For an inventory application I am currently developing, I needed a way to generate a barcode for products that were input into the system.

Fortunately Tore Darell has developed a super simple barcode library named Barby

Barby generated the barcodes perfectly. I choose to use the RMagick outputter, as I already had that set up on my system.

Simple Example using the RMagick Outputter

require 'rubygems'
require 'barby'
require 'barby/outputter/rmagick_outputter'

barcode = Barby::Code128B.new('Barcode Code Here')
File.open('code128B.png', 'w'){|f|
  f.write barcode.to_png
}

Produces

See the Barby documentation for the different barcodes that are currently supported. The above example uses 128 with type B. (I don’t really understand all the different types of barcodes yet).

Extension

The above image is fine, but I needed to also output the code that was input underneath the barcode. The reason for this is so a human can recognise the codes without getting the barcode scanner out.

So I wrote this very quick extension to the Rmagic Outputter. It basically uses Rmagic to extend the canvas by 10 px in height and outputs the code at the bottom

Here is the extension with example usage at the bottom:

require 'rubygems'
require 'barby'
require 'barby/outputter/rmagick_outputter'

module Barby
  class CustomRmagickOutputter < RmagickOutputter
    register :to_image_with_data
    def to_image_with_data
      #Make canvas  bigger
      canvas = Magick::ImageList.new
      canvas.new_image(full_width , full_height + 10)
      canvas << to_image
      canvas = canvas.flatten_images
      #Make the text
      text = Magick::Draw.new
      text.font_family = 'helvetica'
      text.pointsize = 14
      text.gravity = Magick::SouthGravity
      text.annotate(canvas , 0,0,0,0, barcode.data)
      canvas
    end
  end
end

barcode = Barby::Code128B.new('Barcode Code Here')
barcode.to_image_with_data.write('barcode_2.png')

This outputs:

As you can see the code is on the bottom which is what I needed. I hope this has helped someone. I would love to hear your comments.

You might also have noticed I have removed all the spam comments and am now using Disqus

Hamza