115 lines
3.0 KiB
Python
Executable File
115 lines
3.0 KiB
Python
Executable File
"""Module: barcode.upc
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:Provided barcodes: UPC-A
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"""
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__docformat__ = "restructuredtext en"
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from functools import reduce
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from barcode.base import Barcode
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from barcode.charsets import upc as _upc
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from barcode.errors import IllegalCharacterError, NumberOfDigitsError
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class UniversalProductCodeA(Barcode):
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"""Universal Product Code (UPC) barcode.
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UPC-A consists of 12 numeric digits.
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"""
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name = "UPC-A"
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digits = 11
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def __init__(self, upc, writer=None, make_ean=False):
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"""Initializes new UPC-A barcode.
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:param str upc: The upc number as string.
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:param writer: barcode.writer instance. The writer to render the
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barcode (default: SVGWriter).
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:param bool make_ean: Indicates if a leading zero should be added to
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the barcode. This converts the UPC into a valid European Article
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Number (EAN).
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"""
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self.ean = make_ean
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upc = upc[: self.digits]
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if not upc.isdigit():
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raise IllegalCharacterError("UPC code can only contain numbers.")
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if len(upc) != self.digits:
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raise NumberOfDigitsError(
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"UPC must have {} digits, not {}.".format(self.digits, len(upc))
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)
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self.upc = upc
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self.upc = "{}{}".format(upc, self.calculate_checksum())
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self.writer = writer or Barcode.default_writer()
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def __str__(self):
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if self.ean:
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return "0" + self.upc
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else:
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return self.upc
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def get_fullcode(self):
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if self.ean:
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return "0" + self.upc
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else:
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return self.upc
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def calculate_checksum(self):
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"""Calculates the checksum for UPCA/UPC codes
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:return: The checksum for 'self.upc'
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:rtype: int
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"""
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def sum_(x, y):
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return int(x) + int(y)
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upc = self.upc[0 : self.digits]
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oddsum = reduce(sum_, upc[::2])
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evensum = reduce(sum_, upc[1::2])
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check = (evensum + oddsum * 3) % 10
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if check == 0:
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return 0
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else:
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return 10 - check
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def build(self):
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"""Builds the barcode pattern from 'self.upc'
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:return: The pattern as string
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:rtype: str
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"""
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code = _upc.EDGE[:]
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for _i, number in enumerate(self.upc[0:6]):
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code += _upc.CODES["L"][int(number)]
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code += _upc.MIDDLE
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for number in self.upc[6:]:
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code += _upc.CODES["R"][int(number)]
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code += _upc.EDGE
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return [code]
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def to_ascii(self):
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"""Returns an ascii representation of the barcode.
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:rtype: str
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"""
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code = self.build()
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for i, line in enumerate(code):
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code[i] = line.replace("1", "|").replace("0", "_")
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return "\n".join(code)
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def render(self, writer_options=None, text=None):
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options = {"module_width": 0.33}
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options.update(writer_options or {})
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return Barcode.render(self, options, text)
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UPCA = UniversalProductCodeA
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