Class: Barcode1DTools::Code11

Inherits:
Barcode1D show all
Defined in:
lib/barcode1dtools/code11.rb

Overview

Barcode1DTools::Code11 - Create and decode bar patterns for Code11. The value encoded is a string which may contain the digits 0-9 and the dash symbol “-”. The standard specifies one or two check digits may be added depending on the length of the payload. Use :checksum_included => true if you have already added a checksum and wish to have it validated, or :skip_checksum => true if you don’t wish to add one or have it validated.

Code 11 is used in the telecom industry for equipment labeling. It should not be used in any new applications.

val = “29382-38” bc = Barcode1DTools::Code11.new(val) pattern = bc.bars rle_pattern = bc.rle width = bc.width

The object created is immutable.

Barcode1DTools::Code11 creates the patterns that you need to display Code11 barcodes. It can also decode a simple w/n string.

Code11 characters consist of 3 bars and 2 spaces, with a narrow space between them. Three of the characters- 0, 9, and “-” - are 6 units wide. The rest are 7 units wide.

There are three formats for the returned pattern:

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.

wn -   The native format for this barcode type.  The string
       consists of a series of "w" and "n" characters.  The first
       item is always a black line, with subsequent characters
       alternating between spaces and lines.  A "wide" item
       is twice the width of a "narrow" item.

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

Rendering

The standard w/n ratio seems to be 2:1. There seem to be no real standards for display.

Constant Summary collapse

CHAR_SEQUENCE =

Character sequence - 0-based offset in this string is character number

"0123456789-"
PATTERNS =

Patterns for making bar codes

{
  '0'=> {'val'=>0 ,'wn'=>'nnnnw'},
  '1'=> {'val'=>1 ,'wn'=>'wnnnw'},
  '2'=> {'val'=>2 ,'wn'=>'nwnnw'},
  '3'=> {'val'=>3 ,'wn'=>'wwnnn'},
  '4'=> {'val'=>4 ,'wn'=>'nnwnw'},
  '5'=> {'val'=>5 ,'wn'=>'wnwnn'},
  '6'=> {'val'=>6 ,'wn'=>'nwwnn'},
  '7'=> {'val'=>7 ,'wn'=>'nnnww'},
  '8'=> {'val'=>8 ,'wn'=>'wnnwn'},
  '9'=> {'val'=>9 ,'wn'=>'wnnnn'},
  '-'=> {'val'=>10 ,'wn'=>'nnwnn'}
}
GUARD_PATTERN_WN = 
'nnwwn'
DEFAULT_OPTIONS = 
{
  :line_character => '1',
  :space_character => '0',
  :w_character => 'w',
  :n_character => 'n',
  :wn_ratio => '2'
}

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 = {}) ⇒ Code11

Options are :line_character, :space_character, :w_character, :n_character, :checksum_included, and :skip_checksum.

Raises:



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# File 'lib/barcode1dtools/code11.rb', line 185

def initialize(value, options = {})

  @options = DEFAULT_OPTIONS.merge(options)

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

  @value = value.to_s

  if @options[:skip_checksum]
    @encoded_string = value.to_s
    @value = value.to_s
    @check_digit = nil
  elsif @options[:checksum_included]
    raise ChecksumError unless self.class.validate_check_digit_for(value)
    @encoded_string = value.to_s
    @value, @check_digit = self.class.split_payload_and_check_digits(value)
  else
    @value = value.to_s
    @check_digit = self.class.generate_check_digit_for(@value)
    @encoded_string = "#{@value}#{@check_digit}"
  end
end

Instance Attribute Details

#payload ⇒ Object (readonly)

Returns the value of attribute payload.



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# File 'lib/barcode1dtools/code11.rb', line 94

def payload
  @payload
end

#start_character ⇒ Object (readonly)

Returns the value of attribute start_character.



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# File 'lib/barcode1dtools/code11.rb', line 94

def start_character
  @start_character
end

#stop_character ⇒ Object (readonly)

Returns the value of attribute stop_character.



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# File 'lib/barcode1dtools/code11.rb', line 94

def stop_character
  @stop_character
end

Class Method Details

.can_encode?(value) ⇒ Boolean

Code11 can encode digits and dashes.

Returns:

  • (Boolean) 


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# File 'lib/barcode1dtools/code11.rb', line 98

def can_encode?(value)
  value.to_s =~ /\A[0-9\-]+\z/
end

.decode(str, options = {}) ⇒ Object

Decode a string in rle format. This will return a Code11 object.



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# File 'lib/barcode1dtools/code11.rb', line 133

def decode(str, options = {})
  if str =~ /[^1-3]/ && str =~ /[^wn]/
    raise UnencodableCharactersError, "Pattern must be rle or wn"
  end

  # ensure a wn string
  if str =~ /[1-3]/
    str = str.tr('123','nww')
  end

  if str.reverse =~ /\A#{GUARD_PATTERN_WN}n.*?#{GUARD_PATTERN_WN}\z/
    str.reverse!
  end

  unless str =~ /\A#{GUARD_PATTERN_WN}n(.*?)#{GUARD_PATTERN_WN}\z/
    raise UnencodableCharactersError, "Start/stop pattern is not detected."
  end

  # Adding an "n" to make it easier to scan
  wn_pattern = $1

  # Each pattern is 3 bars and 2 spaces, with a space between.
  unless wn_pattern.size % 6 == 0
    raise UnencodableCharactersError, "Wrong number of bars."
  end

  decoded_string = ''

  wn_pattern.scan(/(.{5})n/).each do |chunk|

    chunk = chunk.first
    found = false

    PATTERNS.each do |char,hsh|
      if chunk == hsh['wn']
        decoded_string += char
        found = true
        break;
      end
    end

    raise UndecodableCharactersError, "Invalid sequence: #{chunk}" unless found

  end

  Code11.new(decoded_string, options)
end

.generate_check_digit_for(value) ⇒ Object 



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# File 'lib/barcode1dtools/code11.rb', line 102

def generate_check_digit_for(value)
  mult = 0
  sum_c = value.to_s.reverse.split('').inject(0) { |a,c| mult = (mult == 11 ? 1 : mult + 1); a + mult * PATTERNS[c]['val'] }
  check_c = CHAR_SEQUENCE[sum_c % 11,1]
  if value.to_s.size > 9
    mult = 0
    sum_k = (value.to_s + check_c).reverse.split('').inject(0) { |a,c| mult = (mult == 10 ? 1 : mult + 1); a + mult * PATTERNS[c]['val'] }
    check_k = CHAR_SEQUENCE[sum_k % 9,1]
  else
    check_k = ''
  end
  "#{check_c}#{check_k}"
end

.split_payload_and_check_digits(value) ⇒ Object 



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# File 'lib/barcode1dtools/code11.rb', line 121

def split_payload_and_check_digits(value)
  if value.to_s.size > 11
    # two check digits
    md = value.to_s.match(/\A(.*)(..)\z/)
  else
    md = value.to_s.match(/\A(.*)(.)\z/)
  end
  [md[1], md[2]]
end

.validate_check_digit_for(value) ⇒ Object 



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# File 'lib/barcode1dtools/code11.rb', line 116

def validate_check_digit_for(value)
  payload, check_digits = split_payload_and_check_digits(value)
  self.generate_check_digit_for(payload) == check_digits
end

Instance Method Details

#bars ⇒ Object

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



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# File 'lib/barcode1dtools/code11.rb', line 220

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/code11.rb', line 215

def rle
  @rle ||= self.class.wn_to_rle(self.wn, @options)
end

#width ⇒ Object

returns the total unit width of the bar code



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# File 'lib/barcode1dtools/code11.rb', line 225

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

#wn ⇒ Object

Returns a string of “w” or “n” (“wide” and “narrow”)



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# File 'lib/barcode1dtools/code11.rb', line 210

def wn
  @wn ||= wn_str.tr('wn', @options[:w_character].to_s + @options[:n_character].to_s)
end