private static void TransformPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
TransformedBitmap target = ((TransformedBitmap)d);
target.TransformPropertyChangedHook(e);
// The first change to the default value of a mutable collection property (e.g. GeometryGroup.Children)
// will promote the property value from a default value to a local value. This is technically a sub-property
// change because the collection was changed and not a new collection set (GeometryGroup.Children.
// Add versus GeometryGroup.Children = myNewChildrenCollection). However, we never marshalled
// the default value to the compositor. If the property changes from a default value, the new local value
// needs to be marshalled to the compositor. We detect this scenario with the second condition
// e.OldValueSource != e.NewValueSource. Specifically in this scenario the OldValueSource will be
// Default and the NewValueSource will be Local.
if (e.IsASubPropertyChange &&
(e.OldValueSource == e.NewValueSource))
{
return;
}
target.PropertyChanged(TransformProperty);
}