com.vividsolutions.jts.operation.buffer
Class BufferSubgraph
java.lang.Object
com.vividsolutions.jts.operation.buffer.BufferSubgraph
- Comparable
public class BufferSubgraph
extends java.lang.Object
implements Comparable
A connected subset of the graph of
DirectedEdges
and
Node
s.
Its edges will generate either
- a single polygon in the complete buffer, with zero or more holes, or
- one or more connected holes
compareTo
public int compareTo(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.
computeDepth
public void computeDepth(int outsideDepth)
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.
node
- a node to start the graph traversal from
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.
getDirectedEdges
public List getDirectedEdges()
getEnvelope
public Envelope getEnvelope()
Computes the envelope of the edges in the subgraph.
The envelope is cached after being computed.
- the envelope of the graph.
getNodes
public List getNodes()
getRightmostCoordinate
public Coordinate getRightmostCoordinate()
Gets the rightmost coordinate in the edges of the subgraph