Node-quirc NPM

node-quirc

A Node.js Addon of the quirc library (QR decoder library - https://github.com/dlbeer/quirc).

installation

First, You need libpng and libjpeg (and their header files) installed. Then, simply

% npm install node-quirc

documentation

node-quirc aim to be simple to use, the module exposes a decode() function and a constants object.

decode(img, callback)

img must be either a Buffer of a PNG or JPEG encoded image file, or a decoded image in ImageData format with 1 (grayscale), 3 (RGB) or 4 (RGBA) channels.

When callback is provided, it is expected to be a "classic" Node.js callback function, taking an error as first argument and the result as second argument. Because the provided image file may contains several QR Code, the result is always an array on success.

When decode is called only with img as argument, a Promise is returned.

const fs    = require("fs");
const quirc = require("node-quirc");

// load the image file
const img = fs.readFileSync("./test/data/Hello+World.png");

// callback version
quirc.decode(img, (err, codes) => {
    if (err) {
        // handle err.
        console.error(`decode failed: ${err.message}`);
    } else {
        // do something with codes.
        console.dir(codes);
        console.log(codes.map((code) => code.data.toString('utf8')));
    }
});

// Promise version
quirc.decode(img).then((codes) => {
    // do something with codes.
}).catch((err) => {
    // handle err.
});

// alternatively, use an already-loaded ImageData, e.g. from the `canvas` library
const context = canvas.getContext('2d');
const imageData = context.getImageData(0, 0, 800, 600);
quirc.decode(imageData).then((codes) => {
    // do something with codes.
    console.log(`codes read from ImageData (size=${
        imageData.data.length
    }, width=${imageData.width}, height=${
        imageData.height
    }):`, codes);
}).catch((err) => {
    // handle err.
});

output:

[
  {
    version: 1,
    ecc_level: 'H',
    mask: 1,
    mode: 'BYTE',
    eci: 'UTF_8',
    data: Buffer [Uint8Array] [ 72, 101, 108, 108, 111 ]
  },
  {
    version: 1,
    ecc_level: 'H',
    mask: 3,
    mode: 'BYTE',
    eci: 'UTF_8',
    data: Buffer [Uint8Array] [ 87, 111, 114, 108, 100 ]
  }
]
[ 'Hello', 'World' ]