private EdgeRing FindEdgeRing(PolygonizeDirectedEdge startDE)
{
PolygonizeDirectedEdge de = startDE;
EdgeRing er = new EdgeRing(factory);
do
{
er.Add(de);
de.Ring = er;
de = de.Next;
Debug.Assert(de != null, "found null DE in ring");
Debug.Assert(de == startDE || !de.InRing, "found DE already in ring");
}while (de != startDE);
return(er);
}
/// <summary>
/// Find the innermost enclosing shell EdgeRing containing the argument
/// EdgeRing, if any.
/// The innermost enclosing ring is the smallest enclosing ring.
/// The algorithm used depends on the fact that:
/// <para>
/// ring A Contains ring B iff envelope(ring A) Contains envelope(ring B)
/// </para>
/// This routine is only safe to use if the chosen point of the hole
/// is known to be properly contained in a shell
/// (which is guaranteed to be the case if the hole does not touch its shell)
/// </summary>
/// <returns> Returns a containing EdgeRing, if there is one or
/// <see langword="null"/> if no containing EdgeRing is found.
/// </returns>
public static EdgeRing FindEdgeRingContaining(EdgeRing testEr, ArrayList shellList)
{
LinearRing testRing = testEr.Ring;
Envelope testEnv = testRing.Bounds;
Coordinate testPt = testRing.GetCoordinate(0);
EdgeRing minShell = null;
Envelope minEnv = null;
for (IEnumerator it = shellList.GetEnumerator(); it.MoveNext();)
{
EdgeRing tryShell = (EdgeRing)it.Current;
LinearRing tryRing = tryShell.Ring;
Envelope tryEnv = tryRing.Bounds;
if (minShell != null)
{
minEnv = minShell.Ring.Bounds;
}
bool isContained = false;
// the hole envelope cannot equal the shell envelope
if (tryEnv.Equals(testEnv))
{
continue;
}
testPt = PointNotInList(testRing.Coordinates, tryRing.Coordinates);
if (tryEnv.Contains(testEnv) && CGAlgorithms.IsPointInRing(testPt, tryRing.Coordinates))
{
isContained = true;
}
// check if this new containing ring is smaller than the current minimum ring
if (isContained)
{
if (minShell == null || minEnv.Contains(tryEnv))
{
minShell = tryShell;
}
}
}
return(minShell);
}