public bool IsInteriorsConnected()
{
// node the edges, in case holes touch the shell
ArrayList splitEdges = new ArrayList();
_geomGraph.ComputeSplitEdges(splitEdges);
// polygonize the edges
PlanarGraph graph = new PlanarGraph(new OverlayNodeFactory());
graph.AddEdges(splitEdges);
SetAllEdgesInResult(graph);
graph.LinkAllDirectedEdges();
ArrayList edgeRings = buildEdgeRings(graph.EdgeEnds);
/**
* Mark all the edges for the edgeRings corresponding to the shells
* of the input polygons. Note only ONE ring gets marked for each shell.
*/
VisitShellInteriors(_geomGraph.Geometry, graph);
/**
* If there are any unvisited shell edges
* (i.e. a ring which is not a hole and which has the interior
* of the parent area on the RHS)
* this means that one or more holes must have split the interior of the
* polygon into at least two pieces. The polygon is thus invalid.
*/
return(!HasUnvisitedShellEdge(edgeRings));
}