title: How to move a drawn image on HTML5 canvas?
body: <p>Assuming i have an HTML5 canvas on which i've already drawn multiple images, and i don't have the final resulting image "in hand", and now i want to move the whole image in the canvas up? (just if like the user chose to 'scroll down' the image)</p>
  
  <p>If i had the final image, i could have clear the canvas and draw it again in a 'y' coordinate which is negative, that'll work.
  The problem is that calling toDataUrl() in order to get the final image - is very CPU consuming.</p>
  
  <p>Any other way to achieve this?
  Why can't i just tell the canvas to 'move everything up / down' by x pixels...?</p>
  
  <p>thanks!</p>