The .NET Framework for Silverlight uses a hub-and-spoke model to package and deploy resources. The hub is the main assembly that contains the nonlocalizable executable code and the resources for a single culture, which is called the neutral or default culture. The default culture is the fallback culture for the application. The spokes connect to satellite assemblies, and each satellite assembly contains the resources for a single supported culture, but does not contain any code. At run time, a resource is loaded from the appropriate resource file, depending on the value of the application's current user interface (UI) culture, which is defined by the CultureInfo..::.CurrentUICulture [ http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo.currentuiculture(VS.95).aspx ] property.

The Hierarchical Organization of Resources

To understand how resources are loaded, it is useful to think of them as organized in a hierarchical manner. A localized application can have resource files at three levels:

• At the top of the hierarchy are the fallback resources for the default culture, for example, English ("en"). These are the only resources that do not have their own file; they are stored in the main assembly.

• At the second level are the resources for any neutral cultures. A neutral culture is associated with a language but not a region. For example, French ("fr") is a neutral culture.

• At the bottom of the hierarchy are the resources for any specific cultures. A specific culture is associated with a language and a region. For example, French Canadian (fr-CA) is a specific culture.

When an application tries to load a localized resource, the Resource Manager does the following:

1. It tries to load the resource that belongs to the user's specific culture. If there is no satellite assembly for the specific culture, or if the resource cannot be found in it, the search for the resource continues with step 2.

2. If there is no satellite assembly for the specific culture or the resource cannot be found in it, or if resources for the cultures defined by operating-system fallback logic cannot be found, the Resource Manager tries to load the resource from the satellite assembly for the parent of the current UI culture (the neutral culture).

3. If the operating system provides a list of preferred fallback languages, the Resource Manager iterates the list and tries to load the resource for each culture until it finds a match. If there is no match, or if the operating system does not support fallback logic, it continues to the next step.

4. If that satellite assembly does not exist, or if the resource cannot be found in it, the Resource Manager loads the fallback resources from the assembly that is specified by the System.Resources..::.NeutralResourcesLanguageAttribute [ http://msdn.microsoft.com/en-us/library/system.resources.neutralresourceslanguageattribute(VS.95).aspx ] class.

5. If no resources are found, resources for the invariant culture are used.

Important Note:

It is best to generalize as much as possible when deciding whether to store resources in satellite assemblies for specific cultures or for the neutral culture. For example, when you localize an application for the French (France) culture ("fr-FR"), we recommend that you store all resources that are common to French cultures in the satellite assembly for the neutral culture. This enables users of other French-speaking cultures, such as the French (Canada) culture ("fr-CA"), to access localized resources instead of the resources for the default culture.

Including Resources in a Silverlight-based Application

Dim greeting As String = My.Resources.StringLibrary.Greeting

ResourceManager rm = null;
rm = new ResourceManager("SilverlightApplication.StringLibrary", Assembly.GetExecutingAssembly());

string greeting = rm.GetString("Greeting");

Making XAML Localizable

To support localized out-of-browser applications, you have to create a new .xap file for each localized culture or locale that your application supports. In Visual Studio, you can do this by creating new build configurations. For more information, see Deploying a Targeted Localized Application later in this topic.

Note:
For more information about developing out-of-browser applications, see Out-of-Browser Support [ http://msdn.microsoft.com/en-us/library/dd550721(VS.95).aspx ] and How to: Configure an Application for Out-of-Browser Support [ http://msdn.microsoft.com/en-us/library/dd833073(VS.95).aspx ] .

You may also want to make the window title, shortcut name, and description of the out-of-browser application localizable. Ordinarily, an out-of-browser application retrieves its window settings from the application's OutOfBrowserSettings.xml configuration file. To localize the application's window settings, you create a unique OutOfBrowserSettings.xml file for each culture that you support. For example, if you localize your application for the French (France) culture, you would create an OutOfBrowserSettings.fr-FR.xml file. You can then modify the project settings to use the new settings file. For detailed instructions, see How to: Customize Your Localized Out of Browser Application How to: Localize Information About an Out-of-Browser Application [ http://msdn.microsoft.com/en-us/library/dd772170(VS.95).aspx ] .

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A translated string may take more room on the screen than the original string. If you are developing your Silverlight-based application in English and localizing it, you should assume that strings in some languages are about 40% longer than in English. For this reason, it is recommended that you use automatic layout for elements that contain localized text. This involves the following:

• Avoid the Canvas [ http://msdn.microsoft.com/en-us/library/system.windows.controls.canvas(VS.95).aspx ] control, which uses hard-coded sizes and positions. Instead, use the Grid [ http://msdn.microsoft.com/en-us/library/system.windows.controls.grid(VS.95).aspx ] control, the StackPanel [ http://msdn.microsoft.com/en-us/library/system.windows.controls.stackpanel(VS.95).aspx ] , or other panel elements that support automatic layout.

• Avoid Glyphs [ http://msdn.microsoft.com/en-us/library/system.windows.documents.glyphs(VS.95).aspx ] . Instead, use the TextBlock [ http://msdn.microsoft.com/en-us/library/system.windows.controls.textblock(VS.95).aspx ] or TextBox [ http://msdn.microsoft.com/en-us/library/system.windows.controls.textbox(VS.95).aspx ] controls.

• For long strings, set TextWrapping="Wrap" on TextBlock [ http://msdn.microsoft.com/en-us/library/system.windows.controls.textblock(VS.95).aspx ] controls.

• Do not set the Height and Width properties of your TextBlock [ http://msdn.microsoft.com/en-us/library/system.windows.controls.textblock(VS.95).aspx ] control. Let the Silverlight runtime decide the size automatically. You may also set either the Height or the Width property and let Silverlight calculate the other property. If you do this, be sure to set TextWrapping="Wrap".

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To properly display Chinese, Japanese, and Korean text, Silverlight needs to know which language it is displaying, because the same Unicode characters are displayed differently depending on language. Silverlight determines the language from the FrameworkElement..::.Language [ http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.language(VS.95).aspx ] property or from the xml:lang attribute. If your XAML applies to only a single language, you can simply set the property at the top of the file, as shown in the following example, which sets the language to Japanese.

<UserControl Language="ja-JP" />

However, if you want your XAML to be localizable, you want to set the Language property to a localized value. To do this, create an entry such as Language in your resource file, and assign it a value that is the name of the localized language or culture. Change the XAML to use a {Binding} markup extension in the same way that you would localize any other property. For example:

<UserControl Language="{Binding Path=SilverlightApp.Language, 
             Source={StaticResource LocalizedStrings}}"

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In most cases, you want users to download a Silverlight-based application that contains only the resources of their neutral and specific culture, instead of the resources in the complete set of localized satellite assemblies. You can use Visual Studio to create a localized Silverlight-based application that contains a designated subset of your application's satellite assemblies. For instructions, see How to: Create a Build that Targets a Specific Culture [ http://msdn.microsoft.com/en-us/library/dd941932(VS.95).aspx ] . You can then use ASP.NET to deploy the application based on the user's culture.

Determining the User's Culture

Imports System.Globalization
Imports System.Threading

Partial Class _Default
    Inherits System.Web.UI.Page

   Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
      ' Create array of available languages.
      Dim availableCultures() As String = {"fr-FR", "en-US"}
      Dim availableNeutralCultures() As String = {"fr", "en"}
      Dim url As String = "TestPage.html"

      ' Get user's language preferences.
      Dim currentUi As CultureInfo = Thread.CurrentThread.CurrentUICulture
      ' Redirect if user language preference is available.
      For Each culture As String In availableCultures
         If culture = currentUi.Name Then Response.Redirect(culture + "/" + url)
      Next

      ' Get user's neutral culture.
      Dim neutralCulture As CultureInfo = currentUi.Parent
      ' Determine if neutral culture is supported.
      For Each culture As String In availableNeutralCultures
         If culture = neutralCulture.Name Then Response.Redirect(culture + "/" + url)
      Next

      ' Fall through to non-localized version of application.
      Response.Redirect(url)
   End Sub
End Class

using System;
using System.Globalization;
using System.Net;
using System.Threading;
using System.Web;
using System.Web.UI; 

public partial class _Default : System.Web.UI.Page
{
   protected void Page_Load(object sender, EventArgs e)
   {
      // Create array of available languages.
      string[] availableCultures = {"fr-FR", "en-US"};
      string[] availableNeutralCultures = { "fr", "en" };
      string url = "TestPage.html";

      // Get user's language preferences.
      CultureInfo currentUi = Thread.CurrentThread.CurrentUICulture; 

      // Redirect if user language preference is available.
      foreach (string culture in availableCultures)
      {
         if (culture == currentUi.Name)
            Response.Redirect(culture + "/" + url);
      }

      // Get user's neutral culture.
      CultureInfo neutralCulture = currentUi.Parent;
      // Determine if neutral culture is supported.
      foreach (string culture in availableNeutralCultures)
      {
         if (culture == neutralCulture.Name)
            Response.Redirect(culture + "/" + url);
      }

      // Fall through to non-localized version of application.
      Response.Redirect(url);
    }
}

In some cases, you may want to retrieve resources from a culture other than the user's current culture. You can do this in two ways:

• You can set the current culture and current UI culture of a Silverlight-based application in the Object tag that is responsible for loading the application from an HTML page by adding parameters such as the following:

  <param name="uiculture" value="pt-BR" />
  <param name="culture" value="pt-BR" />
  

  In this case, the values of uiculture and culture are used to initialize the thread cultures of the Silverlight-based application to "pt-BR" if that culture is supported on the client. If the value of the culture or uiculture parameter is auto or if the parameter is absent, the current culture and current UI culture default to the values defined by the client operating system that is running the browser.

• You can set the current culture and current UI culture programmatically, typically in the application's Application..::.Startup [ http://msdn.microsoft.com/en-us/library/system.windows.application.startup(VS.95).aspx ] event handler, by assigning a CultureInfo [ http://msdn.microsoft.com/en-us/library/system.globalization.cultureinfo(VS.95).aspx ] object that represents the specified culture to the System.Threading.Thread.CurrentThread.CurrentUICulture property. The following example illustrates how to do this. It creates an array of culture names, selects one at random, and uses it to set the application's current UI culture.

  Visual Basic

  Private Sub Application_Startup(ByVal o As Object, ByVal e As StartupEventArgs) Handles Me.Startup
     ' Create an array of culture names.
     Dim cultureStrings() As String = {"en-US", "fr-FR", "ru-RU", "en-GB"}
     ' Get a random integer.
     Dim rnd As New Random()
     Dim index As Integer = rnd.Next(0, cultureStrings.Length)
     ' Set the current culture and the current UI culture.
     Thread.CurrentThread.CurrentCulture = New CultureInfo(cultureStrings(index))
     Thread.CurrentThread.CurrentUICulture = New CultureInfo(cultureStrings(index))
  
     Me.RootVisual = New Page()
  End Sub
  

  C#

  private void Application_Startup(object sender, StartupEventArgs e)
  {
     // Create an array of culture names.
     string[] cultureStrings = { "en-US", "fr-FR", "ru-RU", "en-GB", "fr-BE", "de-DE" };
     // Get a random integer.
     Random rnd = new Random();
     int index = rnd.Next(0, cultureStrings.Length);
     // Set the current UI culture.
     Thread.CurrentThread.CurrentCulture = new CultureInfo(cultureStrings[index]);
     Thread.CurrentThread.CurrentUICulture = new CultureInfo(cultureStrings[index]);
  
      // Load the main control
      this.RootVisual = new Page();
  }
  

You can also retrieve a culture-specific resource on a resource-by-resource basis. To do this, specify the culture whose resource is to be retrieved in the call to the resource retrieval method. For example, to retrieve a string for the Spanish (Spain) culture ("es-ES") when the application's current culture is English (United Kingdom) ("en-GB"), you would call the ResourceManager..::.GetString(String, CultureInfo) [ http://msdn.microsoft.com/en-us/library/bsb0cfet(VS.95).aspx ] method instead of the ResourceManager..::.GetString(String) [ http://msdn.microsoft.com/en-us/library/d17ax2xk(VS.95).aspx ] method. Similarly, to retrieve an image or some other binary resource, call the ResourceManager..::.GetObject(String, CultureInfo) [ http://msdn.microsoft.com/en-us/library/2kd8ks0y(VS.95).aspx ] method instead of the ResourceManager..::.GetObject(String) [ http://msdn.microsoft.com/en-us/library/963f81yd(VS.95).aspx ] method.

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Concepts

Other Resources