+ // max vertical step in a tile in naut. miles
+ static final double tile_size_nmi = 1.0;
+
+ static final int px_size = 512;
+
+ private static Point2D.Double translatePoint(Point2D.Double p,
+ Point2D.Double d)
+ {
+ return new Point2D.Double(p.x + d.x, p.y + d.y);
+ }
+
+ static class LatLng {
+ public double lat, lng;
+ public LatLng(double lat, double lng) {
+ this.lat = lat;
+ this.lng = lng;
+ }
+ }
+
+ // based on google js
+ // http://maps.gstatic.com/intl/en_us/mapfiles/api-3/2/10/main.js
+ // search for fromLatLngToPoint and fromPointToLatLng
+ private static Point2D.Double pt(LatLng latlng, int zoom) {
+ double scale_x = 256/360.0 * Math.pow(2, zoom);
+ double scale_y = 256/(2.0*Math.PI) * Math.pow(2, zoom);
+ return pt(latlng, scale_x, scale_y);
+ }
+
+ private static Point2D.Double pt(LatLng latlng,
+ double scale_x, double scale_y)
+ {
+ Point2D.Double res = new Point2D.Double();
+ double e;
+
+ res.x = latlng.lng * scale_x;
+
+ e = Math.sin(Math.toRadians(latlng.lat));
+ e = Math.max(e,-(1-1.0E-15));
+ e = Math.min(e, 1-1.0E-15 );
+
+ res.y = 0.5*Math.log((1+e)/(1-e))*-scale_y;
+ return res;
+ }
+
+ static private LatLng latlng(Point2D.Double pt,
+ double scale_x, double scale_y)
+ {
+ double lat, lng;
+ double rads;
+
+ lng = pt.x/scale_x;
+ rads = 2 * Math.atan(Math.exp(-pt.y/scale_y));
+ lat = Math.toDegrees(rads - Math.PI/2);
+
+ return new LatLng(lat,lng);
+ }
+
+ int zoom;
+ double scale_x, scale_y;
+
+ private Point2D.Double pt(double lat, double lng) {
+ return pt(new LatLng(lat, lng), scale_x, scale_y);
+ }
+
+ private LatLng latlng(double x, double y) {
+ return latlng(new Point2D.Double(x,y), scale_x, scale_y);
+ }
+ private LatLng latlng(Point2D.Double pt) {
+ return latlng(pt, scale_x, scale_y);
+ }
+
+ AltosSiteMapTile [] mapTiles = new AltosSiteMapTile[9];
+ Point2D.Double [] tileOffset = new Point2D.Double[9];
+
+ private Point2D.Double getBaseLocation(double lat, double lng) {
+ Point2D.Double locn, north_step;
+
+ zoom = 2;
+ // stupid loop structure to please Java's control flow analysis
+ do {
+ zoom++;
+ scale_x = 256/360.0 * Math.pow(2, zoom);
+ scale_y = 256/(2.0*Math.PI) * Math.pow(2, zoom);
+ locn = pt(lat, lng);
+ north_step = pt(lat+tile_size_nmi/60.0, lng);
+ if (locn.y - north_step.y > px_size)
+ break;
+ } while (zoom < 22);
+ locn.x = -px_size * Math.floor(locn.x/px_size);
+ locn.y = -px_size * Math.floor(locn.y/px_size);
+ return locn;
+ }
+