# File lib/prawn/text.rb, line 27
    def height_of(string, options={})
      process_final_gap_option(options)
      box = Text::Box.new(string,
                          options.merge(:height   => 100000000,
                                        :document => self))
      box.render(:dry_run => true)
      height = box.height - box.descender
      height += box.line_height + box.leading - box.ascender if @final_gap
      height
    end