/*
* 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.linearref;
import org.locationtech.jts.geom.Coordinate;
import org.locationtech.jts.geom.Geometry;
import org.locationtech.jts.geom.LineString;
import org.locationtech.jts.geom.Lineal;
import org.locationtech.jts.geom.MultiLineString;
/**
* 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:
*
* <pre>
* for (LinearIterator it = new LinearIterator(...); it.hasNext(); it.next()) {
* ...
* int ci = it.getComponentIndex(); // for example
* int vi = it.getVertexIndex(); // for example
* ...
* }
* </pre>
*
* @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 <tt>true</tt> if the
* current state of the iterator represents a valid location
* on the linear geometry.
*
* @return <code>true</code> 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 <code>true</code> 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, <code>null</code> is returned.
*
* @return a {@link Coordinate} or <code>null</code>
*/
public Coordinate getSegmentEnd()
{
if (vertexIndex < getLine().getNumPoints() - 1)
return currentLine.getCoordinateN(vertexIndex + 1);
return null;
}
}