655: replace qr_code_scanner with mobile_scanner

.vscode/tasks.json

@@ -48,7 +48,8 @@
             "args": [
                 "flutter",
                 "run",
-                "--dart-define=environment=local"
+                "--dart-define=environment=local",
+                "--flavor=Bayern"
             ],
             "problemMatcher": [
                 "$gradle"

frontend/android/app/build.gradle

@@ -123,7 +123,7 @@ android {
     }
 
     defaultConfig {
-        minSdkVersion 20
+        minSdkVersion 21
         targetSdkVersion 33
         multiDexEnabled true
         versionCode flutterVersionCode.toInteger()

frontend/lib/qr_code_scanner/qr_code_scanner.dart

@@ -1,8 +1,9 @@
 import 'dart:math';
 
 import 'package:ehrenamtskarte/qr_code_scanner/qr_code_scanner_controls.dart';
+import 'package:ehrenamtskarte/qr_code_scanner/qr_overlay_shape.dart';
 import 'package:flutter/material.dart';
-import 'package:qr_code_scanner/qr_code_scanner.dart';
+import 'package:mobile_scanner/mobile_scanner.dart';
 
 const scanDelayAfterErrorMs = 500;
 
@@ -18,7 +19,10 @@ class QrCodeScanner extends StatefulWidget {
 }
 
 class _QRViewState extends State<QrCodeScanner> {
-  QRViewController? _controller;
+  final MobileScannerController _controller = MobileScannerController(
+    torchEnabled: false,
+    formats: [BarcodeFormat.qrCode],
+  );
   final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
   bool isProcessingCode = false;
 
@@ -29,35 +33,47 @@ class _QRViewState extends State<QrCodeScanner> {
       children: <Widget>[
         Expanded(
           flex: 4,
-          child: QRView(
-            key: qrKey,
-            onQRViewCreated: _onQrViewCreated,
-            overlay: QrScannerOverlayShape(
-              borderColor: Theme.of(context).colorScheme.secondary,
-              borderRadius: 10,
-              borderLength: 30,
-              borderWidth: 10,
-              cutOutSize: _calculateScanArea(context),
-            ),
-          ),
-        ),
-        if (controller != null)
-          Expanded(
-            flex: 1,
-            child: FittedBox(
-              fit: BoxFit.contain,
-              child: Column(
-                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
-                children: <Widget>[
-                  Container(
-                    margin: const EdgeInsets.all(8),
-                    child: const Text('Halten Sie die Kamera auf den QR Code.'),
+          child: Stack(
+            children: [
+              MobileScanner(
+                key: qrKey,
+                onDetect: (barcode, args) => _onCodeScanned(barcode),
+                allowDuplicates: false,
+                controller: controller,
+              ),
+              Padding(
+                padding: EdgeInsets.zero,
+                child: Container(
+                  decoration: ShapeDecoration(
+                    shape: QrScannerOverlayShape(
+                      borderRadius: 10,
+                      borderColor: Theme.of(context).colorScheme.secondary,
+                      borderLength: 30,
+                      borderWidth: 10,
+                      cutOutSize: _calculateScanArea(context),
+                    ),
                   ),
-                  QrCodeScannerControls(controller: controller)
-                ],
+                ),
               ),
+            ],
+          ),
+        ),
+        Expanded(
+          flex: 1,
+          child: FittedBox(
+            fit: BoxFit.contain,
+            child: Column(
+              mainAxisAlignment: MainAxisAlignment.spaceEvenly,
+              children: <Widget>[
+                Container(
+                  margin: const EdgeInsets.all(8),
+                  child: const Text('Halten Sie die Kamera auf den QR Code.'),
+                ),
+                QrCodeScannerControls(controller: controller)
+              ],
             ),
-          )
+          ),
+        )
       ],
     );
   }
@@ -76,37 +92,14 @@ class _QRViewState extends State<QrCodeScanner> {
     return scanArea;
   }
 
-  void _onQrViewCreated(QRViewController controller) {
-    setState(() {
-      _controller = controller;
-    });
-    controller.scannedDataStream.listen(_onCodeScanned);
-  }
-
   Future<void> _onCodeScanned(Barcode scanData) async {
     final controller = _controller;
-    final code = scanData.code;
-    if (controller == null || code == null) {
-      return;
-    }
-
-    // needed because this method gets called multiple times in a row after one
-    // qr code gets detected, therefore we need to protect it
-    if (isProcessingCode) {
+    final code = scanData.rawValue;
+    if (code == null) {
       return;
     }
-    isProcessingCode = true;
-    controller.pauseCamera();
 
     await widget.onCodeScanned(code);
-
-    // give the user time to move the camara away from the qr code
-    await Future.delayed(const Duration(milliseconds: scanDelayAfterErrorMs));
-
-    if (mounted) {
-      controller.resumeCamera();
-    }
-    isProcessingCode = false;
   }
 
   @override

frontend/lib/qr_code_scanner/qr_code_scanner_controls.dart

@@ -1,84 +1,44 @@
-import 'dart:async';
-
 import 'package:flutter/material.dart';
-import 'package:qr_code_scanner/qr_code_scanner.dart';
+import 'package:mobile_scanner/mobile_scanner.dart';
 
 class QrCodeScannerControls extends StatelessWidget {
-  final QRViewController controller;
-
-  // Not really nice. We need to update the button texts after we pressed them.
-  // Other possibility would be to convert this to a stateful widget without
-  // state and just call setState({}) to trigger redrawing of whole widget.
-  final StreamController<bool> flashStreamController = StreamController();
-  final StreamController<CameraFacing> cameraStreamController = StreamController<CameraFacing>();
-
-  QrCodeScannerControls({super.key, required this.controller}) {
-    updateFlashStream();
-    updateCameraStream();
-  }
-
-  Future<void> updateFlashStream() =>
-      controller.getFlashStatus().then((flashStatus) => flashStreamController.add(flashStatus ?? false));
+  final MobileScannerController controller;
 
-  Future<void> updateCameraStream() => controller.getCameraInfo().then(cameraStreamController.add);
+  const QrCodeScannerControls({super.key, required this.controller});
 
   @override
   Widget build(BuildContext context) {
-    return FutureBuilder<SystemFeatures>(
-      future: _tryToGetSystemFeatures(),
-      builder: (context, snapshot) {
-        final SystemFeatures? systemFeatures = snapshot.data;
-
-        if (snapshot.hasData || systemFeatures == null) {
-          return const Center();
-        }
-
-        return Row(
-          mainAxisAlignment: MainAxisAlignment.center,
-          crossAxisAlignment: CrossAxisAlignment.center,
-          children: <Widget>[
-            if (systemFeatures.hasFlash)
-              Container(
-                margin: const EdgeInsets.all(8),
-                child: OutlinedButton(
-                  onPressed: () => controller.toggleFlash().whenComplete(updateFlashStream),
-                  child: StreamBuilder<bool>(
-                    stream: flashStreamController.stream,
-                    builder: (ctx, snapshot) => Text(
-                      snapshot.data == null ? "Blitz aus" : "Blitz an",
-                      style: const TextStyle(fontSize: 16),
-                    ),
-                  ),
-                ),
+    return Row(
+      mainAxisAlignment: MainAxisAlignment.center,
+      crossAxisAlignment: CrossAxisAlignment.center,
+      children: <Widget>[
+        Container(
+          margin: const EdgeInsets.all(8),
+          child: OutlinedButton(
+            onPressed: () => controller.toggleTorch(),
+            child: ValueListenableBuilder(
+              valueListenable: controller.torchState,
+              builder: (ctx, state, child) => Text(
+                state == TorchState.on ? "Blitz aus" : "Blitz an",
+                style: const TextStyle(fontSize: 16),
+              ),
+            ),
+          ),
+        ),
+        Container(
+          margin: const EdgeInsets.all(8),
+          child: OutlinedButton(
+            onPressed: () => controller.switchCamera(),
+            child: ValueListenableBuilder(
+              valueListenable: controller.cameraFacingState,
+              builder: (ctx, state, child) => Text(
+                state == CameraFacing.back ? "Frontkamera" : "Standard-Kamera",
+                style: const TextStyle(fontSize: 16),
               ),
-            if (systemFeatures.hasBackCamera && systemFeatures.hasFrontCamera)
-              Container(
-                margin: const EdgeInsets.all(8),
-                child: OutlinedButton(
-                  onPressed: () => controller.flipCamera().whenComplete(updateCameraStream),
-                  child: StreamBuilder<CameraFacing>(
-                    stream: cameraStreamController.stream,
-                    builder: (ctx, snapshot) => Text(
-                      snapshot.data == CameraFacing.back ? "Frontkamera" : "Standard-Kamera",
-                      style: const TextStyle(fontSize: 16),
-                    ),
-                  ),
-                ),
-              )
-          ],
-        );
-      },
+            ),
+          ),
+        )
+      ],
     );
   }
-
-  Future<SystemFeatures> _tryToGetSystemFeatures() async {
-    for (var i = 0; i < 10; i++) {
-      try {
-        return await controller.getSystemFeatures();
-      } on CameraException {
-        await Future.delayed(const Duration(milliseconds: 50));
-      }
-    }
-    return SystemFeatures(true, true, true);
-  }
 }