/// <summary>
/// Returns the DirectedEdge that starts from the given node, or null if the
/// node is not one of the two nodes associated with this Edge.
/// </summary>
/// <param name="fromNode"></param>
/// <returns></returns>
public DirectedEdge GetDirEdge(Node fromNode)
{
if (dirEdge[0].FromNode == fromNode)
return dirEdge[0];
if (dirEdge[1].FromNode == fromNode)
return dirEdge[1];
// node not found
// possibly should throw an exception here?
return null;
}
/// <summary>
///
/// </summary>
/// <param name="coordinate"></param>
/// <returns></returns>
private Node GetNode(ICoordinate coordinate)
{
Node node = FindNode(coordinate);
if (node == null)
{
node = new Node(coordinate);
Add(node);
}
return node;
}
/// <summary>
/// Deletes all edges at a node.
/// </summary>
/// <param name="node"></param>
public static void DeleteAllEdges(Node node)
{
IList edges = node.OutEdges.Edges;
for (IEnumerator i = edges.GetEnumerator(); i.MoveNext(); )
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge) i.Current;
de.Marked = true;
PolygonizeDirectedEdge sym = (PolygonizeDirectedEdge) de.Sym;
if (sym != null) sym.Marked = true;
}
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
private void BuildEdgeStringsStartingAt(Node node)
{
IEnumerator i = node.OutEdges.GetEnumerator();
while (i.MoveNext())
{
LineMergeDirectedEdge directedEdge = (LineMergeDirectedEdge) i.Current;
if (directedEdge.Edge.IsMarked)
continue;
edgeStrings.Add(BuildEdgeStringStartingWith(directedEdge));
}
}
/// <summary>
/// Adds a node to the map, replacing any that is already at that location.
/// Only subclasses can add Nodes, to ensure Nodes are of the right type.
/// </summary>
/// <param name="node"></param>
/// <returns>The added node.</returns>
protected void Add(Node node)
{
nodeMap.Add(node);
}
/// <summary>
/// Removes a node from the graph, along with any associated DirectedEdges and
/// Edges.
/// </summary>
/// <param name="node"></param>
public void Remove(Node node)
{
// unhook all directed edges
IList outEdges = node.OutEdges.Edges;
for (IEnumerator i = outEdges.GetEnumerator(); i.MoveNext(); )
{
DirectedEdge de = (DirectedEdge) i.Current;
DirectedEdge sym = de.Sym;
// remove the diredge that points to this node
if (sym != null)
Remove(sym);
// remove this diredge from the graph collection
dirEdges.Remove(de);
Edge edge = de.Edge;
if (edge != null)
edges.Remove(edge);
}
// remove the node from the graph
nodeMap.Remove(node.Coordinate);
node.Remove();
}
/// <summary>
/// Finds an <see cref="DirectedEdge" /> for an unvisited edge (if any),
/// choosing the <see cref="DirectedEdge" /> which preserves orientation, if possible.
/// </summary>
/// <param name="node">The <see cref="Node" /> to examine.</param>
/// <returns>
/// The <see cref="DirectedEdge" /> found,
/// or <c>null</c> if none were unvisited.
/// </returns>
private static DirectedEdge FindUnvisitedBestOrientedDE(Node node)
{
DirectedEdge wellOrientedDE = null;
DirectedEdge unvisitedDE = null;
foreach(object obj in node.OutEdges)
{
DirectedEdge de = (DirectedEdge) obj;
if (!de.Edge.IsVisited)
{
unvisitedDE = de;
if (de.EdgeDirection)
wellOrientedDE = de;
}
}
if (wellOrientedDE != null)
return wellOrientedDE;
return unvisitedDE;
}
/// <summary>
/// Constructs a directed edge connecting the <c>from</c> node to the
/// <c>to</c> node.
/// </summary>
/// <param name="from"></param>
/// <param name="to"></param>
/// <param name="directionPt">
/// Specifies this DirectedEdge's direction (given by an imaginary
/// line from the <c>from</c> node to <c>directionPt</c>).
/// </param>
/// <param name="edgeDirection">
/// Whether this DirectedEdge's direction is the same as or
/// opposite to that of the parent Edge (if any).
/// </param>
public PolygonizeDirectedEdge(Node from, Node to, ICoordinate directionPt, bool edgeDirection)
: base(from, to, directionPt, edgeDirection)
{
}
/// <summary>
/// Constructs a LineMergeDirectedEdge connecting the <c>from</c> node to the <c>to</c> node.
/// </summary>
/// <param name="from"></param>
/// <param name="to"></param>
/// <param name="directionPt">
/// specifies this DirectedEdge's direction (given by an imaginary
/// line from the <c>from</c> node to <c>directionPt</c>).
/// </param>
/// <param name="edgeDirection">
/// whether this DirectedEdge's direction is the same as or
/// opposite to that of the parent Edge (if any).
/// </param>
public LineMergeDirectedEdge(Node from, Node to, ICoordinate directionPt, bool edgeDirection)
: base(from, to, directionPt, edgeDirection)
{
}
/// <summary>
/// Returns all Edges that connect the two nodes (which are assumed to be different).
/// </summary>
/// <param name="node0"></param>
/// <param name="node1"></param>
/// <returns></returns>
public static IList getEdgesBetween(Node node0, Node node1)
{
IList edges0 = DirectedEdge.ToEdges(node0.OutEdges.Edges);
ISet commonEdges = new HashedSet(edges0);
IList edges1 = DirectedEdge.ToEdges(node1.OutEdges.Edges);
commonEdges.RetainAll(edges1);
return new ArrayList(commonEdges);
}
/// <summary>
/// If <c>node</c> is one of the two nodes associated with this Edge,
/// returns the other node; otherwise returns null.
/// </summary>
/// <param name="node"></param>
/// <returns></returns>
public Node GetOppositeNode(Node node)
{
if (dirEdge[0].FromNode == node)
return dirEdge[0].ToNode;
if (dirEdge[1].FromNode == node)
return dirEdge[1].ToNode;
// node not found
// possibly should throw an exception here?
return null;
}
/// <summary>
///
/// </summary>
/// <param name="pt"></param>
/// <returns></returns>
private Node GetNode(ICoordinate pt)
{
Node node = FindNode(pt);
if (node == null)
{
node = new Node(pt);
// ensure node is only added once to graph
Add(node);
}
return node;
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
/// <returns></returns>
private static int GetDegreeNonDeleted(Node node)
{
IList edges = node.OutEdges.Edges;
int degree = 0;
for (IEnumerator i = edges.GetEnumerator(); i.MoveNext(); )
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge) i.Current;
if (! de.IsMarked)
degree++;
}
return degree;
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
/// <param name="label"></param>
/// <returns></returns>
private static int GetDegree(Node node, long label)
{
IList edges = node.OutEdges.Edges;
int degree = 0;
for (IEnumerator i = edges.GetEnumerator(); i.MoveNext(); )
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge) i.Current;
if (de.Label == label)
degree++;
}
return degree;
}
/// <summary>
///
/// </summary>
/// <param name="node"></param>
private static void ComputeNextCWEdges(Node node)
{
DirectedEdgeStar deStar = node.OutEdges;
PolygonizeDirectedEdge startDE = null;
PolygonizeDirectedEdge prevDE = null;
// the edges are stored in CCW order around the star
for (IEnumerator i = deStar.Edges.GetEnumerator(); i.MoveNext(); )
{
PolygonizeDirectedEdge outDE = (PolygonizeDirectedEdge) i.Current;
if (outDE.IsMarked) continue;
if (startDE == null)
startDE = outDE;
if (prevDE != null)
{
PolygonizeDirectedEdge sym = (PolygonizeDirectedEdge) prevDE.Sym;
sym.Next = outDE;
}
prevDE = outDE;
}
if (prevDE != null)
{
PolygonizeDirectedEdge sym = (PolygonizeDirectedEdge) prevDE.Sym;
sym.Next = startDE;
}
}
/// <summary>
/// Computes the next edge pointers going CCW around the given node, for the
/// given edgering label.
/// This algorithm has the effect of converting maximal edgerings into minimal edgerings
/// </summary>
/// <param name="node"></param>
/// <param name="label"></param>
private static void ComputeNextCCWEdges(Node node, long label)
{
DirectedEdgeStar deStar = node.OutEdges;
//PolyDirectedEdge lastInDE = null;
PolygonizeDirectedEdge firstOutDE = null;
PolygonizeDirectedEdge prevInDE = null;
// the edges are stored in CCW order around the star
IList edges = deStar.Edges;
//for (IEnumerator i = deStar.Edges.GetEnumerator(); i.MoveNext(); ) {
for (int i = edges.Count - 1; i >= 0; i--)
{
PolygonizeDirectedEdge de = (PolygonizeDirectedEdge) edges[i];
PolygonizeDirectedEdge sym = (PolygonizeDirectedEdge) de.Sym;
PolygonizeDirectedEdge outDE = null;
if (de.Label == label) outDE = de;
PolygonizeDirectedEdge inDE = null;
if (sym.Label == label) inDE = sym;
if (outDE == null && inDE == null) continue; // this edge is not in edgering
if (inDE != null)
prevInDE = inDE;
if (outDE != null)
{
if (prevInDE != null)
{
prevInDE.Next = outDE;
prevInDE = null;
}
if (firstOutDE == null)
firstOutDE = outDE;
}
}
if (prevInDE != null)
{
Assert.IsTrue(firstOutDE != null);
prevInDE.Next = firstOutDE;
}
}