@asymmetric-effort/qrcode-scanner
v0.0.12
Published
A simple React Component using the client's webcam to read barcodes and QR codes.
Downloads
13
Maintainers
Readme
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 astopStream
prop to stop the video streams whentrue
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>