Android Open Source - aBusTripMK Mercator

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License

The source code is released under:

GNU General Public License

Java Source Code

// Created by plusminus on 17:53:07 - 25.09.2008
package org.andnav.osm.views.util;
/*from w w  w  .j a v a2s  .  c  o m*/
import org.andnav.osm.util.BoundingBoxE6;
import org.andnav.osm.util.GeoPoint;
import org.andnav.osm.views.util.constants.OpenStreetMapViewConstants;

import android.graphics.Point;

/**
 * http://wiki.openstreetmap.org/index.php/Mercator 
 * @author Nicolas Gramlich
 *
 */
public class Mercator implements OpenStreetMapViewConstants {
        // ===========================================================
        // Constants
        // ===========================================================

        final static double DEG2RAD = Math.PI / 180;
        
        // ===========================================================
        // Fields
        // ===========================================================

        // ===========================================================
        // Constructors
        // ===========================================================

        // ===========================================================
        // Getter & Setter
        // ===========================================================

        // ===========================================================
        // Methods from SuperClass/Interfaces
        // ===========================================================

        // ===========================================================
        // Methods
        // ===========================================================
        
        /**
         * Mercator projection of GeoPoint at given zoom level 
         * @param aLat latitude in degrees [-89000000 to 89000000]
         * @param aLon longitude in degrees [-180000000 to 180000000]
         * @param zoom zoom level
         * @param aUseAsReturnValue
         * @return Point with x,y in the range [-2^(zoom-1) to 2^(zoom-1)]
         */
        public static int[] projectGeoPoint(final int aLatE6, final int aLonE6, final int aZoom, final int[] reuse) {
                return projectGeoPoint(aLatE6 * 1E-6, aLonE6 * 1E-6, aZoom, reuse);
        }
        
        /**
         * Mercator projection of GeoPoint at given zoom level 
         * @param aLat latitude in degrees [-89 to 89]
         * @param aLon longitude in degrees [-180 to 180]
         * @param zoom zoom level
         * @param aUseAsReturnValue
         * @return Point with x,y in the range [-2^(zoom-1) to 2^(zoom-1)]
         */
        public static int[] projectGeoPoint(final double aLat, final double aLon, final int aZoom, final int[] aUseAsReturnValue) {
                final int[] out = (aUseAsReturnValue != null) ? aUseAsReturnValue : new int[2];

                out[MAPTILE_LONGITUDE_INDEX] = (int) Math.floor((aLon + 180) / 360 * (1 << aZoom));
                out[MAPTILE_LATITUDE_INDEX] = (int) Math.floor((1 - Math.log(Math.tan(aLat * DEG2RAD) + 1 / Math.cos(aLat * DEG2RAD)) / Math.PI) / 2 * (1 << aZoom));

                return out;
        }
        
        /**
         * Mercator projection of GeoPoint at given zoom level 
         * @param aGeoPoint
         * @param zoom zoom level
         * @param aUseAsReturnValue
         * @return Point with x,y in the range [-2^(zoom-1) to 2^(zoom-1)]
         */
        public static Point projectGeoPoint(final GeoPoint aGeoPoint, final int aZoom, final Point aUseAsReturnValue) {
                final Point p = (aUseAsReturnValue != null) ? aUseAsReturnValue : new Point();
                
                final double aLon = aGeoPoint.getLongitudeE6()*1E-6;
                final double aLat = aGeoPoint.getLatitudeE6()*1E-6; 
                p.x = (int) Math.floor((aLon + 180) / 360 * (1 << aZoom));
                p.y = (int) Math.floor((1 - Math.log(Math.tan(aLat * DEG2RAD) + 1 / Math.cos(aLat * DEG2RAD)) / Math.PI) / 2 * (1 << aZoom));
                
                return p;
        }
        
        /**
         * Get bounding box from reverse Mercator projection.
         * @param left
         * @param top
         * @param right
         * @param bottom
         * @param zoom
         * @return
         */
        public static BoundingBoxE6 getBoundingBoxFromCoords(final int left, final int top, final int right, final int bottom, final int zoom) {
                return new BoundingBoxE6(tile2lat(top, zoom), tile2lon(right, zoom), tile2lat(bottom, zoom), tile2lon(left, zoom));
        }
        
        /**
         * Get bounding box from reverse Mercator projection.
         * @param aMapTile
         * @param aZoom
         * @return
         */
        public static BoundingBoxE6 getBoundingBoxFromMapTile(final int[] aMapTile, final int aZoom) {
                final int y = aMapTile[MAPTILE_LATITUDE_INDEX];
                final int x = aMapTile[MAPTILE_LONGITUDE_INDEX];
                return new BoundingBoxE6(tile2lat(y, aZoom), tile2lon(x + 1, aZoom), tile2lat(y + 1, aZoom), tile2lon(x, aZoom));
        }
        
        /**
         * Reverse Mercator projection of Point at given zoom level
         * 
         */
        public static GeoPoint projectPoint(int x, int y, int aZoom) {
                return new GeoPoint((int)(tile2lat(y, aZoom)*1E6), (int)(tile2lon(x, aZoom)*1E6));
        }
        
        public static double tile2lon(int x, int aZoom) {
                return ((double)x / (1 << aZoom) * 360.0) - 180;
        }

        public static double tile2lat(int y, int aZoom) {
                final double n = Math.PI - ((2.0 * Math.PI * y) / (1 << aZoom));
                return 180.0 / Math.PI * Math.atan(0.5 * (Math.exp(n) - Math.exp(-n)));
        }

        // ===========================================================
        // Inner and Anonymous Classes
        // ===========================================================
}

Java Source Code List

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