# File lib/prawn/font/afm.rb, line 25
      def initialize(document, name, options={})
        unless BUILT_INS.include?(name)
          raise Prawn::Errors::UnknownFont, "#{name} is not a known font."
        end

        super

        @attributes     = {}
        @glyph_widths   = {}
        @bounding_boxes = {}
        @kern_pairs     = {}

        file_name = @name.dup
        file_name << ".afm" unless file_name =~ /\.afm$/
        file_name = file_name[0] == ?/ ? file_name : find_font(file_name)

        parse_afm(file_name)

        @ascender  = @attributes["ascender"].to_i
        @descender = @attributes["descender"].to_i
        @line_gap  = Float(bbox[3] - bbox[1]) - (@ascender - @descender)
      end