title: How to draw overlay on image using canvas?
body: <p>I want to draw shape(poly, rect, circle) on image JavaScript. and want to generate Hotspot using selected shape, bellow is example link what I want. And How do I draw overlay an canvas over the image? </p>
  
  <p>e.g.
  <a href="https://google-developers.appspot.com/maps/documentation/javascript/examples/drawing-tools" rel="nofollow">https://google-developers.appspot.com/maps/documentation/javascript/examples/drawing-tools</a>
  http://www.maschek.hu/imagemap/imgmap</p>