MercatorProjection.java
- /*
- * *************************************************************************************************************************************************************
- *
- * MapView: a JavaFX map renderer for tile-based servers
- * http://tidalwave.it/projects/mapview
- *
- * Copyright (C) 2024 - 2025 by Tidalwave s.a.s. (http://tidalwave.it)
- *
- * *************************************************************************************************************************************************************
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
- * CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.
- *
- * *************************************************************************************************************************************************************
- *
- * git clone https://bitbucket.org/tidalwave/mapview-src
- * git clone https://github.com/tidalwave-it/mapview-src
- *
- * *************************************************************************************************************************************************************
- */
- package it.tidalwave.mapviewer.spi;
- import jakarta.annotation.Nonnull;
- import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
- import it.tidalwave.mapviewer.MapCoordinates;
- import it.tidalwave.mapviewer.MapPoint;
- import it.tidalwave.mapviewer.Projection;
- import lombok.RequiredArgsConstructor;
- import static java.lang.Math.*;
- /***************************************************************************************************************************************************************
- *
- * An implementation of the Mercator Projection.
- *
- * @author Fabrizio Giudici
- *
- **************************************************************************************************************************************************************/
- @RequiredArgsConstructor
- public class MercatorProjection implements Projection
- {
- private static final double EARTH_RADIUS = 6378137;
- private static final double EARTH_CIRCUMFERENCE = EARTH_RADIUS * 2.0 * PI;
- private final int tileSize;
- /***********************************************************************************************************************************************************
- * {@inheritDoc}
- **********************************************************************************************************************************************************/
- @Override @Nonnull
- public MapPoint coordinatesToMapPoint (@Nonnull final MapCoordinates coordinates, final double zoomLevel)
- {
- final double arc = arc(zoomLevel);
- final double sinLat = sin(toRadians(coordinates.latitude()));
- final double metersX = EARTH_RADIUS * toRadians(coordinates.longitude());
- final double metersY = EARTH_RADIUS / 2 * log((1 + sinLat) / (1 - sinLat));
- final double x = (EARTH_CIRCUMFERENCE / 2 + metersX) / arc;
- final double y = (EARTH_CIRCUMFERENCE / 2 - metersY) / arc;
- return MapPoint.of(x, y);
- }
- /***********************************************************************************************************************************************************
- * {@inheritDoc}
- **********************************************************************************************************************************************************/
- @Override @Nonnull @SuppressFBWarnings("FL_FLOATS_AS_LOOP_COUNTERS")
- public MapCoordinates mapPointToCoordinates (@Nonnull final MapPoint mapPoint, final double zoomLevel)
- {
- final double arc = arc(zoomLevel);
- final double metersX = mapPoint.x() * arc - EARTH_CIRCUMFERENCE / 2;
- final double metersY = EARTH_CIRCUMFERENCE / 2 - mapPoint.y() * arc;
- final double exp = exp(metersY / (EARTH_RADIUS / 2));
- double lon = toDegrees(metersX / EARTH_RADIUS);
- final double lat = toDegrees(asin((exp - 1) / (exp + 1)));
- while (lon <= -180)
- {
- lon += 360;
- }
- while (lon > 180)
- {
- lon -= 360;
- }
- return MapCoordinates.of(lat, lon);
- }
- /***********************************************************************************************************************************************************
- * {@inheritDoc}
- **********************************************************************************************************************************************************/
- @Override
- public final double metersPerPixel (@Nonnull final MapCoordinates coordinates, final double zoomLevel)
- {
- return arc(zoomLevel) * cos(toRadians(coordinates.latitude()));
- }
-
- /***********************************************************************************************************************************************************
- * {@return the arc length, in meters, that corresponds to a tile}.
- * @param zoomLevel the zoom level
- **********************************************************************************************************************************************************/
- private double arc (final double zoomLevel)
- {
- return EARTH_CIRCUMFERENCE / (pow(2, zoomLevel) * tileSize); // was EARTH_CIRCUMFERENCE / ((1 << (maxZoomLevel - zoomLevel)) * tileSize);
- }
- }