Question

I’m trying to draw a route in a mapView from the current location (got from GPS) to the way he travels.

I am able to fetch the location of the user as he moves in a particular direction, but I was not able to draw the path.

What is the best way to draw the route path as he moves from place to place continuously?

I want the method to be good (in terms of performance).

Answer 1

You will have to keep track of the current location & previous location (in global variable for example) in order to draw the path [except the first time you only have current location, so you do nothing until the next point].

        int x1 = -1, y1 = -1, x2 = -1, y2 = -1;
        Paint paint = new Paint();
        paint.setColor(Color.rgb(0x7b, 0x7b, 0xff));
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeWidth(5);

                Point prevloc = new Point();
                mv.getProjection().toPixels(new GeoPoint((int (prevlocation.getLatitude()*1.0E6),(int) (prevlocation.getLongitude()*1.0E6)), prevloc);
                Point loc = new Point();
                mv.getProjection().toPixels(new GeoPoint((int (location.getLatitude()*1.0E6),(int) (location.getLongitude()*1.0E6)), loc);
                x2 = prevloc.x;
                y2 = prevloc.y;
                if (first)
                {
                    x2 = loc.x;
                    y2 = loc.y;
                }
                if (!first) {
                    canvas.drawLine(x1, y1, x2, y2, paint);
                }
                x1 = x2;
                y1 = y2;

This will be called in draw() and you to somehow call this draw function through drawing overlay in onLocationChanged() function.

note: canvas and mv are parameters passed to draw() function and first is a global boolean variable to indicate this is the first point you get or not.