пятница, 10 августа 2012 г.

WP7 Localization Explained

I believe you are going to create a new Windows Phone Application to follow me in this article.
I’ll assume you understand that everything that applies for a language, also applies for the language-Culture.
I.e. you can use “en” for English or “en-UK” for English and United Kingdom culture.
The language will affect the translation and what’s written in the resource files will be used for that sake, and the culture will affect the formats of date, currency…etc.

Step 1 – Add Resource Files:
Anyone who has brief experience with localization in .net, will guess the first step.
You have to add a Resource file for each language you need to use in your application.
You should have a file for the default language and others for each other language used, having the same name as the default language file but with a small extension using each language abbreviation.
Let’s say I’m going to support English (default) and Italian. Then I should end up having something like:

MyResources.resx
MyResources.it.resx

If it’s your first time to use a resource file, this is added from: Project (right click) => Add => New Item => (pick Resource File).
- Needless to say, when you fill the resource files, the Name of each resource should match, and only the value should reflect the translation.
- So say I’m going to have (Hello/Hello) & (Hello/Ciao) as the English & Italian (Name/Value)s.

Step 2 – Declare the Languages you support:
We should tell the application which languages we are supporting. Guess it’s not smart enough to figure this out by itself.
And for this you we’ll have to close the project/solution. Then open the project file in notepad, and add the supported languages (except the default one) in the supported cultures tag, using semi-colon as a separator, as follows:
it;You’ll also need to define the default language in case the user is using a language you don’t support, and thus the default language should be used then.
For that you need to go to the Project Properties => Application (Tab) => Assembly Information (button) => Set the (Neutral Language).

Step 3 – Use Resource-File in code behind:
Let’s see if this is going to work.
In the MainPage.xaml.cs, I’ll write the following in the CTor of the page.
PageTitle.Text = MyResources.Hello;
Step 4 – Test:
Now you can test this on a device, and it should display the “Ciao” if you went to the phone settings and set “Italiano” as the display language.
But the Emulator won’t let you change the “Display Language”, so if you want to test this in the Emulator, you will have to set the language-culture in code. (Just for testing).
So go the App.xaml.cs and write the following in CTor or in the Launching event handler.
Thread.CurrentThread.CurrentUICulture = new System.Globalization.CultureInfo("it");You may also add the following if you are testing the culture (format of dates, currencies…etc.)
Thread.CurrentThread.CurrentCulture = new System.Globalization.CultureInfo("it");** Don’t forget to remove these when you finish testing.
Now you should see the localization working. I hate to say it but that’s not the end of it.

(UPDATE)
Now you can change the display language in the emulator, all you have to do is to click on the: "tap here to accept changes and restart your phone." link, which appears when you select a different Display Language.
Still this might be consume more time than applying the change in code.


Step 5 – Access the Resource Files in XAML:
To use the resource files in XAML, you need to map them to a Static Resource, to able to bind to them.
Say you have a TextBlock as follows.
And instead of hardcoding the Text, we want to use the resource files. In other words we want to bind the Text property of the TextBlock to the appropriate key/property of the resource files.
We will go and define the generated Resource class as a static resource in the App.xaml, as follows:


Please make sure you replace MyNamespace with the namespace under which MyResources is defined.
If you try to run the application now the following exception will blow right in your face:
AG_E_PARSER_UNKNOWN_TYPE [Line: 10 Position: 65]
Of type: System.Windows.Markup.XamlParseException
This issue has been reported here: http://connect.microsoft.com/VisualStudio/feedback/details/628281/silverlight-wp7-resource-files-and-binding

That’s because the class generated for the resource file was marked internal, and to access it from the XAML we need it to be public.
If you open each of the resx files, you will find an option in the toolbar to change the access modifier.
This should change the access modifier of the classes, but we still need to change the access modifier of the CTor. So you will have to open the default language resx.cs file, and look for the CTor and change the internal to public.

Now the application can run safely without weird exceptions.
And now it’s safe to go back to the TextBlock and change it to the following to use the Static Resource we just defined in the App.xaml:
That’s all? You wish…
The problem now is: whenever you add extra resources to the resource files, the resx.cs class is re-generated and the modifier of the CTor gets set back to internal. So if you are happy with manually changing it each time you add a new resource and build your application, then you are done.
If it’s cumbersome tedious thing to manage, then we need to find another solution.

Step 5.2 – Access the Resource Files in XAML:
To overcome this internal access modifier thing, we will create a class that wraps the generated resources class, and use that as our static resource in the App.xaml, as follows:
public class MyResourcesWrapper
{
public MyResourcesWrapper()
{
}

private static MyResources _myWrappedResources = new MyResources();

public MyResources MyWrappedResources { get { return _myWrappedResources; } }
}
And then our TextBlock should be changed to:
You will need to modify the Resource definition in the App.xaml into the following:



One extra step to go (if you need to localize the application bar).

Step 6 – Localizing the ApplicationBar:
The application bar is not growing out of the Silverlight, it’s a shell system tray.
So using the binding method in the xaml file won’t work.
We will have to add items to the application bar in the code behind and set the required localized text as we’ve done earlier in step 3.
e.g.
MainPage.xaml


MainPage.xaml.cs

ApplicationBar = new ApplicationBar();

var appBarButton = new ApplicationBarIconButton(new Uri("/Images/appbar_button1.png", UriKind.Relative));
appBarButton.Text = MyResources.Hello;
ApplicationBar.Buttons.Add(appBarButton);

var appBarMenuItem = new ApplicationBarMenuItem(MyResources.Hello);
ApplicationBar.MenuItems.Add(appBarMenuItem);

References:

How to: Build a Localized Application for Windows Phone:
http://msdn.microsoft.com/en-us/library/ff637520%28v=VS.92%29.aspx
CultureInfo Class:
http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo(VS.95).aspx
Extra link for the WP7 toolkit controls:
http://blogs.msdn.com/b/delay/archive/2010/12/20/quot-and-she-d-say-can-you-see-what-i-m-saying-quot-how-to-localize-a-windows-phone-7-application-that-uses-the-windows-phone-toolkit-into-different-languages.aspx

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