refactor: abstract torch support

@@ -34,9 +34,6 @@ class MobileScannerWebPlugin {
   // ID of the video feed
   String viewID = 'WebScanner-${DateTime.now().millisecondsSinceEpoch}';
 
-  // Determine wether device has flas
-  bool hasFlash = false;
-
   final html.DivElement vidDiv = html.DivElement();
 
   late final WebBarcodeReaderBase _barCodeReader =
@@ -63,15 +60,7 @@ class MobileScannerWebPlugin {
 
   /// Can enable or disable the flash if available
   Future<void> _torch(arguments) async {
-    // if (hasFlash) {
-    //   final track = _localStream?.getVideoTracks();
-    //   await track!.first.applyConstraints({
-    //     'advanced': {'torch': arguments == 1}
-    //   });
-    // } else {
-    //   controller.addError('Device has no flash');
-    // }
-    controller.addError('Device has no flash');
+    _barCodeReader.toggleTorch(enabled: arguments == 1);
   }
 
   /// Starts the video stream and the scanner
@@ -97,7 +86,8 @@ class MobileScannerWebPlugin {
       return {
         'ViewID': viewID,
         'videoWidth': _barCodeReader.videoWidth,
-        'videoHeight': _barCodeReader.videoHeight
+        'videoHeight': _barCodeReader.videoHeight,
+        'torchable': _barCodeReader.hasTorch,
       };
     }
     try {
@@ -115,7 +105,7 @@ class MobileScannerWebPlugin {
         'ViewID': viewID,
         'videoWidth': _barCodeReader.videoWidth,
         'videoHeight': _barCodeReader.videoHeight,
-        'torchable': hasFlash
+        'torchable': _barCodeReader.hasTorch,
       };
     } catch (e) {
       throw PlatformException(code: 'MobileScannerWeb', message: '$e');

@@ -29,6 +29,12 @@ abstract class WebBarcodeReaderBase {
 
   /// Stops streaming video
   Future<void> stop();
+
+  /// Can enable or disable the flash if available
+  Future<void> toggleTorch({required bool enabled});
+
+  /// Determine whether device has flash
+  bool get hasTorch;
 }
 
 mixin InternalStreamCreation on WebBarcodeReaderBase {
@@ -86,3 +92,30 @@ mixin InternalStreamCreation on WebBarcodeReaderBase {
     videoContainer.children = [];
   }
 }
+
+/// Mixin for libraries that don't have built-in torch support
+mixin InternalTorchDetection on InternalStreamCreation {
+  @override
+  bool get hasTorch {
+    // TODO: fix flash light. See https://github.com/dart-lang/sdk/issues/48533
+    // final track = _localStream?.getVideoTracks();
+    // if (track != null) {
+    //   final imageCapture = html.ImageCapture(track.first);
+    //   final photoCapabilities = await imageCapture.getPhotoCapabilities();
+    // }
+    return false;
+  }
+
+  @override
+  Future<void> toggleTorch({required bool enabled}) async {
+    if (hasTorch) {
+      final track = localMediaStream?.getVideoTracks();
+      await track?.first.applyConstraints({
+        'advanced': [
+          {'torch': enabled}
+        ]
+      });
+    }
+  }
+}
+

@@ -20,7 +20,8 @@ class Code {
 }
 
 
-class JsQrCodeReader extends WebBarcodeReaderBase with InternalStreamCreation {
+class JsQrCodeReader extends WebBarcodeReaderBase
+    with InternalStreamCreation, InternalTorchDetection {
   JsQrCodeReader({required super.videoContainer});
 
   @override
@@ -34,13 +35,6 @@ class JsQrCodeReader extends WebBarcodeReaderBase with InternalStreamCreation {
 
     final stream = await initMediaStream(cameraFacing);
 
-    // TODO: fix flash light. See https://github.com/dart-lang/sdk/issues/48533
-    // final track = _localStream?.getVideoTracks();
-    // if (track != null) {
-    //   final imageCapture = html.ImageCapture(track.first);
-    //   final photoCapabilities = await imageCapture.getPhotoCapabilities();
-    // }
-
     prepareVideoElement(video);
     if (stream != null) {
       await attachStreamToVideo(stream, video);