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EAN13.py

00001 '''
Copyright (C) 2007 Martin Owens

Thanks to Lineaire Chez of Inkbar ( www.inkbar.lineaire.net )

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
'''

from Base import Barcode
import sys

mapLeftFaimly = [
      [ "0001101","0011001","0010011","0111101","0100011","0110001","0101111","0111011","0110111","0001011" ],
      [ "0100111","0110011","0011011","0100001","0011101","0111001","0000101","0010001","0001001","0010111" ],
]
mapRight   = [ "1110010","1100110","1101100","1000010","1011100","1001110","1010000","1000100","1001000","1110100" ]
mapFaimly  = [ '000000','001011','001101','001110','010011','011001','011100','010101','010110','011010' ]

guardBar = '202';
centerBar = '02020';

00034 class Object(Barcode):
      def encode(self, number):
            result = ''

            if len(number) < 12 or len(number) > 13 or not number.isdigit():
                  sys.stderr.write("Can not encode '" + number + "' into EAN13 Barcode, Size must be 12 numbers only\n")
                  return

            if len(number) == 12:
                  number = number + self.getChecksum(number)
            else:
                  if not self.varifyChecksum(number):
                        sys.stderr.write("EAN13 Checksum not correct for this barcode, omit last charicter to generate new checksum.\n")
                        return

            result = result + guardBar
            family = mapFaimly[int(number[0])]

            i = 0
            for i in range(0,6):
                  mapLeft = mapLeftFaimly[int(family[i])]
                  result += mapLeft[int(number[i+1])]

            result += centerBar

            for i in range (7,13):
                  result += mapRight[int(number[i])]

            result = result + guardBar;

            self.label    = number[0] + '    ' + number[1:7] + '    ' + number[7:] + '       '
            self.inclabel = self.label
            return result;

      def getChecksum(self, number):
            # UPCA/EAN13
            weight=[3,1]*6
            magic=10
            sum = 0
            # We need to work from left to right so reverse
            number = number[::-1]
            # checksum based on first 12 digits.
            for i in range(len(number)):
               sum = sum + int(number[i]) * weight[i]

            # Mod it down to a single digit
            z = ( magic - (sum % magic) ) % magic
            if z < 0 or z >= magic:
               return 0

            return str(z)

      def varifyChecksum(self, number):
            new = self.getChecksum(number[:12])
            existing = number[12]
            return new == existing

      def getStyle(self, index):
            result = { 'width' : '1', 'top' : int(self.y), 'write' : True }
            if index==0: # White Space
                  result['write'] = False
            elif index==1: # Black Bar
                  result['height'] = int(self.height)
            elif index==2: # Guide Bar
                  result['height'] = int(self.height) + 5
            return result


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