com.vividsolutions.jts.operation.valid.SweeplineNestedRingTester Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of jts Show documentation

The JTS Topology Suite is an API for modelling and manipulating 2-dimensional linear geometry. It provides numerous geometric predicates and functions. JTS conforms to the Simple Features Specification for SQL published by the Open GIS Consortium.

There is a newer version: 1.13

Show newest version


/*
 * 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.valid;

import java.util.*;
import com.vividsolutions.jts.algorithm.*;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.geomgraph.*;
import com.vividsolutions.jts.index.sweepline.*;
import com.vividsolutions.jts.util.*;

/**
 * Tests whether any of a set of {@link LinearRing}s are
 * nested inside another ring in the set, using a {@link SweepLineIndex}
 * index to speed up the comparisons.
 *
 * @version 1.7
 */
public class SweeplineNestedRingTester
{

  private GeometryGraph graph;  // used to find non-node vertices
  private List rings = new ArrayList();
  //private Envelope totalEnv = new Envelope();
  private SweepLineIndex sweepLine;
  private Coordinate nestedPt = null;

  public SweeplineNestedRingTester(GeometryGraph graph)
  {
    this.graph = graph;
  }

  public Coordinate getNestedPoint() { return nestedPt; }

  public void add(LinearRing ring)
  {
    rings.add(ring);
  }

  public boolean isNonNested()
  {
    buildIndex();

    OverlapAction action = new OverlapAction();

    sweepLine.computeOverlaps(action);
    return action.isNonNested;
  }

  private void buildIndex()
  {
    sweepLine = new SweepLineIndex();

    for (int i = 0; i < rings.size(); i++) {
      LinearRing ring = (LinearRing) rings.get(i);
      Envelope env = ring.getEnvelopeInternal();
      SweepLineInterval sweepInt = new SweepLineInterval(env.getMinX(), env.getMaxX(), ring);
      sweepLine.add(sweepInt);
    }
  }

  private boolean isInside(LinearRing innerRing, LinearRing searchRing)
  {
    Coordinate[] innerRingPts = innerRing.getCoordinates();
    Coordinate[] searchRingPts = searchRing.getCoordinates();

    if (! innerRing.getEnvelopeInternal().intersects(searchRing.getEnvelopeInternal()))
      return false;

    Coordinate innerRingPt = IsValidOp.findPtNotNode(innerRingPts, searchRing, graph);
    Assert.isTrue(innerRingPt != null, "Unable to find a ring point not a node of the search ring");

    boolean isInside = CGAlgorithms.isPointInRing(innerRingPt, searchRingPts);
    if (isInside) {
      nestedPt = innerRingPt;
      return true;
    }
    return false;
  }


  class OverlapAction
    implements SweepLineOverlapAction
  {
    boolean isNonNested = true;

  public void overlap(SweepLineInterval s0, SweepLineInterval s1)
  {
    LinearRing innerRing = (LinearRing) s0.getItem();
    LinearRing searchRing = (LinearRing) s1.getItem();
    if (innerRing == searchRing) return;

    if (isInside(innerRing, searchRing))
      isNonNested = false;
  }

  }
}