Class: Barcode1DTools::Codabar
- Defined in:
- lib/barcode1dtools/codabar.rb
Overview
Barcode1DTools::Codabar - Create and decode bar patterns for Codabar. The value encoded is a string which may contain the digits 0-9 and the symbols dash “-”, dollar sign “$”, plus sign “+”, colon “:”, forward slash “/”, and dot “.”. There are four start/stop characters which are A, B, C, and D or T, N, asterisk “*”, and E. Note that A and T are equivalent, as are B and N, C and asterisk, and D and E. Any may be used as start and stop characters giving 16 possible combinations.
Because there is no standard for check digits, we implement neither generation nor checking of one. It is up to the caller to present a check digit if it is part of the payload.
Additionally, the caller must present the start and stop characters as part of the value. When decoding, the start/stop characters will be presented as A, B, C, or D.
Example
val = "A29322930C"
bc = Barcode1DTools::Codabar.new(val)
pattern = bc.
rle_pattern = bc.rle
width = bc.width
The object created is immutable.
Barcode1DTools::Codabar creates the patterns that you need to display Codabar barcodes. It can also decode a simple w/n string.
Codabar characters consist of 4 bars and 3 spaces, with a narrow space between them. The main characters (0-9, dash, and dollar sign) each have one wide bar and one wide space (hence the alternate name “code 2 of 7”). The start/stop codes have one wide bar and two adjacent wide spaces. The extended characters (dot, forward slash, colon, and plus sign) each have three wide bars and all narrow spaces.
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 original Codabar specification actually included a varied w/n ratio depending on whether there were two or three wide elements in a character. Those with two wide elements used a 3:1 ratio while those with three wide elements used a 2:1 ratio. In that way, the characters were consistently 10 units wide.
Our default ratio is 3:1 for the entire code, but if you include :varied_wn_ratio => true in the options the rle and bars strings will have variable ratio that shifts between 2:1 and 3:1 and the “wn_ratio” option will be ignored.
Constant Summary collapse
- CHAR_SEQUENCE =
Character sequence - 0-based offset in this string is character number
"0123456789-$:/.+ABCD"
- PATTERNS =
Patterns for making bar codes
{ '0'=> {'val'=>0 ,'wn'=>'nnnnnww'}, '1'=> {'val'=>1 ,'wn'=>'nnnnwwn'}, '2'=> {'val'=>2 ,'wn'=>'nnnwnnw'}, '3'=> {'val'=>3 ,'wn'=>'wwnnnnn'}, '4'=> {'val'=>4 ,'wn'=>'nnwnnwn'}, '5'=> {'val'=>5 ,'wn'=>'wnnnnwn'}, '6'=> {'val'=>6 ,'wn'=>'nwnnnnw'}, '7'=> {'val'=>7 ,'wn'=>'nwnnwnn'}, '8'=> {'val'=>8 ,'wn'=>'nwwnnnn'}, '9'=> {'val'=>9 ,'wn'=>'wnnwnnn'}, '-'=> {'val'=>10 ,'wn'=>'nnnwwnn'}, '$'=> {'val'=>11 ,'wn'=>'nnwwnnn'}, ':'=> {'val'=>12 ,'wn'=>'wnnnwnw'}, '/'=> {'val'=>13 ,'wn'=>'wnwnnnw'}, '.'=> {'val'=>14 ,'wn'=>'wnwnwnn'}, '+'=> {'val'=>15 ,'wn'=>'nnwnwnw'}, 'A'=> {'val'=>16 ,'wn'=>'nnwwnwn'}, 'B'=> {'val'=>17 ,'wn'=>'nwnwnnw'}, 'C'=> {'val'=>18 ,'wn'=>'nnnwnww'}, 'D'=> {'val'=>19 ,'wn'=>'nnnwwwn'}, 'T'=> {'val'=>16 ,'wn'=>'nnwwnwn'}, 'N'=> {'val'=>17 ,'wn'=>'nwnwnnw'}, '*'=> {'val'=>18 ,'wn'=>'nnnwnww'}, 'E'=> {'val'=>19 ,'wn'=>'nnnwwwn'} }
- DEFAULT_OPTIONS =
{ :line_character => '1', :space_character => '0', :w_character => 'w', :n_character => 'n', :wn_ratio => '3', :varied_wn_ratio => false }
Instance Attribute Summary collapse
-
#payload ⇒ Object
readonly
The actual payload (between start/stop characters).
-
#start_character ⇒ Object
readonly
Holds the start character.
-
#stop_character ⇒ Object
readonly
Holds the stop character.
Attributes inherited from Barcode1D
#check_digit, #encoded_string, #options, #value
Class Method Summary collapse
-
.can_encode?(value) ⇒ Boolean
Returns true if the value presented can be encoded in a Codabar barcode.
-
.decode(str, options = {}) ⇒ Object
Decode a string in rle format.
-
.generate_check_digit_for(value) ⇒ Object
Generate a check digit.
-
.validate_check_digit_for(value) ⇒ Object
Validate the check digit.
Instance Method Summary collapse
-
#bars ⇒ Object
Returns the bar pattern.
-
#initialize(value, options = {}) ⇒ Codabar
constructor
Create a new Codabar object.
-
#rle ⇒ Object
Returns a run-length-encoded string representation.
-
#width ⇒ Object
Returns the total unit width of the bar code.
-
#wn ⇒ Object
Returns a string of “w” or “n” (“wide” and “narrow”).
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 = {}) ⇒ Codabar
Create a new Codabar object. Options are :line_character, :space_character, :w_character, :n_character, and :varied_wn_ratio.
212 213 214 215 216 217 218 219 220 221 222 223 224 225 |
# File 'lib/barcode1dtools/codabar.rb', line 212 def initialize(value, = {}) @options = DEFAULT_OPTIONS.merge() # Can we encode this value? raise UnencodableCharactersError unless self.class.can_encode?(value) @value = value.to_s @check_digit = nil @encoded_string = @value md = @value.match(/\A([ABCDTNE\*])(.*?)([ABCDTNE\*])\z/) @start_character, @payload, @stop_character = md[1], md[2], md[3] end |
Instance Attribute Details
#payload ⇒ Object (readonly)
The actual payload (between start/stop characters)
132 133 134 |
# File 'lib/barcode1dtools/codabar.rb', line 132 def payload @payload end |
#start_character ⇒ Object (readonly)
Holds the start character
128 129 130 |
# File 'lib/barcode1dtools/codabar.rb', line 128 def start_character @start_character end |
#stop_character ⇒ Object (readonly)
Holds the stop character
130 131 132 |
# File 'lib/barcode1dtools/codabar.rb', line 130 def stop_character @stop_character end |
Class Method Details
.can_encode?(value) ⇒ Boolean
Returns true if the value presented can be encoded in a Codabar barcode. Codabar can encode digits, dash, dollar, colon, forward slash, dot, and plus. The string must start and stop with start/stop characters.
140 141 142 |
# File 'lib/barcode1dtools/codabar.rb', line 140 def can_encode?(value) value.to_s =~ /\A[ABCD][0-9\$:\/\.\+\-]*[ABCD]\z/ || value.to_s =~ /\A[TN\*E][0-9\$:\/\.\+\-]*[TN\*E]\z/ end |
.decode(str, options = {}) ⇒ Object
Decode a string in rle format. This will return a Codabar object.
158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 |
# File 'lib/barcode1dtools/codabar.rb', line 158 def decode(str, = {}) 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 start_stop_pattern_match = Regexp.new(['A','B','C','D'].collect { |c| PATTERNS[c]['wn'] }.join('|')) if str.reverse =~ /\A#{start_stop_pattern_match}n.*?#{start_stop_pattern_match}\z/ str.reverse! end unless str =~ /\A(#{start_stop_pattern_match}n.*?#{start_stop_pattern_match})\z/ raise UnencodableCharactersError, "Start/stop pattern is not detected." end # Adding an "n" to make it easier to scan wn_pattern = $1 + 'n' # Each pattern is 4 bars and 3 spaces, with a space between. unless wn_pattern.size % 8 == 0 raise UnencodableCharactersError, "Wrong number of bars." end decoded_string = '' wn_pattern.scan(/(.{7})n/).each do |chunk| chunk = chunk.first found = false PATTERNS.each do |char,hsh| if !['T', 'E', '*', 'N'].include?(char) && chunk == hsh['wn'] decoded_string += char found = true break; end end raise UndecodableCharactersError, "Invalid sequence: #{chunk}" unless found end Codabar.new(decoded_string) end |
.generate_check_digit_for(value) ⇒ Object
Generate a check digit. For Codabar, this will raise a NotImplementedError.
146 147 148 |
# File 'lib/barcode1dtools/codabar.rb', line 146 def generate_check_digit_for(value) raise NotImplementedError end |
.validate_check_digit_for(value) ⇒ Object
Validate the check digit. For Codabar, this will raise a NotImplementedError.
152 153 154 |
# File 'lib/barcode1dtools/codabar.rb', line 152 def validate_check_digit_for(value) raise NotImplementedError end |
Instance Method Details
#bars ⇒ Object
Returns the bar pattern
242 243 244 |
# File 'lib/barcode1dtools/codabar.rb', line 242 def @bars ||= self.class.(self.rle, @options) end |
#rle ⇒ Object
Returns a run-length-encoded string representation
233 234 235 236 237 238 239 |
# File 'lib/barcode1dtools/codabar.rb', line 233 def rle if @options[:varied_wn_ratio] @rle ||= @encoded_string.split('').collect { |c| PATTERNS[c]['wn'] }.collect { |p| p.tr('wn',(p=~/.*w.*w.*w/ ? '21' : '31')) }.join('1') else @rle ||= self.class.wn_to_rle(self.wn, @options) end end |
#width ⇒ Object
Returns the total unit width of the bar code
247 248 249 |
# File 'lib/barcode1dtools/codabar.rb', line 247 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”)
228 229 230 |
# File 'lib/barcode1dtools/codabar.rb', line 228 def wn @wn ||= wn_str.tr('wn', @options[:w_character].to_s + @options[:n_character].to_s) end |