Android: DrivingDirections removed since API 1.0 - how to do it in 1.5/1.6?

Question

It seems that DrivingDirections have been removed since Android API 1.0

What's the way now to display a map with two points (one of them might be the current location, but can also be any other location) and the direction from one to another in Android 1.6?

Answer 1

If you just need the point connected with a line you do not need the full kml. A much faster way to do it is to just use the JSON returned from Google Maps API with output=dragdir

private String getUrl(String start, String end) {
    //If params GeoPoint convert to lat,long string here
    StringBuffer urlString = new StringBuffer();
    urlString.append("http://maps.google.com/maps?f=d&hl=en");
    urlString.append("&saddr=");// from
    urlString.append(start);
    urlString.append("&daddr=");// to
    urlString.append(end);
    urlString.append("&ie=UTF8&0&om=0&output=dragdir"); //DRAGDIR RETURNS JSON
    Log.i("URLString", urlString.toString());
    return urlString.toString();
}

This urlString can be used to get a JSON file, which you can easily extract the information using String's split()

private String getConnection(String url) {
    URL inUrl = new URL(url);
    URLConnection yc = inUrl.openConnection();
    BufferedReader in = new BufferedReader( new InputStreamReader(yc.getInputStream()));
    String inputLine;
    String encoded = "";
    while ((inputLine = in.readLine()) != null)
        encoded = encoded.concat(inputLine);
    in.close();
    String polyline = encoded.split("points:")[1].split(",")[0];
    polyline = polyline.replace("\"", "");
    polyline = polyline.replace("\\\\", "\\");
    return polyline;
}

The returned String is a polyline which can be decoded into an list of Geopoints using the method below.

private static ArrayList<GeoPoint> decodePolyline(String encoded) {
    ArrayList<GeoPoint> geopoints = 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) (((double) lat / 1E5) * 1E6), (int) (((double) lng / 1E5) * 1E6));
        geopoints.add(p);
    }
 return geopoints;
}

The last step is to draw these points to a mapView, for that we need an overlay item that will handle a ArrayList of GeoPoints.

public class PathOverlay extends Overlay {

    private ArrayList<GeoPoint> pointList;

    public PathOverlay(ArrayList<GeoPoint> pointList) {
            this.pointList = pointList;     
    }

    @Override
    public void draw(Canvas canvas, MapView mapView, boolean shadow) {
        Point current = new Point();
        Path path = new Path();
        Projection projection = mapView.getProjection();
        Iterator<GeoPoint> iterator = pointList.iterator();
        if (iterator.hasNext()) {
            projection.toPixels(iterator.next(), current);
            path.moveTo((float) current.x, (float) current.y);
        } else return;
        while(iterator.hasNext()) {
            projection.toPixels(iterator.next(), current);
            path.lineTo((float) current.x, (float) current.y);
        }

        Paint pathPaint = new Paint();
        pathPaint.setAntiAlias(true);
        pathPaint.setStrokeWidth(3.0f);
        pathPaint.setColor(Color.GREEN);
        pathPaint.setStyle(Style.STROKE);
        canvas.drawPath(path, pathPaint);
    }
}

If your not sure about some of the intermediate steps, such as how to get the overlay onto the MapView or how to set up a router class let me know and I can send you the complete code.