com.vividsolutions.jts.operation.relate.EdgeEndBuilder Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of JTSplus Show documentation
JTS Topology Suite 1.14 with additional functions for GeoSpark
There is a newer version: 0.1.4



/*
 * 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);
  }

}