fix: harden scanner camera preview recovery
This commit is contained in:
Lukas Müllner
parent
bebd21097d
commit
d566621033
1 changed files with 114 additions and 28 deletions
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@ -30,7 +30,8 @@ class ScannerScreen extends StatefulWidget {
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State<ScannerScreen> createState() => _ScannerScreenState();
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}
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class _ScannerScreenState extends State<ScannerScreen> {
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class _ScannerScreenState extends State<ScannerScreen>
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with WidgetsBindingObserver {
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static const _autoScanTickInterval = Duration(milliseconds: 700);
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static const _scanCooldownSuccess = Duration(milliseconds: 1500);
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static const _scanCooldownNoMatch = Duration(milliseconds: 2200);
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@ -48,48 +49,103 @@ class _ScannerScreenState extends State<ScannerScreen> {
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bool _autoScanEnabled = false;
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Timer? _autoScanTimer;
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DateTime _nextScanAllowedAt = DateTime.fromMillisecondsSinceEpoch(0);
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bool _isInitializingCamera = false;
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String? _cameraError;
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@override
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void initState() {
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super.initState();
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WidgetsBinding.instance.addObserver(this);
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_activeCollectionId = widget.activeCollectionId;
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_autoScanEnabled = widget.onDetected != null;
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_textRecognizer = TextRecognizer();
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_initCamera();
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}
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@override
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void didChangeAppLifecycleState(AppLifecycleState state) {
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if (state == AppLifecycleState.inactive ||
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state == AppLifecycleState.paused ||
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state == AppLifecycleState.detached) {
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_disposeCamera();
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return;
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}
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if (state == AppLifecycleState.resumed) {
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_initCamera(force: true);
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}
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}
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void _handleCollectionChanged(String? value) {
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if (value == null) return;
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setState(() => _activeCollectionId = value);
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widget.onCollectionChanged?.call(value);
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}
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Future<void> _initCamera() async {
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Future<void> _initCamera({bool force = false}) async {
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if (_isInitializingCamera) return;
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if (_cameraReady && !force) return;
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_isInitializingCamera = true;
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try {
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await _disposeCamera();
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final cameras = await availableCameras();
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if (cameras.isEmpty) {
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if (!mounted) return;
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ScaffoldMessenger.of(context).showSnackBar(
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const SnackBar(content: Text('No camera available')),
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);
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return;
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throw Exception('No camera available');
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}
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// Use the first back-facing camera.
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final backCamera = cameras.firstWhere(
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(c) => c.lensDirection == CameraLensDirection.back,
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orElse: () => cameras.first,
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);
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_cameraController = CameraController(
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final controller = CameraController(
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backCamera,
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ResolutionPreset.medium,
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enableAudio: false,
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);
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await _cameraController!.initialize();
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if (!mounted) return;
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setState(() => _cameraReady = true);
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await controller.initialize();
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if (!mounted) {
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await controller.dispose();
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return;
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}
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_cameraController = controller;
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setState(() {
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_cameraReady = true;
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_cameraError = null;
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_statusText = 'Ready to scan';
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});
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_startAutoScanLoop();
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} catch (e) {
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if (!mounted) return;
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setState(() {
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_cameraReady = false;
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_cameraError = 'Camera unavailable. Please retry.';
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_statusText = 'Camera unavailable';
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});
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ScaffoldMessenger.of(context).showSnackBar(
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SnackBar(
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content: Text('Camera init failed: $e'),
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backgroundColor: Colors.red,
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),
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);
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} finally {
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_isInitializingCamera = false;
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}
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}
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Future<void> _disposeCamera() async {
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_autoScanTimer?.cancel();
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_autoScanTimer = null;
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final controller = _cameraController;
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_cameraController = null;
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_cameraReady = false;
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if (controller != null) {
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await controller.dispose();
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}
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}
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void _startAutoScanLoop() {
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@ -210,8 +266,13 @@ class _ScannerScreenState extends State<ScannerScreen> {
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@override
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void dispose() {
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WidgetsBinding.instance.removeObserver(this);
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_autoScanTimer?.cancel();
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_cameraController?.dispose();
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final controller = _cameraController;
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_cameraController = null;
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if (controller != null) {
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controller.dispose();
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}
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_textRecognizer.close();
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super.dispose();
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}
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@ -302,7 +363,32 @@ class _ScannerScreenState extends State<ScannerScreen> {
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),
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// ── Camera preview ──
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Expanded(
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child: _cameraReady
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child: _cameraError != null
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? Center(
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child: Padding(
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padding: const EdgeInsets.symmetric(horizontal: 24),
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child: Column(
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mainAxisSize: MainAxisSize.min,
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children: [
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const Icon(Icons.camera_alt_outlined,
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size: 46, color: AppColors.error),
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const SizedBox(height: 12),
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Text(
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_cameraError!,
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textAlign: TextAlign.center,
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style: const TextStyle(color: AppColors.textSecondary),
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),
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const SizedBox(height: 12),
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OutlinedButton.icon(
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onPressed: () => _initCamera(force: true),
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icon: const Icon(Icons.refresh),
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label: const Text('Retry Camera'),
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),
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],
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),
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),
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)
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: _cameraReady
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? Stack(
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fit: StackFit.expand,
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children: [
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@ -440,7 +526,7 @@ class _ScannerScreenState extends State<ScannerScreen> {
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_isBusy ? 'Scanning…' : 'Capture & Scan',
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style: const TextStyle(color: Colors.white, fontWeight: FontWeight.w600),
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),
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onPressed: _isBusy ? null : _captureAndScan,
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onPressed: _isBusy || !_cameraReady ? null : _captureAndScan,
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style: ElevatedButton.styleFrom(
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backgroundColor: Colors.transparent,
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shadowColor: Colors.transparent,
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