philss / qrusty

Elixir QR Code library that leverages precompiled Rust

Qrusty

QR Code generator that leverages precompiled Rust.

The "precompiled" implies that using this library does not require installing Rust.

Installation

The package can be installed by adding qrusty to your list of dependencies in mix.exs:

def deps do
  [
    {:qrusty, "~> 0.1.4"}
  ]
end

Usage

Qrusty documentation.

The following QR formats are supported:

• SVG (:svg)
• PNG (:png)
• JPG (:jpg)
• base64 PNG (:png64)
• base64 JPG (:jpg64)

Options

• width: width in pixels (default: 200)
• height: height in pixels (default: 200)
• size: shorthand for width and height (default: 200)
• ec: error correction level :l, :m, :q, :h (default: :m)

SVG

> {:ok, %Qrusty.QR{encoded_data: svg}} = Qrusty.qr("https://elixir-lang.org/", :svg, size: 200)

File.write("./assets/qr.svg", svg)

PNG/JPG

> {:ok, %Qrusty.QR{encoded_data: binary}} = Qrusty.qr("https://elixir-lang.org/", :png, width: 200, height: 200)

File.write("./assets/qr.png", binary)

> {:ok, %Qrusty.QR{encoded_data: binary}} = Qrusty.qr("https://elixir-lang.org/", :jpg, width: 200, height: 200)

File.write("./assets/qr.jpg", binary)

Base64 PNG/JPG

# :png64 or :jpg64
> {:ok, %Qrusty.QR{encoded_data: binary_64}} = Qrusty.qr("https://elixir-lang.org/", :png64, width: 200, height: 200)

# Heex Template (for example)
<a href={"data:image/png;base64, " <> binary_64} download="qr.png">
  <img src={"data:image/png;base64, "<> binary_64}></img>
</a>

Format	Sample
SVG
PNG
JPG
PNG64	sample
JPG64	--

Error correction:

L	M	Q	H

Benchmarks

Benchmarks have been included to compare Qrusty (Rust based) against other Elixir based QR libraries. Specifically EQRCode (SVG, PNG), and QRCode (SVG only).

Note: since the execution time of generating a single QR code is so fast, benchmarking was not very accurate. To compensate, the benchmarks measure the execution time for generating 100 QR codes.

Usage

Run the following:

mix run benchmarks/png.exs
mix run benchmarks/svg.exs
...

Summary

The full results are here.

Qrusty vs EQRCode (x times faster)

	100x100	200x200	500x500
PNG	27.43x	18.86x	7.21x
SVG	42.46x	42.70x	42.72x
JPG	-	-	-

Trends: QRusty executes faster than QRCode, but the gains decrease with larger image sizes.

Qrusty vs QRCode (x times faster)

	100x100	200x200	500x500
PNG	-	-	-
SVG	11.87x	11.78x	12.02x
JPG	-	-	-

[1]: saving PNG would require Mogrify, which requires installing ImageMagick.

[2]: QRCode doesn't take a size/width/height param so it's safe to say ≈ 11.8x

Development

You will need the following installed:

• Elixir
• Rust
• Cross

1. Increment the version in mix.exs so that the build on github can no longer be found
2. Compile locally: mix compile.local or QRUSTY_BUILD=true iex -S mix

Contributions

Contributions are welcome.

Rust Contribution Rules

• The Rust layer should be as thin as possible
• The Rust layer should not deal with errors caused by human input (ex: invalid input args). Deal with interface errors in Elixir
• Default values, etc. should all be handled on the Elixir side

Basically, the end user is an Elixir developer, so keep as much code as possible in Elixir for readability. Leverage Rust only for its performance benefits/access to system level libraries, etc. 🙏

Thanks

• Thanks to kennytm for qrcode-rust
• Thanks to qm3ster for this PR to support image v0.24
• Thanks to the creators of EQRCode

Copyright and License

This library is released under the MIT License. See the LICENSE.md file.