Lowercase numbers in Prawn for Adobe Pro fonts.

prawn_lowercase_numbers.rb

# Lowercase numbers in Prawn.
# Works with Adobe Pro fonts only: http://en.wikipedia.org/wiki/Text_figures

require "rubygems"
require "prawn"

class Prawn::Document
  def adobe_pro_osf(text)
    text.to_s.gsub(/\d/) { ["F64#{($&.to_i + 3).to_s(16)}".hex].pack("U") }
  end
end


pdf = Prawn::Document.new

pdf.font_families.update("Garamond" => {
  :normal      => '/Users/henrik/Sites/auktion/app/pdf/assets/Garamond3LTStd.ttf',
  :bold        => '/Users/henrik/Sites/auktion/app/pdf/assets/Garamond3LTStd-Bold.ttf',
  :italic      => '/Users/henrik/Sites/auktion/app/pdf/assets/Garamond3LTStd-Italic.ttf',
  :bold_italic => '/Users/henrik/Sites/auktion/app/pdf/assets/Garamond3LTStd-BoldItalic.ttf'
})
pdf.font 'Garamond'

pdf.text("Upper case: 0123456789")
pdf.text("Lower case: #{pdf.adobe_pro_osf '0123456789'}")

pdf.render_file('/tmp/x.pdf')
`open /tmp/x.pdf`  # OS X

As discussed here: https://groups.google.com/forum/?fromgroups=#!topic/prawn-ruby/BRCVY7DXZt4