quirc-wasm-emcc/src/index.js

Quirc wasm module compiled using Emscripten written in C programming language.

const Module = require('./quirc.js');

const isEmptyObject = (obj) => {
    return Object.entries(obj).length === 0 && typeof obj === "object"
};

const isReady = () => {
    return new Promise(resolve => {
        setInterval(() => {
            let asmModule = Module.asm;
            if (!isEmptyObject(asmModule)) resolve();
        }, 100);
    })
};

const decodeQrCode = (rawJpeg) => {
    let rawJpegObj = {};

    /*
    * Create new unsigned int array of rawJpeg
    * */
    rawJpegObj.asTypedArray = new Uint8Array(rawJpeg);

    /*
    * Allocate memory to store the rawJpegAsTypedArray
    * */
    let srcBuf = Module._malloc(rawJpegObj.asTypedArray.length * rawJpegObj.asTypedArray.BYTES_PER_ELEMENT);

    /*
    * Write rawJpegAsTypedArray to allocated memory
    * */
    Module.writeArrayToMemory(rawJpegObj.asTypedArray, srcBuf);

    /*
    * Load image from allocated memory buffer
    * */
    let pImage = Module._setSrcImage(srcBuf, rawJpegObj.asTypedArray.length);

    /*
    * Get the image data such as width, height, and image
    * */
    let width = Module.getValue(pImage + 0, 'i32');
    let height = Module.getValue(pImage + 4, 'i32');
    let image = Module.getValue(pImage + 8, 'i32');

    /*
    * Decode image data and return the result
    * */
    const QUIRC_MAX_PAYLOAD = 8896;
    let resultPtr = Module._decode_qr(image, width, height);
    const strArray = [];
    for (let pointer = 0; pointer < QUIRC_MAX_PAYLOAD; pointer++) {
        let char = Module.HEAP8[resultPtr / Uint8Array.BYTES_PER_ELEMENT + pointer];
        if (char !== 0) {
            strArray.push(char);
        } else {
            break;
        }
    }
    let resultStr = String.fromCharCode.apply(null, strArray);

    /*
    * Clean the buffer
    * */
    Module._free(srcBuf);
    Module._free(image);
    Module._free(pImage);
    delete rawJpegObj.asTypedArray;

    return resultStr;
};

module.exports = {decodeQrCode, isReady};