One of the enumeration values.
This property is read/write. The default value is EvenOdd.
FillRule is mainly relevant for two types of geometries, PathGeometry and GeometryGroup. On other geometries such as RectangleGeometry, the property exists but will have no effect because there is no way to specify segment relationships so that a fill rule behavior is relevant in the properties of these geometries.
The value of the IsClosed property on a PathFigure within a PathGeometry does not affect the calculation of the fill area. It only affects whether that segment is drawn; the fill area is evaluated as if the first and last segments were connected.