
$Id: languages.txt 582 2014-12-11 17:47:28Z imoore76 $

This outlines in-depth the process used by phpVirtualBox's translation mechanisms and describes
how a developer may add new translations. If the reader, as an end-user simply wishes to translate
phpVirtualBox into a new language, see:
http://sourceforge.net/p/phpvirtualbox/wiki/Home/#translating-phpvirtualbox

.. I) phpVirtualBox translation mechanism
....... a) Contexts
....... b) Data structure
....... c) Runtime translations in JavaScript
....... d) Runtime translations in PHP

.. II) Adding a new language
....... a) Creating phpVirtualBox XML translation file
....... b) Converting QT .qm files
....... c) Updating language selection


I. phpVirtualBox translation mechanism

The translation mechanism in phpVirtualBox uses a combination of PHP serialized data along with
runtime parsed XML files. 

VirtualBox's QT language files are pre-parsed (before runtime) and serialized into data consumable
by PHP's unserialize function. These files contain all translations performed by VirtualBox's
translators for the VirtualBox GUI frontend. Serialized translation files are placed in the 
languages/source folder.

Some text that appears in phpVirtualBox is not in, or applicable to the VirtualBox GUI and therefore
has no corresponding translation in VirtualBox's language files. This text is translated in XML files
in the languages/ folder.

lib/language.php contanis the __vbox_language class. Upon instantiation this class:

	1) Determines which language to use by checking phpVirtualBox settings for the default language,
		and for the cookie vboxLanguage if passed by the web browser - the browser's cookie will
		overwrite the default language defined in config.php
	
	2) Unserializes the language data from the appropriate file in the languages/source folder
	
	3) Parses the XML data from the appropriate XML file in the languages folder
	
	4) Merges language data into a single array structure allowing the XML translations to overwrite
		serialized data translations (if such a scenario exists)
   
I.a Contexts

Language contexts is a translational concept allowing one word (or phrase) to take on many meanings
based on the context in which it is used. When text is being translated, the translation mechanism
must also be passed a context. For instance the "Add" button to add a user may be translated
differently than the "Add" button to add a VirtualMachine.

I.b Data structure

The data structure of parsed languages is a multidimensional associative array / hash / dict that
contains a hierarchy of contexts -> messages -> translation(s). Using PHP's print_r, the output of
this data structure is:

Array
(
    [contexts] => Array
        (
			.....
			
            [UINewHDWizardPageVariant] => Array
                (
                    [messages] => Array
                        (
                            [Storage details] => Array
                                (
                                    [translation] => Detalles de almacenamiento
                                )

                        )
                        .....

                )
.....

("array" refers to an associative array / hash / dict. They are all the same thing in PHP.)

The context UINewHDWizardPageVariant is a key within the contexts array. It has a number of messages.
Storage Details is a key in the messages array. It has a single item called translation that contains
the translation of Storage Details.

I.c Runtime translations in JavaScript

When phpVirtualBox is loaded, it loads js/language.php. This instantiates __vbox_language and dumps
its language data as a JSON encoded object. It also contains the phpVirtualBox JavaScript trans()
function which takes (at a minimum) a context and message, and returns the corresponding translation.

I.d Runtime translations in PHP

lib/language.php contains a trans() function defined in PHP which takes (at a minimum) a context and
message, and returns the corresponding translation using an instance of __vbox_language. Since
language loading is an expensive process (unserializing a large amount of data and parsing XML), the
instantiation of the __vbox_language only occurs if trans() is called in PHP. Subsequent calls to
trans() will of course use the existing instantiation. Translation inside PHP Is rare and restricted
to error messages returned by phpVirtualBox.

II. Adding a new language

Adding a new language requires relatively little work. First, determine the 2 letter language code
for the target language. See http://en.wikipedia.org/wiki/ISO_639-1

II.a Creating phpVirtualBox XML translation file

Copy an existing XML file in phpVirtualBox's languages folder using the 2 letter language code
described above.

Here is an example:

<?xml version="1.0" encoding="utf-8"?>
<language>
        <context>
                <name>phpVirtualBox</name>
                <message>
                        <source>Warning: A VirtualBox internal operation is in progress. Closing this
                        	window or navigating away from this web page may cause unexpected and
                        	undesirable results. Please wait for the operation to complete.
                        </source>
                        <translation>Warnung: Interne Aktion läuft. Wenn Sie dieses Fenster schließen
                        	oder diese Seite verlassen, kann das zu unerwünschten oder
                        	unbeabsichtigten Effekten führen. Bitte warten Sie bis die Aktion
                        	abgeschlossen ist.
                        </translation>
                </message>
                <message>
                        <source>Operation Canceled</source>
                        <translation>Aktion abgebrochen</translation>
                </message>
                 ......
                 
You will see translation messages such as:

<message>
   <source>Operation Canceled</source>
   <translation>Aktion abgebrochen</translation>
</message>

Text within the <source> tag is the text that is to be translated. The translated text goes in the
<translation> tag. E.g.

<message>
   <source>Operation Canceled</source>
   <translation>Your translation of "Operation Canceled" goes here...</translation>
</message>

WARNING: Do not change the text in the <source> tag. Even adding an extra line will break the
translation.

II.b Converting QT .qm files

To convert these files, you will need a copy of Qt Linguist. A google search should yield a download
link. You will also need a copy of VirtualBox installed.

Open Qt Linguist. From the file menu, select Open and select All Files in the Open File dialog.
Navigate to your VirtualBox folder on your computer, then to the nls folder. You should see files
which have the naming convention VirtualBox_xx.qm - where xx is the language code described above.
Select the file and click Open. Just click OK on the subsequent dialog box. Click on Save as... in
the File menu. Save the file as a "Qt translation source" (*.ts) file.

The script languages/source/parse_vbox_lang.php can then be used to parse a .ts file into a .dat file
consumable by phpVirtualBox. E.g.

php languages/source/pasre_vbox_lang.php VirtualBox_es.ts >es.dat

The es.dat file can then be placed in the languages/source/ folder for use by phpVirtualBox.


II.c Updating language selection

Once translation files have been added to languages/ and languages/source/ the interface must be
updated so that the new language is available for selection. Edit panes/settingsGlobalLanguage.html
and add the new language to the JavaScript vboxLanguages array.

var vboxLanguages = [
	{'id':'en','name':'English'},
	{'id':'pt_br','name':'Portuguese (Brazil)','name_tr':'Português (Brasil)'},
	{'id':'ru','name':'Russian','name_tr':'Русский'},
	{'id':'it','name':'Italian','name_tr':'Italiano'},
	....
];

This is an array of associative arrays of language definitions that must contain the following keys:
	id - must match the language file name in languages/ (minus the .xml extension)
	name - the name of the language in English
	name_tr - the name of the language in its native speech


