RQRCodeCore

rqrcode_core is a library for encoding QR Codes in pure Ruby. It has a simple interface with all the standard QR Code options. It was originally adapted in 2008 from a Javascript library by Kazuhiko Arase.

Features:

• rqrcode_core is a Ruby only library. It requires no 3rd party libraries. Just Ruby!
• It is an encoding library. You can't decode QR Codes with it.
• The interface is simple and assumes you just want to encode a string into a QR Code, but also allows for encoding multiple segments.
• QR Code is trade marked by Denso Wave inc.
• Minimum Ruby version is >= 3.2.0

rqrcode_core is the basis of the popular rqrcode gem [https://github.com/whomwah/rqrcode]. This gem allows you to generate different renderings of your QR Code, including png, svg and ansi.

Add this line to your application's Gemfile:

gem "rqrcode_core"

And then execute:

$ bundle

Or install it yourself as:

$ gem install rqrcode_core

$ require "rqrcode_core"
$ qr = RQRCodeCore::QRCode.new("https://kyan.com")
$ 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

$ require "rqrcode_core"
$ qr = RQRCodeCore::QRCode.new([
  {data: "byteencoded", mode: :byte_8bit},
  {data: "A1" * 100, mode: :alphanumeric},
  {data: "1" * 500, mode: :number}
])

This will create a QR Code with byte encoded, alphanumeric and number segments. Any combination of encodings/segments will work provided it fits within size limits.

require "rqrcode_core"

qr = RQRCodeCore::QRCode.new("https://kyan.com")
qr.modules.each do |row|
  row.each do |col|
    print col ? "#" : " "
  end

  print "\n"
end

The library expects a string or array (for multiple encodings) to be parsed in, other args are optional.

data - the string or array you wish to encode

size - the size (integer) of the QR Code (defaults to smallest size needed to encode the string)

max_size - the max_size (Integer) of the QR Code (default RQRCodeCore::QRUtil.max_size)

level  - the error correction level, can be:
  * Level :l 7%  of code can be restored
  * Level :m 15% of code can be restored
  * Level :q 25% of code can be restored
  * Level :h 30% of code can be restored (default :h)

mode - the mode of the QR Code (defaults to alphanumeric or byte_8bit, depending on the input data, only used when data is a string):
  * :number
  * :alphanumeric
  * :byte_8bit

RQRCodeCore::QRCode.new("http://kyan.com", size: 2, level: :m, mode: :byte_8bit)

You can run the test suite using:

$ ./bin/setup
$ rake

or try the project from the console with:

$ ./bin/console

The project uses standardrb and can be run with:

$ ./bin/setup
$ rake standard # check
$ rake standard:fix # fix

If you're running on a 64-bit system, you can dramatically reduce memory consumption by setting:

ENV['RQRCODE_CORE_ARCH_BITS'] = '32'

Or from the command line:

RQRCODE_CORE_ARCH_BITS=32 ruby your_script.rb

Memory Savings:

• Single small QR code: 0.38 MB → 0.10 MB (74% reduction)
• Single large QR code: 8.53 MB → 2.92 MB (66% reduction)
• 100 small QR codes: 37.91 MB → 9.10 MB (76% reduction)
• 10 large QR codes: 85.32 MB → 29.19 MB (66% reduction)

Speed Improvement:

• 2-4% faster across all scenarios (better cache utilization, reduced GC pressure)

Object Allocation:

• 85-87% fewer objects allocated
• Integer allocations nearly eliminated (from 70-76% to ~0%)

The QR code algorithm doesn't require 64-bit integers for its bit manipulation operations—32-bit is sufficient for all calculations. By default, Ruby on 64-bit systems uses 64-bit integers, which causes unnecessary memory allocation during the internal "right shift zero fill" operations.

Recommendation: Use RQRCODE_CORE_ARCH_BITS=32 for production workloads, especially when:

• Generating QR codes in batch
• Running in memory-constrained environments
• Handling high-concurrency web requests
• Processing large QR codes (version 10+)

See test/benchmarks/ARCH_BITS_ANALYSIS.md for detailed benchmark data and analysis.

Bug reports and pull requests are welcome on GitHub at https://github.com/whomwah/rqrcode_core.

The gem is available as open source under the terms of the MIT License.