Padrino使ってQRcodeを表示させる ref: http://qiita.com/items/61189db4743d8cd63ded

file0.txt

$ padrino g project testqr -e slim
$ cd testqr
$ bundle install

file1.txt

gem 'rqrcode'
gem 'rqrcode_to_svg'

file2.txt

$ padrino g controller qrtest get:index get:code

index.slim

object type="image/svg+xml" data="code"

qrtest.rb

Testqr.controllers :qrtest do

  get :index, map: "/index" do
    render "qrtest/index"
  end

  get :code, map: "/code" do
    RQRCode::QRCode.new('http://www.co-meeting.com', size: 4, level: :h ).to_svg
  end
end