hoot.services.geo.QuadTileCalculator.java Source code

Introduction

Here is the source code for hoot.services.geo.QuadTileCalculator.java

Source

/*
 * This file is part of Hootenanny.
 *
 * Hootenanny is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * --------------------------------------------------------------------
 *
 * The following copyright notices are generated automatically. If you
 * have a new notice to add, please use the format:
 * " * @copyright Copyright ..."
 * This will properly maintain the copyright information. DigitalGlobe
 * copyrights will be updated automatically.
 *
 * @copyright Copyright (C) 2013, 2014 DigitalGlobe (http://www.digitalglobe.com/)
 */
package hoot.services.geo;

import org.apache.commons.math.util.MathUtils;

/**
 * Calculates quad tiles: http://wiki.openstreetmap.org/wiki/QuadTiles
 */
public class QuadTileCalculator {
    /**
     * Calculates the quad tile for a point
     * 
     * @param latitude point's latitude
     * @param longitude points longitude
     * @return tile integer
     */
    public static long tileForPoint(final double latitude, final double longitude) {
        int lonInt = (int) MathUtils.round(((longitude + 180.0) * 65535.0 / 360.0), 0);
        int latInt = (int) MathUtils.round(((latitude + 90.0) * 65535.0 / 180.0), 0);

        //use a long here, because java doesn't have unsigned int
        long tileUnsigned = 0;
        for (int i = 15; i >= 0; i--) {
            //use y, x ordering
            tileUnsigned = (tileUnsigned << 1) | ((lonInt >> i) & 1);
            tileUnsigned = (tileUnsigned << 1) | ((latInt >> i) & 1);
        }
        assert (tileUnsigned >= 0);
        return tileUnsigned;
    }
}