[camera_web] Skip video input devices that cannot be started in availableCameras

packages/camera/camera_web/CHANGELOG.md

@@ -1,5 +1,7 @@
-## NEXT
+## 0.3.5+7
 
+* Fixes `availableCameras` failing when a video input device cannot be started, for example
+  a virtual camera without a video source. Such devices are now skipped.
 * Updates minimum supported SDK version to Flutter 3.41/Dart 3.11.
 
 ## 0.3.5+6

packages/camera/camera_web/example/integration_test/camera_web_devices_test.dart

@@ -380,6 +380,63 @@ void main() {
         expect(stops.every((bool e) => e), isTrue);
       });
 
+      testWidgets('skips a video input device '
+          'that cannot be started', (WidgetTester tester) async {
+        final unreadableVideoDevice =
+            createJSInteropWrapper(FakeMediaDeviceInfo('1', 'Camera 1', MediaDeviceKind.videoInput))
+                as MediaDeviceInfo;
+
+        final videoDevice =
+            createJSInteropWrapper(FakeMediaDeviceInfo('2', 'Camera 2', MediaDeviceKind.videoInput))
+                as MediaDeviceInfo;
+
+        final videoStream =
+            createJSInteropWrapper(
+                  FakeMediaStream(<MediaStreamTrack>[
+                    createJSInteropWrapper(MockMediaStreamTrack()) as MediaStreamTrack,
+                  ]),
+                )
+                as MediaStream;
+
+        mockMediaDevices.enumerateDevices = () {
+          return Future<JSArray<MediaDeviceInfo>>.value(
+            <MediaDeviceInfo>[unreadableVideoDevice, videoDevice].toJS,
+          ).toJS;
+        }.toJS;
+
+        when(
+          cameraService.getMediaStreamForOptions(
+            CameraOptions(video: VideoConstraints(deviceId: unreadableVideoDevice.deviceId)),
+          ),
+        ).thenThrow(CameraWebException(0, CameraErrorCode.notReadable, 'description'));
+
+        when(
+          cameraService.getMediaStreamForOptions(
+            CameraOptions(video: VideoConstraints(deviceId: videoDevice.deviceId)),
+          ),
+        ).thenAnswer((_) => Future<MediaStream>.value(videoStream));
+
+        final List<CameraDescription> cameras = await CameraPlatform.instance.availableCameras();
+
+        expect(
+          cameras,
+          equals(<CameraDescription>[
+            CameraDescription(
+              name: videoDevice.label,
+              lensDirection: CameraLensDirection.external,
+              sensorOrientation: 0,
+            ),
+          ]),
+        );
+
+        expect(
+          (CameraPlatform.instance as CameraPlugin).camerasMetadata,
+          equals(<CameraDescription, CameraMetadata>{
+            cameras.first: CameraMetadata(deviceId: videoDevice.deviceId, facingMode: null),
+          }),
+        );
+      });
+
       group('throws CameraException', () {
         testWidgets('when MediaDevices.enumerateDevices throws DomException', (
           WidgetTester tester,
@@ -418,6 +475,37 @@ void main() {
           );
         });
 
+        testWidgets('when no video input device can be started', (WidgetTester tester) async {
+          final videoDevice =
+              createJSInteropWrapper(
+                    FakeMediaDeviceInfo('1', 'Camera 1', MediaDeviceKind.videoInput),
+                  )
+                  as MediaDeviceInfo;
+
+          mockMediaDevices.enumerateDevices = () {
+            return Future<JSArray<MediaDeviceInfo>>.value(<MediaDeviceInfo>[videoDevice].toJS).toJS;
+          }.toJS;
+
+          final exception = CameraWebException(0, CameraErrorCode.notReadable, 'description');
+
+          when(
+            cameraService.getMediaStreamForOptions(
+              CameraOptions(video: VideoConstraints(deviceId: videoDevice.deviceId)),
+            ),
+          ).thenThrow(exception);
+
+          expect(
+            CameraPlatform.instance.availableCameras(),
+            throwsA(
+              isA<CameraException>().having(
+                (CameraException e) => e.code,
+                'code',
+                exception.code.toString(),
+              ),
+            ),
+          );
+        });
+
         testWidgets('when CameraService.getMediaStreamForOptions '
             'throws PlatformException', (WidgetTester tester) async {
           final exception = PlatformException(

packages/camera/camera_web/lib/src/camera_web.dart

@@ -119,13 +119,23 @@ class CameraPlugin extends CameraPlatform {
           /// https://developer.mozilla.org/en-US/docs/Web/API/MediaDeviceInfo/deviceId#browser_compatibility
           .where((web.MediaDeviceInfo device) => device.deviceId.isNotEmpty);
 
+      // The first error of a video input device that could not be started.
+      CameraWebException? videoInputDeviceException;
+
       // Map video input devices to camera descriptions.
       for (final videoInputDevice in videoInputDevices) {
         // Get the video stream for the current video input device
         // to later use for the available video tracks.
-        final web.MediaStream videoStream = await _getVideoStreamForDevice(
-          videoInputDevice.deviceId,
-        );
+        final web.MediaStream videoStream;
+        try {
+          videoStream = await _getVideoStreamForDevice(videoInputDevice.deviceId);
+        } on CameraWebException catch (e) {
+          // Skip a video input device that cannot be started,
+          // e.g. a virtual camera without a video source,
+          // so that the remaining cameras stay available.
+          videoInputDeviceException ??= e;
+          continue;
+        }
 
         // Get all video tracks in the video stream
         // to later extract the lens direction from the first track.
@@ -176,6 +186,12 @@ class CameraPlugin extends CameraPlatform {
         }
       }
 
+      // Report the error of a video input device that could not be started
+      // if no camera is available.
+      if (cameras.isEmpty && videoInputDeviceException != null) {
+        throw videoInputDeviceException;
+      }
+
       return cameras;
     } on web.DOMException catch (e) {
       throw CameraException(e.name, e.message);

packages/camera/camera_web/pubspec.yaml

@@ -2,7 +2,7 @@ name: camera_web
 description: A Flutter plugin for getting information about and controlling the camera on Web.
 repository: https://github.com/flutter/packages/tree/main/packages/camera/camera_web
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+camera%22
-version: 0.3.5+6
+version: 0.3.5+7
 
 environment:
   sdk: ^3.11.0