QR Code Detector

Node.js native addon for detecting and decoding QR codes using OpenCV. This module runs QR code detection in separate worker threads to ensure non-blocking operation.

Features

• Single QR Code Detection: Detect and decode a single QR code in an image
• Multiple QR Code Detection: Detect and decode multiple QR codes in a single image
• Quick Detection: Check if an image contains a QR code without decoding
• Non-blocking: Uses worker threads for asynchronous processing
• Multiple Input Formats: Supports both file paths and image buffers
• Corner Detection: Returns corner coordinates of detected QR codes
• Base64 Image Export: Extracted QR code region as base64-encoded PNG

Installation

npm install

Prerequisites

• Node.js >= 14.0.0
• OpenCV 4.x installed on your system

macOS

brew install opencv

Linux

sudo apt-get install libopencv-dev

Usage

Detect Single QR Code

const { detectQRCode } = require('./qr-detector');

// Using file path
const result = await detectQRCode('/path/to/image.jpg');
console.log(result);
// {
//   detected: true,
//   data: 'https://example.com',
//   corners: [
//     { x: 100, y: 100 },
//     { x: 200, y: 100 },
//     { x: 200, y: 200 },
//     { x: 100, y: 200 }
//   ],
//   qrCodeImage: 'data:image/png;base64,iVBORw0KGgo...'
// }

// Using buffer
const fs = require('fs');
const imageBuffer = fs.readFileSync('/path/to/image.jpg');
const result = await detectQRCode(imageBuffer);

Detect Multiple QR Codes

const { detectMultipleQRCodes } = require('./qr-detector');

const result = await detectMultipleQRCodes('/path/to/image.jpg');
console.log(result);
// {
//   detected: true,
//   count: 2,
//   qrCodes: [
//     {
//       data: 'https://example.com',
//       corners: [...]
//     },
//     {
//       data: 'Another QR code data',
//       corners: [...]
//     }
//   ]
// }

Quick Detection (Without Decoding)

const { hasQRCode } = require('./qr-detector');

const result = await hasQRCode('/path/to/image.jpg');
console.log(result);
// {
//   hasQRCode: true,
//   corners: [...]
// }

API

detectQRCode(input)

Detects and decodes a single QR code in an image.

Parameters:

• input (string|Buffer): Image file path or buffer

Returns: Promise

• detected (boolean): Whether a QR code was detected
• data (string|null): Decoded QR code data
• corners (Array): Corner points of the QR code
• qrCodeImage (string): Base64-encoded PNG of extracted QR code (format: data:image/png;base64,...)

detectMultipleQRCodes(input)

Detects and decodes multiple QR codes in an image.

Parameters:

• input (string|Buffer): Image file path or buffer

Returns: Promise

• detected (boolean): Whether any QR codes were detected
• count (number): Number of QR codes detected
• qrCodes (Array): Array of detected QR codes with data and corners

hasQRCode(input)

Checks if an image contains a QR code without decoding it (faster).

Parameters:

• input (string|Buffer): Image file path or buffer

Returns: Promise

• hasQRCode (boolean): Whether a QR code was detected
• corners (Array): Corner points of the QR code

Architecture

This module follows the same architecture as the camera-sabotage-detector:

1. C++ Native Addon: Uses OpenCV's QRCodeDetector for high-performance detection
2. N-API: Ensures compatibility across Node.js versions
3. Worker Threads: Runs detection in separate threads for non-blocking operation
4. Multiple Input Formats: Supports both file paths and image buffers

License

MIT