is there a way i can animate a polyline?

Question

Something similar to a pulsing ring around a marker. What I want to achieve is this... I have many polylines all having Lat/Lng. At a time t, a user can decide to pick any polyline of their choosing. I get their current real-time location coordinates via Bluetooth. I want to use that location to determine how far they are from the polyline they have selected and depending on the distance, change/animate that polyline. I am using google maps API, android studio, kotlin

Answer 1

Here's a simple example - a method which takes a Polyline instance and a handler (must be on main looper) and begins a repeating update to the polyline width.

(Added the Kotlin)

private lateinit var polyline: Polyline;
private lateinit var handler : Handler;

override fun onMapReady(googleMap: GoogleMap) {
    mMap = googleMap

    var ptlist = ArrayList<LatLng>();

    // add polyline
    ptlist.add(LatLng(40.437761, -3.704751));
    ptlist.add(LatLng( 40.405072, -3.678678));
    ptlist.add(LatLng( 40.397158, -3.742706));
    ptlist.add(LatLng(40.437761, -3.704751));

    handler = Handler(Looper.getMainLooper());

    polyline = mMap.addPolyline(PolylineOptions().addAll(ptlist));

    val runnableCode = object: Runnable {
        override fun run() {
            var w = polyline.width;
            w = w + 0.5f;
            if (w > 25.0) {
                w = 1.0f;
            }
            polyline.setWidth(w);
            handler.postDelayed(this, 50);
        }
    }

    mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(LatLng(40.415521, -3.700995), 12f));
    handler.postDelayed(runnableCode, 50);

}

In this example, the witdh of polyline p will vary from [25.0 1.0] incrementing by 0.5 every 200 milliseconds. When it reaches the maximum width it is reset to a width of 1.0. The original width is ignored.

Obviously change the parameters as needed - or make it pulse in and out.

(Java equivalent - animation parameters different.)

public void pulsePolyline(final Polyline p, final Handler h)
{
    h.postDelayed(new Runnable() {
        @Override
        public void run() {

            float w = p.getWidth();
            w = (w + 0.1);
            if (w > 10.0) w = 1.0;
            p.setWidth(w);
            h.postDelayed(this, 200);
        }
   }, 200);
}

Note the handler must be from the main thread (or looper) as in:

new Handler(Looper.getMainLooper())