class Canvas
  constructor: (w, h) ->
    @cnv = document.createElement 'canvas'
    @cnv.width  = w
    @cnv.height = h
    @ctx = @cnv.getContext '2d'

    @drawLayers = []
    @running    = false


  start: ->
    @running = true
    render = =>
      if @running
        requestAnimationFrame =>
          i(@cnv) for i in @drawLayers
          @render()

  stop: -> @running = false


  addLayer: (cb) ->
    @drawLayers.push cb