fix the barcode scanner controller example

+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/material.dart';
-import 'package:image_picker/image_picker.dart';
 import 'package:mobile_scanner/mobile_scanner.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';
 import 'package:mobile_scanner_example/scanner_error_widget.dart';
 
 
 class BarcodeScannerWithController extends StatefulWidget {
 class BarcodeScannerWithController extends StatefulWidget {
@@ -25,29 +27,23 @@ class _BarcodeScannerWithControllerState
     // returnImage: false,
     // returnImage: false,
   );
   );
 
 
-  bool isStarted = true;
+  StreamSubscription<Object?>? _barcodesSubscription;
 
 
-  void _startOrStop() {
-    try {
-      if (isStarted) {
-        controller.stop();
-      } else {
-        controller.start();
+  @override
+  void initState() {
+    super.initState();
+    _barcodesSubscription = controller.barcodes.listen((event) {
+      if (!context.mounted) {
+        return;
       }
       }
+
       setState(() {
       setState(() {
-        isStarted = !isStarted;
+        barcode = event;
       });
       });
-    } on Exception catch (e) {
-      ScaffoldMessenger.of(context).showSnackBar(
-        SnackBar(
-          content: Text('Something went wrong! $e'),
-          backgroundColor: Colors.red,
-        ),
-      );
-    }
-  }
+    });
 
 
-  int? numberOfCameras;
+    controller.start();
+  }
 
 
   @override
   @override
   Widget build(BuildContext context) {
   Widget build(BuildContext context) {
@@ -59,22 +55,11 @@ class _BarcodeScannerWithControllerState
           return Stack(
           return Stack(
             children: [
             children: [
               MobileScanner(
               MobileScanner(
-                onScannerStarted: (arguments) {
-                  if (mounted && arguments?.numberOfCameras != null) {
-                    numberOfCameras = arguments!.numberOfCameras;
-                    setState(() {});
-                  }
-                },
                 controller: controller,
                 controller: controller,
                 errorBuilder: (context, error, child) {
                 errorBuilder: (context, error, child) {
                   return ScannerErrorWidget(error: error);
                   return ScannerErrorWidget(error: error);
                 },
                 },
                 fit: BoxFit.contain,
                 fit: BoxFit.contain,
-                onDetect: (barcode) {
-                  setState(() {
-                    this.barcode = barcode;
-                  });
-                },
               ),
               ),
               Align(
               Align(
                 alignment: Alignment.bottomCenter,
                 alignment: Alignment.bottomCenter,
@@ -85,44 +70,8 @@ class _BarcodeScannerWithControllerState
                   child: Row(
                   child: Row(
                     mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                     mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                     children: [
                     children: [
-                      ValueListenableBuilder(
-                        valueListenable: controller.hasTorchState,
-                        builder: (context, state, child) {
-                          if (state != true) {
-                            return const SizedBox.shrink();
-                          }
-                          return IconButton(
-                            color: Colors.white,
-                            icon: ValueListenableBuilder<TorchState>(
-                              valueListenable: controller.torchState,
-                              builder: (context, state, child) {
-                                switch (state) {
-                                  case TorchState.off:
-                                    return const Icon(
-                                      Icons.flash_off,
-                                      color: Colors.grey,
-                                    );
-                                  case TorchState.on:
-                                    return const Icon(
-                                      Icons.flash_on,
-                                      color: Colors.yellow,
-                                    );
-                                }
-                              },
-                            ),
-                            iconSize: 32.0,
-                            onPressed: () => controller.toggleTorch(),
-                          );
-                        },
-                      ),
-                      IconButton(
-                        color: Colors.white,
-                        icon: isStarted
-                            ? const Icon(Icons.stop)
-                            : const Icon(Icons.play_arrow),
-                        iconSize: 32.0,
-                        onPressed: _startOrStop,
-                      ),
+                      ToggleFlashlightButton(controller: controller),
+                      StartStopMobileScannerButton(controller: controller),
                       Center(
                       Center(
                         child: SizedBox(
                         child: SizedBox(
                           width: MediaQuery.of(context).size.width - 200,
                           width: MediaQuery.of(context).size.width - 200,
@@ -140,55 +89,8 @@ class _BarcodeScannerWithControllerState
                           ),
                           ),
                         ),
                         ),
                       ),
                       ),
-                      IconButton(
-                        color: Colors.white,
-                        icon: ValueListenableBuilder<CameraFacing>(
-                          valueListenable: controller.cameraFacingState,
-                          builder: (context, state, child) {
-                            switch (state) {
-                              case CameraFacing.front:
-                                return const Icon(Icons.camera_front);
-                              case CameraFacing.back:
-                                return const Icon(Icons.camera_rear);
-                            }
-                          },
-                        ),
-                        iconSize: 32.0,
-                        onPressed: (numberOfCameras ?? 0) < 2
-                            ? null
-                            : () => controller.switchCamera(),
-                      ),
-                      IconButton(
-                        color: Colors.white,
-                        icon: const Icon(Icons.image),
-                        iconSize: 32.0,
-                        onPressed: () async {
-                          final ImagePicker picker = ImagePicker();
-                          // Pick an image
-                          final XFile? image = await picker.pickImage(
-                            source: ImageSource.gallery,
-                          );
-                          if (image != null) {
-                            if (await controller.analyzeImage(image.path)) {
-                              if (!context.mounted) return;
-                              ScaffoldMessenger.of(context).showSnackBar(
-                                const SnackBar(
-                                  content: Text('Barcode found!'),
-                                  backgroundColor: Colors.green,
-                                ),
-                              );
-                            } else {
-                              if (!context.mounted) return;
-                              ScaffoldMessenger.of(context).showSnackBar(
-                                const SnackBar(
-                                  content: Text('No barcode found!'),
-                                  backgroundColor: Colors.red,
-                                ),
-                              );
-                            }
-                          }
-                        },
-                      ),
+                      SwitchCameraButton(controller: controller),
+                      AnalyzeImageFromGalleryButton(controller: controller),
                     ],
                     ],
                   ),
                   ),
                 ),
                 ),
@@ -199,4 +101,11 @@ class _BarcodeScannerWithControllerState
       ),
       ),
     );
     );
   }
   }
+
+  @override
+  Future<void> dispose() async {
+    _barcodesSubscription?.cancel();
+    await controller.dispose();
+    super.dispose();
+  }
 }
 }