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/**
* IntegerGeoPoint
* Copyright 2009 by Michael Peter Christen; mc@yacy.net, Frankfurt a. M., Germany
* first published 08.10.2009 on http://yacy.net
*
* This file is part of YaCy Content Integration
*
* 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 program in the file lgpl21.txt
* If not, see <http://www.gnu.org/licenses/>.
*/
package net.yacy.cora.geo;
/**
* GeoPoint implementation with Integer accuracy
*/
public class IntegerGeoPoint implements GeoPoint {
private final long latlon; // using one variable for the coordinate pair saves some space
public IntegerGeoPoint(double lat, double lon) {
this.latlon = (((long) coord2int(lat)) << 32) | (coord2int(lon));
}
public IntegerGeoPoint(int lat, int lon) {
this.latlon = (((long) coord2int(lat / 1e6d)) << 32) | (coord2int(lon / 1e6d));
}
@Override
public double lat() {
return int2coord((int) (this.latlon >>> 32));
}
@Override
public double lon() {
return int2coord((int) (this.latlon & (Integer.MAX_VALUE)));
}
/**
* get the implementation-dependent accuracy of the latitude
* @return
*/
@Override
public double accuracyLat() {
return Math.abs(int2coord(1) - int2coord(2));
}
/**
* get the implementation-dependent accuracy of the longitude
* @return
*/
@Override
public double accuracyLon() {
return Math.abs(int2coord(1) - int2coord(2));
}
private static final double maxint = new Double(Integer.MAX_VALUE).doubleValue();
private static final double upscale = maxint / 360.0d;
private static final int coord2int(double coord) {
return (int) ((coord + 180.0d) * upscale);
}
private static final double int2coord(int z) {
return (z / upscale) - 180.0d;
}
/**
* compute the hash code of a coordinate
* this produces identical hash codes for locations that are close to each other
*/
@Override
public int hashCode() {
return (int) ((this.latlon & Integer.MAX_VALUE) >> 1) + (int) (this.latlon >> 33);
}
/**
* equality test that is needed to use the class inside HashMap/HashSet
*/
@Override
public boolean equals(final Object o) {
if (!(o instanceof IntegerGeoPoint)) return false;
IntegerGeoPoint oo = (IntegerGeoPoint) o;
return (this.latlon == oo.latlon);
}
@Override
public String toString() {
return "[" + this.lat() + "," + this.lon() + "]";
}
public static void main(String[] args) {
double lat = 13.419444d;
double lon = 52.548611d;
GeoPoint c = new IntegerGeoPoint(lat, lon);
System.out.println(c.toString() + " #" + c.hashCode());
System.out.println("error: lat: " + (Math.abs(c.lat() - lat) / meter) + " meter; lon: " + (Math.abs(c.lon() - lon) / meter) + " meter");
System.out.println("accuracyLat = " + c.accuracyLat() / meter + " meter, accuracyLon = " + c.accuracyLon() / meter + " meter");
}
}
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