Stream HTML5 canvas activity using WebRTC

I'd like to stream the activity of an HTML5 canvas using WebRTC. One user broadcast his canvas and the connected peer see what the remote peer is doing on his canvas, if he is drawing a line or anything, i'd like the connected peer to see the changes on his own canvas.

My question, is this possible out of the box with WebRTC? After my searches, i would say that it's not the case.

If not, how would you approach such a system?

Thanks.