Merge pull request #143 from r4khul/feat/flash

Add QR scanner torch control using MobileScannerController

lib/qr_code_screen.dart

@@ -12,8 +12,21 @@ class QrCodeScreen extends StatefulWidget {
 }
 
 class _QrCodeScreenState extends State<QrCodeScreen> {
+  late final MobileScannerController _controller;
   bool _scanned = false;
 
+  @override
+  void initState() {
+    super.initState();
+    _controller = MobileScannerController();
+  }
+
+  @override
+  void dispose() {
+    _controller.dispose();
+    super.dispose();
+  }
+
   void _onDetect(BarcodeCapture capture) async {
     if (_scanned) return;
     final barcode = capture.barcodes.first;
@@ -31,8 +44,26 @@ class _QrCodeScreenState extends State<QrCodeScreen> {
     return Scaffold(
       appBar: AppBar(
         title: Text(AppLocalizations.of(context)!.settingsTitle),
+        actions: [
+          ValueListenableBuilder<MobileScannerState>(
+            valueListenable: _controller,
+            builder: (context, state, _) {
+              return IconButton(
+                icon: Icon(
+                  state.torchState == TorchState.on
+                      ? Icons.flash_on
+                      : Icons.flash_off,
+                ),
+                onPressed: state.torchState == TorchState.unavailable
+                    ? null
+                    : () => _controller.toggleTorch(),
+              );
+            },
+          ),
+        ],
       ),
       body: MobileScanner(
+        controller: _controller,
         fit: BoxFit.cover,
         onDetect: _onDetect,
       ),