/// <summary>
/// Removes a handler for the SourceChanged event to the element.
/// </summary>
/// <param name="e">The element to remove the handler from.</param>
/// <param name="handler">The hander to remove.</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 RemoveHandler() method.
/// </remarks>
public static void RemoveSourceChangedHandler(IInputElement e, SourceChangedEventHandler handler)
{
if (e == null)
{
throw new ArgumentNullException("e");
}
if (!InputElement.IsValid(e))
{
throw new ArgumentException(SR.Get(SRID.Invalid_IInputElement), "e");
}
DependencyObject o = (DependencyObject)e;
// 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 = null;
EventHandlersStore store;
// Either UIElement or ContentElement.
if (InputElement.IsUIElement(o))
{
UIElement uie = o as UIElement;
uie.RemoveHandler(SourceChangedEvent, handler);
store = uie.EventHandlersStore;
if (store != null)
{
info = store[SourceChangedEvent];
}
if (info == null || info.Count == 0)
{
uie.VisualAncestorChanged -= new Visual.AncestorChangedEventHandler(uie.OnVisualAncestorChanged);;
RemoveElementFromWatchList(uie);
}
}
else if (InputElement.IsUIElement3D(o))
{
UIElement3D uie3D = o as UIElement3D;
uie3D.RemoveHandler(SourceChangedEvent, handler);
store = uie3D.EventHandlersStore;
if (store != null)
{
info = store[SourceChangedEvent];
}
if (info == null || info.Count == 0)
{
uie3D.VisualAncestorChanged -= new Visual.AncestorChangedEventHandler(uie3D.OnVisualAncestorChanged);;
RemoveElementFromWatchList(uie3D);
}
}
else
{
ContentElement ce = o as ContentElement;
ce.RemoveHandler(SourceChangedEvent, handler);
store = ce.EventHandlersStore;
if (store != null)
{
info = store[SourceChangedEvent];
}
if (info == null || info.Count == 0)
{
RemoveElementFromWatchList(ce);
}
}
}
}
