source: josm/trunk/src/org/openstreetmap/josm/data/coor/LatLon.java@ 1108

// License: GPL. Copyright 2007 by Immanuel Scholz and others
package org.openstreetmap.josm.data.coor;


import static org.openstreetmap.josm.tools.I18n.tr;

import org.openstreetmap.josm.data.Bounds;
import org.openstreetmap.josm.data.projection.Projection;

import java.text.DecimalFormat;
import java.text.NumberFormat;

/**
 * LatLon are unprojected latitude / longitude coordinates.
 * 
 * This class is immutable.
 * 
 * @author Imi
 */
public class LatLon extends Coordinate {

    private static DecimalFormat cDmsMinuteFormatter = new DecimalFormat("00");
    private static DecimalFormat cDmsSecondFormatter = new DecimalFormat("00.0");
    private static DecimalFormat cDdFormatter = new DecimalFormat("###0.0000");
    
    /** 
     * Possible ways to display coordinates 
     */ 
    public enum CoordinateFormat { 
        DECIMAL_DEGREES {public String toString() {return tr("Decimal Degrees");}},  
        DEGREES_MINUTES_SECONDS {public String toString() {return tr("Degrees Minutes Seconds");}}; 
    } 
    
    public static String dms(double pCoordinate) { 

        double tAbsCoord = Math.abs(pCoordinate);
        int tDegree = (int) tAbsCoord;
        double tTmpMinutes = (tAbsCoord - tDegree) * 60;
        int tMinutes = (int) tTmpMinutes;
        double tSeconds = (tTmpMinutes - tMinutes) * 60;

        return tDegree + "\u00B0" + cDmsMinuteFormatter.format(tMinutes) + "\'" 
            + cDmsSecondFormatter.format(tSeconds) + "\"";
    } 

    public LatLon(double lat, double lon) {
        super(lon, lat);
    }

    public double lat() {
        return y;
    }
    
    public String latToString(CoordinateFormat d) {
        switch(d) {
        case DECIMAL_DEGREES: return cDdFormatter.format(y);
        case DEGREES_MINUTES_SECONDS: return dms(y) + ((y < 0) ? tr("S") : tr("N"));
        default: return "ERR";
        }
    }
    
    public double lon() {
        return x;
    }
    
    public String lonToString(CoordinateFormat d) {
        switch(d) {
        case DECIMAL_DEGREES: return cDdFormatter.format(x);
        case DEGREES_MINUTES_SECONDS: return dms(x) + ((x < 0) ? tr("W") : tr("E"));
        default: return "ERR";
        }
    }
    
  

    /**
     * @return <code>true</code> if the other point has almost the same lat/lon
     * values, only differing by no more than
     * 1 / {@link org.openstreetmap.josm.data.projection.Projection#MAX_SERVER_PRECISION MAX_SERVER_PRECISION}.
     */
    public boolean equalsEpsilon(LatLon other) {
        final double p = 1/Projection.MAX_SERVER_PRECISION;
        return Math.abs(lat()-other.lat()) <= p && Math.abs(lon()-other.lon()) <= p;
    }

    /**
     * @return <code>true</code>, if the coordinate is outside the world, compared
         * by using lat/lon.
         */
        public boolean isOutSideWorld() {
                return lat() < -Projection.MAX_LAT || lat() > Projection.MAX_LAT || 
                        lon() < -Projection.MAX_LON || lon() > Projection.MAX_LON;
        }

        /**
         * @return <code>true</code> if this is within the given bounding box.
         */
        public boolean isWithin(Bounds b) {
                return lat() >= b.min.lat() && lat() <= b.max.lat() && lon() > b.min.lon() && lon() < b.max.lon();
        }
        
        /**
         * Computes the distance between this lat/lon and another point on the earth.
         * Uses spherical law of cosines formula, not Haversine.
         * @param other the other point.
         * @return distance in metres.
         */
        public double greatCircleDistance(LatLon other) {
                return (Math.acos(
                        Math.sin(Math.toRadians(lat())) * Math.sin(Math.toRadians(other.lat())) + 
                    Math.cos(Math.toRadians(lat()))*Math.cos(Math.toRadians(other.lat())) *
                                  Math.cos(Math.toRadians(other.lon()-lon()))) * 6378135);
        }
        
        /**
         * Returns the heading, in radians, that you have to use to get from 
         * this lat/lon to another.
         * 
         * @param other the "destination" position
         * @return heading 
         */
        public double heading(LatLon other) {
                double rv;
                if (other.lat() == lat()) {
                        rv = (other.lon()>lon() ? Math.PI / 2 : Math.PI * 3 / 2);
                } else {
                        rv = Math.atan((other.lon()-lon())/(other.lat()-lat()));
                        if (rv < 0) rv += Math.PI;
                        if (other.lon() < lon()) rv += Math.PI;
                }
                return rv;
        }

        /**
         * Returns this lat/lon pair in human-readable format.
         * 
         * @return String in the format "lat=1.23456°, lon=2.34567°"
         */
        public String toDisplayString() {
                NumberFormat nf = NumberFormat.getInstance();
                nf.setMaximumFractionDigits(5);
                return "lat=" + nf.format(lat()) + "°, lon=" + nf.format(lon()) + "°";
        }
        
        @Override public String toString() {
                return "LatLon[lat="+lat()+",lon="+lon()+"]";
    }
}