barcode_scanner_controller.dart
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import 'dart:async';
import 'package:flutter/material.dart';
import 'package:mobile_scanner/mobile_scanner.dart';
import 'package:mobile_scanner_example/scanner_button_widgets.dart';
import 'package:mobile_scanner_example/scanner_error_widget.dart';
class BarcodeScannerWithController extends StatefulWidget {
const BarcodeScannerWithController({super.key});
@override
State<BarcodeScannerWithController> createState() =>
_BarcodeScannerWithControllerState();
}
class _BarcodeScannerWithControllerState
extends State<BarcodeScannerWithController> with WidgetsBindingObserver {
final MobileScannerController controller = MobileScannerController(
autoStart: false,
torchEnabled: true,
useNewCameraSelector: true,
);
Barcode? _barcode;
StreamSubscription<Object?>? _subscription;
Widget _buildBarcode(Barcode? value) {
if (value == null) {
return const Text(
'Scan something!',
overflow: TextOverflow.fade,
style: TextStyle(color: Colors.white),
);
}
return Text(
value.displayValue ?? 'No display value.',
overflow: TextOverflow.fade,
style: const TextStyle(color: Colors.white),
);
}
void _handleBarcode(BarcodeCapture barcodes) {
if (mounted) {
setState(() {
_barcode = barcodes.barcodes.firstOrNull;
});
}
}
@override
void initState() {
super.initState();
WidgetsBinding.instance.addObserver(this);
_subscription = controller.barcodes.listen(_handleBarcode);
unawaited(controller.start());
}
@override
void didChangeAppLifecycleState(AppLifecycleState state) {
if (!controller.value.hasCameraPermission) {
return;
}
switch (state) {
case AppLifecycleState.detached:
case AppLifecycleState.hidden:
case AppLifecycleState.paused:
return;
case AppLifecycleState.resumed:
_subscription = controller.barcodes.listen(_handleBarcode);
unawaited(controller.start());
case AppLifecycleState.inactive:
unawaited(_subscription?.cancel());
_subscription = null;
unawaited(controller.stop());
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('With controller')),
backgroundColor: Colors.black,
body: Stack(
children: [
MobileScanner(
controller: controller,
errorBuilder: (context, error, child) {
return ScannerErrorWidget(error: error);
},
fit: BoxFit.contain,
),
Align(
alignment: Alignment.bottomCenter,
child: Container(
alignment: Alignment.bottomCenter,
height: 100,
color: const Color.fromRGBO(0, 0, 0, 0.4),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
children: [
ToggleFlashlightButton(controller: controller),
StartStopMobileScannerButton(controller: controller),
PauseMobileScannerButton(controller: controller),
Expanded(child: Center(child: _buildBarcode(_barcode))),
SwitchCameraButton(controller: controller),
AnalyzeImageFromGalleryButton(controller: controller),
],
),
),
),
],
),
);
}
@override
Future<void> dispose() async {
WidgetsBinding.instance.removeObserver(this);
unawaited(_subscription?.cancel());
_subscription = null;
super.dispose();
await controller.dispose();
}
}