QrPhinx

Installation

NPM

Available on npm.

npm install qrphinx --save

// ES6 import
import qrPhinx from "qrphinx" || import qrPhinx, { QRCode } from 'qrphinx';

// CommonJS require
const qrPhinx = require("qrphinx");

qrPhinx(...);

Browser

Alternatively for frontend use qrPhinx.js can be included with a script tag

<script src="qrPhinx.js"></script>
<script>
  qrPhinx(...);
</script>

A note on webcams

If you want to use qrPhinx to scan a webcam stream you'll need to extract the ImageData from the video stream. This can then be passed to qrPhinx. For more advanced questions you can refer to the getUserMedia docs or the fairly comprehensive webRTC sample code, both of which are great resources for consuming a webcam stream.

Usage

qrPhinx exports a method that takes in 3 arguments representing the image data you wish to decode. Additionally can take an options object to further configure scanning behavior.

const code = qrPhinx(imageData, width, height, options?);

if (code) {
  console.log("Found QR code", code);
}

Arguments

• imageData - An Uint8ClampedArray of RGBA pixel values in the form [r0, g0, b0, a0, r1, g1, b1, a1, ...]. As such the length of this array should be 4 * width * height. This data is in the same form as the ImageData interface, and it's also commonly returned by node modules for reading images.
• width - The width of the image you wish to decode.
• height - The height of the image you wish to decode.
• options (optional) - Additional options.
  • inversionAttempts - (attemptBoth (default), dontInvert, onlyInvert, or invertFirst) - Should qrPhinx attempt to invert the image to find QR codes with white modules on black backgrounds instead of the black modules on white background. This option defaults to attemptBoth for backwards compatibility but causes a ~50% performance hit, and will probably be default to dontInvert in future versions.

Return value

If a QR is able to be decoded the library will return an object with the following keys.

• binaryData - Uint8ClampedArray - The raw bytes of the QR code.
• data - The string version of the QR code data.
• location - An object with keys describing key points of the QR code. Each key is a point of the form {x: number, y: number}. Has points for the following locations.
  • Corners - topRightCorner/topLeftCorner/bottomRightCorner/bottomLeftCorner;
  • Finder patterns - topRightFinderPattern/topLeftFinderPattern/bottomLeftFinderPattern
  • May also have a point for the bottomRightAlignmentPattern assuming one exists and can be located.

Because the library is written in typescript you can also view the type definitions to understand the API.

Test

Tests can be run with

npm test

Besides unit tests the test suite contains several hundred images that can be found in the /tests/end-to-end/ folder. After testing any changes, you can compile the production version by running

npm run-script build