title: Put movable circle over google map and get center position and radius
body: <p>I would like to put in my map on site something similar like on this <a href="http://www.apartmentfinder.com/Georgia/Atlanta-Apartments" rel="nofollow noreferrer">site</a></p>
  
  <p><img src="https://i.stack.imgur.com/4PUCH.jpg" alt="enter image description here"></p>
  
  <p>When choose Personalize Your Search, I need to get gps of circle center and zoom and radius. </p>
  
  <p>How could I achieve this?</p>
  
  <p>All help is appreciated.</p>