/// <summary>
///
/// </summary>
/// <param name="er"></param>
/// <returns></returns>
public int GetOutgoingDegree(EdgeRing er)
{
int degree = 0;
foreach (DirectedEdge de in Edges)
if (de.EdgeRing == er)
degree++;
return degree;
}
/// <summary> /// /// </summary> /// <param name="de"></param> /// <param name="er"></param> public abstract void SetEdgeRing(DirectedEdge de, EdgeRing er);
/// <summary>
///
/// </summary>
/// <param name="ring"></param>
public void AddHole(EdgeRing ring)
{
_holes.Add(ring);
}
/// <summary>
///
/// </summary>
/// <param name="er"></param>
public void LinkMinimalDirectedEdges(EdgeRing er)
{
// find first area edge (if any) to start linking at
DirectedEdge firstOut = null;
DirectedEdge incoming = null;
int state = ScanningForIncoming;
// link edges in CW order
for (int i = _resultAreaEdgeList.Count - 1; i >= 0; i--)
{
DirectedEdge nextOut = this._resultAreaEdgeList[i];
DirectedEdge nextIn = nextOut.Sym;
// record first outgoing edge, in order to link the last incoming edge
if (firstOut == null && nextOut.EdgeRing == er)
firstOut = nextOut;
switch (state)
{
case ScanningForIncoming:
if (nextIn.EdgeRing != er)
continue;
incoming = nextIn;
state = LinkingToOutgoing;
break;
case LinkingToOutgoing:
if (nextOut.EdgeRing != er)
continue;
incoming.NextMin = nextOut;
state = ScanningForIncoming;
break;
default:
break;
}
}
if (state == LinkingToOutgoing)
{
Assert.IsTrue(firstOut != null, "found null for first outgoing dirEdge");
Assert.IsTrue(firstOut.EdgeRing == er, "unable to link last incoming dirEdge");
incoming.NextMin = firstOut;
}
}
/// <summary>
///
/// </summary>
/// <param name="de"></param>
/// <param name="er"></param>
public override void SetEdgeRing(DirectedEdge de, EdgeRing er)
{
de.MinEdgeRing = er;
}
/// <summary> /// /// </summary> /// <param name="de"></param> /// <param name="er"></param> abstract public void SetEdgeRing(DirectedEdge de, EdgeRing er);
/// <summary>
///
/// </summary>
/// <param name="ring"></param>
public void AddHole(EdgeRing ring)
{
_holes.Add(ring);
}
/// <summary>
/// This method assigns the holes for a Polygon (formed from a list of
/// MinimalEdgeRings) to its shell.
/// Determining the holes for a MinimalEdgeRing polygon serves two purposes:
/// it is faster than using a point-in-polygon check later on.
/// it ensures correctness, since if the PIP test was used the point
/// chosen might lie on the shell, which might return an incorrect result from the
/// PIP test.
/// </summary>
/// <param name="shell"></param>
/// <param name="minEdgeRings"></param>
private static void PlacePolygonHoles(EdgeRing shell, IEnumerable<EdgeRing> minEdgeRings)
{
foreach (MinimalEdgeRing er in minEdgeRings)
{
if (er.IsHole)
er.Shell = shell;
}
}
/// <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="testEr"></param>
/// <param name="shellList"></param>
/// <returns>Containing EdgeRing, if there is one <br/> or
/// <value>null</value> if no containing EdgeRing is found.</returns>
private static EdgeRing FindEdgeRingContaining(EdgeRing testEr, IEnumerable<EdgeRing> shellList)
{
ILinearRing teString = testEr.LinearRing;
Envelope testEnv = teString.EnvelopeInternal;
Coordinate testPt = teString.GetCoordinateN(0);
EdgeRing minShell = null;
Envelope minEnv = null;
foreach (EdgeRing tryShell in shellList)
{
ILinearRing tryRing = tryShell.LinearRing;
Envelope tryEnv = tryRing.EnvelopeInternal;
if (minShell != null)
minEnv = minShell.LinearRing.EnvelopeInternal;
bool isContained = false;
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;
}
