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#
# Copyright (C) 2010 Martin Owens
#
# 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
#
"""
Some basic common code shared between EAN and UCP generators.
"""
from Base import Barcode
import sys
MAPPING = [
# Left side of barcode Family '0'
[ "0001101", "0011001", "0010011", "0111101", "0100011",
"0110001", "0101111", "0111011", "0110111", "0001011" ],
# Left side of barcode Family '1' and flipped to right side.
[ "0100111", "0110011", "0011011", "0100001", "0011101",
"0111001", "0000101", "0010001", "0001001", "0010111" ],
]
# This chooses which of the two encodings above to use.
FAMILIES = [ '000000', '001011', '001101', '001110', '010011',
'011001', '011100', '010101', '010110', '011010' ]
GUARD_BAR = '202'
CENTER_BAR = '02020'
class EanBarcode(Barcode):
"""Simple base class for all EAN type barcodes"""
length = None
lengths = None
checks = []
def intarray(self, number):
"""Convert a string of digits into an array of ints"""
return [ int(i) for i in number ]
def encode_interleaved(self, family, number, fams=FAMILIES):
"""Encode any side of the barcode, interleaved"""
result = []
encset = self.intarray(fams[family])
for i in range(len(number)):
thismap = MAPPING[encset[i]]
result.append( thismap[number[i]] )
return result
def encode_right(self, number):
"""Encode the right side of the barcode, non-interleaved"""
result = []
for n in number:
# The right side is always the reverse of the left's family '1'
result.append( MAPPING[1][n][::-1] )
return result
def encode_left(self, number):
"""Encode the left side of the barcode, non-interleaved"""
result = []
for n in number:
result.append( MAPPING[0][n] )
return result
def space(self, *spacing):
"""Space out an array of numbers"""
result = ''
for space in spacing:
if isinstance(space, list):
for i in space:
result += str(i)
elif isinstance(space, int):
result += ' ' * space
return result
def getLengths(self):
"""Return a list of acceptable lengths"""
if self.length:
return [ self.length ]
return self.lengths[:]
def encode(self, code):
"""Encode any EAN barcode"""
if not code.isdigit():
return self.error(code, 'Not a Number, must be digits 0-9 only')
lengths = self.getLengths() + self.checks
if len(code) not in lengths:
return self.error(code, 'Wrong size, must be %s digits' %
(', '.join(self.space(lengths))))
if self.checks:
if len(code) not in self.checks:
code = self.appendChecksum(code)
elif not self.verifyChecksum(code):
return self.error(code, 'Checksum failed, omit for new sum')
return self._encode(self.intarray(code))
def _encode(self, n):
raise NotImplementedError("_encode should be provided by parent EAN")
def enclose(self, left, right=[], guard=GUARD_BAR, center=CENTER_BAR):
"""Standard Enclosure"""
parts = [ guard ] + left + [ center ] + right + [ guard ]
return ''.join( parts )
def getChecksum(self, number, magic=10):
"""Generate a UPCA/EAN13/EAN8 Checksum"""
weight = [3,1] * len(number)
result = 0
# We need to work from left to right so reverse
number = number[::-1]
# checksum based on first digits.
for i in range(len(number)):
result += int(number[i]) * weight[i]
# Modulous result to a single digit checksum
checksum = magic - (result % magic)
if checksum < 0 or checksum >= magic:
return '0'
return str(checksum)
def appendChecksum(self, number):
"""Apply the checksum to a short number"""
return number + self.getChecksum(number)
def verifyChecksum(self, number):
"""Verify any checksum"""
return self.getChecksum(number[:-1]) == number[-1]
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