Crystal Lang QR Code

Native crystal lang QR code, no external dependencies

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     qr-code:
       github: spider-gazelle/qr-code

2. Run shards install

Usage

require "qr-code"

qr = QRCode.new("my string to generate", size: 4, level: :h)
puts qr.to_s

output

xxxxxxx x  x x   x x  xx  xxxxxxx
x     x  xxx  xxxxxx xxx  x     x
x xxx x  xxxxx x       xx x xxx x
... etc

Doing your own rendering

require "qr-code"

qr = QRCode.new("my string to generate", size: 4, level: :h)
qr.modules.each do |row|
  row.each do |col|
    print col ? '#' : ' '
  end

  print "\n"
end

Rendering a SVG

require "qr-code"

svg_string = QRCode.new("my string to generate").as_svg

Rendering a PNG

you'll need to add stumpy_png to your shard.yml dependencies

require "qr-code"
require "qr-code/export/png"

# size == width, and QR codes are square
png_bytes = QRCode.new("my string to generate").as_png(size: 256)

Credits

Based off the ruby gem: https://github.com/whomwah/rqrcode_core Which was adapted from the javascript library: https://github.com/kazuhikoarase/qrcode-generator