dataToCanvas.coffee

# Converts a data image uri to canvas image
#
# reader  = new FileReader()
# reader.onload = (evt) =>
#   App.Util.dataToCanvas evt, el: @ui.thumb, width: 80, height: 40
# reader.readAsDataURL(...)
#
# @ui.thumb = jquery selector
# ultimately the jquery dependency can be 86ed from this...
#
Util.dataToCanvas = (evt, options={}) ->
  {el, width, height} = options
  img     = $('<img>', src: evt.target.result)
  canvas  = $(el)[0]
  context = canvas.getContext('2d')
  context.filter = 'best'
  context.antialias = 'subpixel'
  context.imageSmoothingEnabled = true
  context.webkitImageSmoothingEnabled = true
  context.mozImageSmoothingEnabled = true
  img.load ->
    scaled = Util.scaleProportion(width, height, @width, @height)
    canvas.setAttribute 'width', width
    canvas.setAttribute 'height', height
    context.drawImage this,
      (canvas.width / 2 - scaled.width / 2),
      (canvas.height / 2 - scaled.height / 2),
      scaled.width,
      scaled.height