BarcodeBC > Articles > How to Scan QR Codes with a Device Camera on Windows Using the Fluent UI Library in Flutter?
To read and scan QR Codes with a device camera on Windows using the Fluent UI library in Flutter, you can use the camera and qr_code_scanner packages. Here are the general steps.
1. Add the camera and qr_code_scanner dependencies to your pubspec.yaml file.
dependencies: camera: ^0.10.1+1 qr_code_scanner: ^0.4.0
2. Import the necessary packages.
import 'package:camera/camera.dart'; import 'package:flutter/material.dart'; import 'package:qr_code_scanner/qr_code_scanner.dart';
3. Define the stateful widget for the QR Code scanner screen.
class QrCodeScannerScreen extends StatefulWidget {
@override
_QrCodeScannerScreenState createState() => _QrCodeScannerScreenState();
}
class _QrCodeScannerScreenState extends State<QrCodeScannerScreen> {
CameraController? _cameraController;
QRViewController? _qrViewController;
final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
@override
void initState() {
super.initState();
_initializeCamera();
}
@override
void dispose() {
_cameraController?.dispose();
_qrViewController?.dispose();
super.dispose();
}
void _initializeCamera() async {
final cameras = await availableCameras();
final camera = cameras.first;
_cameraController = CameraController(camera, ResolutionPreset.high);
_qrViewController = QRViewController(
qrKey: qrKey,
cameraController: _cameraController!,
overlay: QrScannerOverlayShape(
borderColor: Colors.blue,
borderRadius: 10,
borderLength: 30,
borderWidth: 10,
cutOutSize: 300,
),
onScanned: _onScanned,
);
_cameraController?.initialize().then((_) {
if (!mounted) {
return;
}
_qrViewController?.resumeCamera();
setState(() {});
});
}
void _onScanned(String data) {
// Handle the scanned data here
print('Scanned data: $data');
}
@override
Widget build(BuildContext context) {
if (_cameraController == null || !_cameraController!.value.isInitialized) {
return Container();
}
return Scaffold(
appBar: AppBar(
title: Text('QR Code Scanner'),
),
body: Stack(
children: [
QRView(
key: qrKey,
onQRViewCreated: (controller) => _qrViewController = controller,
),
Positioned.fill(
child: Align(
alignment: Alignment.bottomCenter,
child: Padding(
padding: const EdgeInsets.all(16.0),
child: ElevatedButton(
onPressed: () {
// Do something when the button is pressed
},
child: Text('Button'),
),
),
),
),
],
),
);
}
}
4. Use the QrCodeScannerScreen widget in your app.
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'My App',
home: QrCodeScannerScreen(),
);
}
}
This will create a QR Code scanner screen with a camera preview and a button at the bottom. When the QR Code is scanned, the onScanned callback is called with the scanned data. You can replace the button with any other widget or UI component that you need.
There are several ways to improve the QR Code scanning speed.
1. Use a faster QR Code scanning library: Make sure you are using a fast QR Code scanning library that can efficiently process the image frames from the device camera.
2. Optimize camera settings: Adjust the camera settings to optimize image quality and lighting conditions for QR Code scanning. This can include adjusting the focus, brightness, and contrast of the camera.
3. Reduce image resolution: Lowering the image resolution can reduce the amount of data the scanning library has to process, which can improve scanning speed.
4. Use multi-threading: Multi-threading can be used to offload the image processing and scanning to a separate thread, which can improve overall performance.
5. Use a more powerful device: If possible, use a more powerful device with a faster processor and more memory to improve the QR Code scanning speed.
To connect a barcode scanner to a Flutter app, you need to use a plugin that provides access to the scanner's hardware interface. There are several Flutter barcode scanner plugins available, such as the flutter_barcode_scanner, qr_code_scanner, and barcode_scan plugins. Here's a brief example of how to use the flutter_barcode_scanner plugin.
1. Add the flutter_barcode_scanner dependency to your pubspec.yaml file.
dependencies: flutter_barcode_scanner: ^3.0.0
2. Import the flutter_barcode_scanner package in your Dart code.
import 'package:flutter_barcode_scanner/flutter_barcode_scanner.dart';
3. Call the FlutterBarcodeScanner.scanBarcode method to initiate the barcode scanning process.
String barcodeScanRes = await FlutterBarcodeScanner.scanBarcode(
"#FF0000", "Cancel", false, ScanMode.QR);
This method takes four arguments.
a. '#FF0000': The color of the scanning line.
b. '"Cancel"': The text displayed on the cancel button.
c. 'false': Whether to show the flash button.
d. 'ScanMode.QR': The type of barcode being scanned (in this case, QR Code).
4. The 'scanBarcode' method returns a 'Future<String>' that resolves to the scanned barcode string. You can then use this string in your app as needed.
print("Scanned barcode: $barcodeScanRes");
Note that the above example is just a basic implementation of the barcode scanning and reading process using the flutter_barcode_scanner plugin. Depending on your specific requirements, you may need to customize the implementation to suit your needs.