Application: gvSIG desktop

/*

 * Created on 02-oct-2006

 *

 * gvSIG. Sistema de Informaci?n Geogr?fica de la Generalitat Valenciana

 *

 * Copyright (C) 2004 IVER T.I. and Generalitat Valenciana.

 *

 * This program is free software; you can redistribute it and/or

 * modify it under the terms of the GNU General Public License

 * as published by the Free Software Foundation; either version 2

 * of the License, or (at your option) any later version.

 *

 * This program 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 General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, write to the Free Software

 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307,USA.

 *

 * For more information, contact:

 *

 *  Generalitat Valenciana

 *   Conselleria d'Infraestructures i Transport

 *   Av. Blasco Ib??ez, 50

 *   46010 VALENCIA

 *   SPAIN

 *

 *      +34 963862235

 *   gvsig@gva.es

 *      www.gvsig.gva.es

 *

 *    or

 *

 *   IVER T.I. S.A

 *   Salamanca 50

 *   46005 Valencia

 *   Spain

 *

 *   +34 963163400

 *   dac@iver.es

 */

/* CVS MESSAGES:

*

* $Id: SnapSimpleMCSweepLineIntersector.java 9178 2006-12-04 19:30:23Z azabala $

* $Log$

* Revision 1.3  2006-12-04 19:30:23  azabala

* *** empty log message ***

*

* Revision 1.1  2006/10/05 19:20:57  azabala

* first version in cvs

*

* Revision 1.1  2006/10/02 19:06:26  azabala

* First version in CVS

*

*

*/

package com.vividsolutions.jts.geomgraph.index;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Iterator;

import java.util.List;

import com.vividsolutions.jts.geomgraph.Edge;

import com.vividsolutions.jts.geomgraph.index.MonotoneChain;

import com.vividsolutions.jts.geomgraph.index.MonotoneChainEdge;

import com.vividsolutions.jts.geomgraph.index.SegmentIntersector;

import com.vividsolutions.jts.geomgraph.index.SimpleMCSweepLineIntersector;

import com.vividsolutions.jts.geomgraph.index.SweepLineEvent;

public class SnapSimpleMCSweepLineIntersector extends

                SimpleMCSweepLineIntersector {

         List events = new ArrayList();

          // statistics information

          int nOverlaps;

          public SnapSimpleMCSweepLineIntersector() {

          }

          public void computeIntersections(List edges, 

                          SegmentIntersector si, 

                          boolean testAllSegments)

          {

            if (testAllSegments)

              add(edges, null);

            else

              add(edges);

            computeIntersections(si);

          }

          public void computeIntersections(List edges0, List edges1, SegmentIntersector si)

          {

            add(edges0, edges0);

            add(edges1, edges1);

            computeIntersections(si);

          }

          private void add(List edges)

          {

            for (Iterator i = edges.iterator(); i.hasNext(); ) {

              Edge edge = (Edge) i.next();

              // edge is its own group

              add(edge, edge);

            }

          }

          private void add(List edges, Object edgeSet)

          {

            for (Iterator i = edges.iterator(); i.hasNext(); ) {

              Edge edge = (Edge) i.next();

              add(edge, edgeSet);

            }

          }

          private void add(Edge edge, Object edgeSet)

          {

            MonotoneChainEdge mce = edge.getMonotoneChainEdge();

            int[] startIndex = mce.getStartIndexes();

            for (int i = 0; i < startIndex.length - 1; i++) {

              MonotoneChain mc = new MonotoneChain(mce, i);

              SweepLineEvent insertEvent = new SweepLineEvent(edgeSet, 

                              mce.getMinX(i), 

                              null, mc);

              events.add(insertEvent);

              events.add(new SweepLineEvent(edgeSet, mce.getMaxX(i), insertEvent, mc));

            }

          }

          /**

           * Because Delete Events have a link to their corresponding Insert event,

           * it is possible to compute exactly the range of events which must be

           * compared to a given Insert event object.

           */

          private void prepareEvents()

          {

            Collections.sort(events);

            for (int i = 0; i < events.size(); i++ )

            {

              SweepLineEvent ev = (SweepLineEvent) events.get(i);

              if (ev.isDelete()) {

                ev.getInsertEvent().setDeleteEventIndex(i);

              }

            }

          }

          private void computeIntersections(SegmentIntersector si)

          {

            nOverlaps = 0;

            prepareEvents();

            for (int i = 0; i < events.size(); i++ )

            {

              SweepLineEvent ev = (SweepLineEvent) events.get(i);

              if (ev.isInsert()) {

                processOverlaps(i, ev.getDeleteEventIndex(), ev, si);

              }

            }

          }

          private void processOverlaps(int start, int end, SweepLineEvent ev0, SegmentIntersector si)

          {

            MonotoneChain mc0 = (MonotoneChain) ev0.getObject();

            /**

             * Since we might need to test for self-intersections,

             * include current insert event object in list of event objects to test.

             * Last index can be skipped, because it must be a Delete event.

             */

            for (int i = start; i < end; i++ ) {

              SweepLineEvent ev1 = (SweepLineEvent) events.get(i);

              if (ev1.isInsert()) {

                MonotoneChain mc1 = (MonotoneChain) ev1.getObject();

                // don't compare edges in same group

                // null group indicates that edges should be compared

                if (ev0.edgeSet == null || (ev0.edgeSet != ev1.edgeSet)) {

                  mc0.computeIntersections(mc1, si);

                  nOverlaps++;

                }

              }

            }

          }

}