title: How to change 1 meter to pixel distance?
body: <p>When I develop an Android map application, I want to draw a circle on the map whose radius is 1 meter. As you known, I can't draw 1 meter directly, I should convert 1 meter to the distance of two pixels depend on the zoom level. How to I convert it, is there anything API I can use.</p>
  
  <p>Canvas.draw(x, y, radius), what value should I put to this method ?</p>