title: Zoom Canvas to Mouse Cursor
body: <p>I'm programming a HTML5 &lt; canvas > project that involves zooming in and out of images using the scroll wheel.
  I want to zoom towards the cursor like google maps does but I'm completely lost on how to calculate the movements.</p>
  
  <p>What I have: image x and y (top-left corner); image width and height; cursor x and y relative to the center of the canvas.</p>