Add support for null-safety (#278)

example/lib/main.dart

@@ -7,17 +7,13 @@ import 'package:qr_code_scanner/qr_code_scanner.dart';
 void main() => runApp(MaterialApp(home: QRViewExample()));
 
 class QRViewExample extends StatefulWidget {
-  const QRViewExample({
-    Key key,
-  }) : super(key: key);
-
   @override
   State<StatefulWidget> createState() => _QRViewExampleState();
 }
 
 class _QRViewExampleState extends State<QRViewExample> {
-  Barcode result;
-  QRViewController controller;
+  Barcode? result;
+  QRViewController? controller;
   final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
 
   // In order to get hot reload to work we need to pause the camera if the platform
@@ -26,9 +22,9 @@ class _QRViewExampleState extends State<QRViewExample> {
   void reassemble() {
     super.reassemble();
     if (Platform.isAndroid) {
-      controller.pauseCamera();
+      controller!.pauseCamera();
     }
-    controller.resumeCamera();
+    controller!.resumeCamera();
   }
 
   @override
@@ -46,7 +42,7 @@ class _QRViewExampleState extends State<QRViewExample> {
                 children: <Widget>[
                   if (result != null)
                     Text(
-                        'Barcode Type: ${describeEnum(result.format)}   Data: ${result.code}')
+                        'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                   else
                     Text('Scan a code'),
                   Row(
@@ -79,7 +75,7 @@ class _QRViewExampleState extends State<QRViewExample> {
                               builder: (context, snapshot) {
                                 if (snapshot.data != null) {
                                   return Text(
-                                      'Camera facing ${describeEnum(snapshot.data)}');
+                                      'Camera facing ${describeEnum(snapshot.data!)}');
                                 } else {
                                   return Text('loading');
                                 }

example/pubspec.yaml

@@ -3,7 +3,7 @@ description: Demonstrates how to use the flutter_qr plugin.
 publish_to: 'none'
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
 
 dependencies:
   flutter:

lib/src/lifecycle_event_handler.dart

@@ -7,22 +7,22 @@ class LifecycleEventHandler extends WidgetsBindingObserver {
     this.suspendingCallBack,
   });
 
-  final AsyncCallback resumeCallBack;
-  final AsyncCallback suspendingCallBack;
+  final AsyncCallback? resumeCallBack;
+  final AsyncCallback? suspendingCallBack;
 
   @override
   Future<void> didChangeAppLifecycleState(AppLifecycleState state) async {
     switch (state) {
       case AppLifecycleState.resumed:
         if (resumeCallBack != null) {
-          await resumeCallBack();
+          await resumeCallBack!();
         }
         break;
       case AppLifecycleState.inactive:
       case AppLifecycleState.paused:
       case AppLifecycleState.detached:
         if (suspendingCallBack != null) {
-          await suspendingCallBack();
+          await suspendingCallBack!();
         }
         break;
     }

lib/src/qr_code_scanner.dart

@@ -14,29 +14,27 @@ import 'types/camera_exception.dart';
 import 'types/features.dart';
 
 typedef QRViewCreatedCallback = void Function(QRViewController);
-typedef PermissionSetCallback = void Function(QRViewController, bool);
+typedef PermissionSetCallback = void Function(QRViewController, bool?);
 
 /// The [QRView] is the view where the camera
 /// and the barcode scanner gets displayed.
 class QRView extends StatefulWidget {
   const QRView({
-    @required Key key,
-    @required this.onQRViewCreated,
+    required Key key,
+    required this.onQRViewCreated,
     this.overlay,
     this.overlayMargin = EdgeInsets.zero,
     this.cameraFacing = CameraFacing.back,
     this.onPermissionSet,
     this.formatsAllowed,
-  })  : assert(key != null),
-        assert(onQRViewCreated != null),
-        super(key: key);
+  }) : super(key: key);
 
   /// [onQRViewCreated] gets called when the view is created
   final QRViewCreatedCallback onQRViewCreated;
 
   /// Use [overlay] to provide an overlay for the view.
   /// This can be used to create a certain scan area.
-  final QrScannerOverlayShape overlay;
+  final QrScannerOverlayShape? overlay;
 
   /// Use [overlayMargin] to provide a margin to [overlay]
   final EdgeInsetsGeometry overlayMargin;
@@ -48,10 +46,10 @@ class QRView extends StatefulWidget {
   final CameraFacing cameraFacing;
 
   /// Calls the provided [onPermissionSet] callback when the permission is set.
-  final PermissionSetCallback onPermissionSet;
+  final PermissionSetCallback? onPermissionSet;
 
   /// Use [formatsAllowed] to specify which formats needs to be scanned.
-  final List<BarcodeFormat> formatsAllowed;
+  final List<BarcodeFormat>? formatsAllowed;
 
   @override
   State<StatefulWidget> createState() => _QRViewState();
@@ -59,7 +57,7 @@ class QRView extends StatefulWidget {
 
 class _QRViewState extends State<QRView> {
   var _channel;
-  var _observer;
+  late var _observer;
 
   @override
   void initState() {
@@ -68,11 +66,12 @@ class _QRViewState extends State<QRView> {
         resumeCallBack: () async => {
               if (_channel != null)
                 {
-                  QRViewController.updateDimensions(widget.key, _channel,
+                  QRViewController.updateDimensions(
+                      widget.key as GlobalKey<State<StatefulWidget>>, _channel,
                       overlay: widget.overlay)
                 }
             });
-    WidgetsBinding.instance.addObserver(_observer);
+    WidgetsBinding.instance!.addObserver(_observer);
   }
 
   @override
@@ -90,12 +89,13 @@ class _QRViewState extends State<QRView> {
   @override
   void dispose() {
     super.dispose();
-    WidgetsBinding.instance.removeObserver(_observer);
+    WidgetsBinding.instance!.removeObserver(_observer);
   }
 
   bool onNotification(notification) {
     Future.microtask(() => {
-          QRViewController.updateDimensions(widget.key, _channel,
+          QRViewController.updateDimensions(
+              widget.key as GlobalKey<State<StatefulWidget>>, _channel,
               overlay: widget.overlay)
         });
 
@@ -109,7 +109,7 @@ class _QRViewState extends State<QRView> {
         Container(
           padding: widget.overlayMargin,
           decoration: ShapeDecoration(
-            shape: widget.overlay,
+            shape: widget.overlay!,
           ),
         )
       ],
@@ -149,13 +149,15 @@ class _QRViewState extends State<QRView> {
 
     // Start scan after creation of the view
     final controller = QRViewController._(
-        _channel, widget.key, widget.onPermissionSet, widget.cameraFacing)
-      .._startScan(widget.key, widget.overlay, widget.formatsAllowed);
+        _channel,
+        widget.key as GlobalKey<State<StatefulWidget>>?,
+        widget.onPermissionSet,
+        widget.cameraFacing)
+      .._startScan(widget.key as GlobalKey<State<StatefulWidget>>,
+          widget.overlay, widget.formatsAllowed);
 
     // Initialize the controller for controlling the QRView
-    if (widget.onQRViewCreated != null) {
-      widget.onQRViewCreated(controller);
-    }
+    widget.onQRViewCreated(controller);
   }
 }
 
@@ -164,18 +166,18 @@ class _QrCameraSettings {
     this.cameraFacing,
   });
 
-  final CameraFacing cameraFacing;
+  final CameraFacing? cameraFacing;
 
   Map<String, dynamic> toMap() {
     return <String, dynamic>{
-      'cameraFacing': cameraFacing.index,
+      'cameraFacing': cameraFacing!.index,
     };
   }
 }
 
 class QRViewController {
-  QRViewController._(MethodChannel channel, GlobalKey qrKey,
-      PermissionSetCallback onPermissionSet, CameraFacing cameraFacing)
+  QRViewController._(MethodChannel channel, GlobalKey? qrKey,
+      PermissionSetCallback? onPermissionSet, CameraFacing cameraFacing)
       : _channel = channel,
         _cameraFacing = cameraFacing {
     _channel.setMethodCallHandler((call) async {
@@ -183,10 +185,10 @@ class QRViewController {
         case 'onRecognizeQR':
           if (call.arguments != null) {
             final args = call.arguments as Map;
-            final code = args['code'] as String;
-            final rawType = args['type'] as String;
+            final code = args['code'] as String?;
+            final rawType = args['type'] as String?;
             // Raw bytes are only supported by Android.
-            final rawBytes = args['rawBytes'] as List<int>;
+            final rawBytes = args['rawBytes'] as List<int>?;
             final format = BarcodeTypesExtension.fromString(rawType);
             if (format != null) {
               final barcode = Barcode(code, format, rawBytes);
@@ -205,7 +207,7 @@ class QRViewController {
               _hasPermissions = false;
             }
             if (onPermissionSet != null) {
-              onPermissionSet(this, call.arguments as bool);
+              onPermissionSet(this, call.arguments as bool?);
             }
           }
           break;
@@ -213,27 +215,27 @@ class QRViewController {
     });
   }
 
-  final MethodChannel _channel;
+  late final MethodChannel _channel;
   final CameraFacing _cameraFacing;
   final StreamController<Barcode> _scanUpdateController =
       StreamController<Barcode>();
 
   Stream<Barcode> get scannedDataStream => _scanUpdateController.stream;
 
-  SystemFeatures _features;
-  bool _hasPermissions;
+  SystemFeatures? _features;
+  bool? _hasPermissions;
 
-  SystemFeatures get systemFeatures => _features;
-  bool get hasPermissions => _hasPermissions;
+  SystemFeatures? get systemFeatures => _features;
+  bool? get hasPermissions => _hasPermissions;
 
   /// Starts the barcode scanner
-  Future<void> _startScan(GlobalKey key, QrScannerOverlayShape overlay,
-      List<BarcodeFormat> barcodeFormats) async {
+  Future<void> _startScan(GlobalKey key, QrScannerOverlayShape? overlay,
+      List<BarcodeFormat>? barcodeFormats) async {
     // We need to update the dimension before the scan is started.
     try {
       await QRViewController.updateDimensions(key, _channel, overlay: overlay);
       return await _channel.invokeMethod(
-          'startScan', barcodeFormats?.map((e) => e.asInt())?.toList() ?? []);
+          'startScan', barcodeFormats?.map((e) => e.asInt()).toList() ?? []);
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
     }
@@ -242,7 +244,7 @@ class QRViewController {
   /// Gets information about which camera is active.
   Future<CameraFacing> getCameraInfo() async {
     try {
-      var cameraFacing = await _channel.invokeMethod('getCameraInfo') as int;
+      var cameraFacing = await _channel.invokeMethod('getCameraInfo') as int?;
       if (cameraFacing == -1) return _cameraFacing;
       return CameraFacing
           .values[await _channel.invokeMethod('getCameraInfo') as int];
@@ -262,7 +264,7 @@ class QRViewController {
   }
 
   /// Get flashlight status
-  Future<bool> getFlashStatus() async {
+  Future<bool?> getFlashStatus() async {
     try {
       return await _channel.invokeMethod('getFlashInfo');
     } on PlatformException catch (e) {
@@ -273,7 +275,7 @@ class QRViewController {
   /// Toggles the flashlight between available modes
   Future<void> toggleFlash() async {
     try {
-      await _channel.invokeMethod('toggleFlash') as bool;
+      await _channel.invokeMethod('toggleFlash') as bool?;
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
     }
@@ -310,7 +312,8 @@ class QRViewController {
   Future<SystemFeatures> getSystemFeatures() async {
     try {
       var features =
-          await _channel.invokeMapMethod<String, dynamic>('getSystemFeatures');
+          await (_channel.invokeMapMethod<String, dynamic>('getSystemFeatures')
+              as FutureOr<Map<String, dynamic>>);
       return SystemFeatures.fromJson(features);
     } on PlatformException catch (e) {
       throw CameraException(e.code, e.message);
@@ -325,11 +328,11 @@ class QRViewController {
 
   /// Updates the view dimensions for iOS.
   static Future<void> updateDimensions(GlobalKey key, MethodChannel channel,
-      {QrScannerOverlayShape overlay}) async {
+      {QrScannerOverlayShape? overlay}) async {
     if (defaultTargetPlatform == TargetPlatform.iOS) {
       // Add small delay to ensure the renderbox is loaded
       await Future.delayed(Duration(milliseconds: 100));
-      final RenderBox renderBox = key.currentContext.findRenderObject();
+      final renderBox = key.currentContext!.findRenderObject() as RenderBox;
       try {
         await channel.invokeMethod('setDimensions', {
           'width': renderBox.size.width,

lib/src/qr_scanner_overlay_shape.dart

@@ -29,14 +29,14 @@ class QrScannerOverlayShape extends ShapeBorder {
   EdgeInsetsGeometry get dimensions => const EdgeInsets.all(10);
 
   @override
-  Path getInnerPath(Rect rect, {TextDirection textDirection}) {
+  Path getInnerPath(Rect rect, {TextDirection? textDirection}) {
     return Path()
       ..fillType = PathFillType.evenOdd
       ..addPath(getOuterPath(rect), Offset.zero);
   }
 
   @override
-  Path getOuterPath(Rect rect, {TextDirection textDirection}) {
+  Path getOuterPath(Rect rect, {TextDirection? textDirection}) {
     Path _getLeftTopPath(Rect rect) {
       return Path()
         ..moveTo(rect.left, rect.bottom)
@@ -60,7 +60,7 @@ class QrScannerOverlayShape extends ShapeBorder {
   }
 
   @override
-  void paint(Canvas canvas, Rect rect, {TextDirection textDirection}) {
+  void paint(Canvas canvas, Rect rect, {TextDirection? textDirection}) {
     final width = rect.width;
     final borderWidthSize = width / 2;
     final height = rect.height;

lib/src/types/barcode.dart

@@ -8,9 +8,9 @@ import 'barcode_format.dart';
 class Barcode {
   Barcode(this.code, this.format, this.rawBytes);
 
-  final String code;
+  final String? code;
   final BarcodeFormat format;
 
   /// Raw bytes are only supported by Android.
-  final List<int> rawBytes;
+  final List<int>? rawBytes;
 }

lib/src/types/barcode_format.dart

@@ -61,7 +61,7 @@ extension BarcodeTypesExtension on BarcodeFormat {
     return index;
   }
 
-  static BarcodeFormat fromString(String format) {
+  static BarcodeFormat? fromString(String? format) {
     switch (format) {
       case 'AZTEC':
         return BarcodeFormat.aztec;

lib/src/types/camera_exception.dart

@@ -7,7 +7,7 @@ class CameraException implements Exception {
   String code;
 
   /// Textual description of the error.
-  String description;
+  String? description;
 
   @override
   String toString() => 'CameraException($code, $description)';

pubspec.yaml

@@ -5,7 +5,7 @@ homepage: https://juliuscanute.com
 repository: https://github.com/juliuscanute/qr_code_scanner
 
 environment:
-  sdk: ">=2.6.0 <3.0.0"
+  sdk: '>=2.12.0 <3.0.0'
   flutter: ">=1.10.0"
 
 dependencies:
@@ -13,7 +13,7 @@ dependencies:
     sdk: flutter
 
 dev_dependencies:
-  pedantic: ^1.9.2
+  pedantic: ^1.11.0
 
 flutter:
   plugin: