Class: Barcode1DTools::EAN13

Inherits:
Barcode1D show all
Defined in:
lib/barcode1dtools/ean13.rb

Overview

Barcode1DTools::EAN_13 - Create pattern for EAN-13 barcodes. The value encoded is an integer, and a checksum digit will be added. You can add the option :checksum_included => true when initializing to specify that you have already included a checksum.

Example

# Note that this number is a UPC-A, with the number system of 08,
# manufacturer's code of "28999", product code of "00682", and a
# checksum of "3" (not included)
num = '082899900682'
bc = Barcode1DTools::EAN13.new(num)
pattern = bc.bars
rle_pattern = bc.rle
width = bc.width
check_digit = Barcode1DTools::EAN13.generate_check_digit_for(num)

The object created is immutable.

Formats

There are two formats for the returned pattern (wn format is not available):

bars - 1s and 0s specifying black lines and white spaces. Actual characters can be changed from “1” and 0“ with options :line_character and :space_character.

rle - Run-length-encoded version of the pattern. The first number is always a black line, with subsequent digits alternating between spaces and lines. The digits specify the width of each line or space.

The “width” method will tell you the total end-to-end width, in units, of the entire barcode.

Unlike some of the other barcodes, e.g. Code 3 of 9, there is no “w/n” format for EAN & UPC style barcodes because the bars and spaces are variable width from 1 to 4 units.

Miscellaneous Information

An EAN-13 with an initial “number system” digit of “0” is a UPC-A. The BarcodeTools::UPC_A module actually just uses this EAN13 module.

An EAN-13 barcode has 4 elements:

  1. A two-digit “number system” designation

  2. A 5-digit manufacturer’s code

  3. A 5-digit product code

  4. A single digit checksum

There is some flexibility in EAN-13 on the digit layout. Sometimes, the first three digits indicate numbering system, i.e. some number systems are further split up. An example is “74”, which is used for Central America with “740” for Guatemala, “741” for El Salvador, etc.

Note that JAN codes (Japanese) are simply EAN-13’s, and they always start with “49”. The table below shows “49” to be “Japan”.

Also note that many books use a “bookland” code, perhaps along with a UPC Supplemental. The bookland code is really an EAN-13 with the initial 3 digits of “978”. The next 9 digits are the first 9 digits of the ISBN, and of course we still include the final check digit. An ISBN is 10 digits, however, the final digit is also a check digit, so it is not necessary.

Here is the complete table from www.barcodeisland.com:

00-13: USA & Canada          590: Poland               780: Chile
20-29: In-Store Functions    594: Romania              784: Paraguay
30-37: France                599: Hungary              785: Peru
40-44: Germany               600 & 601: South Africa   786: Ecuador
45:  Japan (also 49)         609: Mauritius            789: Brazil
46:  Russian Federation      611: Morocco              80 - 83: Italy
471: Taiwan                  613: Algeria              84: Spain
474: Estonia                 619: Tunisia              850: Cuba
475: Latvia                  622: Egypt                858: Slovakia
477: Lithuania               625: Jordan               859: Czech Republic
479: Sri Lanka               626: Iran                 860: Yugloslavia
480: Philippines             64:  Finland              869: Turkey
482: Ukraine                 690-692: China            87:  Netherlands
484: Moldova                 70:  Norway               880: South Korea
485: Armenia                 729: Israel               885: Thailand
486: Georgia                 73:  Sweden               888: Singapore
487: Kazakhstan              740: Guatemala            890: India
489: Hong Kong               741: El Salvador          893: Vietnam
49:  Japan (JAN-13)          742: Honduras             899: Indonesia
50:  United Kingdom          743: Nicaragua            90 & 91: Austria
520: Greece                  744: Costa Rica           93:  Australia
528: Lebanon                 746: Dominican Republic   94:  New Zealand
529: Cyprus                  750: Mexico               955: Malaysia
531: Macedonia               759: Venezuela            977: ISSN
535: Malta                   76:  Switzerland          978: ISBN
539: Ireland                 770: Colombia             979: ISMN
54:  Belgium & Luxembourg    773: Uruguay              980: Refund receipts
560: Portugal                775: Peru                 981 & 982: CCC
569: Iceland                 777: Bolivia              99:  Coupons
57:  Denmark                 779: Argentina
ISSN

International Standard Serial Number for Periodicals

ISBN

International Standard Book Numbering

ISMN

International Standard Music Number

CCC

Common Currency Coupons

Rendering

When rendered, the initial digit of the number system is shown to the left and above the rest of the digits. The other two sets of six digits each are shown at the bottom of the code, aligned with the bottom of the code, and with the middle guard pattern bars extending down between them. The lower digits may be aligned flush with the bottom of the barcode, or the center of the text may be aligned with the bottom of the barcode. Typically, the barcode is 1-1.5“ across and 60% or more of the width in height. There should be at least 10 units of quiet space on each side.

Direct Known Subclasses

UPC_A

Constant Summary collapse

LEFT_PATTERNS =

Patterns for the left side, split between odd and even parity

{
  '0' => { 'o' => '0001101', 'e' => '0100111'},
  '1' => { 'o' => '0011001', 'e' => '0110011'},
  '2' => { 'o' => '0010011', 'e' => '0011011'},
  '3' => { 'o' => '0111101', 'e' => '0100001'},
  '4' => { 'o' => '0100011', 'e' => '0011101'},
  '5' => { 'o' => '0110001', 'e' => '0111001'},
  '6' => { 'o' => '0101111', 'e' => '0000101'},
  '7' => { 'o' => '0111011', 'e' => '0010001'},
  '8' => { 'o' => '0110111', 'e' => '0001001'},
  '9' => { 'o' => '0001011', 'e' => '0010111'},
}
LEFT_PATTERNS_RLE =

Patterns for the left side, split between odd and even parity, in RLE format. Note that all left side patterns start with a space and end with a bar.

{
  '0' => { 'o' => '3211', 'e' => '1123'},
  '1' => { 'o' => '2221', 'e' => '1222'},
  '2' => { 'o' => '2122', 'e' => '2212'},
  '3' => { 'o' => '1411', 'e' => '1141'},
  '4' => { 'o' => '1132', 'e' => '2311'},
  '5' => { 'o' => '1231', 'e' => '1321'},
  '6' => { 'o' => '1114', 'e' => '4111'},
  '7' => { 'o' => '1312', 'e' => '2131'},
  '8' => { 'o' => '1213', 'e' => '3121'},
  '9' => { 'o' => '3112', 'e' => '2113'},
}
LEFT_PARITY_PATTERNS =

Left parity patterns. An extra digit is encoded in the parity.

{
  '0' => 'oooooo',
  '1' => 'ooeoee',
  '2' => 'ooeeoe',
  '3' => 'ooeeeo',
  '4' => 'oeooee',
  '5' => 'oeeooe',
  '6' => 'oeeeoo',
  '7' => 'oeoeoe',
  '8' => 'oeoeeo',
  '9' => 'oeeoeo',
}
RIGHT_PATTERNS =

Bar patterns for right side.

{
  '0' => '1110010',
  '1' => '1100110',
  '2' => '1101100',
  '3' => '1000010',
  '4' => '1011100',
  '5' => '1001110',
  '6' => '1010000',
  '7' => '1000100',
  '8' => '1001000',
  '9' => '1110100',
}
RIGHT_PATTERNS_RLE =

Bar patterns for right side as RLE. Note that on the right side each pattern starts with a bar and ends with a space.

{
  '0' => '3211',
  '1' => '2221',
  '2' => '2122',
  '3' => '1411',
  '4' => '1132',
  '5' => '1231',
  '6' => '1114',
  '7' => '1312',
  '8' => '1213',
  '9' => '3112',
}
SIDE_GUARD_PATTERN =

AAAAHHHHHHHHH side + middle + side is 666, the number of the beast

'101'
MIDDLE_GUARD_PATTERN = 
'01010'
SIDE_GUARD_PATTERN_RLE =

Side guard pattern - Starts with bar

'111'
MIDDLE_GUARD_PATTERN_RLE =

Middle guard pattern - Starts with space

'11111'
DEFAULT_OPTIONS = 
{
  :line_character => '1',
  :space_character => '0'
}

Instance Attribute Summary collapse

Attributes inherited from Barcode1D

#check_digit, #encoded_string, #options, #value

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from Barcode1D

bar_pair, bars_to_rle, rle_to_bars, rle_to_wn, wn_pair, wn_to_rle

Constructor Details

#initialize(value, options = {}) ⇒ EAN13

Create a new EAN-13 barcode object. Options are :line_character, :space_character, and :checksum_included.

Raises:



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# File 'lib/barcode1dtools/ean13.rb', line 341

def initialize(value, options = {})

  @options = DEFAULT_OPTIONS.merge(options)

  # Can we encode this value?
  raise UnencodableCharactersError unless self.class.can_encode?(value, @options)

  if @options[:checksum_included]
    @encoded_string = value.to_s
    raise ChecksumError unless self.class.validate_check_digit_for(@encoded_string)
    md = @encoded_string.match(/^(\d+?)(\d)$/)
    @value, @check_digit = md[1], md[2].to_i
  else
    # need to add a checksum
    @value = value.to_s
    @check_digit = self.class.generate_check_digit_for(@value)
    @encoded_string = "#{@value}#{@check_digit}"
  end

  md = @value.match(/^(\d{2})(\d{5})(\d{5})/)
  @number_system, @manufacturers_code, @product_code = md[1], md[2], md[3]
end

Instance Attribute Details

#manufacturers_code ⇒ Object (readonly)

Specific for EAN - the manufacturer’s code part of the payload



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# File 'lib/barcode1dtools/ean13.rb', line 216

def manufacturers_code
  @manufacturers_code
end

#number_system ⇒ Object (readonly)

Specific for EAN - the number system part of the payload



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# File 'lib/barcode1dtools/ean13.rb', line 214

def number_system
  @number_system
end

#product_code ⇒ Object (readonly)

Specific for EAN - the product code part of the payload



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# File 'lib/barcode1dtools/ean13.rb', line 218

def product_code
  @product_code
end

Class Method Details

.can_encode?(value, options = nil) ⇒ Boolean

Returns true if value can be encoded. Must be 12 or 13 digits.

Returns:

  • (Boolean) 


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# File 'lib/barcode1dtools/ean13.rb', line 222

def can_encode?(value, options = nil)
  if !options
    value.to_s =~ /^[0-9]{12,13}$/
  elsif (options[:checksum_included])
    value.to_s =~ /^[0-9]{13}$/
  else
    value.to_s =~ /^[0-9]{12}$/
  end
end

.decode(str) ⇒ Object

Decode a string representing an rle or bar pattern EAN-13. Note that the string might be backward or forward. This will return an EAN13 object.

Raises:



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# File 'lib/barcode1dtools/ean13.rb', line 252

def decode(str)
  if str.length == 95
    # bar pattern
    str = bars_to_rle(str)
  elsif str.length == 59
    # rle
  else
    raise UnencodableCharactersError, "Pattern must be 95 unit bar pattern or 59 character rle."
  end

  # Check the guard patterns
  unless str[0..2] == SIDE_GUARD_PATTERN_RLE && str[56..58] == SIDE_GUARD_PATTERN_RLE && str[27..31] == MIDDLE_GUARD_PATTERN_RLE
    raise UnencodableCharactersError, "Missing or incorrect guard patterns"
  end

  # Now I have an rle pattern, simply need to decode
  # according to the LEFT_PATTERNS_RLE, keeping track
  # of the parity for each position.

  # Set up the decoder
  left_parity_sequence = ''
  left_digits = ''
  right_parity_sequence = ''
  right_digits = ''
  left_initial_offset = SIDE_GUARD_PATTERN_RLE.length
  right_initial_offset = SIDE_GUARD_PATTERN_RLE.length + (4*6) + MIDDLE_GUARD_PATTERN_RLE.length

  # Decode the left side
  (0..5).each do |left_offset|
    found = false
    digit_rle = str[(left_initial_offset + left_offset*4),4]
    ['o','e'].each do |parity|
      ('0'..'9').each do |digit|
        if LEFT_PATTERNS_RLE[digit][parity] == digit_rle
          left_parity_sequence += parity
          left_digits += digit
          found = true
          break
        end
      end
    end
    raise UndecodableCharactersError, "Invalid sequence: #{digit_rle}" unless found
  end

  # Decode the right side
  (0..5).each do |right_offset|
    found = false
    digit_rle = str[(right_initial_offset + right_offset*4),4]
    ['o','e'].each do |parity|
      ('0'..'9').each do |digit|
        if LEFT_PATTERNS_RLE[digit][parity] == digit_rle
          right_parity_sequence += parity
          right_digits += digit
          found = true
          break
        end
      end
    end
    raise UndecodableCharactersError, "Invalid sequence: #{digit_rle}" unless found
  end

  # If left parity sequence is 'eeeeee', the string is reversed
  if left_parity_sequence == 'eeeeee'
    left_digits, right_digits, left_parity_sequence = right_digits.reverse, left_digits.reverse, right_parity_sequence.reverse.tr('eo','oe')
  end

  # Now, find the parity digit
  parity_digit = nil
  ('0'..'9').each do |x|
    if LEFT_PARITY_PATTERNS[x] == left_parity_sequence
      parity_digit = x
      break
    end
  end

  raise UndecodableCharactersError, "Weird parity: #{left_parity_sequence}" unless parity_digit

  # Debugging
  #puts "Left digits: #{left_digits} Left parity: #{left_parity_sequence}"
  #puts "Right digits: #{right_digits} Right parity: #{right_parity_sequence}"
  #puts "Parity: #{parity_digit}"

  EAN13.new(parity_digit + left_digits + right_digits, :checksum_included => true)
end

.generate_check_digit_for(value) ⇒ Object

Generates check digit given a string to encode. It assumes there is no check digit on the “value”.

Raises:



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# File 'lib/barcode1dtools/ean13.rb', line 234

def generate_check_digit_for(value)
  raise UnencodableCharactersError unless self.can_encode?(value, :checksum_included => false)
  mult = 3
  value = value.split('').inject(0) { |a,c| mult = 4 - mult ; a + c.to_i * mult }
  (10 - (value % 10)) % 10
end

.validate_check_digit_for(value) ⇒ Object

Validates the check digit given a string - assumes check digit is last digit of string.

Raises:



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# File 'lib/barcode1dtools/ean13.rb', line 243

def validate_check_digit_for(value)
  raise UnencodableCharactersError unless self.can_encode?(value, :checksum_included => true)
  md = value.match(/^(\d{12})(\d)$/)
  self.generate_check_digit_for(md[1]) == md[2].to_i
end

Instance Method Details

#bars ⇒ Object

Returns 1s and 0s (for “black” and “white”)



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# File 'lib/barcode1dtools/ean13.rb', line 381

def bars
  @bars ||= self.class.rle_to_bars(self.rle, @options)
end

#rle ⇒ Object

Returns a run-length-encoded string representation



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# File 'lib/barcode1dtools/ean13.rb', line 371

def rle
  if @rle
    @rle
  else
    md = @encoded_string.match(/^(\d)(\d{6})(\d{6})/)
    @rle = gen_rle(md[1], md[2], md[3])
  end
end

#width ⇒ Object

Returns the total unit width of the bar code



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# File 'lib/barcode1dtools/ean13.rb', line 386

def width
  @width ||= rle.split('').inject(0) { |a,c| a + c.to_i }
end

#wn ⇒ Object

Note that EANs cannot produce a w/n string, so this will raise an error.

Raises:



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# File 'lib/barcode1dtools/ean13.rb', line 366

def wn
  raise NotImplementedError
end