Setting the Culture in WPF Applications

The culture of an application not only specifies its language but also more specific culture related things such as date (e.g., mm/dd/yy or dd/mm/yyy) and number formatting (1.23 or 1,23) and default currency.

Usually your application gets its culture from the operating system. In some cases, you might want to set it yourself. The most obvious way to set a culture pragmatically in C# is as follows.

xmlLanguage = XmlLanguage.GetLanguage("nl-BE");
Thread.CurrentThread.CurrentCulture = xmlLanguage;
Thread.CurrentThread.CurrentUICulture = xmlLanguage;

There are two caveats to this. First of all, this only sets the culture for a specific thread. To my knowledge, there is no way to set the culture application-wide so you will have to set the culture for each thread you create. If you only need the culture to localize the user interface, I suppose this is not required since the UI runs on a single thread anyway.

I thought this was all there was to it, until I used a binding in XAML which had a culture specific formatting string:

<TextBlock Text="{Binding Order.Price, StringFormat='{0:F2}'}"/>

Depending on the culture, the ‘F2’ formatting string produces “1.23” or “1,23”. The problem was that it did not format as I expected based on the previously set culture. By adding a DebugConverter to the binding, I was able to inspect which culture was used by the binding. It was ‘en-US’ instead of ‘nl-BE’, the former being the default culture used by a binding. Apparently, the culture used by the binding and passed to its (optional) converter, if not set explicitly by assigning the Binding.ConverterCulture property, can be set globally at the top element of the XAML document with the xml:lang attribute.

Alternatively, you can set the culture globally as follows (see this post on msdn).

FrameworkElement.LanguageProperty.OverrideMetadata(
    typeof( System.Windows.FrameworkElement ),
    new FrameworkPropertyMetadata(XmlLanguage.GetLanguage("nl-BE") ) );

From now on, each binding will use the nl-Be culture by default.

Concatenate/Format Strings in XAML

Often, you will need to put dynamically concatenated strings on the screen. By this, I mean strings that are built at runtime by concatenating several static and non-static substrings. Something you would do in code as follows:

string formattedString = FirstName + " " + LastName;
// This is better performance-wise since a StringBuilder will be used internally, which means less objects will be created.
string betterFormattedString = string.Format("{0} {1}", FirstName, LastName);

To do this in XAML, you can take the naive approach below.

<StackPanel Orientation="Horizontal"/>
 <TextBlock Text="{Binding Name}"/>
 <TextBlock Text=" "/>
 <TextBlock Text="{Binding LastName}"/>
</StackPanel>

In this example, four UI elements are created: one StackPanel and three TextBlocks. This will have a performance impact since all these elements will need to go through a measurement and layout pass. In case this structure is used once or just a few times, you won’t notice this. However, if it is used in a datatemplate for use inside a list with many elements, you will notice a performance hit.

A better way to concatenate strings in XAML is shown below.

<TextBlock>
  <TextBlock.Text>
    <MultiBinding StringFormat="{}{0} {1}">
      <Binding Path="Name"/>
      <Binding Path="LastName"/>
    </MultiBinding>
  </TextBlock.Text>
</TextBlock>

In this case, we only create one UI element instead of four! Not only is this better performance-wise, it is also much more readable.