com.vividsolutions.jts.operation.relate.EdgeEndBuilder Maven / Gradle / Ivy
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/*
* 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.operation.relate;
/**
* An EdgeEndBuilder creates EdgeEnds for all the "split edges"
* created by the
* intersections determined for an Edge.
*
* @version 1.7
*/
import java.util.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geomgraph.*;
import com.vividsolutions.jts.util.*;
/**
* Computes the {@link EdgeEnd}s which arise from a noded {@link Edge}.
*
* @version 1.7
*/
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();
computeEdgeEnds(e, l);
}
return l;
}
/**
* Creates stub edges for all the intersections in this
* Edge (if any) and inserts them into the graph.
*/
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.
*
* eiCurr will always be an EdgeIntersection, but eiPrev may be null.
*/
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.
*
* eiCurr will always be an EdgeIntersection, but eiNext may be null.
*/
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);
}
}