com.vividsolutions.jts.operation.buffer
Class BufferSubgraph

java.lang.Object
  com.vividsolutions.jts.operation.buffer.BufferSubgraph

All Implemented Interfaces:

java.lang.Comparable

public class BufferSubgraph
extends java.lang.Object
implements java.lang.Comparable

A connected subset of the graph of DirectedEdges and Nodes. Its edges will generate either

• a single polygon in the complete buffer, with zero or more holes, or
• one or more connected holes

Version:

1.7

Constructor Summary

BufferSubgraph()

Method Summary

int	compareTo(java.lang.Object o) BufferSubgraphs are compared on the x-value of their rightmost Coordinate.
void	computeDepth(int outsideDepth)
void	create(Node node) Creates the subgraph consisting of all edges reachable from this node.
void	findResultEdges() Find all edges whose depths indicates that they are in the result area(s).
java.util.List	getDirectedEdges()
Envelope	getEnvelope() Computes the envelope of the edges in the subgraph.
java.util.List	getNodes()
Coordinate	getRightmostCoordinate() Gets the rightmost coordinate in the edges of the subgraph

Methods inherited from class java.lang.Object

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

Constructor Detail

BufferSubgraph

public BufferSubgraph()

Method Detail

getDirectedEdges

public java.util.List getDirectedEdges()

getNodes

public java.util.List getNodes()

getEnvelope

public Envelope getEnvelope()

Computes the envelope of the edges in the subgraph. The envelope is cached after being computed.

Returns:

the envelope of the graph.

getRightmostCoordinate

public Coordinate getRightmostCoordinate()

Gets the rightmost coordinate in the edges of the subgraph

create

public void create(Node node)

Creates the subgraph consisting of all edges reachable from this node. Finds the edges in the graph and the rightmost coordinate.

Parameters:

node - a node to start the graph traversal from

computeDepth

public void computeDepth(int outsideDepth)

findResultEdges

public void findResultEdges()

Find all edges whose depths indicates that they are in the result area(s). Since we want polygon shells to be oriented CW, choose dirEdges with the interior of the result on the RHS. Mark them as being in the result. Interior Area edges are the result of dimensional collapses. They do not form part of the result area boundary.

compareTo

public int compareTo(java.lang.Object o)

BufferSubgraphs are compared on the x-value of their rightmost Coordinate. This defines a partial ordering on the graphs such that:

g1 >= g2 <==> Ring(g2) does not contain Ring(g1)

where Polygon(g) is the buffer polygon that is built from g.

This relationship is used to sort the BufferSubgraphs so that shells are guaranteed to be built before holes.

Specified by:

compareTo in interface java.lang.Comparable