Add a value converter to a binding using XAML

   
  


<StackPanel xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  xmlns:c="clr-namespace:WpfApplication1" Width="300" Height="300"
  Name="Page1">
  <StackPanel.Resources>
    <c:MyData x:Key="myDataSource"/>
    <c:MyConverter x:Key="MyConverterReference"/>
    <Style TargetType="TextBlock">
      <Setter Property="FontSize" Value="15"/>
      <Setter Property="Margin" Value="3"/>
    </Style>
  </StackPanel.Resources>
  
  <StackPanel.DataContext>
    <Binding Source="{StaticResource myDataSource}"/>
  </StackPanel.DataContext>

  <TextBlock Text="Unconverted data:"/>
  <TextBlock Text="{Binding Path=TheDate}"/>
  <TextBlock Text="Converted data:"/>
  <TextBlock Name="myconvertedtext" Foreground="{Binding Path=TheDate,Converter={StaticResource MyConverterReference}}">
    <TextBlock.Text>
      <Binding Path="TheDate" Converter="{StaticResource MyConverterReference}"/>
    </TextBlock.Text>
  </TextBlock>
</StackPanel>
//File:Window.xaml.cs
using System;
using System.Globalization;
using System.ComponentModel;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Data;
using System.Windows.Media;


namespace WpfApplication1
{
  public class MyConverter : IValueConverter
  {
    public object Convert(object o, Type type,object parameter, CultureInfo culture){
        DateTime date = (DateTime)o;
        switch (type.Name)
        {
            case "String":
                return date.ToString("F", culture);
            case "Brush":
                return Brushes.Red;
            default:
                return o;
      }
    }
    public object ConvertBack(object o, Type type,object parameter, CultureInfo culture){
          return null;
    }
  }
  public class MyData: INotifyPropertyChanged{
    private DateTime thedate;
    public MyData(){
      thedate = DateTime.Now;
    }
    public DateTime TheDate
    {
      get{return thedate;}
      set{
        thedate = value;
        OnPropertyChanged("TheDate");
      }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void OnPropertyChanged(String info)
    {
      if (PropertyChanged !=null)
      {
        PropertyChanged(this, new PropertyChangedEventArgs(info));
      }
    }
  }
}