@sec-ant/zxing-wasm

@sec-ant/zxing-wasm

An ES6 module wrapper of zxing-wasm-build.

Build

git clone https://github.com/Sec-ant/zxing-wasm
cd zxing-wasm
npm i
npm run fetch
npm run build

Install

npm i @sec-ant/zxing-wasm

Usage

This package exports 3 subpaths: full, reader and writer. You can choose whichever fits your needs. However, bear in mind that subpath imports needs a moduleResolution of node16 or nodenext in your tsconfig.json file.

@sec-ant/zxing-wasm or @sec-ant/zxing-wasm/full

These imports includes functions to both read and write barcodes. The wasm binary size is ~1.25 MB.

import {
  readBarcodeFromImageFile,
  readBarcodeFromImageData,
  writeBarcodeToImageFile,
} from "@sec-ant/zxing-wasm";

or

import {
  readBarcodeFromImageFile,
  readBarcodeFromImageData,
  writeBarcodeToImageFile,
} from "@sec-ant/zxing-wasm/full";

@sec-ant/zxing-wasm/reader

This subpath only includes functions to read barcodes. The wasm binary size is ~948 KB.

import {
  readBarcodeFromImageFile,
  readBarcodeFromImageData,
} from "@sec-ant/zxing-wasm/reader";

@sec-ant/zxing-wasm/writer

This subpath only includes functions to write barcodes. The wasm binary size is ~392 KB.

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

readBarcodeFromImageFile and readBarcodeFromImageData

These are 2 functions to read barcodes.

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

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

Both of these 2 functions accepts the same second input: ZXingReadOptions:

interface ZXingReadOptions {
  /* Try better to find barcodes, default = true */
  tryHarder?: boolean;
  /* An array of barcode formats to detect, default = [] (indicates any format) */
  formats?: readonly ZXingReadInputBarcodeFormat[];
  /* Upper limit of the number of barcodes to be detected, default = Infinite */
  maxNumberOfSymbols?: number;
}

The allowed barcode formats to read are:

type ZXingReadInputBarcodeFormat =
  | "Aztec"
  | "Codabar"
  | "Code128"
  | "Code39"
  | "Code93"
  | "DataBar"
  | "DataBarExpanded"
  | "DataMatrix"
  | "EAN-13"
  | "EAN-8"
  | "ITF"
  | "Linear-Codes"
  | "Matrix-Codes"
  | "MaxiCode"
  | "MicroQRCode"
  | "PDF417"
  | "QRCode"
  | "UPC-A"
  | "UPC-E";

The return result of these 2 functions is a Promise of an array of ZXingReadOutput:

interface ZXingReadOutput {
  /* detected barcode format */
  format: ZXingReadOutputBarcodeFormat;
  /* detected barcode text */
  text: string;
  /* error message (if any) */
  error: string;
  /* detected barcode position:
    {
      bottomLeft:  { x, y },
      bottomRight: { x, y },
      topLeft:     { x, y },
      topLeft:     { x, y }
    }
  */
  position: ZXingPosition;
}

e.g.

import {
  readBarcodeFromImageFile,
  readBarcodeFromImageData,
  ZXingReadOptions,
} from "@sec-ant/zxing-wasm/reader";

const zxingReadOptions: ZXingReadOptions = {
  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 imageFileReadOutputs = await readBarcodeFromImageFile(
  imageFile,
  zxingReadOptions
);

console.log(imageFileReadOutputs[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 imageDataReadOutputs = await readBarcodeFromImageData(
  imageData,
  zxingReadOptions
);

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

writeBarcodeToImageFile

There is currently only 1 function to write barcodes. The first argument of this function is a text string to be encoded and the second argument is a ZXingWriteOptions:

interface ZXingWriteOptions {
  /* barcode format to write
     "DataBar", "DataBarExpanded", "MaxiCode" and "MicroQRCode" are currently not supported
     default = "QRCode" */
  format?: ZXingWriteInputBarcodeFormat;
  /* encoding charset, default = "UTF-8" */
  charset?: ZXingCharacterSet;
  /* barcode margin, default = 10 */
  quietZone?: number;
  /* barcode width, default = 200 */
  width?: number;
  /* barcode height, default = 200 */
  height?: number;
  /* (E)rror (C)orrection (C)apability level, -1 ~ 8, default = -1 (default) */
  eccLevel?: ZXingECCLevel;
}

The return result of this function is a Promise of ZXingWriteOutput:

interface ZXingWriteOutput {
  /* a png image blob, or null */
  image: Blob | null;
  /* the error reason if image is null */
  error: string;
}

e.g.

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

const writeOutput = await writeBarcodeToImageFile("Hello world!", {
  format: "QRCode",
  charset: "UTF-8",
  quietZone: 5,
  width: 150,
  height: 150,
  eccLevel: 2,
});

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 wasm binary 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 or other CDNs), 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.

import {
  setZXingModuleOverrides,
  writeBarcodeToImageFile,
} from "@sec-ant/zxing-wasm";

// override the locateFile function
setZXingModuleOverrides({
  locateFile: (path, prefix) => {
    if (path.endsWith(".wasm")) {
      return `https://esm.sh/@sec-ant/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 module overrides. So there'll be a cold start in the first function call (or several calls if they appear in a very short period). If you want to manully 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, the wasm Module object this wrapper library is built upon.

import { getZXingModule } from "@sec-ant/zxing-wasm";

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

zxingModulePromise2 = getZXingModule();

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

getZXingModule can also optionally accept a ZXingModuleOverrides argument.

import { getZXingModule } from "@sec-ant/zxing-wasm";

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

License

MIT