com.vividsolutions.jts.shape.random.RandomPointsBuilder Maven / Gradle / Ivy
The 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.shape.random;
import com.vividsolutions.jts.algorithm.locate.IndexedPointInAreaLocator;
import com.vividsolutions.jts.algorithm.locate.PointOnGeometryLocator;
import com.vividsolutions.jts.geom.*;
import com.vividsolutions.jts.shape.GeometricShapeBuilder;
/**
* Creates random point sets contained in a
* region defined by either a rectangular or a polygonal extent.
*
* @author mbdavis
*
*/
public class RandomPointsBuilder
extends GeometricShapeBuilder
{
protected Geometry maskPoly = null;
private PointOnGeometryLocator extentLocator;
/**
* Create a shape factory which will create shapes using the default
* {@link GeometryFactory}.
*/
public RandomPointsBuilder()
{
super(new GeometryFactory());
}
/**
* Create a shape factory which will create shapes using the given
* {@link GeometryFactory}.
*
* @param geomFact the factory to use
*/
public RandomPointsBuilder(GeometryFactory geomFact)
{
super(geomFact);
}
/**
* Sets a polygonal mask.
*
* @param mask
* @throws IllegalArgumentException if the mask is not polygonal
*/
public void setExtent(Geometry mask)
{
if (! (mask instanceof Polygonal))
throw new IllegalArgumentException("Only polygonal extents are supported");
this.maskPoly = mask;
setExtent(mask.getEnvelopeInternal());
extentLocator = new IndexedPointInAreaLocator(mask);
}
public Geometry getGeometry()
{
Coordinate[] pts = new Coordinate[numPts];
int i = 0;
while (i < numPts) {
Coordinate p = createRandomCoord(getExtent());
if (extentLocator != null && ! isInExtent(p))
continue;
pts[i++] = p;
}
return geomFactory.createMultiPoint(pts);
}
protected boolean isInExtent(Coordinate p)
{
if (extentLocator != null)
return extentLocator.locate(p) != Location.EXTERIOR;
return getExtent().contains(p);
}
protected Coordinate createCoord(double x, double y)
{
Coordinate pt = new Coordinate(x, y);
geomFactory.getPrecisionModel().makePrecise(pt);
return pt;
}
protected Coordinate createRandomCoord(Envelope env)
{
double x = env.getMinX() + env.getWidth() * Math.random();
double y = env.getMinY() + env.getHeight() * Math.random();
return createCoord(x, y);
}
}