/*
* The JTS Topology Suite is a collection of Java classes that
* implement the fundamental operations required to validate a given
* geo-spatial data set to a known topological specification.
*
* Copyright (C) 2001 Vivid Solutions
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* For more information, contact:
*
* Vivid Solutions
* Suite #1A
* 2328 Government Street
* Victoria BC V8T 5G5
* Canada
*
* (250)385-6040
* www.vividsolutions.com
*/
package com.vividsolutions.jts.planargraph;
import java.util.*;
import com.vividsolutions.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 wich 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));
}
}