WPF localization: DynamicResource with StringFormat?
I am doing localization in .NET 4 with ResourceDictionary. Does anyone have a solution for using a value with a string format?
For example, let's say I have a value with the key "SomeKey":
<ResourceDictionary ...>
<s:String x:Key="SomeKey">You ran {0} miles</s:String>
</ResourceDictionary>
Using it in the TextBlock:
<TextBlock Text="{DynamicResource SomeKey}" />
How could I concatenate, for example, an integer with a SomeKey value as a format string?
source to share
So, I finally came up with a solution that allows me to have formatted strings in my ResourceDictionary and be able to dynamically change the language at runtime. I think it could be improved, but it works.
This class converts the resource key to its value from the ResourceDictionary:
public class Localization
{
public static object GetResource(DependencyObject obj)
{
return (object)obj.GetValue(ResourceProperty);
}
public static void SetResource(DependencyObject obj, object value)
{
obj.SetValue(ResourceProperty, value);
}
// Using a DependencyProperty as the backing store for Resource. This enables animation, styling, binding, etc...
public static readonly DependencyProperty ResourceProperty =
DependencyProperty.RegisterAttached("Resource", typeof(object), typeof(Localization), new PropertyMetadata(null, OnResourceChanged));
private static void OnResourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
//check if ResourceReferenceExpression is already registered
if (d.ReadLocalValue(ResourceProperty).GetType().Name == "ResourceReferenceExpression")
return;
var fe = d as FrameworkElement;
if (fe == null)
return;
//register ResourceReferenceExpression - what DynamicResourceExtension outputs in ProvideValue
fe.SetResourceReference(ResourceProperty, e.NewValue);
}
}
This class allows you to use a value from a ResourceDictionary as a format parameter in String.Format ()
public class FormatStringConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (values[0] == DependencyProperty.UnsetValue || values[0] == null)
return String.Empty;
var format = (string)values[0];
var args = values.Where((o, i) => { return i != 0; }).ToArray();
return String.Format(format, args);
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
Example 1 . In this example, I use the FormatStringConverter on a MultiBinding to convert its Binding collection to the desired output. If, for example, the value "SomeKey" is "Object ID - {0}" and the value "Id" is "1", then the output will be "Object ID is 1".
<TextBlock ap:Localization.Resource="SomeKey">
<TextBlock.Text>
<MultiBinding Converter="{StaticResource formatStringConverter}">
<Binding Path="(ap:Localization.Resource)" RelativeSource="{RelativeSource Self}" />
<Binding Path="Id" />
</MultiBinding>
</TextBlock.Text>
</TextBlock>
Example 2 . In this example, I am using a bind with a converter to change the resource key to something more verbose to prevent collisions. If, for example, I have an enum Enum.Value (displayed as "Value" by default), I use a converter to attach its namespace to make the key more unique. Thus, the value becomes "My.Enums.Namespace.Enum.Value". The Text property will then resolve with any value "My.Enums.Namespace.Enum.Value" in the ResourceDictionary.
<ComboBox ItemsSource="{Binding Enums}"
SelectedItem="{Binding SelectedEnum}">
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock ap:Localization.Resource="{Binding Converter={StaticResource enumToResourceKeyConverter}}"
Text="{Binding Path=ap:Localization.Resource), RelativeSource={RelativeSource Self}}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
Example 3 . In this example, the key is a literal and is only used to find its corresponding value in the ResourceDictionary. If, for example, "SomeKey" is "SomeValue", then it will simply return "SomeValue".
<TextBlock ap:Localization.Resource="SomeKey"
Text="{Binding Path=ap:Localization.Resource), RelativeSource={RelativeSource Self}}"/>
source to share
You need to bind to the ViewModel.Value somehow and then use the (nested) binding to the format string.
If you only have one value:
<TextBlock
Text="{Binding Path=DemoValue, StringFormat={StaticResource SomeKey}}" />
If you also have {1}
etc., you will need MultiBinding.
Edit:
If you really want to change languages in live form, then the sane way is probably to do all the formatting in the ViewModel. Anyway, I rarely use StringFormat or MultiBinding in MVVM.
source to share