utils.ex

  def jpeg_size(path) do
     bin = File.read!(WPI.Database.Media.complete_path(path))
     case jpeg_size(path, bin, {}) do
       {} -> nil
       size -> size
     end
  end

  def jpeg_size(path, << 255, 192, 0, 17, 8, height::size(16), width::size(16), rest::binary >>, size) do
    if {width, height} > size do
      jpeg_size(path, rest, {width, height})
    else
      jpeg_size(path, rest, size)
    end
  end

  def jpeg_size(path, << _, bin::binary >>, size) do
    jpeg_size(path, bin, size)
  end

  def jpeg_size(path, << >>, size) do
    size
  end