///<summary>
/// Returns the boundary, or the empty geometry if this Geometry is empty.
///</summary>
///<remarks>For a discussion
/// of this function, see the OpenGIS Simple Features Specification. As stated in SFS
/// Section 2.1.13.1, "the boundary of a Geometry is a set of Geometries of the next lower dimension."</remarks>
///<returns>Returns the closure of the combinatorial boundary of this Geometry</returns>
public override Geometry GetBoundary()
{
if (IsEmpty())
{
return(_geometryFactory.CreateGeometryCollection(null));
}
//LineString[] allRings = new LineString[_geometries.Length];
ArrayList allRings = new ArrayList();
for (int i = 0; i < _geometries.Length; i++)
{
Polygon polygon = (Polygon)_geometries[i];
GeometryCollection rings = (GeometryCollection)polygon.GetBoundary();
for (int j = 0; j < rings.GetNumGeometries(); j++)
{
//allRings[j] = rings[j-i] as LineString;
allRings.Add(rings.GetGeometryN(j));
}
}
return(_geometryFactory.CreateMultiLineString(GeometryFactory.ToLineStringArray(allRings)));
}
