# File lib/pdf/reader/text_receiver.rb, line 219
    def media_box_check (dict)
      corners = (@upper_corners.last || {:urx => 0, :ury => 0}).dup

      if dict.has_key?(:MediaBox)
        media_box = dict[:MediaBox]
        corners[:urx] = media_box[2] - media_box[0]
        corners[:ury] = media_box[3] - media_box[1]
      end

      corners
    end