/// <summary>
/// Adds a handler for the SourceChanged event to the element.
/// </summary>
/// <param name="element">The element to add the handler too.</param>
/// <param name="handler">The hander to add.</param>
/// <remarks>
/// Even though this is a routed event handler, there are special
/// restrictions placed on this event.
/// 1) You cannot use the UIElement or ContentElement AddHandler() method.
/// 2) Class handlers are not allowed.
/// 3) The handlers will receive the SourceChanged event even if it was handled.
/// Callers must have UIPermission(UIPermissionWindow.AllWindows) to call this API.
/// </remarks>
public static void AddSourceChangedHandler(IInputElement element, SourceChangedEventHandler handler)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
// Either UIElement or ContentElement
if (!InputElement.IsValid(element))
{
throw new ArgumentException(SR.Get(SRID.Invalid_IInputElement), "element");
}
DependencyObject o = (DependencyObject)element;
// o.VerifyAccess();
// I would rather throw an exception here, but the CLR doesn't
// so we won't either.
if (handler != null)
{
FrugalObjectList <RoutedEventHandlerInfo> info;
if (InputElement.IsUIElement(o))
{
UIElement uie = o as UIElement;
uie.AddHandler(SourceChangedEvent, handler);
info = uie.EventHandlersStore[SourceChangedEvent];
if (1 == info.Count)
{
uie.VisualAncestorChanged += new Visual.AncestorChangedEventHandler(uie.OnVisualAncestorChanged);
AddElementToWatchList(uie);
}
}
else if (InputElement.IsUIElement3D(o))
{
UIElement3D uie3D = o as UIElement3D;
uie3D.AddHandler(SourceChangedEvent, handler);
info = uie3D.EventHandlersStore[SourceChangedEvent];
if (1 == info.Count)
{
uie3D.VisualAncestorChanged += new Visual.AncestorChangedEventHandler(uie3D.OnVisualAncestorChanged);
AddElementToWatchList(uie3D);
}
}
else
{
ContentElement ce = o as ContentElement;
ce.AddHandler(SourceChangedEvent, handler);
info = ce.EventHandlersStore[SourceChangedEvent];
if (1 == info.Count)
{
AddElementToWatchList(ce);
}
}
}
}
