com.vividsolutions.jts.algorithm.InteriorPointLine 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.algorithm;

import com.vividsolutions.jts.geom.*;

/**
 * Computes a point in the interior of an linear geometry.
 * Algorithm
 * 
 * Find an interior vertex which is closest to
 * the centroid of the linestring.
 * 
If there is no interior vertex, find the endpoint which is
 * closest to the centroid.
 * 
 *
 * @version 1.7
 */
public class InteriorPointLine {

  private Coordinate centroid;
  private double minDistance = Double.MAX_VALUE;

  private Coordinate interiorPoint = null;

  public InteriorPointLine(Geometry g)
  {
    centroid = g.getCentroid().getCoordinate();
    addInterior(g);
    if (interiorPoint == null)
      addEndpoints(g);
  }

  public Coordinate getInteriorPoint()
  {
    return interiorPoint;
  }

  /**
   * Tests the interior vertices (if any)
   * defined by a linear Geometry for the best inside point.
   * If a Geometry is not of dimension 1 it is not tested.
   * @param geom the geometry to add
   */
  private void addInterior(Geometry geom)
  {
    if (geom instanceof LineString) {
      addInterior(geom.getCoordinates());
    }
    else if (geom instanceof GeometryCollection) {
      GeometryCollection gc = (GeometryCollection) geom;
      for (int i = 0; i < gc.getNumGeometries(); i++) {
        addInterior(gc.getGeometryN(i));
      }
    }
  }
  private void addInterior(Coordinate[] pts)
  {
    for (int i = 1; i < pts.length - 1; i++) {
      add(pts[i]);
    }
  }
  /**
   * Tests the endpoint vertices
   * defined by a linear Geometry for the best inside point.
   * If a Geometry is not of dimension 1 it is not tested.
   * @param geom the geometry to add
   */
  private void addEndpoints(Geometry geom)
  {
    if (geom instanceof LineString) {
      addEndpoints(geom.getCoordinates());
    }
    else if (geom instanceof GeometryCollection) {
      GeometryCollection gc = (GeometryCollection) geom;
      for (int i = 0; i < gc.getNumGeometries(); i++) {
        addEndpoints(gc.getGeometryN(i));
      }
    }
  }
  private void addEndpoints(Coordinate[] pts)
  {
    add(pts[0]);
    add(pts[pts.length - 1]);
  }

  private void add(Coordinate point)
  {
    double dist = point.distance(centroid);
    if (dist < minDistance) {
      interiorPoint = new Coordinate(point);
      minDistance = dist;
    }
  }

}