title: How to get mouse is over shape on canvas
body: <p>I have a canvas where user can select things on images by drawing shape around it. So there might be more than one shape on canvas</p>
  
  <p>Now what I want is when mouseover shape I want to change opacity of canvas except custom shape(where mouse over is). </p>
  
  <p>It is like reverse area effect that some jQuery plugin doing 
  <a href="http://davidlynch.org/projects/maphilight/docs/demo_simple.html" rel="nofollow noreferrer">http://davidlynch.org/projects/maphilight/docs/demo_simple.html</a> (reverse effect here)</p>