/// <summary>
/// Finds and removes all cut edges from the graph.
/// </summary>
/// <returns>A list of the <c>LineString</c>s forming the removed cut edges.</returns>
public virtual IList DeleteCutEdges()
{
ComputeNextCwEdges();
// label the current set of edgerings
FindLabeledEdgeRings(DirectedEdges);
/*
* Cut Edges are edges where both dirEdges have the same label.
* Delete them, and record them
*/
IList cutLines = new ArrayList();
for (IEnumerator i = DirectedEdges.GetEnumerator(); i.MoveNext();)
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge)i.Current;
if (de.IsMarked)
{
continue;
}
PolygonizeDirectedEdge sym = (PolygonizeDirectedEdge)de.Sym;
if (de.Label == sym.Label)
{
de.IsMarked = true;
sym.IsMarked = true;
// save the line as a cut edge
PolygonizeEdge e = (PolygonizeEdge)de.Edge;
cutLines.Add(e.Line);
}
}
return(cutLines);
}
/// <summary>
/// Computes the EdgeRings formed by the edges in this graph.
/// </summary>
/// <returns>A list of the{EdgeRings found by the polygonization process.</returns>
public virtual IList GetEdgeRings()
{
// maybe could optimize this, since most of these pointers should be set correctly already by deleteCutEdges()
ComputeNextCwEdges();
// clear labels of all edges in graph
Label(DirectedEdges, -1);
IList maximalRings = FindLabeledEdgeRings(DirectedEdges);
ConvertMaximalToMinimalEdgeRings(maximalRings);
// find all edgerings
IList edgeRingList = new ArrayList();
for (IEnumerator i = DirectedEdges.GetEnumerator(); i.MoveNext();)
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge)i.Current;
if (de.IsMarked)
{
continue;
}
if (de.IsInRing)
{
continue;
}
EdgeRing er = FindEdgeRing(de);
edgeRingList.Add(er);
}
return(edgeRingList);
}