Class BufferSubgraph
java.lang.Object
org.locationtech.jts.operation.buffer.BufferSubgraph
- All Implemented Interfaces:
Comparable
A connected subset of the graph of
DirectedEdge
s 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
- Version:
- 1.7
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Field Summary
FieldsModifier and TypeFieldDescriptionprivate List
private Envelope
private RightmostEdgeFinder
private List
private Coordinate
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionprivate void
Adds the argument node and all its out edges to the subgraphprivate void
addReachable
(Node startNode) Adds all nodes and edges reachable from this node to the subgraph.private void
int
BufferSubgraphs are compared on the x-value of their rightmost Coordinate.void
computeDepth
(int outsideDepth) private void
computeDepths
(DirectedEdge startEdge) Compute depths for all dirEdges via breadth-first traversal of nodes in graphprivate void
private void
void
Creates the subgraph consisting of all edges reachable from this node.void
Find all edges whose depths indicates that they are in the result area(s).Computes the envelope of the edges in the subgraph.getNodes()
Gets the rightmost coordinate in the edges of the subgraph
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Field Details
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finder
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dirEdgeList
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nodes
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rightMostCoord
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env
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Constructor Details
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BufferSubgraph
public BufferSubgraph()
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Method Details
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getDirectedEdges
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getNodes
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getEnvelope
Computes the envelope of the edges in the subgraph. The envelope is cached after being computed.- Returns:
- the envelope of the graph.
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getRightmostCoordinate
Gets the rightmost coordinate in the edges of the subgraph -
create
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
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addReachable
Adds all nodes and edges reachable from this node to the subgraph. Uses an explicit stack to avoid a large depth of recursion.- Parameters:
node
- a node known to be in the subgraph
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add
Adds the argument node and all its out edges to the subgraph- Parameters:
node
- the node to addnodeStack
- the current set of nodes being traversed
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clearVisitedEdges
private void clearVisitedEdges() -
computeDepth
public void computeDepth(int outsideDepth) -
computeDepths
Compute depths for all dirEdges via breadth-first traversal of nodes in graph- Parameters:
startEdge
- edge to start processing with
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computeNodeDepth
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copySymDepths
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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
BufferSubgraphs are compared on the x-value of their rightmost Coordinate. This defines a partial ordering on the graphs such that:g1 >= g2 invalid input: '<'==> 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 interfaceComparable
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