com.hazelcast.shaded.org.locationtech.jts.planargraph.DirectedEdgeStar Maven / Gradle / Ivy
/*
* Copyright (c) 2016 Vivid Solutions.
*
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License 2.0
* and Eclipse Distribution License v. 1.0 which accompanies this distribution.
* The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
* and the Eclipse Distribution License is available at
*
* http://www.eclipse.org/org/documents/edl-v10.php.
*/
package com.hazelcast.shaded.org.locationtech.jts.planargraph;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;
import com.hazelcast.shaded.org.locationtech.jts.geom.Coordinate;
/**
* A sorted collection of {@link DirectedEdge}s which leave a {@link Node}
* in a {@link PlanarGraph}.
*
* @version 1.7
*/
public class DirectedEdgeStar
{
/**
* The underlying list of outgoing DirectedEdges
*/
protected List outEdges = new ArrayList<>();
private boolean sorted = false;
/**
* Constructs a DirectedEdgeStar with no edges.
*/
public DirectedEdgeStar() {
}
/**
* Adds a new member to this DirectedEdgeStar.
*/
public void add(DirectedEdge de)
{
outEdges.add(de);
sorted = false;
}
/**
* Drops a member of this DirectedEdgeStar.
*/
public void remove(DirectedEdge de)
{
outEdges.remove(de);
}
/**
* Returns an Iterator over the DirectedEdges, in ascending order by angle with the positive x-axis.
*/
public Iterator iterator()
{
sortEdges();
return outEdges.iterator();
}
/**
* Returns the number of edges around the Node associated with this DirectedEdgeStar.
*/
public int getDegree() { return outEdges.size(); }
/**
* Returns the coordinate for the node at which this star is based
*/
public Coordinate getCoordinate()
{
Iterator it = iterator();
if (! it.hasNext()) return null;
DirectedEdge e = (DirectedEdge) it.next();
return e.getCoordinate();
}
/**
* Returns the DirectedEdges, in ascending order by angle with the positive x-axis.
*/
public List getEdges()
{
sortEdges();
return outEdges;
}
private void sortEdges()
{
if (! sorted) {
Collections.sort(outEdges);
sorted = true;
}
}
/**
* Returns the zero-based index of the given Edge, after sorting in ascending order
* by angle with the positive x-axis.
*/
public int getIndex(Edge edge)
{
sortEdges();
for (int i = 0; i < outEdges.size(); i++) {
DirectedEdge de = (DirectedEdge) outEdges.get(i);
if (de.getEdge() == edge)
return i;
}
return -1;
}
/**
* Returns the zero-based index of the given DirectedEdge, after sorting in ascending order
* by angle with the positive x-axis.
*/
public int getIndex(DirectedEdge dirEdge)
{
sortEdges();
for (int i = 0; i < outEdges.size(); i++) {
DirectedEdge de = (DirectedEdge) outEdges.get(i);
if (de == dirEdge)
return i;
}
return -1;
}
/**
* Returns value of i modulo the number of edges in this DirectedEdgeStar
* (i.e. the remainder when i is divided by the number of edges)
*
* @param i an integer (positive, negative or zero)
*/
public int getIndex(int i)
{
int modi = i % outEdges.size();
//I don't think modi can be 0 (assuming i is positive) [Jon Aquino 10/28/2003]
if (modi < 0) modi += outEdges.size();
return modi;
}
/**
* Returns the {@link DirectedEdge} on the left-hand (CCW)
* side of the given {@link DirectedEdge}
* (which must be a member of this DirectedEdgeStar).
*/
public DirectedEdge getNextEdge(DirectedEdge dirEdge)
{
int i = getIndex(dirEdge);
return (DirectedEdge) outEdges.get(getIndex(i + 1));
}
/**
* Returns the {@link DirectedEdge} on the right-hand (CW)
* side of the given {@link DirectedEdge}
* (which must be a member of this DirectedEdgeStar).
*/
public DirectedEdge getNextCWEdge(DirectedEdge dirEdge)
{
int i = getIndex(dirEdge);
return (DirectedEdge) outEdges.get(getIndex(i - 1));
}
}
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