Android Open Source - android-open-street-map Polyline Util

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License

The source code is released under:

Apache License

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Java Source Code

package com.android.lib.map.osm.utils;
//  w  w w .  j  a v a 2  s  .  c o m
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import com.android.lib.map.osm.GeoPoint;

public class PolylineUtil {

    public static List<GeoPoint> decodePoly(String encoded) {

        List<GeoPoint> poly = new ArrayList<GeoPoint>();
        int index = 0, len = encoded.length();
        int lat = 0, lng = 0;

        while (index < len) {
            int b, shift = 0, result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlat = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lat += dlat;

            shift = 0;
            result = 0;
            do {
                b = encoded.charAt(index++) - 63;
                result |= (b & 0x1f) << shift;
                shift += 5;
            } while (b >= 0x20);
            int dlng = ((result & 1) != 0 ? ~(result >> 1) : (result >> 1));
            lng += dlng;

            GeoPoint p = new GeoPoint((int) ((lat / 1E5) * 1E6),
                 (int) ((lng / 1E5) * 1E6));
            poly.add(p);
        }

        return poly;
    }

  public static HashMap<String, String> encodePoly(List<GeoPoint> geopoints, int level, int step) {

    HashMap<String, String> resultMap = new HashMap<String, String>();
    StringBuffer encodedPoints = new StringBuffer();
    StringBuffer encodedLevels = new StringBuffer();

    int plat = 0;
    int plng = 0;

    for (GeoPoint g : geopoints) {
      int late5 = floor1e5(g.getLatitudeE6() / 1E6);
      int lnge5 = floor1e5(g.getLongitudeE6() / 1E6);
      
      int dlat = late5 - plat;
      int dlng = lnge5 - plng;

      plat = late5;
      plng = lnge5;

      encodedPoints.append(encodeSignedNumber(dlat)).append(encodeSignedNumber(dlng));
      encodedLevels.append(encodeNumber(level));

    }
    resultMap.put("encodedPoints", encodedPoints.toString());
    resultMap.put("encodedLevels", encodedLevels.toString());

    return resultMap;
  }
  
  private static String encodeSignedNumber(int num) {
    int sgn_num = num << 1;
    if (num < 0) {
      sgn_num = ~(sgn_num);
    }
    return (encodeNumber(sgn_num));
  }
  
  private static String encodeNumber(int num) {

    StringBuffer encodeString = new StringBuffer();

    while (num >= 0x20) {
      int nextValue = (0x20 | (num & 0x1f)) + 63;
      encodeString.append((char) (nextValue));
      num >>= 5;
    }

    num += 63;
    encodeString.append((char) (num));

    return encodeString.toString();
  }
  
  private static int floor1e5(double coordinate) {
    return (int) Math.floor(coordinate * 1e5);
  }
  
}

Java Source Code List