title: User Editable Vector Shapes on a HTML5 Canvas
body: <p>I want to be able to draw some basic vector shapes onto a HTML5 Canvas element.</p>
  
  <p>The user should be able to use the mouse to directly draw any of these:</p>
  
  <ul>
  <li><p>Square</p></li>
  <li><p>Circle</p></li>
  <li><p>Polygon</p></li>
  </ul>
  
  <p>Onto the Canvas - these will later be used for hotspots on an image.</p>
  
  <p>It is important that the user should be able to draw these vector shapes themselves by directly clicking within the canvas.</p>
  
  <p>Is there an existing library that will help with this?</p>
  
  <p>If there is no library, consider that I am an experienced web designer with an excellent knowledge of javascript, but I have very little experience with programming vectors.  Where is the best place for me to go to fix this so I can build what I need?</p>