title: How to set canvas translation to top left corner after rotation
body: <p>I'm drawing a symbol with simple lines, but want the user to be able to specify the rotation (in 90degrees only).
  Which also means that the dimensions of my canvas change.</p>
  
  <p>No I calculate the dimensions, and set the canvas size. Then I set the center of the rotation to the center of my canvas (via <code>ctx.translate</code>) and rotate to the arbitrary degrees.</p>
  
  <p>Now my problem is: How do I set the translation back to the upper left corner, so I can draw my symbol normally from that position? Do I really have to calculate the values with the rotation?</p>
  
  <p>Thanks.</p>