title: Draw on surfaceView
body: <p>I want to crop the image before capturing it just like google goggle does.
  I may have to draw a rectangle for that and then add a onTouchListener.
  But I am not able to figure out how to draw a rectangle on the surfaceView that we use for Camera preview.</p>
  
  <p>Is there any source I can look into as a guide on how to about it?</p>