Class: Barcode1DTools::Matrix2of5

Inherits:
Barcode1D
  • Object
show all
Defined in:
lib/barcode1dtools/matrix2of5.rb

Overview

Barcode1DTools::Matrix2of5 - Create and decode bar patterns for Matrix 2 of 5. The value encoded is a number with digits 0-9. Internally, the value is treated as a string to preserve leading zeroes.

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.

Matrix 2 of 5 is low-density and limited. It should not be used in any new applications.

Example

val = "3423"
bc = Barcode1DTools::Matrix2of5.new(val)
pattern = bc.bars
rle_pattern = bc.rle
width = bc.width

The object created is immutable.

Barcode1DTools::Matrix2of5 creates the patterns that you need to display Matrix 2 of 5 barcodes. It can also decode a simple w/n string.

Matrix2of5 characters consist of 3 bars and 2 spaces, with a narrow space between them. 2 of the bars/spaces in each symbol are 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. Note that the position weights are 1, 2, 4, and 7, and the last bit is parity. Each letter is an alternating bar then space, and there is a narrow space between each character.

{
  '0'=> {'val'=>0 ,'wn'=>'nnwwn'},
  '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'=>'nwnwn'}
}
GUARD_PATTERN_LEFT_WN =

Left guard pattern

'wnnnn'
GUARD_PATTERN_RIGHT_WN =

Right guard pattern

'wnnnn'
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 = {}) ⇒ Matrix2of5

Create a new Matrix2of5 object with a given value. Options are :line_character, :space_character, :w_character, :n_character, :checksum_included, and :skip_checksum.

Raises:



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# File 'lib/barcode1dtools/matrix2of5.rb', line 177

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]
    @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
    @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 is encodable in this symbology. Matrix2of5 can encode digits.

Returns:

  • (Boolean) 


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# File 'lib/barcode1dtools/matrix2of5.rb', line 103

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

.decode(str, options = {}) ⇒ Object

Decode a string in rle or w/n format. This will return a Matrix2of5 object.



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# File 'lib/barcode1dtools/matrix2of5.rb', line 125

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_LEFT_WN}n.*?#{GUARD_PATTERN_RIGHT_WN}\z/
    str.reverse!
  end

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

  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

  Matrix2of5.new(decoded_string, options)
end

.generate_check_digit_for(value) ⇒ Object

Generates a check digit for a given value using the Luhn algorithm.

Raises:



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# File 'lib/barcode1dtools/matrix2of5.rb', line 108

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

.validate_check_digit_for(value) ⇒ Object

Returns true if the final digit if the given string is a valid check digit for the rest of the string.

Raises:



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# File 'lib/barcode1dtools/matrix2of5.rb', line 117

def validate_check_digit_for(value)
  raise UnencodableCharactersError unless self.can_encode?(value)
  md = value.match(/^(\d+?)(\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/matrix2of5.rb', line 213

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/matrix2of5.rb', line 208

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/matrix2of5.rb', line 218

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/matrix2of5.rb', line 203

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