com.vividsolutions.jts.simplify.LineSegmentIndex 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.simplify;

import java.util.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.index.*;
import com.vividsolutions.jts.index.quadtree.Quadtree;

/**
 * An spatial index on a set of {@link LineSegment}s.
 * Supports adding and removing items.
 *
 * @author Martin Davis
 */
class LineSegmentIndex
{
  private Quadtree index = new Quadtree();

  public LineSegmentIndex()
  {
  }

  public void add(TaggedLineString line) {
    TaggedLineSegment[] segs = line.getSegments();
    for (int i = 0; i < segs.length; i++) {
      TaggedLineSegment seg = segs[i];
      add(seg);
    }
  }

  public void add(LineSegment seg)
  {
    index.insert(new Envelope(seg.p0, seg.p1), seg);
  }

  public void remove(LineSegment seg)
  {
    index.remove(new Envelope(seg.p0, seg.p1), seg);
  }

  public List query(LineSegment querySeg)
  {
    Envelope env = new Envelope(querySeg.p0, querySeg.p1);

    LineSegmentVisitor visitor = new LineSegmentVisitor(querySeg);
    index.query(env, visitor);
    List itemsFound = visitor.getItems();

//    List listQueryItems = index.query(env);
//    System.out.println("visitor size = " + itemsFound.size()
//                       + "  query size = " + listQueryItems.size());
//    List itemsFound = index.query(env);

    return itemsFound;
  }
}

/**
 * ItemVisitor subclass to reduce volume of query results.
 */
class LineSegmentVisitor
    implements ItemVisitor
{
// MD - only seems to make about a 10% difference in overall time.

  private LineSegment querySeg;
  private ArrayList items = new ArrayList();

  public LineSegmentVisitor(LineSegment querySeg) {
    this.querySeg = querySeg;
  }

  public void visitItem(Object item)
  {
    LineSegment seg = (LineSegment) item;
    if (Envelope.intersects(seg.p0, seg.p1, querySeg.p0, querySeg.p1))
      items.add(item);
  }

  public ArrayList getItems() { return items; }
}