/**
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.sis.core;
//JDK imports
import java.awt.geom.Area;
import java.awt.geom.Path2D;
import java.awt.geom.Rectangle2D;
//SIS imports
import org.apache.sis.distance.DistanceUtils;
/**
* Represents a 2D point associated with a radius to enable great circle
* estimation on earth surface.
*
*/
public class LatLonPointRadius {
private LatLon center;
private double radius;
/**
* Creates a representation of point-radius search region.
*
* @param center
* the center of the search region
* @param radius
* the radius of the search region
*/
public LatLonPointRadius(LatLon center, double radius) {
this.center = center;
this.radius = radius;
}
/**
* Gets the circular region approximation on the earth surface using haversine
* formula.
*
* @param numberOfPoints
* the number of points used to estimate the circular region
* @return an array of LatLon representing the points that estimate the
* circular region
*/
public LatLon[] getCircularRegionApproximation(int numberOfPoints) {
if (this.radius >= DistanceUtils.HALF_EARTH_CIRCUMFERENCE) {
LatLon[] points = new LatLon[5];
points[0] = new LatLon(-90.0, -180.0);
points[1] = new LatLon(90.0, -180.0);
points[2] = new LatLon(90.0, 180.0);
points[3] = new LatLon(-90.0, 180.0);
points[4] = points[0];
return points;
}
// plus one to add closing point
LatLon[] points = new LatLon[numberOfPoints + 1];
for (int i = 0; i < 360; i += (360 / numberOfPoints)) {
points[i] = DistanceUtils.getPointOnGreatCircle(this.center.getLat(),
this.center.getLon(), radius, i);
}
points[numberOfPoints] = points[0];
return points;
}
/**
* Calculates the rectangular region enclosing the circular search region.
*
* @param numberOfPoints
* the number of points used to estimate the circular search region
* @return Java Rectangle2D object that bounds the circlar search region
*/
public Rectangle2D getRectangularRegionApproximation(int numberOfPoints) {
if (this.radius >= DistanceUtils.HALF_EARTH_CIRCUMFERENCE) {
return new Rectangle2D.Double(0.0, 0.0, 360.0, 180.0);
}
int numberOfCrossOvers = 0;
Path2D path = new Path2D.Double();
LatLon initPT = DistanceUtils.getPointOnGreatCircle(this.center.getLat(),
this.center.getLon(), this.radius, 0);
path.moveTo(initPT.getShiftedLon(), initPT.getShiftedLat());
LatLon currPT = initPT;
for (int i = 1; i < 360; i++) {
LatLon pt = DistanceUtils.getPointOnGreatCircle(this.center.getLat(),
this.center.getLon(), this.radius, i);
path.lineTo(pt.getShiftedLon(), pt.getShiftedLat());
if (dateLineCrossOver(currPT.getNormLon(), pt.getNormLon())) {
numberOfCrossOvers++;
}
currPT = pt;
}
if (dateLineCrossOver(initPT.getNormLon(), currPT.getNormLon())) {
numberOfCrossOvers++;
}
/**
* If the path crosses the dateline once, it's a special case, so take care
* of it differently. It will need to include areas around the pole.
*/
if (numberOfCrossOvers == 1) {
Rectangle2D r = path.getBounds2D();
Rectangle2D lowerHalf = new Rectangle2D.Double(0.0, 0.0, 360.0, r
.getMaxY());
if (lowerHalf.contains(this.center.getShiftedLon(), this.center
.getShiftedLat())) {
return lowerHalf;
} else {
return new Rectangle2D.Double(0.0, r.getMinY(), 360.0, 180.0 - r
.getMinY());
}
}
if (path.contains(this.center.getShiftedLon(), this.center.getShiftedLat())) {
Rectangle2D r = path.getBounds2D();
if ((r.getMaxX() - r.getMinX()) > 359.0) {
return new Rectangle2D.Double(0.0, 0.0, 360.0, 180.0);
} else if (r.getMinX() < 0 || r.getMaxX() > 360.0) {
/**
* For circles that crosses the dateline instead of splitting in half
* and having to go down the tree twice, for first version span
* longitude 360.0 and use the exact height of the box
*/
return new Rectangle2D.Double(0.0, r.getY(), 360.0, r.getHeight());
} else {
return path.getBounds2D();
}
} else {
Area pathArea = new Area(path);
Area wholeMap = new Area(new Rectangle2D.Double(0.0, 0.0, 360.0, 180.0));
wholeMap.subtract(pathArea);
return wholeMap.getBounds2D();
}
}
/**
* Returns true if the line segment connecting the two specified longitudes
* crosses the international dateline.
*
* @param longitude1
* first longitude
* @param longitude2
* second longitude
* @return true if the line segment crosses the internation dateline, false
* otherwise
*/
private boolean dateLineCrossOver(double longitude1, double longitude2) {
if (Math.abs(longitude1 - longitude2) > 180.0)
return true;
return false;
}
}