-use absolute x/y position and scale in MapPosition

- scale calculations look much nicer now, better always
   use 'double' unless you are sure about precision required
- finally got rid of zoomLevel relative coordinates
- cleanup MapPosition and MercatorProjection API functions

src/org/oscim/database/mapfile/Projection.java

@@ -0,0 +1,108 @@
+/*
+ * Copyright 2010, 2011, 2012 mapsforge.org
+ *
+ * This program 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 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License along with
+ * this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package org.oscim.database.mapfile;
+
+import org.oscim.core.MercatorProjection;
+import org.oscim.core.Tile;
+
+public class Projection {
+
+
+	/**
+	 * Converts a tile X number at a certain zoom level to a longitude
+	 * coordinate.
+	 *
+	 * @param tileX
+	 *            the tile X number that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the number should be converted.
+	 * @return the longitude value of the tile X number.
+	 */
+	public static double tileXToLongitude(long tileX, int zoomLevel) {
+		return MercatorProjection.pixelXToLongitude(tileX * Tile.TILE_SIZE, zoomLevel);
+	}
+
+	/**
+	 * Converts a tile Y number at a certain zoom level to a latitude
+	 * coordinate.
+	 *
+	 * @param tileY
+	 *            the tile Y number that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the number should be converted.
+	 * @return the latitude value of the tile Y number.
+	 */
+	public static double tileYToLatitude(long tileY, int zoomLevel) {
+		return MercatorProjection.pixelYToLatitude(tileY * Tile.TILE_SIZE, zoomLevel);
+	}
+
+	/**
+	 * Converts a latitude coordinate (in degrees) to a tile Y number at a
+	 * certain zoom level.
+	 *
+	 * @param latitude
+	 *            the latitude coordinate that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the coordinate should be converted.
+	 * @return the tile Y number of the latitude value.
+	 */
+	public static long latitudeToTileY(double latitude, int zoomLevel) {
+		return pixelYToTileY(MercatorProjection.latitudeToPixelY(latitude, zoomLevel), zoomLevel);
+	}
+
+	/**
+	 * Converts a longitude coordinate (in degrees) to the tile X number at a
+	 * certain zoom level.
+	 *
+	 * @param longitude
+	 *            the longitude coordinate that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the coordinate should be converted.
+	 * @return the tile X number of the longitude value.
+	 */
+	public static long longitudeToTileX(double longitude, int zoomLevel) {
+		return pixelXToTileX(MercatorProjection.longitudeToPixelX(longitude, zoomLevel), zoomLevel);
+	}
+
+	/**
+	 * Converts a pixel X coordinate to the tile X number.
+	 *
+	 * @param pixelX
+	 *            the pixel X coordinate that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the coordinate should be converted.
+	 * @return the tile X number.
+	 */
+	public static int pixelXToTileX(double pixelX, int zoomLevel) {
+		return (int) Math.min(Math.max(pixelX / Tile.TILE_SIZE, 0),
+				Math.pow(2, zoomLevel) - 1);
+	}
+	/**
+	 * Converts a pixel Y coordinate to the tile Y number.
+	 *
+	 * @param pixelY
+	 *            the pixel Y coordinate that should be converted.
+	 * @param zoomLevel
+	 *            the zoom level at which the coordinate should be converted.
+	 * @return the tile Y number.
+	 */
+	public static int pixelYToTileY(double pixelY, int zoomLevel) {
+		return (int) Math.min(Math.max(pixelY / Tile.TILE_SIZE, 0),
+				Math.pow(2, zoomLevel) - 1);
+	}
+	private Projection(){
+
+	}
+}