org.locationtech.jts.operation.valid.IndexedNestedRingTester Maven / Gradle / Ivy

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/*
 * Copyright (c) 2016 Vivid Solutions.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
 * and the Eclipse Distribution License is available at
 *
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */
package org.locationtech.jts.operation.valid;

import java.util.ArrayList;
import java.util.List;

import org.locationtech.jts.algorithm.PointLocation;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.Envelope;
import org.locationtech.jts.geom.LinearRing;
import org.locationtech.jts.geomgraph.GeometryGraph;
import org.locationtech.jts.index.SpatialIndex;
import org.locationtech.jts.index.strtree.STRtree;

/**
 * Tests whether any of a set of {@link LinearRing}s are
 * nested inside another ring in the set, using a spatial
 * index to speed up the comparisons.
 *
 * @version 1.7
 */
public class IndexedNestedRingTester
{
  private GeometryGraph graph;  // used to find non-node vertices
  private List rings = new ArrayList();
  private Envelope totalEnv = new Envelope();
  private SpatialIndex index;
  private Coordinate nestedPt;

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

  public Coordinate getNestedPoint() { return nestedPt; }

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

  public boolean isNonNested()
  {
    buildIndex();

    for (int i = 0; i < rings.size(); i++) {
      LinearRing innerRing = (LinearRing) rings.get(i);
      Coordinate[] innerRingPts = innerRing.getCoordinates();

      List results = index.query(innerRing.getEnvelopeInternal());
//System.out.println(results.size());
      for (int j = 0; j < results.size(); j++) {
        LinearRing searchRing = (LinearRing) results.get(j);
        Coordinate[] searchRingPts = searchRing.getCoordinates();

        if (innerRing == searchRing)
          continue;

        if (! innerRing.getEnvelopeInternal().intersects(searchRing.getEnvelopeInternal()))
          continue;

        Coordinate innerRingPt = IsValidOp.findPtNotNode(innerRingPts, searchRing, graph);
        
        /**
         * If no non-node pts can be found, this means
         * that the searchRing touches ALL of the innerRing vertices.
         * This indicates an invalid polygon, since either
         * the two holes create a disconnected interior, 
         * or they touch in an infinite number of points 
         * (i.e. along a line segment).
         * Both of these cases are caught by other tests,
         * so it is safe to simply skip this situation here.
         */
        if (innerRingPt == null)
          continue;

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

  private void buildIndex()
  {
    index = new STRtree();

    for (int i = 0; i < rings.size(); i++) {
      LinearRing ring = (LinearRing) rings.get(i);
      Envelope env = ring.getEnvelopeInternal();
      index.insert(env, ring);
    }
  }
}