1 files changed, 29 insertions, 11 deletions

diff --git a/main/src/cgeo/geocaching/connector/gc/Tile.java b/main/src/cgeo/geocaching/connector/gc/Tile.java
index 003ff37..e62debb 100644
--- a/main/src/cgeo/geocaching/connector/gc/Tile.java
+++ b/main/src/cgeo/geocaching/connector/gc/Tile.java
@@ -13,30 +13,45 @@ import cgeo.geocaching.geopoint.Geopoint;
  */
 public class Tile {
 
+    public static final double LATITUDE_MIN = -85.05112878;
+    public static final double LATITUDE_MAX = 85.05112878;
+    public static final double LONGITUDE_MIN = -180;
+    public static final double LONGITUDE_MAX = 180;
+
     public static final int TILE_SIZE = 256;
     public static final int ZOOMLEVEL_MAX = 18;
     public static final int ZOOMLEVEL_MIN = 0;
 
+    public static final int[] NUMBER_OF_TILES = new int[ZOOMLEVEL_MAX - ZOOMLEVEL_MIN + 1];
+    public static final int[] NUMBER_OF_PIXELS = new int[ZOOMLEVEL_MAX - ZOOMLEVEL_MIN + 1];
+    static {
+        for (int z = ZOOMLEVEL_MIN; z <= ZOOMLEVEL_MAX; z++) {
+            NUMBER_OF_TILES[z] = 1 << z;
+            NUMBER_OF_PIXELS[z] = TILE_SIZE * 1 << z;
+        }
+    }
+
     private final int tileX;
     private final int tileY;
     private final int zoomlevel;
-    private final int numberOfTiles;
 
     public Tile(Geopoint origin, int zoomlevel) {
+        assert zoomlevel >= ZOOMLEVEL_MIN && zoomlevel <= ZOOMLEVEL_MAX : "zoomlevel out of range";
+
         this.zoomlevel = zoomlevel;
-        numberOfTiles = 1 << zoomlevel;
         tileX = calcX(origin);
         tileY = calcY(origin);
     }
 
     public Tile(int tileX, int tileY, int zoomlevel) {
+        assert zoomlevel >= ZOOMLEVEL_MIN && zoomlevel <= ZOOMLEVEL_MAX : "zoomlevel out of range";
+
         this.zoomlevel = zoomlevel;
-        numberOfTiles = 1 << zoomlevel;
         this.tileX = tileX;
         this.tileY = tileY;
     }
 
-    public long getZoomlevel() {
+    public int getZoomlevel() {
         return zoomlevel;
     }
 
@@ -46,7 +61,7 @@ public class Tile {
      * @see http://developers.cloudmade.com/projects/tiles/examples/convert-coordinates-to-tile-numbers
      */
     private int calcX(final Geopoint origin) {
-        return (int) ((origin.getLongitude() + 180.0) / 360.0 * numberOfTiles);
+        return (int) ((origin.getLongitude() + 180.0) / 360.0 * NUMBER_OF_TILES[this.zoomlevel]);
     }
 
     public int getX() {
@@ -63,9 +78,13 @@ public class Tile {
      * @see http://developers.cloudmade.com/projects/tiles/examples/convert-coordinates-to-tile-numbers
      */
     private int calcY(final Geopoint origin) {
-        double lat_rad = Math.toRadians(origin.getLatitude());
 
-        return (int) ((1 - (Math.log(Math.tan(lat_rad) + (1 / Math.cos(lat_rad))) / Math.PI)) / 2 * numberOfTiles);
+        // double latRad = Math.toRadians(origin.getLatitude());
+        // return (int) ((1 - (Math.log(Math.tan(latRad) + (1 / Math.cos(latRad))) / Math.PI)) / 2 * numberOfTiles);
+
+        // Optimization from Bing
+        double sinLatRad = Math.sin(Math.toRadians(origin.getLatitude()));
+        return (int) ((0.5 - Math.log((1 + sinLatRad) / (1 - sinLatRad)) / (4 * Math.PI)) * NUMBER_OF_TILES[this.zoomlevel]);
     }
 
     /**
@@ -77,11 +96,10 @@ public class Tile {
 
         double pixX = tileX * TILE_SIZE + pos.x * 4;
         double pixY = tileY * TILE_SIZE + pos.y * 4;
-        long numberOfPixels = TILE_SIZE * numberOfTiles;
 
-        double lon = ((360.0 * pixX) / numberOfPixels) - 180.0;
-        double latRad = Math.atan(Math.sinh(Math.PI * (1 - 2 * pixY / numberOfPixels)));
-        return new Geopoint(latRad * Geopoint.rad2deg, lon);
+        double lonDeg = ((360.0 * pixX) / NUMBER_OF_PIXELS[this.zoomlevel]) - 180.0;
+        double latRad = Math.atan(Math.sinh(Math.PI * (1 - 2 * pixY / NUMBER_OF_PIXELS[this.zoomlevel])));
+        return new Geopoint(Math.toDegrees(latRad), lonDeg);
     }
 
     @Override