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.

Example

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.

Formats

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 =

Guard pattern for Code 11

'nnwwn'
DEFAULT_OPTIONS = 
{
  :line_character => '1',
  :space_character => '0',
  :w_character => 'w',
  :n_character => 'n',
  :wn_ratio => '2'
}

Instance Attribute Summary

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

Create a new Code 11 object with a value. Options are :line_character, :space_character, :w_character, :n_character, :checksum_included, and :skip_checksum.

Raises:



196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
 
# File 'lib/barcode1dtools/code11.rb', line 196

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

Class Method Details

.can_encode?(value) ⇒ Boolean

Returns true if the value presented can be encoded in Code 11. Code11 can encode digits and dashes.

Returns:

  • (Boolean) 


100
101
102
 
# File 'lib/barcode1dtools/code11.rb', line 100

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.



143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
 
# File 'lib/barcode1dtools/code11.rb', line 143

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

Generates a check digit for the given value. Note that Code 11 barcodes may have two check digits if the size of the value is 10 or more characters.



107
108
109
110
111
112
113
114
115
116
117
118
119
 
# File 'lib/barcode1dtools/code11.rb', line 107

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

Split the given value into a payload and check digit or digits.



131
132
133
134
135
136
137
138
139
 
# File 'lib/barcode1dtools/code11.rb', line 131

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

Returns true if the given check digit(s) is correct. The check digit is the last one or two characters of the value that is passed.



124
125
126
127
 
# File 'lib/barcode1dtools/code11.rb', line 124

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 the bar/space pattern as 1s and 0s.



231
232
233
 
# File 'lib/barcode1dtools/code11.rb', line 231

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

#rle ⇒ Object

Returns a run-length-encoded string representation



226
227
228
 
# File 'lib/barcode1dtools/code11.rb', line 226

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

#width ⇒ Object

Returns the total unit width of the bar code



236
237
238
 
# File 'lib/barcode1dtools/code11.rb', line 236

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”)



221
222
223
 
# File 'lib/barcode1dtools/code11.rb', line 221

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