You cannot set this value on a RoutedEventArgs that has already been routed (for instance, if you obtained the arguments through a handler). Attempting to do so will generate an exception. You can only set it on an instance that has not yet been used to generate an invocation of the event.

The value of RoutedEvent cannot be nullNothingnullptra null reference (Nothing in Visual Basic) at any time.

The following example creates new routed event data with an initial constructor and then sets the RoutedEvent property as a subsequent operation. You must have RoutedEvent set prior to raising the routed event.

        Protected Overridable Sub OnSelectedColorChanged(ByVal oldColor As Color, ByVal newColor As Color)

            Dim newEventArgs As New RoutedPropertyChangedEventArgs(Of Color)(oldColor, newColor)
            newEventArgs.RoutedEvent = ColorPicker.SelectedColorChangedEvent
            MyBase.RaiseEvent(newEventArgs)
        End Sub

protected virtual void OnSelectedColorChanged(Color oldColor, Color newColor)
{

    RoutedPropertyChangedEventArgs<Color> newEventArgs =
        new RoutedPropertyChangedEventArgs<Color>(oldColor, newColor);
    newEventArgs.RoutedEvent = ColorPicker.SelectedColorChangedEvent;
    RaiseEvent(newEventArgs);
}

.NET Framework

.NET Framework Client Profile

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

Other Resources