private static void OnUriSourceChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
DeepZoomImageTileSource deepZoomImageTileSource = (DeepZoomImageTileSource)d;
Uri oldUriSource = (Uri)e.OldValue;
Uri uriSource = deepZoomImageTileSource.UriSource;
deepZoomImageTileSource.OnUriSourceChanged(oldUriSource, uriSource);
}