/// <summary>
/// Find the innermost enclosing shell EdgeRing containing the argument EdgeRing, if any.
/// The innermost enclosing ring is the <i>smallest</i> enclosing ring.
/// The algorithm used depends on the fact that:
/// ring A contains ring B iff envelope(ring A) contains envelope(ring B).
/// 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>
/// <param name="shellList"></param>
/// <param name="testEr"></param>
/// <returns>Containing EdgeRing, if there is one, OR
/// null if no containing EdgeRing is found.</returns>
public static EdgeRing FindEdgeRingContaining(EdgeRing testEr, IList shellList)
{
ILinearRing teString = testEr.Ring;
IEnvelope testEnv = teString.EnvelopeInternal;
EdgeRing minShell = null;
IEnvelope minEnv = null;
for (IEnumerator it = shellList.GetEnumerator(); it.MoveNext(); )
{
EdgeRing tryShell = (EdgeRing)it.Current;
ILinearRing tryRing = tryShell.Ring;
IEnvelope tryEnv = tryRing.EnvelopeInternal;
if (minShell != null)
minEnv = minShell.Ring.EnvelopeInternal;
bool isContained = false;
// the hole envelope cannot equal the shell envelope
if (tryEnv.Equals(testEnv)) continue;
Coordinate testPt = PtNotInList(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;
}
/// <summary>
///
/// </summary>
/// <param name="holeER"></param>
/// <param name="shellList"></param>
private static void AssignHoleToShell(EdgeRing holeER, IList shellList)
{
EdgeRing shell = EdgeRing.FindEdgeRingContaining(holeER, shellList);
if (shell != null)
shell.AddHole(holeER.Ring);
}
/// <summary>
///
/// </summary>
/// <param name="startDE"></param>
/// <returns></returns>
private EdgeRing FindEdgeRing(PolygonizeDirectedEdge startDE)
{
PolygonizeDirectedEdge de = startDE;
EdgeRing er = new EdgeRing(_factory);
do
{
er.Add(de);
de.Ring = er;
de = de.Next;
Assert.IsTrue(de != null, "found null DE in ring");
Assert.IsTrue(de == startDE || ! de.IsInRing, "found DE already in ring");
}
while (de != startDE);
return er;
}