Android Google Map how to check if user is in marker circle region - google-maps

Question

I am using Google Maps, and want to be able to detect if a user is in the radius of a Marker (placed on map), using the users current location. I have the users current location coordinates (latitude and longitude) and the marker's coordinates, but do not know how to calculate whether the user is in the area. The picture below might best describe what I want to do.
I have an algorithm like this:
map.OnInfoWindowClickListener(new OnInfoWindowClickListener()){
public void isUserInArea(Marker marker){
float[] distance = new float[2];
//users current location
Location.distanceBetween(currentLocation.getLatitude(),currentLocatiocation.getLongitude(),
marker.getPosition().latitude, marker.getPosition().longitude, distance);
}
Which doesn't find if the current location is within marker region because I can't get hold of the markers circle. It's the closest i've got to it however. Would appreciate help.
To help, I add a circle to a map like this
// adding circle to map
circleOptions = new CircleOptions();
circleOptions.center(new LatLng(locationlist.get(i)
.getLatitude(), locationlist.get(i).getLongitude()));
circleOptions.radius(20);
circleOptions.strokeColor(Color.BLUE);
circleOptions.fillColor(Color.BLUE);
map.addCircle(circleOptions);
//check that all tasks are in circle radius
Marker locationMarker = map.addMarker(markerOp);
locationMarker.showInfoWindow();

Answer 1

I use this:
Location.distanceBetween(mMarker.getPosition().latitude,
mMarker.getPosition().longitude, mCircle.getCenter().latitude,
mCircle.getCenter().longitude, distance);
if (distance[0] > mCircle.getRadius()) {
//Do what you need
}else if (distance[0] < mCircle.getRadius()) {
//Do what you need
}

Answer 2

Why don't you use proximity alerts?
This is what you can do: instead of drawing a circle, place a Marker on the map like so:
map.addMarker(new MarkerOptions()
.title(name)
.icon(BitmapDescriptorFactory.fromResource(R.drawable.gpsmap))
.position(coordinates)
.flat(true)
.rotation(90));
and then add a proximity alert to it calling the following method:
// Proximity alert
private void addProximityAlert(double lat, double lng, int id){
Intent intent = new Intent(PROX_ALERT_INTENT);
PendingIntent proximityIntent = PendingIntent.getBroadcast(this, id, intent, Intent.FLAG_ACTIVITY_NEW_TASK);
locationManager.addProximityAlert(lat, lng, POINT_RADIUS, EXPIRATION, proximityIntent);
}
where EXPIRATION = -1 (so the proximity alert doesn't expire) and POINT_RADIUS takes the values of the radius of your previous circle.
Then you need to add a proximity alert listener to the map:
IntentFilter filter = new IntentFilter(PROX_ALERT_INTENT);
registerReceiver(new ProximityIntentReceiver(), filter);
where PROX_ALERT_INTENT = "yourProjectPackageName.ProximityActivity";
Hope this helps

Answer 3

This tutorial can help your requirement.
User entry exit proximity alert
all the best.