com.vividsolutions.jts.linearref.LinearIterator Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of JTSplus Show documentation
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.linearref;

import com.vividsolutions.jts.geom.*;

/**
 * An iterator over the components and coordinates of a linear geometry
 * ({@link LineString}s and {@link MultiLineString}s.
 *
 * The standard usage pattern for a {@link LinearIterator} is:
 *
 *  * for (LinearIterator it = new LinearIterator(...); it.hasNext(); it.next()) {
 *   ...
 *   int ci = it.getComponentIndex();   // for example
 *   int vi = it.getVertexIndex();      // for example
 *   ...
 * }
 * 
 *
 * @version 1.7
 */
public class LinearIterator
{
  private static int segmentEndVertexIndex(LinearLocation loc)
  {
    if (loc.getSegmentFraction() > 0.0)
      return loc.getSegmentIndex() + 1;
    return loc.getSegmentIndex();
  }

  private Geometry linearGeom;
  private final int numLines;

  /**
   * Invariant: currentLine <> null if the iterator is pointing at a valid coordinate
   */
  private LineString currentLine;
  private int componentIndex = 0;
  private int vertexIndex = 0;

  /**
   * Creates an iterator initialized to the start of a linear {@link Geometry}
   *
   * @param linear the linear geometry to iterate over
   * @throws IllegalArgumentException if linearGeom is not lineal
   */
  public LinearIterator(Geometry linear) {
    this(linear, 0, 0);
  }

  /**
   * Creates an iterator starting at
   * a {@link LinearLocation} on a linear {@link Geometry}
   *
   * @param linear the linear geometry to iterate over
   * @param start the location to start at
   * @throws IllegalArgumentException if linearGeom is not lineal
   */
  public LinearIterator(Geometry linear, LinearLocation start) {
    this(linear, start.getComponentIndex(), segmentEndVertexIndex(start));
  }

  /**
   * Creates an iterator starting at
   * a specified component and vertex in a linear {@link Geometry}
   *
   * @param linearGeom the linear geometry to iterate over
   * @param componentIndex the component to start at
   * @param vertexIndex the vertex to start at
   * @throws IllegalArgumentException if linearGeom is not lineal
   */
  public LinearIterator(Geometry linearGeom, int componentIndex, int vertexIndex) 
  {
  	if (! (linearGeom instanceof Lineal))
  			throw new IllegalArgumentException("Lineal geometry is required");
    this.linearGeom = linearGeom;
    numLines = linearGeom.getNumGeometries();
    this.componentIndex = componentIndex;
    this.vertexIndex = vertexIndex;
    loadCurrentLine();
  }

  private void loadCurrentLine()
  {
    if (componentIndex >= numLines) {
      currentLine = null;
      return;
    }
    currentLine = (LineString) linearGeom.getGeometryN(componentIndex);
  }

  /**
   * Tests whether there are any vertices left to iterator over.
   * Specifically, hasNext() return true if the
   * current state of the iterator represents a valid location
   * on the linear geometry. 
   * 
   * @return true if there are more vertices to scan
   */
  public boolean hasNext()
  {
    if (componentIndex >= numLines) return false;
    if (componentIndex == numLines - 1
        && vertexIndex >= currentLine.getNumPoints())
      return false;
    return true;
  }

  /**
   * Moves the iterator ahead to the next vertex and (possibly) linear component.
   */
  public void next()
  {
    if (! hasNext()) return;

    vertexIndex++;
    if (vertexIndex >= currentLine.getNumPoints()) {
      componentIndex++;
      loadCurrentLine();
      vertexIndex = 0;
    }
  }

  /**
   * Checks whether the iterator cursor is pointing to the
   * endpoint of a component {@link LineString}.
   *
   * @return true if the iterator is at an endpoint
   */
  public boolean isEndOfLine() {
    if (componentIndex >= numLines) return false;
    //LineString currentLine = (LineString) linear.getGeometryN(componentIndex);
    if (vertexIndex < currentLine.getNumPoints() - 1)
      return false;
    return true;
  }

  /**
   * The component index of the vertex the iterator is currently at.
   * @return the current component index
   */
  public int getComponentIndex() { return componentIndex; }

  /**
   * The vertex index of the vertex the iterator is currently at.
   * @return the current vertex index
   */
  public int getVertexIndex() { return vertexIndex; }

  /**
   * Gets the {@link LineString} component the iterator is current at.
   * @return a linestring
   */
  public LineString getLine()  {    return currentLine;  }

  /**
   * Gets the first {@link Coordinate} of the current segment.
   * (the coordinate of the current vertex).
   * @return a {@link Coordinate}
   */
  public Coordinate getSegmentStart() { return currentLine.getCoordinateN(vertexIndex); }

  /**
   * Gets the second {@link Coordinate} of the current segment.
   * (the coordinate of the next vertex).
   * If the iterator is at the end of a line, null is returned.
   *
   * @return a {@link Coordinate} or null
   */
  public Coordinate getSegmentEnd()
  {
    if (vertexIndex < getLine().getNumPoints() - 1)
      return currentLine.getCoordinateN(vertexIndex + 1);
    return null;
  }
}