Node.java

/*
 * 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.index.quadtree;

import org.locationtech.jts.geom.Envelope;
import org.locationtech.jts.util.Assert;

/**
 * Represents a node of a {@link Quadtree}.  Nodes contain
 * items which have a spatial extent corresponding to the node's position
 * in the quadtree.
 *
 * @version 1.7
 */
public class Node
  extends NodeBase
{
  public static Node createNode(Envelope env)
  {
    Key key = new Key(env);
    Node node = new Node(key.getEnvelope(), key.getLevel());
    return node;
  }

  public static Node createExpanded(Node node, Envelope addEnv)
  {
    Envelope expandEnv = new Envelope(addEnv);
    if (node != null) expandEnv.expandToInclude(node.env);

    Node largerNode = createNode(expandEnv);
    if (node != null) largerNode.insertNode(node);
    return largerNode;
  }

  private Envelope env;
  private double centrex;
  private double centrey;
  private int level;

  public Node(Envelope env, int level)
  {
    //this.parent = parent;
    this.env = env;
    this.level = level;
    centrex = (env.getMinX() + env.getMaxX()) / 2;
    centrey = (env.getMinY() + env.getMaxY()) / 2;
  }

  public Envelope getEnvelope() { return env; }

  protected boolean isSearchMatch(Envelope searchEnv)
  {
  	if (searchEnv == null) return false;
    return env.intersects(searchEnv);
  }

  /**
   * Returns the subquad containing the envelope <tt>searchEnv</tt>.
   * Creates the subquad if
   * it does not already exist.
   * 
   * @return the subquad containing the search envelope
   */
  public Node getNode(Envelope searchEnv)
  {
    int subnodeIndex = getSubnodeIndex(searchEnv, centrex, centrey);
    // if subquadIndex is -1 searchEnv is not contained in a subquad
    if (subnodeIndex != -1) {
      // create the quad if it does not exist
      Node node = getSubnode(subnodeIndex);
      // recursively search the found/created quad
      return node.getNode(searchEnv);
    }
    else {
      return this;
    }
  }

  /**
   * Returns the smallest <i>existing</i>
   * node containing the envelope.
   */
  public NodeBase find(Envelope searchEnv)
  {
    int subnodeIndex = getSubnodeIndex(searchEnv, centrex, centrey);
    if (subnodeIndex == -1)
      return this;
    if (subnode[subnodeIndex] != null) {
      // query lies in subquad, so search it
      Node node = subnode[subnodeIndex];
      return node.find(searchEnv);
    }
    // no existing subquad, so return this one anyway
    return this;
  }

  void insertNode(Node node)
  {
    Assert.isTrue(env == null || env.contains(node.env));
//System.out.println(env);
//System.out.println(quad.env);
    int index = getSubnodeIndex(node.env, centrex, centrey);
//System.out.println(index);
    if (node.level == level - 1) {
      subnode[index] = node;
//System.out.println("inserted");
    }
    else {
      // the quad is not a direct child, so make a new child quad to contain it
      // and recursively insert the quad
      Node childNode = createSubnode(index);
      childNode.insertNode(node);
      subnode[index] = childNode;
    }
  }

  /**
   * get the subquad for the index.
   * If it doesn't exist, create it
   */
  private Node getSubnode(int index)
  {
    if (subnode[index] == null) {
      subnode[index] = createSubnode(index);
    }
    return subnode[index];
  }

  private Node createSubnode(int index)
  {
        // create a new subquad in the appropriate quadrant

      double minx = 0.0;
      double maxx = 0.0;
      double miny = 0.0;
      double maxy = 0.0;

      switch (index) {
      case 0:
        minx = env.getMinX();
        maxx = centrex;
        miny = env.getMinY();
        maxy = centrey;
        break;
      case 1:
        minx = centrex;
        maxx = env.getMaxX();
        miny = env.getMinY();
        maxy = centrey;
        break;
      case 2:
        minx = env.getMinX();
        maxx = centrex;
        miny = centrey;
        maxy = env.getMaxY();
        break;
      case 3:
        minx = centrex;
        maxx = env.getMaxX();
        miny = centrey;
        maxy = env.getMaxY();
        break;
      }
      Envelope sqEnv = new Envelope(minx, maxx, miny, maxy);
      Node node = new Node(sqEnv, level - 1);
    return node;
  }

}