com.vividsolutions.jts.geomgraph
Class PlanarGraph

java.lang.Object
  com.vividsolutions.jts.geomgraph.PlanarGraph

Direct Known Subclasses:

GeometryGraph

public class PlanarGraph
extends java.lang.Object

The computation of the IntersectionMatrix relies on the use of a structure called a "topology graph". The topology graph contains nodes and edges corresponding to the nodes and line segments of a Geometry. Each node and edge in the graph is labeled with its topological location relative to the source geometry.

Note that there is no requirement that points of self-intersection be a vertex. Thus to obtain a correct topology graph, Geometrys must be self-noded before constructing their graphs.

Two fundamental operations are supported by topology graphs:

• Computing the intersections between all the edges and nodes of a single graph
• Computing the intersections between the edges and nodes of two different graphs

Version:

1.7

Field Summary

protected java.util.List	edgeEndList
protected java.util.List	edges
protected NodeMap	nodes

Constructor Summary

PlanarGraph()

PlanarGraph(NodeFactory nodeFact)

Method Summary

void	add(EdgeEnd e)
void	addEdges(java.util.List edgesToAdd) Add a set of edges to the graph.
Node	addNode(Coordinate coord)
Node	addNode(Node node)
Node	find(Coordinate coord)
Edge	findEdge(Coordinate p0, Coordinate p1) Returns the edge whose first two coordinates are p0 and p1
EdgeEnd	findEdgeEnd(Edge e) Returns the EdgeEnd which has edge e as its base edge (MD 18 Feb 2002 - this should return a pair of edges)
Edge	findEdgeInSameDirection(Coordinate p0, Coordinate p1) Returns the edge which starts at p0 and whose first segment is parallel to p1
java.util.Collection	getEdgeEnds()
java.util.Iterator	getEdgeIterator()
java.util.Iterator	getNodeIterator()
java.util.Collection	getNodes()
protected void	insertEdge(Edge e)
boolean	isBoundaryNode(int geomIndex, Coordinate coord)
void	linkAllDirectedEdges() Link the DirectedEdges at the nodes of the graph.
void	linkResultDirectedEdges() Link the DirectedEdges at the nodes of the graph.
static void	linkResultDirectedEdges(java.util.Collection nodes) For nodes in the Collection, link the DirectedEdges at the node that are in the result.
void	printEdges(java.io.PrintStream out)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

edges

protected java.util.List edges

nodes

protected NodeMap nodes

edgeEndList

protected java.util.List edgeEndList

Constructor Detail

PlanarGraph

public PlanarGraph(NodeFactory nodeFact)

PlanarGraph

public PlanarGraph()

Method Detail

linkResultDirectedEdges

public static void linkResultDirectedEdges(java.util.Collection nodes)

For nodes in the Collection, link the DirectedEdges at the node that are in the result. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).

getEdgeIterator

public java.util.Iterator getEdgeIterator()

getEdgeEnds

public java.util.Collection getEdgeEnds()

isBoundaryNode

public boolean isBoundaryNode(int geomIndex,
                              Coordinate coord)

insertEdge

protected void insertEdge(Edge e)

add

public void add(EdgeEnd e)

getNodeIterator

public java.util.Iterator getNodeIterator()

getNodes

public java.util.Collection getNodes()

addNode

public Node addNode(Node node)

addNode

public Node addNode(Coordinate coord)

find

public Node find(Coordinate coord)

Returns:

the node if found; null otherwise

addEdges

public void addEdges(java.util.List edgesToAdd)

Add a set of edges to the graph. For each edge two DirectedEdges will be created. DirectedEdges are NOT linked by this method.

linkResultDirectedEdges

public void linkResultDirectedEdges()

Link the DirectedEdges at the nodes of the graph. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).

linkAllDirectedEdges

public void linkAllDirectedEdges()

Link the DirectedEdges at the nodes of the graph. This allows clients to link only a subset of nodes in the graph, for efficiency (because they know that only a subset is of interest).

findEdgeEnd

public EdgeEnd findEdgeEnd(Edge e)

Returns the EdgeEnd which has edge e as its base edge (MD 18 Feb 2002 - this should return a pair of edges)

Returns:

the edge, if found null if the edge was not found

findEdge

public Edge findEdge(Coordinate p0,
                     Coordinate p1)

Returns the edge whose first two coordinates are p0 and p1

Returns:

the edge, if found null if the edge was not found

findEdgeInSameDirection

public Edge findEdgeInSameDirection(Coordinate p0,
                                    Coordinate p1)

Returns the edge which starts at p0 and whose first segment is parallel to p1

Returns:

the edge, if found null if the edge was not found

printEdges

public void printEdges(java.io.PrintStream out)