Backup file into QR code

qrcode-backup.rb

#!/usr/bin/env ruby
require 'chunky_png'
require 'rqrcode_png'

CHUNK_SIZE=4096/6 # 5462 bits, QRCode 29 = 5608 bits
IMG_SIZE = 800
IMG_PER_LINE = 2

def chunk(string, size)
	string.scan /.{1,#{size}}/om
end

class QRCodeImage
	def initialize(qr)
		@qr = qr
	end

	def each_dark_pixel(&block)
		@qr.modules.each_index do |row|
			@qr.modules.each_index do |column|
				if @qr.dark? row, column
					yield column, row
				end
			end 
		end
	end

	def render(size, color = ::ChunkyPNG::Color::BLACK)
		qr_size = @qr.module_count
		qr = ::ChunkyPNG::Image.new qr_size, qr_size, ::ChunkyPNG::Color::WHITE
		self.each_dark_pixel do |row, column|
			qr[row, column] = color
		end

		border = (4*size/(qr_size+8).to_f).ceil # QRCode expect a 4 modules wide quiet zone
		qr_size = size-2*border
		qr = qr.resize qr_size, qr_size
		img = ::ChunkyPNG::Image.new size, size, ::ChunkyPNG::Color::WHITE
		img.replace qr, border, border
	end
end

file = ARGV[0]
data = File.read file
chunks = chunk data, CHUNK_SIZE
cols = chunks.length < IMG_PER_LINE ? chunks.length : IMG_PER_LINE
rows = (chunks.length / IMG_PER_LINE.to_f).ceil

png = ChunkyPNG::Image.new cols*IMG_SIZE, rows*IMG_SIZE, ChunkyPNG::Color::WHITE

n = 0
chunks.each do |chunk|
	qr = RQRCode::QRCode.new chunk, size: 29, level: :h
	img = QRCodeImage.new(qr).render IMG_SIZE
	offset = n.divmod cols
	png.replace! img, IMG_SIZE*offset[1], IMG_SIZE*offset[0]
	n += 1
end
png.save "#{file}.png"

qrcode-restore.rb

#!/usr/bin/env ruby
require 'qrio'

ARGV.each do |file|
	qr = Qrio::Qr.load file
	p qr.text

	qr.save_image(
	  "#{file}-annotated",
	  :crop => true,
	  :annotate => [
		:finder_patterns,
		:angles
	  ]
	)
end