@asymmetric-effort/qrcode-scanner

React QR Barcode Scanner

This is a simple React component built in Typescript to provide a webcam-based barcode scanner using react-webcam and @zxing/library. This component works on Computers and Mobile Devices (iOS 11 and above and Android Phones).

Thanks to the initial repo: https://github.com/dashboardphilippines/react-webcam-barcode-scanner

Installation

npm i react-qr-barcode-scanner

Usage in React:

import React from "react";
import BarcodeScannerComponent from "react-qr-barcode-scanner";

function App() {
  const [data, setData] = React.useState("Not Found");

  return (
    <>
      <BarcodeScannerComponent
        width={500}
        height={500}
        onUpdate={(err, result) => {
          if (result) setData(result.text);
          else setData("Not Found");
        }}
      />
      <p>{data}</p>
    </>
  );
}

export default App;

Props

onUpdate

Type: function, Required, Argument: error, result

Function that returns the result for every captured frame. Text from barcode can be accessed from result.text if there is a result.

onError

Type: function, Optional, Argument: error

If passed to the component, this function is called when there is an error with the camera (rather than with with reading the QR code, which would be passed to onUpdate). An example would be an error thrown when the user does not allow the required camera permission. This can be handled with an onError function similar to this:

const onError = (error) => {
  if (error.name === "NotAllowedError") {
    // Handle messaging in our app after the user chooses to not allow the camera permissions
  }
};

width

Type: number or string, Optional, Default: 100%

height

Type: number or string, Optional, Default: 100%

facingMode

Type: environment or user, Optional, Default: environment

user is the user-facing (front) camera, and environment is the rear camera.

torch

Type: boolean, Optional

Turn the camera flashlight on or off.

delay

Type: number, Optional, Default: 500

videoConstraints

Type: MediaTrackConstraints, Optional

stopStream

Type: boolean, Optional

This prop is a workaround for a bug where the browser freezes if the webcam component is unmounted or removed. See known issues for more about this issue.

Supported Barcode Formats

These formats are supported by ZXing:

1D product	1D industrial	2D
UPC-A	Code 39	QR Code
UPC-E	Code 128	Data Matrix
EAN-8	ITF	Aztec
EAN-13	RSS-14	PDF 417

Known Issues

• The camera can only be accessed over https or localhost

• Browser compatibility is limited by react-webcam's usage of the Stream API: https://caniuse.com/stream. On iOS-Devices with iOS < 14.3 camera access works only in native Safari and not in other Browsers (Chrome, etc) or Apps that use an UIWebView or WKWebView. iOS 14.3 (released in December 2020) now supports WebRTC in 3rd party browsers as well.

• There is a bug in the react-webcam package that causes the browser to freeze when the component is unmounted or removed, or the camera video constraints are changed (for example, switching cameras or navigating away from the screen with the camera component). Please see this thread regarding the reported issue: https://github.com/mozmorris/react-webcam/issues/244. As a workaround, react-qr-barcode-scanner allows passing a stopStream prop to stop the video streams when true is passed, allowing you to close the stream before unmounting the component or doing some other action that may cause the freeze. I found I needed to set a timeout to wait one tick before dismissing the modal in my use case to prevent the freeze. PRs to improve this issue are welcome!

  Example:

  const [stopStream, setStopStream] = useState(false)
  //...
  const dismissQrReader = () => {
    // Stop the QR Reader stream (fixes issue where the browser freezes when closing the modal) and then dismiss the modal one tick later
    setStopStream(true)
    setTimeout(() => closeModal(), 0)
  }
  //...
  <Modal>
    <BarcodeScanner onUpdate={onUpdate} stopStream={stopStream} />
    <button onClick={dismissQrReader}>
  </Modal>