How to Add Snap to Roads Google Map in Android Studio

问题

Hello I would like to ask how to add Snap to Road when I have the route given by google map API. I have a bunch of Lat lang from point A line to point B line and draw a lines like Polylines, but what i want is how to add this code snap to Road from given route? this is how to add more points from the Point A to Point B, here is what i want to add, https://developers.google.com/maps/documentation/roads/snap

my project is look like this

回答1:

1. Get overview_polyline by Json and Gson (should use https://maps.googleapis.com/maps/api/directions/json?origin=...&destination=place_id:...&mode=DRIVING&key=...)

2. Decode it to List by function

   public List<LatLng> decodePoly(String encoded) {
   // encoded is overview_polyline.points; 
   List<LatLng> poly = new ArrayList<LatLng>();
   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;
   
       LatLng p = new LatLng((((double) lat / 1E5)),
               (((double) lng / 1E5)));
       poly.add(p);
   }
   return poly;
   }
   

   3.Add to map:

   PolylineOptions polylineOptions= new PolylineOptions();
   polylineOptions.addAll(decodePoly(overview_polyline.points));
   mGoogleMap.addPolyline(polylineOptions.width(5).color(Color.BLUE).geodesic(false));
   

来源：https://stackoverflow.com/questions/35472005/how-to-add-snap-to-roads-google-map-in-android-studio