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.

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:
   • You can use editors like Visual Studio Code or Android Studio.
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.