fix the pageview sample

+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/material.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
 import 'package:mobile_scanner/mobile_scanner.dart';
 import 'package:mobile_scanner_example/scanner_error_widget.dart';
 import 'package:mobile_scanner_example/scanner_error_widget.dart';
@@ -9,27 +11,72 @@ class BarcodeScannerPageView extends StatefulWidget {
   State<BarcodeScannerPageView> createState() => _BarcodeScannerPageViewState();
   State<BarcodeScannerPageView> createState() => _BarcodeScannerPageViewState();
 }
 }
 
 
-class _BarcodeScannerPageViewState extends State<BarcodeScannerPageView>
-    with SingleTickerProviderStateMixin {
-  BarcodeCapture? capture;
+class _BarcodeScannerPageViewState extends State<BarcodeScannerPageView> {
+  final MobileScannerController scannerController = MobileScannerController();
+
+  final PageController pageController = PageController();
+
+  @override
+  void initState() {
+    super.initState();
+    scannerController.start();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(title: const Text('With PageView')),
+      backgroundColor: Colors.black,
+      body: PageView(
+        controller: pageController,
+        onPageChanged: (index) async {
+          // Stop the camera view for the current page,
+          // and then restart the camera for the new page.
+          await scannerController.stop();
+
+          // When switching pages, add a delay to the next start call.
+          // Otherwise the camera will start before the next page is displayed.
+          await Future.delayed(const Duration(seconds: 1, milliseconds: 500));
+
+          if (!mounted) {
+            return;
+          }
+
+          scannerController.start();
+        },
+        children: [
+          _BarcodeScannerPage(controller: scannerController),
+          const SizedBox(),
+          _BarcodeScannerPage(controller: scannerController),
+          _BarcodeScannerPage(controller: scannerController),
+        ],
+      ),
+    );
+  }
+
+  @override
+  Future<void> dispose() async {
+    await scannerController.dispose();
+    pageController.dispose();
+    super.dispose();
+  }
+}
+
+class _BarcodeScannerPage extends StatelessWidget {
+  const _BarcodeScannerPage({required this.controller});
+
+  final MobileScannerController controller;
 
 
-  Widget cameraView() {
-    return Builder(
-      builder: (context) {
+  @override
+  Widget build(BuildContext context) {
     return Stack(
     return Stack(
       children: [
       children: [
         MobileScanner(
         MobileScanner(
-              startDelay: true,
-              controller: MobileScannerController(torchEnabled: true),
+          controller: controller,
           fit: BoxFit.contain,
           fit: BoxFit.contain,
           errorBuilder: (context, error, child) {
           errorBuilder: (context, error, child) {
             return ScannerErrorWidget(error: error);
             return ScannerErrorWidget(error: error);
           },
           },
-              onDetect: (capture) {
-                setState(() {
-                  this.capture = capture;
-                });
-              },
         ),
         ),
         Align(
         Align(
           alignment: Alignment.bottomCenter,
           alignment: Alignment.bottomCenter,
@@ -37,49 +84,30 @@ class _BarcodeScannerPageViewState extends State<BarcodeScannerPageView>
             alignment: Alignment.bottomCenter,
             alignment: Alignment.bottomCenter,
             height: 100,
             height: 100,
             color: Colors.black.withOpacity(0.4),
             color: Colors.black.withOpacity(0.4),
-                child: Row(
-                  mainAxisAlignment: MainAxisAlignment.spaceEvenly,
-                  children: [
-                    Center(
-                      child: SizedBox(
-                        width: MediaQuery.of(context).size.width - 120,
-                        height: 50,
-                        child: FittedBox(
-                          child: Text(
-                            capture?.barcodes.first.rawValue ??
-                                'Scan something!',
+            child: Center(
+              child: StreamBuilder<BarcodeCapture>(
+                stream: controller.barcodes,
+                builder: (context, snapshot) {
+                  final barcodes = snapshot.data?.barcodes;
+
+                  if (barcodes == null || barcodes.isEmpty) {
+                    return const Text(
+                      'Scan Something!',
+                      style: TextStyle(color: Colors.white, fontSize: 20),
+                    );
+                  }
+
+                  return Text(
+                    barcodes.first.rawValue ?? 'No raw value',
                     overflow: TextOverflow.fade,
                     overflow: TextOverflow.fade,
-                            style: Theme.of(context)
-                                .textTheme
-                                .headlineMedium!
-                                .copyWith(color: Colors.white),
-                          ),
-                        ),
-                      ),
+                    style: const TextStyle(color: Colors.white),
+                  );
+                },
               ),
               ),
-                  ],
             ),
             ),
           ),
           ),
         ),
         ),
       ],
       ],
     );
     );
-      },
-    );
-  }
-
-  @override
-  Widget build(BuildContext context) {
-    return Scaffold(
-      appBar: AppBar(title: const Text('With PageView')),
-      backgroundColor: Colors.black,
-      body: PageView(
-        children: [
-          cameraView(),
-          Container(),
-          cameraView(),
-          cameraView(),
-        ],
-      ),
-    );
   }
   }
 }
 }