Custom Markup Extension | WPF Tutorial pdf

In the final section, I will build my custom Markup Extension and use it. For simplicity we use Reflection to Get fields, Methods, and Properties and bind them into a ListBox.
To create a custom Markup Extension, you need to create a class and inherit it from arkupExtension. This class has an abstract method called ProvideValue which you
need to override to make the MarkupExtension work.
So actually the XAML parser calls this ProvideValue to get the output from MarkupExtension. So the actual implementation looks like :
public class ReflectionExtension :
global::System.Windows.Markup.MarkupExtension
{
public Type CurrentType { get; set; }
public bool IncludeMethods { get; set; }
public bool IncludeFields { get; set; }
public bool IncludeEvents { get; set; }
public ReflectionExtension(Type currentType)
{
this.CurrentType = currentType;
}
public override object ProvideValue(IServiceProvider serviceProvider)
{
if (this.CurrentType == null)
throw new ArgumentException("Type argument is not specified");
ObservableCollection<string> collection = new
ObservableCollection<string>();
foreach(PropertyInfo p in this.CurrentType.GetProperties())
collection.Add(string.Format("Property : {0}", p.Name));
if(this.IncludeMethods)
foreach(MethodInfo m in this.CurrentType.GetMethods())
collection.Add(string.Format("Method : {0} with {1}
argument(s)", m.Name, m.GetParameters().Count()));
if(this.IncludeFields)
foreach(FieldInfo f in this.CurrentType.GetFields())
collection.Add(string.Format("Field : {0}", f.Name));
if(this.IncludeEvents)
foreach(EventInfo e in this.CurrentType.GetEvents())
collection.Add(string.Format("Events : {0}", e.Name));
return collection;
}
}
You can see the constructor for this class takes one argument of Type. Now to use it we refer it in XAML and use it in similar fashion as we do with other MarkupExtensions.
<ListBox ItemsSource="{local:Reflection {x:Type Grid}, IncludeMethods=true,
IncludeFields=true, IncludeEvents=true}" MaxHeight="200" Grid.Row="3"
Grid.ColumnSpan="2" />So here the Constructor gets argument from {x:Type Grid}. The first argument for any MarkupExtension is treated as Constructor argument. The other properties are defined using comma separated strings.