zxing-wasm

zxing-wasm

ZXing-C++ WebAssembly as an ES module with types. Read or write barcodes in your browser!

Build

git clone --recurse-submodules https://github.com/Sec-ant/zxing-wasm
cd zxing-wasm
npm i
# install cmake first:
# https://cmake.org/download/
npm run cmake
# install emscripten first:
# https://emscripten.org/docs/getting_started/downloads.html
npm run build:wasm
npm run build

Install

npm i zxing-wasm

Documentation

https://zxing-wasm.netlify.app/

Usage

This package exports 3 subpaths: full, reader and writer. You can choose whichever fits your needs. If you use TypeScript, you should set moduleResolution to bundler, node16 or nodenext in your tsconfig.json file to properly resolve the exported module.

zxing-wasm or zxing-wasm/full

These 2 subpaths include functions to both read and write barcodes. The wasm binary size is ~1.12 MB.

import {
  readBarcodesFromImageFile,
  readBarcodesFromImageData,
  writeBarcodeToImageFile,
} from "zxing-wasm";

or

import {
  readBarcodesFromImageFile,
  readBarcodesFromImageData,
  writeBarcodeToImageFile,
} from "zxing-wasm/full";

zxing-wasm/reader

This subpath only includes functions to read barcodes. The wasm binary size is ~881 KB.

import {
  readBarcodesFromImageFile,
  readBarcodesFromImageData,
} from "zxing-wasm/reader";

zxing-wasm/writer

This subpath only includes a function to write barcodes. The wasm binary size is ~328 KB.

import { writeBarcodeToImageFile } from "zxing-wasm/writer";

readBarcodesFromImageFile and readBarcodesFromImageData

These 2 functions are for reading barcodes.

readBarcodesFromImageFile accepts an image Blob or an image File as the first input. They're encoded images, e.g. .png .jpg files.

readBarcodesFromImageData accepts an ImageData as the first input. They're raw pixels that usually acquired from <canvas> or related APIs.

Both of these 2 functions optionally accept the same second input: DecodeHints.

The return result of these 2 functions is a Promise of an array of ReadResults.

e.g.

import {
  readBarcodesFromImageFile,
  readBarcodesFromImageData,
  type DecodeHints,
} from "zxing-wasm/reader";

const decodeHints: DecodeHints = {
  tryHarder: true,
  formats: ["QRCode"],
  maxNumberOfSymbols: 1,
};

/**
 * Read from image file/blob
 */
const imageFile = await fetch(
  "https://api.qrserver.com/v1/create-qr-code/?size=150x150&data=Hello%20world!",
).then((resp) => resp.blob());

const imageFileReadResults = await readBarcodesFromImageFile(
  imageFile,
  decodeHints,
);

console.log(imageFileReadResults[0].text); // Hello world!

/**
 * Read from image data
 */
const imageData = await createImageBitmap(imageFile).then((imageBitmap) => {
  const { width, height } = imageBitmap;
  const context = new OffscreenCanvas(width, height).getContext(
    "2d",
  ) as OffscreenCanvasRenderingContext2D;
  context.drawImage(imageBitmap, 0, 0, width, height);
  return context.getImageData(0, 0, width, height);
});

const imageDataReadResults = await readBarcodesFromImageData(
  imageData,
  decodeHints,
);

console.log(imageDataReadResults[0].text); // Hello world!

writeBarcodeToImageFile

This function is used to write barcodes. The first argument of this function is a text string to be encoded and the optional second argument is an EncodeHints.

The return result of this function is a Promise of a WriteResult.

e.g.

import { writeBarcodeToImageFile, type EncodeHints } from "zxing-wasm/writer";

const encodeHints: EncodeHints = {
  format: "QRCode",
  width: 150,
  height: 150,
  margin: 10,
  eccLevel: 2,
};

const writeOutput = await writeBarcodeToImageFile("Hello world!", encodeHints);

console.log(writeOutput.image);

Notes

When using this package, the .wasm binary needs to be served along with the JS glue code. In order to provide a smooth dev experience, the serve path is automatically assigned the jsDelivr CDN url upon build.

If you would like to change the serve path (to one of your local network hosts, some other CDNs, or just Base64 encoded data URIs), please use setZXingModuleOverrides to override the locateFile function in advance. locateFile is one of the Emscripten Module attribute hooks that can affect the code execution of the Module object during its lifecycles.

e.g.

import { setZXingModuleOverrides, writeBarcodeToImageFile } from "zxing-wasm";

// override the locateFile function
setZXingModuleOverrides({
  locateFile: (path, prefix) => {
    if (path.endsWith(".wasm")) {
      return `https://esm.sh/zxing-wasm/dist/full/${path}`;
    }
    return prefix + path;
  },
});

// call read or write functions afterwards
const writeOutput = await writeBarcodeToImageFile("Hello world!");

The wasm binary won't be fetched or instantiated unless a read or write function is firstly called, and will only be instantiated once given the same (Object.is) ZXingModuleOverrides. If you want to manually trigger the download and instantiation of the wasm binary prior to any read or write functions, you can use getZXingModule. This function will also return a Promise that resolves to a ZXingModule.

import { getZXingModule } from "zxing-wasm";

/**
 * This function will trigger the download and
 * instantiation of the wasm binary immediately
 */
const zxingModulePromise1 = getZXingModule();

const zxingModulePromise2 = getZXingModule();

console.log(zxingModulePromise1 === zxingModulePromise2); // true

getZXingModule can also optionally accept a ZXingModuleOverrides argument.

import { getZXingModule } from "zxing-wasm";

getZXingModule({
  locateFile: (path, prefix) => {
    if (path.endsWith(".wasm")) {
      return `https://esm.sh/zxing-wasm/dist/full/${path}`;
    }
    return prefix + path;
  },
});

License

MIT