Possible fix for http://stackoverflow.com/questions/17100559/using-the-prawn-qrcode-gem-to-render-a-qr-code-in-a-pdf-via-prawn/17104301?noredirect=1#comment24864876_17104301

gistfile1.rb

class PropertyPdf < Prawn::Document

  def initialize(property)
      super(top_margin: 70)
      @property = property
      @qrcode_content = 'http://tbd.com'
      qrcode = RQRCode::QRCode.new('http://tbd.com', :size => 6, :level => :h )
      building_heading
  end

  def qrcode
    print_qr_code(@qrcode_content, :dot=>2.8)
    render_file("qr3.pdf")
  end

end