printing QR codes through an ESC/POS thermal printer

參考引用來源:printing QR codes through an ESC/POS thermal printer
--


def test_qrcode (printer, text, print_also_text=false, qr_size=6.chr)

  s = text.size + 3
  lsb = (s % 256).chr
  msb = (s / 256).chr

  # https://code.google.com/p/python-escpos/wiki/Usage
  escpos = ""
  escpos << "\x1D\x28\x6B\x03\x00\x31\x43#{qr_size}"
  escpos << "\x1D\x28\x6B\x03\x00\x31\x45\x33"
  escpos << "\x1D\x28\x6B#{lsb}#{msb}\x31\x50\x30"
  escpos << text #
  escpos << "\x1D\x28\x6B\x03\x00\x31\x51\x30"

  # writing byte streams directly to the serial port
  printer.write escpos

end