Building a QR Code Scanner in Flutter: A Complete Beginner’s Guide

Building a QR Code Scanner in Flutter: A Complete Beginner’s Guide

Himanshu Chaurasia

Himanshu Chaurasia

16 Aug 2024

Building a QR Code Scanner in Flutter: A Complete Beginner’s Guide

Introduction

QR codes have become ubiquitous, used for everything from product tracking to personal information sharing. In the realm of mobile apps, incorporating QR code scanning functionality can greatly enhance user experience. In this blog, we’ll walk you through building a QR code scanner in Flutter, complete with simplified code examples and answers to common questions. Whether you're a beginner or looking to add QR scanning to your app, this guide will cover all the essentials.

Table of Contents

  1. What is Flutter?
  2. Setting Up Your Flutter Environment
  3. Adding Dependencies
  4. Building the QR Code Scanner
  5. Handling QR Code Scans
  6. Testing the QR Code Scanner
  7. Common Questions and Troubleshooting
  8. Conclusion

1. What is Flutter?

Flutter is an open-source UI software development toolkit created by Google. It allows developers to build natively compiled applications for mobile, web, and desktop from a single codebase. Flutter uses the Dart programming language and provides a rich set of pre-designed widgets to create beautiful and responsive user interfaces.

2. Setting Up Your Flutter Environment

Before you begin, ensure that you have Flutter and Dart installed. Follow these steps to set up your development environment:

  1. Install Flutter SDK:
    • Download the latest stable version from Flutter's official website.
    • Follow the installation instructions specific to your operating system.
  2. Set Up an Editor:
  3. Create a New Flutter Project:
flutter create qr_code_scanner
cd qr_code_scanner

3. Adding Dependencies

To build a QR code scanner, you need to add a QR code scanning library to your project. We will use the qr_code_scanner package.

  1. Open your pubspec.yaml file and add the qr_code_scanner dependency:

    dependencies:
    flutter:
    sdk: flutter
    qr_code_scanner: ^1.0.0
  2. Run the following command to install the new dependency

    flutter pub get


4. Building the QR Code Scanner

Let’s build a simple QR code scanner screen.

  1. Create a New Dart File: Create a file named qr_scanner.dart in the lib folder.
  2. Write the Code for QR Scanner:

    // lib/qr_scanner.dart

    import 'package:flutter/material.dart';
    import 'package:qr_code_scanner/qr_code_scanner.dart';

    class QRScanner extends StatefulWidget {
    @override
    _QRScannerState createState() => _QRScannerState();
    }

    class _QRScannerState extends State<QRScanner> {
    final GlobalKey<QRViewController> _qrKey = GlobalKey<QRViewController>();
    QRViewController? _controller;

    @override
    void reassemble() {
    super.reassemble();
    if (Platform.isAndroid) {
    _controller?.pauseCamera();
    }
    _controller?.resumeCamera();
    }

    @override
    Widget build(BuildContext context) {
    return Scaffold(
    appBar: AppBar(
    title: Text('QR Code Scanner'),
    ),
    body: Stack(
    children: [
    QRView(
    key: _qrKey,
    onQRViewCreated: _onQRViewCreated,
    ),
    Positioned(
    bottom: 50,
    left: 0,
    right: 0,
    child: Center(
    child: Text(
    'Scan a QR code',
    style: TextStyle(fontSize: 20, color: Colors.white),
    ),
    ),
    ),
    ],
    ),
    );
    }

    void _onQRViewCreated(QRViewController controller) {
    setState(() {
    _controller = controller;
    });
    controller.scannedDataStream.listen((scanData) {
    ScaffoldMessenger.of(context).showSnackBar(
    SnackBar(content: Text('Scan result: ${scanData.code}')),
    );
    });
    }

    @override
    void dispose() {
    _controller?.dispose();
    super.dispose();
    }
    }
  3. Update the Main File: Modify main.dart to include the QRScanner widget.

    // lib/main.dart

    import 'package:flutter/material.dart';
    import 'qr_scanner.dart';

    void main() => runApp(MyApp());

    class MyApp extends StatelessWidget {
    @override
    Widget build(BuildContext context) {
    return MaterialApp(
    title: 'Flutter QR Scanner',
    theme: ThemeData(
    primarySwatch: Colors.blue,
    ),
    home: QRScanner(),
    );
    }
    }

5. Handling QR Code Scans

In the code above, the onQRViewCreated function sets up a listener for scanned QR codes. When a QR code is scanned, the result is shown in a SnackBar. You can customize this to handle the scanned data according to your app’s requirements.

6. Testing the QR Code Scanner

To test the QR code scanner:

  1. Run the App:

    flutter run
  2. Scan a QR Code: Use the app to scan QR codes. Ensure your device has a camera and the camera permissions are granted.

 

Integrating a QR code scanner into your Flutter app is straightforward with the qr_code_scanner package. This guide has walked you through setting up the scanner, handling scans, and addressing common issues. By following these steps, you can enhance your Flutter app with powerful QR code scanning functionality.

 

Adding QR code scanning capabilities can significantly improve user interaction in your app. With Flutter’s simplicity and the qr_code_scanner package’s functionality, implementing this feature has never been easier.

FAQs

Que 1. Why is the camera not working?

Ans. Ensure your app has camera permissions. Check the AndroidManifest.xml for Android or Info.plist for iOS for proper permissions.

Que 2. How do I handle different QR code formats?

Ans. The qr_code_scanner package supports multiple QR code formats. If needed, use the scanData.format property to handle different formats.

Que 3. Can I customize the scanner’s appearance?

Ans. Yes, you can customize the overlay and scanner UI by modifying the QRView widget.

Que 4. How do I handle invalid QR codes?

Ans. Add validation logic in the scannedDataStream.listen callback to check the validity of the QR code content.

About Author

Himanshu Chaurasia

Himanshu Chaurasia

🔹 Full-stack developer specializing in Python, Django, and Django REST Framework. Dedicated to building high-quality web applications and enhancing user experiences with innovative solutions.

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#Flutter

#QRCodeScanner

#MobileDevelpment