@vitorpamplona/instascan

v3.0.2

Published

3 years ago

Fork of Schmich's Instascan with updated libraries (Browser, iOS and Android are working)

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vitorpamplona

qr code quick response scan scanner webcam realtime umd webpack

Instascan

Fork of Schmich's Real-time webcam-driven HTML5 QR code scanner (Instascan) with updated libraries (Browser, iOS and Android are working) Try the live demo.

Installing

NPM

npm install --save @vitorpamplona/instascan

const Instascan = require('instascan');

Browser

Copy instascan.min.js from the releases page and load with:

<script type="text/javascript" src="instascan.min.js"></script>

Example

<!DOCTYPE html>
<html>
  <head>
    <title>Instascan</title>
    <script type="text/javascript" src="instascan.min.js"></script>
  </head>
  <body>
    <video id="preview"></video>
    <script type="text/javascript">
      let scanner = new Instascan.Scanner({ video: document.getElementById('preview') });
      scanner.addListener('scan', function (content) {
        console.log(content);
      });
      Instascan.Camera.getCameras().then(function (cameras) {
        if (cameras.length > 0) {
          scanner.start(cameras[0]);
        } else {
          console.error('No cameras found.');
        }
      }).catch(function (e) {
        console.error(e);
      });
    </script>
  </body>
</html>

API

let scanner = new Instascan.Scanner(opts)

Create a new scanner with options:

let opts = {
  // Whether to scan continuously for QR codes. If false, use scanner.scan() to manually scan.
  // If true, the scanner emits the "scan" event when a QR code is scanned. Default true.
  continuous: true,
  
  // The HTML element to use for the camera's video preview. Must be a <video> element.
  // When the camera is active, this element will have the "active" CSS class, otherwise,
  // it will have the "inactive" class. By default, an invisible element will be created to
  // host the video.
  video: document.getElementById('preview'),
  
  // Whether to horizontally mirror the video preview. This is helpful when trying to
  // scan a QR code with a user-facing camera. Default true.
  mirror: true,
  
  // Whether to include the scanned image data as part of the scan result. See the "scan" event
  // for image format details. Default false.
  captureImage: false,
  
  // Only applies to continuous mode. Whether to actively scan when the tab is not active.
  // When false, this reduces CPU usage when the tab is not active. Default true.
  backgroundScan: true,
  
  // Only applies to continuous mode. The period, in milliseconds, before the same QR code
  // will be recognized in succession. Default 5000 (5 seconds).
  refractoryPeriod: 5000,
  
  // Only applies to continuous mode. The period, in rendered frames, between scans. A lower scan period
  // increases CPU usage but makes scan response faster. Default 1 (i.e. analyze every frame).
  scanPeriod: 1
};

scanner.start(camera)

Activate camera and start scanning using it as the source. Returns promise.
This must be called in order to use scanner.scan or receive scan events.
camera: Instance of Instascan.Camera from Instascan.Camera.getCameras.
.then(function () { ... }): called when camera is active and scanning has started.
.catch(function (err) { ... })
- Called when an error occurs trying to initialize the camera for scanning.
- err: An Instascan.MediaError in the case of a known getUserMedia failure (see error types).

scanner.stop()

Stop scanning and deactivate the camera. Returns promise.
.then(function () { ... }): called when camera and scanning have stopped.

let result = scanner.scan()

Scan video immediately for a QR code.
QR codes recognized with this method are not emitted via the scan event.
If no QR code is detected, result is null.
result.content: Scanned content decoded from the QR code.
result.image: Undefined if scanner.captureImage is false, otherwise, see the scan event for format.

scanner.addListener('scan', callback)

Emitted when a QR code is scanned using the camera in continuous mode (see scanner.continuous).
callback: function (content, image)
- content: Scanned content decoded from the QR code.
- image: null if scanner.captureImage is false, otherwise, a base64-encoded WebP-compressed data URI of the camera frame used to decode the QR code.

scanner.addListener('active', callback)

Emitted when the scanner becomes active as the result of scanner.start or the tab gaining focus.
If opts.video element was specified, it will have the active CSS class.
callback: function ()

scanner.addListener('inactive', callback)

Emitted when the scanner becomes inactive as the result of scanner.stop or the tab losing focus.
If opts.video element was specified, it will have the inactive CSS class.
callback: function ()

Instascan.Camera.getCameras()

Enumerate available video devices. Returns promise.
.then(function (cameras) { ... })
- Called when cameras are available.
- cameras: Array of Instascan.Camera instances available for use.
.catch(function (err) { ... })
- Called when an error occurs while getting cameras.
- err: An Instascan.MediaError in the case of a known getUserMedia failure (see error types).

camera.id

Unique camera ID provided by the browser.
These IDs are stable and can be persisted across instances of your application (e.g. in localStorage).

camera.name

Camera name, including manufacturer and model
e.g. "Microsoft LifeCam HD-3000".

Credits

Writen by Chris Schmich in 2016 and updated by several members of the community. Powered by the Emscripten JavaScript build of the C++ port of the ZXing Java library.