting from step 6 in the Preparing a translation to a new language section.

Translation hints

This section contains important notes about translating the VirtualBox product.

  1. Read the  Qt Linguist manual to get general information about translating Qt applications. Pay special attention to understanding the status of translatable items (unfinished, obsolete).
  1. Properly translate Plural Forms. VirtualBox may contain sentences which include %n markers. This marker is used when numbers could be included either in a singular or plural variant. The Qt translation mechanism allows you to translate this one sentence to different variants to let the result look more natural. For more information on this topic see  Plural Form(s) in Translation(s).
  1. Preserve spaces around (and between) words if they are used for justification purposes. Examples of such items are category names in the global and VM settings dialogs where leading and trailing space characters serve as horizontal item margins. Also, a leading space in the translatable item is often used as a separator from the preceding word that will appear after string concatenation, and therefore needs to be preserved.
  1. Translate only human-readable words and sentences. Leave HTML markup and other sorts of special characters untouched -- otherwise you may completely break the text appearance in the UI.
  1. Don't translate items starting with the # (hash) sign in contexts VBoxGlobalSettingsDlg and VBoxVMSettingsDlg, such as #general, #input and so on. They are responsible for the settings category hyper-link feature on the VM Details page and translating them will break this feature.
  1. When Qt Linguist shows the source text of the translatable item, it uses special text fragments inside it to mark unprintable characters, for example: (new-line) for new-line marks or (sp) for ambiguous space characters. However, if you copy the source text to the translation field (to use it as a template for translation), Qt Linguist will not replace these special fragments back with real control/formatting characters -- they will remain (new line} and (sp) in the translation and will appear like that in the GUI as well. Therefore, you should be careful and always replace them with the corresponding formatting characters (new-line or space) manually.
  1. In general, it's not recommended to translate Ctrl+<latin_letter> shortcuts (for example, Ctrl+S used to open the VM Settings Dialog) because they are intended to be language neutral and should have the same action regardless of the selected UI language. Translate them only if there is a very special reason to do so in your language; otherwise simply leave the original. Note that the action name starting with a different letter or having a different underscored (Alt+<any_letter>) accelerator in your language is not a valid reason to translate the corresponding Ctrl+<latin_letter> shortcut.

Testing the translation

Use these steps to test your translation:

  1. Select File -> Release As... from the main menu of Qt Linguist.
  1. Specify <path_to_VirtualBox_exe>/nls4/VirtualBox_my_MY.qm as the target path and file name and press Ok. This will generate a binary language file and save it to the proper directory.
  1. Repeat the previous step for all other components (qt_my_MY.qm).
  1. Setup the locale corresponding to the my_MY language identifier and start VirtualBox.exe. The language files should be loaded automatically if you did everything right.
  1. Navigate through all parts of the user interface and check the quality and meaningfulness of the translation.

Please note that you cannot test translations with VirtualBox before 1.4.0 because the translation suppport was not enabled in those releases. So either use the last release or compile the current code from SVN.

Submitting the translation

When you think your translation looks good and ready to be shared with others, you may submit the translation source files you created (VirtualBox_my_MY.ts and qt_my_MY.ts, according to the examples above) by packing it to a .zip archive named and attaching to ticket:2018.

The same thing should be done after you have updated an existing translation, but please be careful with the name of the file you are attaching and make sure you will not replace somebody's else attachment with the same name. Note though that you may and normally should replace a previous attachment of the same name if it was also attached by you and if it contains an outdated version of the same translation file you are attaching now.

Please note that you should always run the svn update command as described in Picking up recent changes to the translation files before packing and attaching your .ts files! This way, you will make sure that your version corresponds to the latest version from the VirtualBox SVN repository. Note that if the translation file you attach to ticket:2018 doesn't merge cleanly to the SVN head, it will be rejected because the GUI maintainer at Oracle doesn't know all possible languages and therefore cannot resolve possible merge conflicts for you.

PLEASE REMEMBER that before your translation can be included into the VirtualBox code base and distribution archives, you must allow Oracle Corporation to make use of your contributions. The Contributor_information section describes how to do it. Basically, you have two options: either to fill out the Sun Contributor's Agreement (ICA) and send it to Oracle Corporation or to make the following statement directly in the ticket:2018 comment where you attach your translation source file:

  The <MyLanguage> (<my_MY>) translation attached here by <my_full_name>
  is published under the terms of the [wiki:"MIT license"].

assuming that <MyLanguage> is the language name, <my_MY> is the language identifier and <my_full_name> is your full name that has exactly the same spelling you used in the .ts file itself (in the list of translators in the special context @@@). It's enough to do it only once for a given language. If you translate VirtualBox to more than one language than a separate statement for every language is necessary.

The second requirement for including your translation to the product is to send an e-mail to info {at} where you mention your full name and the language you are translating to. This is necessary to keep track of all active translators and their e-mail addresses internally within Oracle Corporation in order to be able to contact each of them individually.
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