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

I've converted the accepted answer to return a double value, since the Android Google Maps library uses floating point zoom levels, and also account for latitudes away from the equator.

public static double getZoomForMetersWide (
  final double desiredMeters,
  final double mapWidth,
  final double latitude )
{
  final double latitudinalAdjustment = Math.cos( Math.PI * latitude / 180.0 );

  final double arg = EQUATOR_LENGTH * mapWidth * latitudinalAdjustment / ( desiredMeters * 256.0 );

  return Math.log( arg ) / Math.log( 2.0 );
}

As an aside, for best results on Android don't pass the view's real pixel count, but the dimension scaled for the device's pixel density.

DisplayMetrics metrics = getResources().getDisplayMetrics();
float mapWidth = mapView.getWidth() / metrics.scaledDensity;

Hope this helps someone.