Class: RBarcode::Code39

Inherits:
Base
  • Object
show all
Defined in:
lib/rbarcode/code39.rb

Overview

This class takes a string and generates a Code 39-based barcode from that string.

Constant Summary collapse

API_VERSION = 
"0.2"
@@encoding =

quick reference as to what’s up with @@encoding:

  • B => large solid bar

  • b => small solid bar

  • W => large space

  • w => small space

{
  '0' => "bwbWBwBwb",
  '1' => "BwbWbwbwB",
  '2' => "bwBWbwbwB",
  '3' => "BwBWbwbwb",
  '4' => "bwbWBwbwB",
  '5' => "BwbWBwbwb",
  '6' => "bwBWBwbwb",
  '7' => "bwbWbwBwB",
  '8' => "BwbWbwBwb",
  '9' => "bwBWbwBwb",
  'A' => "BwbwbWbwB",
  'B' => "bwBwbWbwB",
  'C' => "BwBwbWbwb",
  'D' => "bwbwBWbwB",
  'E' => "BwbwBWbwb",
  'F' => "bwBwBWbwb",
  'G' => "bwbwbWBwB",
  'H' => "BwbwbWBwb",
  'I' => "bwBwbWBwb",
  'J' => "bwbwBWBwb",
  'K' => "BwbwbwbWB",
  'L' => "bwBwbwbWB",
  'M' => "BwBwbwbWb",
  'N' => "bwbwBwbWB",
  'O' => "BwbwBwbWb",
  'P' => "bwBwBwbWb",
  'Q' => "bwbwbwBWB",
  'R' => "BwbwbwBWb",
  'S' => "bwBwbwBWb",
  'T' => "bwbwBwBWb",
  'U' => "BWbwbwbwB",
  'V' => "bWBwbwbwB",
  'W' => "BWBwbwbwb",
  'X' => "bWbwBwbwB",
  'Y' => "BWbwBwbwb",
  'Z' => "bWBwBwbwb",
  '-' => "bWbwbwBwB",
  '.' => "BWbwbwBwb",
  ' ' => "bWBwbwBwb",
  '$' => "bWbWbWbwb",
  '/' => "bWbWbwbWb",
  '+' => "bWbwbWbWb",
  '%' => "bwbWbWbWb",
  '*' => "bWbwBwBwb"
}

Instance Attribute Summary

Attributes inherited from Base

#required, #text

Instance Method Summary collapse

Methods inherited from Base

#code39, #postnet

Constructor Details

#initialize(options = {}) ⇒ Code39

Takes a string, uppercases it, and wraps it in asterisks. If any character is unavailable in Code 39 encoding, throws a vicious error.



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# File 'lib/rbarcode/code39.rb', line 73

def initialize(options = {})
  @required =  [:text]
  super
  @text.upcase!
  @text.split(//).each do |char|
    if not @@encoding.has_key?(char)
      raise "Unencodable string."
    end
  end

  @text = "*#{@text}*"
end

Instance Method Details

#to_img(filename, width, height) ⇒ Object

The overly complicated image generation code. Your barcode image width and height should be in pixels. The actual barcode will not be that width, instead it will be a multiple of your text string (plus two asterisks - @text) length * 14. White space will center the rest.



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# File 'lib/rbarcode/code39.rb', line 103

def to_img(filename, width, height)
  bar_code_width = width - (width % ( @text.length * 14 ) )
  letter_width = bar_code_width / @text.length
  small_bar_width = letter_width / 14
  large_bar_width = ((7.0 / 3.0) * small_bar_width.to_f).to_i

  canvas = Image.new(width, height)
  gc = Draw.new
  gc.fill('black')
  gc.stroke('black')
  gc.stroke_width(-1)
  # Necessary to prevent massive blurry image nonsense.
  gc.stroke_antialias(false)

  cur_x = (width - bar_code_width) / 2

  self.to_s.split(//).each do |char|
     if char.upcase == "B"
        gc.rectangle(cur_x, 0, cur_x + (char == "B" ? large_bar_width : small_bar_width), height)
     end
     cur_x += char.match(/[BW]/) ? large_bar_width : small_bar_width
  end
  gc.draw(canvas)
  canvas.write(filename)
end

#to_s ⇒ Object

Outputs a string that represents the encoding. Not necessarily useful externally, but who knows?



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# File 'lib/rbarcode/code39.rb', line 89

def to_s
  output = String.new
  @text.split(//).each do |char|
    output += @@encoding[char] + " "
  end
  return output
end