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.
val = “A29322930C” bc = Barcode1DTools::Codabar.new(val) pattern = bc.bars 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.
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
Returns the value of attribute payload.
-
#start_character ⇒ Object
readonly
Returns the value of attribute start_character.
-
#stop_character ⇒ Object
readonly
Returns the value of attribute stop_character.
Attributes inherited from Barcode1D
#check_digit, #encoded_string, #options, #value
Class Method Summary collapse
-
.can_encode?(value) ⇒ Boolean
Codabar can encode digits, dash, dollar, colon, forward slash, dot, and plus.
-
.decode(str, options = {}) ⇒ Object
Decode a string in rle format.
-
.generate_check_digit_for(value) ⇒ Object
We don’t generate a check digit.
- .validate_check_digit_for(value) ⇒ Object
Instance Method Summary collapse
-
#bars ⇒ Object
returns 1s and 0s (for “black” and “white”).
-
#initialize(value, options = {}) ⇒ Codabar
constructor
Options are :line_character, :space_character, :w_character, :n_character, and :varied_wn_ratio.
-
#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
Options are :line_character, :space_character, :w_character, :n_character, and :varied_wn_ratio.
200 201 202 203 204 205 206 207 208 209 210 211 212 213 |
# File 'lib/barcode1dtools/codabar.rb', line 200 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)
Returns the value of attribute payload.
125 126 127 |
# File 'lib/barcode1dtools/codabar.rb', line 125 def payload @payload end |
#start_character ⇒ Object (readonly)
Returns the value of attribute start_character.
125 126 127 |
# File 'lib/barcode1dtools/codabar.rb', line 125 def start_character @start_character end |
#stop_character ⇒ Object (readonly)
Returns the value of attribute stop_character.
125 126 127 |
# File 'lib/barcode1dtools/codabar.rb', line 125 def stop_character @stop_character end |
Class Method Details
.can_encode?(value) ⇒ Boolean
Codabar can encode digits, dash, dollar, colon, forward slash, dot, and plus. The string must start and stop with start/stop characters.
131 132 133 |
# File 'lib/barcode1dtools/codabar.rb', line 131 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.
146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 |
# File 'lib/barcode1dtools/codabar.rb', line 146 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
We don’t generate a check digit
136 137 138 |
# File 'lib/barcode1dtools/codabar.rb', line 136 def generate_check_digit_for(value) raise NotImplementedError end |
.validate_check_digit_for(value) ⇒ Object
140 141 142 |
# File 'lib/barcode1dtools/codabar.rb', line 140 def validate_check_digit_for(value) raise NotImplementedError end |
Instance Method Details
#bars ⇒ Object
returns 1s and 0s (for “black” and “white”)
230 231 232 |
# File 'lib/barcode1dtools/codabar.rb', line 230 def @bars ||= self.class.(self.rle, @options) end |
#rle ⇒ Object
returns a run-length-encoded string representation
221 222 223 224 225 226 227 |
# File 'lib/barcode1dtools/codabar.rb', line 221 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
235 236 237 |
# File 'lib/barcode1dtools/codabar.rb', line 235 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”)
216 217 218 |
# File 'lib/barcode1dtools/codabar.rb', line 216 def wn @wn ||= wn_str.tr('wn', @options[:w_character].to_s + @options[:n_character].to_s) end |