/*
* GeoTools - The Open Source Java GIS Toolkit
* http://geotools.org
*
* (C) 2001-2006 Vivid Solutions
* (C) 2001-2008, Open Source Geospatial Foundation (OSGeo)
*
* 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;
* version 2.1 of the License.
*
* 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.
*/
package org.geotools.geometry.iso.operation.relate;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.geotools.geometry.iso.topograph2D.Coordinate;
import org.geotools.geometry.iso.topograph2D.Edge;
import org.geotools.geometry.iso.topograph2D.EdgeEnd;
import org.geotools.geometry.iso.topograph2D.EdgeIntersection;
import org.geotools.geometry.iso.topograph2D.EdgeIntersectionList;
import org.geotools.geometry.iso.topograph2D.Label;
/**
* An EdgeEndBuilder creates EdgeEnds for all the "split edges" created by the
* intersections determined for an Edge.
* Computes the {@link EdgeEnd}s which arise from a noded {@link Edge}.
*
*
*
*
* @source $URL$
*/
public class EdgeEndBuilder {
public EdgeEndBuilder() {
}
public List computeEdgeEnds(Iterator edges) {
List l = new ArrayList();
for (Iterator i = edges; i.hasNext();) {
Edge e = (Edge) i.next();
this.computeEdgeEnds(e, l);
}
return l;
}
/**
* Creates stub edges for all the intersections in this Edge (if any) and
* inserts them into the graph.
* @param edge
* @param l
*/
public void computeEdgeEnds(Edge edge, List l) {
EdgeIntersectionList eiList = edge.getEdgeIntersectionList();
// Debug.print(eiList);
// ensure that the list has entries for the first and last point of the
// edge
eiList.addEndpoints();
Iterator it = eiList.iterator();
EdgeIntersection eiPrev = null;
EdgeIntersection eiCurr = null;
// no intersections, so there is nothing to do
if (!it.hasNext())
return;
EdgeIntersection eiNext = (EdgeIntersection) it.next();
do {
eiPrev = eiCurr;
eiCurr = eiNext;
eiNext = null;
if (it.hasNext())
eiNext = (EdgeIntersection) it.next();
if (eiCurr != null) {
createEdgeEndForPrev(edge, l, eiCurr, eiPrev);
createEdgeEndForNext(edge, l, eiCurr, eiNext);
}
} while (eiCurr != null);
}
/**
* Create a EdgeStub for the edge before the intersection eiCurr. The
* previous intersection is provided in case it is the endpoint for the stub
* edge. Otherwise, the previous point from the parent edge will be the
* endpoint. <br>
* eiCurr will always be an EdgeIntersection, but eiPrev may be null.
* @param edge
* @param l
* @param eiCurr
* @param eiPrev
*/
private void createEdgeEndForPrev(Edge edge, List l, EdgeIntersection eiCurr,
EdgeIntersection eiPrev) {
int iPrev = eiCurr.segmentIndex;
if (eiCurr.dist == 0.0) {
// if at the start of the edge there is no previous edge
if (iPrev == 0)
return;
iPrev--;
}
Coordinate pPrev = edge.getCoordinate(iPrev);
// if prev intersection is past the previous vertex, use it instead
if (eiPrev != null && eiPrev.segmentIndex >= iPrev)
pPrev = eiPrev.coord;
Label label = new Label(edge.getLabel());
// since edgeStub is oriented opposite to it's parent edge, have to flip
// sides for edge label
label.flip();
EdgeEnd e = new EdgeEnd(edge, eiCurr.coord, pPrev, label);
// e.print(System.out); System.out.println();
l.add(e);
}
/**
* Create a StubEdge for the edge after the intersection eiCurr. The next
* intersection is provided in case it is the endpoint for the stub edge.
* Otherwise, the next point from the parent edge will be the endpoint. <br>
* eiCurr will always be an EdgeIntersection, but eiNext may be null.
* @param edge
* @param l
* @param eiCurr
* @param eiNext
*/
private void createEdgeEndForNext(Edge edge, List l, EdgeIntersection eiCurr,
EdgeIntersection eiNext) {
int iNext = eiCurr.segmentIndex + 1;
// if there is no next edge there is nothing to do
if (iNext >= edge.getNumPoints() && eiNext == null)
return;
Coordinate pNext = edge.getCoordinate(iNext);
// if the next intersection is in the same segment as the current, use
// it as the endpoint
if (eiNext != null && eiNext.segmentIndex == eiCurr.segmentIndex)
pNext = eiNext.coord;
EdgeEnd e = new EdgeEnd(edge, eiCurr.coord, pNext, new Label(edge
.getLabel()));
// Debug.println(e);
l.add(e);
}
}