How to Invoke the command on clicking the SfTreeNavigatorItems

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
<Grid>
<navigation:SfTreeNavigator ItemsSource="{Binding Models}" Header="Enterprise Toolkit"
Width="300" Height="400" HorizontalAlignment="Center" VerticalAlignment="Center">
<!--Invoke the command using EventToCommand-->
<i:Interaction.Behaviors>
<local:EventToCommand Command="{Binding DataContext.Clicked, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window}}" EventName="SelectionChanged"/>
</i:Interaction.Behaviors>
<navigation:SfTreeNavigator.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Models}">
<StackPanel Orientation="Horizontal">
<TextBlock Text="{Binding Header}" Foreground="Green" FontWeight="Bold" VerticalAlignment="Center" Margin="18 0 0 0"/>
</StackPanel>
</HierarchicalDataTemplate>
</navigation:SfTreeNavigator.ItemTemplate>
</navigation:SfTreeNavigator>
</Grid>

 
public class EventToCommand : Behavior<FrameworkElement>
{
//variables
private Delegate _handler;
private EventInfo _oldEvent;
 
// Properties
public string EventName
{
get { return (string)GetValue(EventProperty); }
set
{
SetValue(EventProperty, value);
}
}
public static readonly DependencyProperty EventProperty = DependencyProperty.Register("EventName", typeof(string), typeof(EventToCommand), new PropertyMetadata(null, OnEventChanged));
 
//Commands
public ICommand Command
{
get { return (ICommand)GetValue(CommandProperty); }
set
{
SetValue(CommandProperty, value);
}
}
 
//Dependency property
public static readonly DependencyProperty CommandProperty = DependencyProperty.Register("Command", typeof(ICommand), typeof(EventToCommand), new PropertyMetadata(null));
 
 
 
//  Method to invoke on event changed
private static void OnEventChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
var eventdata = (EventToCommand)d;
 
if (eventdata.AssociatedObject != null)
eventdata.AttachHandler((string)e.NewValue);
}
 
protected override void OnAttached()
{
AttachHandler(this.EventName);
}
 
 
private void AttachHandler(string eventName)
{
 
if (_oldEvent != null)
_oldEvent.RemoveEventHandler(this.AssociatedObject, _handler);
 
 
if (!string.IsNullOrEmpty(eventName))
{
//Getting the type of the control
SfTreeNavigator item = this.AssociatedObject as SfTreeNavigator;
EventInfo ei = null;
if (item != null)
{
ei = item.GetType().GetEvent(eventName);
}
if (ei != null)
{
MethodInfo mi = this.GetType().GetMethod("ExecuteCommand", BindingFlags.Instance | BindingFlags.NonPublic);
_handler = Delegate.CreateDelegate(ei.EventHandlerType, this, mi);
ei.AddEventHandler(item, _handler);
_oldEvent = ei;
}
 
}
}
 
//Method to invoke the commands
private void ExecuteCommand(object sender, EventArgs e)
{
object[] parameter = null;
if (parameter == null)
{
parameter = new object[2];
parameter[0] = sender;
parameter[1] = e;
}
if (this.Command != null)
{
if (this.Command.CanExecute(parameter))
this.Command.Execute(parameter);
}
}
}
 
 

 
public class TreeViewModel
{
public TreeViewModel()
{
//Intializing the command
Clicked = new DelegateCommand<object[]>(executeCommandOne);
}
//Implementing the method to invoke the command
private void executeCommandOne(object[] obj)
{
MessageBox.Show("Command has been invoked");
}
#endregion
 
// Declaring the DelegateCommand
public DelegateCommand<object[]> Clicked { get; set; }
}