private static void StartSpyingFacade( UIElement sourceElement, Compositor compositor, CompositionFacadeType facadeType, out CompositionPropertySet propertySet, out ExpressionAnimation expressionAnimation, out string propertySetPropertyName) { propertySet = null; propertySetPropertyName = null; expressionAnimation = null; if (sourceElement == null) { throw new ArgumentException(); } propertySetPropertyName = FacadeTypeToStringName(facadeType); StartSpy <UIElement>(sourceElement, s_elementsDictionary, compositor, ref propertySetPropertyName, ref propertySetPropertyName, out propertySet, out expressionAnimation); expressionAnimation.SetExpressionReferenceParameter(c_source, sourceElement); }