determine the size for qrcode

qrcode_size.rb

# size - seems to follow this logic
# codes copied from:
# => https://raw.githubusercontent.com/samvincent/rqrcode-rails3/master/lib/rqrcode-rails3/size_calculator.rb
#
#     # | input | modules
#       | size  | created
#-------|-------|--------
#     1 |     7 |      21
#     2 |    14 |      25 (+4)
#     3 |    24 |      29   -
#     4 |    34 |      33   -
#     5 |    44 |      37   -
#     6 |    58 |      41   -
#     7 |    64 |      45   -
#     8 |    84 |      49   -
#     9 |    98 |      53   -
#    10 |   119 |      57   -
#    11 |   137 |      61   -
#    12 |   155 |      65   -
#    13 |   177 |      69   -
#    14 |   194 |      73   -
QR_CHAR_SIZE_VS_SIZE = [7, 14, 24, 34, 44, 58, 64, 84, 98, 119, 137, 155, 177, 194]

def minimum_qr_size_from_string(string)
  QR_CHAR_SIZE_VS_SIZE.each_with_index do |size, index|
    return (index + 1) if string.size < size
  end

  # If it's particularly big, we'll try and create codes until it accepts
  i = QR_CHAR_SIZE_VS_SIZE.size
  begin
    i += 1
    RQRCode::QRCode.new(string, :size => i)
    return i
  rescue RQRCode::QRCodeRunTimeError
    retry
  end
end