zxing.rb

= ZXing

Decode QR codes (and other 1D/2D barcode formats)

QRcode[http://en.wikipedia.org/wiki/QR_Code] generation is well served in the
Ruby community, but decoding seems to be stuck in the Java world. This is an
attempt to bridge the gap by wrapping the
ZXing[http://code.google.com/p/zxing/] library with JRuby. ZXing conveniently
decodes a plethora of barcodes. Their site has a complete list.

== Installation

gem install zxing

== Requirements

• JRuby (tested with 1.5.6), OR
• MRI (1.8.7 and 1.9.2) with jruby-jars gem

== Usage

require 'zxing'

# Pass a path to a file, and it will return the characters encoded within
# the barcode image.  For example, if a QRCode image has the text "QRcode
# string" embedded:
ZXing.decode '/Users/ecin/qrcode.png' #=> "QRcode string"

# ZXing#decode_all returns an array of encoded values.  For example if an
# image has a barcode encoded with the value "test123" and another barcode
# encoded with the value "test456":
ZXing.decode_all 'image_with_multiple_barcodes.png' #=> ["test456", "test123"]

# You can also decode a URL...
ZXing.decode 'http://2d-code.co.uk/images/bbc-logo-in-qr-code.gif'

# or an instance of File
ZXing.decode File.new('qrcode.png')

# or anything that returns a URL or file path when #path is called on it.
class Image
  attr_reader :path
  def initialize(path); @path = path end
end


# ZXing#decode returns nil if it can't decode the image.
ZXing.decode 'image_without_a_code.png' #=> nil

# ZXing#decode! will raise an error if it can't decode the image.
ZXing.decode! 'image_without_a_code.png' #=> raises ZXing::UndecodableError

== Decodable module

A Decodable module is included (pun intended) to ease using the library with objects that return the URL or file path to decode when #path or #to_s is called.

require 'zxing/decodable'

class File
  include Decodable
end

file = File.open('qrcode.png')
file.decode