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ZXing

What is ZXing?

ZXing ("zebra crossing") is an open-source, multi-format 1D/2D barcode image processing library implemented in Java, with ports to other languages.

Browser layer

This is a library for enabling you to use with ease the ZXing for JS library on the browser. It includes features like scanning an <img> element, as well as <video>, images and videos from URLs and also it helps handling webcam use for scanning directly from a hardware connected camera. It does not offers support to any physical barcode readers or things like that.

See @zxing-js/library for the complete API including decoding classes and use outside of the browser.

See @zxing-js/ngx-scanner for using the library in Angular.

See @zxing-js/text-encoding for special character support in barcodes.

Usage (how to use)

Installation, import into app and usage examples in this section.

Instalation

Install via yarn, npm, etc:

yarn add @zxing/browser
npm i @zxing/browser

Or just import an script tag from your favorite NPM registry connected CDN:

<!-- loading ZXingBrowser via UNPKG -->
<script type="text/javascript" src="https://unpkg.com/@zxing/browser@latest"></script>

How to import into your app

ES6 modules

<script type="module">
  import { BrowserQRCodeReader } from '@zxing/browser';

  const codeReader = new BrowserQRCodeReader();

  // do something with codeReader...

</script>
Or asynchronously
<script type="module">
  import('@zxing/browser').then({ BrowserQRCodeReader } => {

    const codeReader = new BrowserQRCodeReader();

    // do something with codeReader...

  });
</script>

With AMD

<script type="text/javascript" src="https://unpkg.com/requirejs"></script>
<script type="text/javascript">
  require(['@zxing/browser'], ZXingBrowser => {

    const codeReader = new ZXingBrowser.BrowserQRCodeReader();

    // do something with codeReader...

  });
</script>

With UMD

<script type="text/javascript" src="https://unpkg.com/@zxing/browser@latest"></script>
<script type="text/javascript">
  window.addEventListener('load', () => {

    const codeReader = new ZXingBrowser.BrowserQRCodeReader();

    // do something with codeReader...

  });
</script>

Using the API

Examples here will assume you already imported ZXingBrowser into your app.

Scan from webcam

Continuous scan (runs and decodes barcodes until you stop it):

const codeReader = new BrowserQRCodeReader();

const videoInputDevices = await ZXingBrowser.BrowserCodeReader.listVideoInputDevices();

// choose your media device (webcam, frontal camera, back camera, etc.)
const selectedDeviceId = videoInputDevices[0].deviceId;

console.log(`Started decode from camera with id ${selectedDeviceId}`);

const previewElem = document.querySelector('#test-area-qr-code-webcam > video');

// you can use the controls to stop() the scan or switchTorch() if available
const controls = await codeReader.decodeFromVideoDevice(selectedDeviceId, previewElem, (result, error, controls) => {
  // use the result and error values to choose your actions
  // you can also use controls API in this scope like the controls
  // returned from the method.
});

// stops scanning after 20 seconds
setTimeout(() => controls.stop(), 20000);

You can also use decodeFromConstraints instead of decodeFromVideoDevice to pass your own constraints for the method choose the device you want directly from your constraints.

Also, decodeOnceFromVideoDevice is available too so you can await the method until it detects the first barcode.

Scan from video or image URL

const codeReader = new ZXingBrowser.BrowserQRCodeReader();

const source = 'https://my-image-or-video/01.png';
const resultImage = await codeReader.decodeFromImageUrl(source);
// or use decodeFromVideoUrl for videos
const resultVideo = await codeReader.decodeFromVideoUrl(source);

Scan from video or image HTML element

const codeReader = new ZXingBrowser.BrowserQRCodeReader();

const sourceElem = document.querySelector('#my-image-id');
const resultImage = await codeReader.decodeFromImageElement(sourceElem);
// or use decodeFromVideoElement for videos
const resultVideo = await codeReader.decodeFromVideoElement(sourceElem);

Other scan methods

There's still other scan methods you can use for decoding barcodes in the browser with BrowserCodeReader family, all of those and previous listed in here:

  • decodeFromCanvas
  • decodeFromImageElement
  • decodeFromImageUrl
  • decodeFromConstraints
  • decodeFromStream
  • decodeFromVideoDevice
  • decodeFromVideoElement
  • decodeFromVideoUrl
  • decodeOnceFromConstraints
  • decodeOnceFromStream
  • decodeOnceFromVideoDevice
  • decodeOnceFromVideoElement
  • decodeOnceFromVideoUrl

That's it for now.

List of browser readers

  • BrowserAztecCodeReader
  • BrowserCodeReader (abstract, needs to be extend for use)
  • BrowserDatamatrixCodeReader
  • BrowserMultiFormatOneDReader
  • BrowserMultiFormatReader (2D + 1D)
  • BrowserPDF417CodeReader
  • BrowserQRCodeReader

Customize BrowserCodeReader options

You can also customize some options on the code reader at instantiation time. More docs comming soon.

Bless