Image Crop from Canvas

gistfile1.coffee

detectCanvas: =>
  if @canvas
    @canvas.replaceWith("<canvas class='picture_canvas' data-block='canvas'></canvas>")

  @canvas = @container.find("*[data-block='canvas']")
  @ctx    = @canvas.get(0).getContext("2d")

handleImage: (e) =>
  @detectCanvas()

  reader = new FileReader()
  reader.onload = (event) =>
    img = new Image()
    img.onload = =>
      MAX_WIDTH  = 320
      MAX_HEIGHT = 320

      if img.width > img.height
        if img.width > MAX_WIDTH
          img.height *= MAX_WIDTH / img.width
          img.width  = MAX_WIDTH
      else
        if img.height > MAX_HEIGHT
          img.width  *= MAX_HEIGHT / img.height
          img.height = MAX_HEIGHT

      @canvas.attr(width: img.width, height: img.height)
      @ctx.drawImage(img, 0, 0, img.width, img.height)