com.revolsys.jts.geomgraph

Class PlanarGraph

java.lang.Object

com.revolsys.jts.geomgraph.PlanarGraph

Direct Known Subclasses:

GeometryGraph

public class PlanarGraph
extends 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

Fields

Modifier and Type	Field and Description
protected List<DirectedEdge>	edgeEndList
protected List<Edge>	edges

Constructor Summary

Constructors

Constructor and Description
PlanarGraph()
PlanarGraph(NodeFactory nodeFact)

Method Summary

Methods

Modifier and Type	Method and Description
void	add(DirectedEdge e)
void	addEdges(List edgesToAdd) Add a set of edges to the graph.
Node	addNode(Node node)
Node	addNode(Point coord)
Iterable<Edge>	edges()
Node	find(Point coord)
Edge	findEdge(Point p0, Point 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(Point p0, Point p1) Returns the edge which starts at p0 and whose first segment is parallel to p1
Collection<DirectedEdge>	getEdgeEnds()
Iterator	getEdgeIterator()
Iterator<Node>	getNodeIterator()
protected NodeMap	getNodeMap()
Collection<Node>	getNodes()
protected void	insertEdge(Edge e)
boolean	isBoundaryNode(int geomIndex, Point 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(Collection nodes) For nodes in the Collection, link the DirectedEdges at the node that are in the result.

Methods inherited from class java.lang.Object

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

Field Detail

edges

protected List<Edge> edges

edgeEndList

protected List<DirectedEdge> edgeEndList

Constructor Detail

PlanarGraph

public PlanarGraph()

PlanarGraph

public PlanarGraph(NodeFactory nodeFact)

Method Detail

linkResultDirectedEdges

public static void linkResultDirectedEdges(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).

add

public void add(DirectedEdge e)

addEdges

public void addEdges(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.

addNode

public Node addNode(Node node)

addNode

public Node addNode(Point coord)

edges

public Iterable<Edge> edges()

find

public Node find(Point coord)

Returns:

the node if found; null otherwise

findEdge

public Edge findEdge(Point p0,
            Point p1)

Returns the edge whose first two coordinates are p0 and p1

Returns:

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

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

findEdgeInSameDirection

public Edge findEdgeInSameDirection(Point p0,
                           Point 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

getEdgeEnds

public Collection<DirectedEdge> getEdgeEnds()

getEdgeIterator

public Iterator getEdgeIterator()

getNodeIterator

public Iterator<Node> getNodeIterator()

getNodeMap

protected NodeMap getNodeMap()

getNodes

public Collection<Node> getNodes()

insertEdge

protected void insertEdge(Edge e)

isBoundaryNode

public boolean isBoundaryNode(int geomIndex,
                     Point coord)

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).

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).