#naoto24kawa/moonqr

Pure QR code encoder/decoder written in MoonBit — no JavaScript dependencies, no WASM runtime coupling. This is the MoonBit-native module published to mooncakes.io; it is also the source compiled to JS and shipped as the npm packages @elchika-inc/moonqr and @elchika-inc/moonqr-scanner — see the repository README for the JS/TS side (if you're building a Node.js or browser app, you probably want the npm packages, not this module directly).

#Packages

Package	What it is
naoto24kawa/moonqr/gf256	GF(256) arithmetic + Reed–Solomon encode/decode, used by both encode and decode
naoto24kawa/moonqr/encode	Text → QR Matrix (module placement, masking, format/version info) + SVG rendering
naoto24kawa/moonqr/decode	RGBA pixels → decoded text (binarization, finder-pattern location, perspective extraction, codeword decode); ported from jsQR

preferred-target is js — see the root README's "Why MoonBit" section for the js vs wasm-gc benchmark that motivated this choice.

The bench package (a Phase-1 backend-selection spike, not part of the public API) is excluded from the published artifact via moon.mod.json's exclude field.

#Install

moon add naoto24kawa/moonqr

#Usage

#Encode

let matrix = @encode.encode("HELLO WORLD", @encode.EcLevel::M, None)
match matrix {
  Some(m) => {
    // m.size x m.size module grid; m.get(x, y) : Bool (true = dark module)
    let svg = @encode.to_svg_string(m, 4, 8) // margin=4 modules, cell=8px
    ...
  }
  None => ... // capacity exceeded, or an explicit `version` too small for the text
}

encode(text, ec, version) returns Matrix?: None for an empty string or when the text doesn't fit the given/selected version. Pass version=None to auto-select the smallest QR version (1–40) that fits; pass Some(v) to force one.

#Decode

// data: RGBA bytes, width * height * 4 long
let result = @decode.decode(data, width, height, true) // invert=true also tries the inverted binarization
match result {
  Some(r) => {
    // r.text : String, r.bytes : Array[Int], r.version : Int,
    // r.ec : @encode.EcLevel, r.corners : Array[Point] (TL, TR, BR, BL, in pixel space)
    ...
  }
  None => ... // no QR code found in the frame
}

#License and attribution

Apache License 2.0 — see LICENSE.

Portions of decode are ported from jsQR (Apache-2.0), and the Reed–Solomon block / alignment-pattern position tables in encode are derived from qrcode-generator (MIT). See NOTICE and THIRD_PARTY_LICENSES for the full attribution.

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