I have been working on using the canvas recently, and I am coming out of it with a bit of code. I've compiled that into a library of code called DrawTools. This library is still a bit haphazard at the moment, but it's starting to round out, as I improve my own knowledge of drawing on the canvas, and gathering positional data on clicks and touches.
I have a small example using the library, that I wanted to share with you, that I put together for one of my students, maybe it will give you an idea of how easily things can be done with it.
... or maybe not, I don't know.