Android: How do I set the zoom level of map view to 1 km radius around my current location?

Question

I want to set the map view zoomed to 1km radius but cant figure out how?

The doc says that the zoom level 1 will map earths equator to 256 pixels. So how do I calcul

Answer 1

FINAL working solution:

public static void getZoomForMetersWide(GoogleMap googleMap, int mapViewWidth, LatLng latLngPoint, int desiredMeters) {
        DisplayMetrics metrics = App.getAppCtx().getResources().getDisplayMetrics();
        float mapWidth = mapViewWidth / metrics.density;

        final int EQUATOR_LENGTH = 40075004;
        final int TIME_ANIMATION_MILIS = 1500;
        final double latitudinalAdjustment = Math.cos(Math.PI * latLngPoint.latitude / 180.0);
        final double arg = EQUATOR_LENGTH * mapWidth * latitudinalAdjustment / (desiredMeters * 256.0);
        double valToZoom = Math.log(arg) / Math.log(2.0);

        googleMap.animateCamera(CameraUpdateFactory.newLatLngZoom(latLngPoint, Float.valueOf(String.valueOf(valToZoom))), TIME_ANIMATION_MILIS , null);
    }

p.s. Using @sho answer and @Lionel Briand comment

Answer 2

although this answer is logical and i find it working but the results are not accurate i dont know why but i tired this approach and this technique is far more accurate.

1) Make a circle on object with desired radius

Circle circle = mGoogleMap.addCircle(new CircleOptions().center(new LatLng(latitude, longitude)).radius(getRadiusInMeters()).strokeColor(Color.RED));           
        circle.setVisible(true);
        getZoomLevel(circle);

2) Pass that object to this function and set the zoom level Here's a link

public int getZoomLevel(Circle circle) {
if (circle != null){
    double radius = circle.getRadius();
    double scale = radius / 500;
    zoomLevel =(int) (16 - Math.log(scale) / Math.log(2));
}
return zoomLevel;
}