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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.index.quadtree;

import com.vividsolutions.jts.geom.Coordinate;
import com.vividsolutions.jts.geom.Envelope;
import com.vividsolutions.jts.util.Assert;

/**
 * QuadRoot is the root of a single Quadtree.  It is centred at the origin,
 * and does not have a defined extent.
 *
 * @version 1.7
 */
public class Root
  extends NodeBase
{

  // the singleton root quad is centred at the origin.
  private static final Coordinate origin = new Coordinate(0.0, 0.0);

  public Root()
  {
  }

  /**
   * Insert an item into the quadtree this is the root of.
   */
  public void insert(Envelope itemEnv, Object item)
  {
    int index = getSubnodeIndex(itemEnv, origin.x, origin.y);
    // if index is -1, itemEnv must cross the X or Y axis.
    if (index == -1) {
      add(item);
      return;
    }
    /**
     * the item must be contained in one quadrant, so insert it into the
     * tree for that quadrant (which may not yet exist)
     */
    Node node = subnode[index];
    /**
     *  If the subquad doesn't exist or this item is not contained in it,
     *  have to expand the tree upward to contain the item.
     */

    if (node == null || ! node.getEnvelope().contains(itemEnv)) {
       Node largerNode = Node.createExpanded(node, itemEnv);
       subnode[index] = largerNode;
    }
    /**
     * At this point we have a subquad which exists and must contain
     * contains the env for the item.  Insert the item into the tree.
     */
    insertContained(subnode[index], itemEnv, item);
    //System.out.println("depth = " + root.depth() + " size = " + root.size());
    //System.out.println(" size = " + size());
  }

  /**
   * insert an item which is known to be contained in the tree rooted at
   * the given QuadNode root.  Lower levels of the tree will be created
   * if necessary to hold the item.
   */
  private void insertContained(Node tree, Envelope itemEnv, Object item)
  {
    Assert.isTrue(tree.getEnvelope().contains(itemEnv));
   /**
    * Do NOT create a new quad for zero-area envelopes - this would lead
    * to infinite recursion. Instead, use a heuristic of simply returning
    * the smallest existing quad containing the query
    */
    boolean isZeroX = IntervalSize.isZeroWidth(itemEnv.getMinX(), itemEnv.getMaxX());
    boolean isZeroY = IntervalSize.isZeroWidth(itemEnv.getMinY(), itemEnv.getMaxY());
    NodeBase node;
    if (isZeroX || isZeroY)
      node = tree.find(itemEnv);
    else
      node = tree.getNode(itemEnv);
    node.add(item);
  }

  protected boolean isSearchMatch(Envelope searchEnv)
  {
    return true;
  }


}