add pause function to web part

@@ -129,6 +129,11 @@ abstract class BarcodeReader {
     throw UnimplementedError('start() has not been implemented.');
   }
 
+  /// Pause the barcode reader.
+  Future<void> pause() {
+    throw UnimplementedError('pause() has not been implemented.');
+  }
+
   /// Stop the barcode reader and dispose of the video stream.
   Future<void> stop() {
     throw UnimplementedError('stop() has not been implemented.');

 import 'dart:async';
+import 'dart:developer';
+import 'dart:html';
 import 'dart:js_interop';
 import 'dart:ui_web' as ui_web;
 
@@ -235,6 +237,11 @@ class MobileScannerWeb extends MobileScannerPlatform {
       throw PermissionRequestPendingException();
     }
 
+    // If the previous state is a pause, reset scanner.
+    if (_barcodesSubscription != null && _barcodesSubscription!.isPaused) {
+      await stop();
+    }
+
     await _barcodeReader.maybeLoadLibrary(
       alternateScriptUrl: _alternateScriptUrl,
     );
@@ -336,6 +343,13 @@ class MobileScannerWeb extends MobileScannerPlatform {
     }
   }
 
+
+  @override
+  Future<void> pause() async {
+    _barcodesSubscription?.pause();
+    await _barcodeReader.pause();
+  }
+
   @override
   Future<void> stop() async {
     if (_barcodesController.isClosed) {

@@ -192,6 +192,11 @@ final class ZXingBarcodeReader extends BarcodeReader {
   }
 
   @override
+  Future<void> pause() async {
+    _reader?.videoElement?.pause();
+  }
+
+  @override
   Future<void> stop() async {
     _onMediaTrackSettingsChanged = null;
     _reader?.stopContinuousDecode.callAsFunction(_reader as JSAny?);