initializeCamera method Null safety

@override Future<void> initializeCamera(int cameraId, {ImageFormatGroup imageFormatGroup = ImageFormatGroup.unknown})

Initializes the camera on the device.

imageFormatGroup is used to specify the image formatting used. On Android this defaults to ImageFormat.YUV_420_888 and applies only to the imageStream. On iOS this defaults to kCVPixelFormatType_32BGRA. On Web this parameter is currently not supported.

Implementation

@override
Future<void> initializeCamera(
  int cameraId, {
  // The image format group is currently not supported.
  ImageFormatGroup imageFormatGroup = ImageFormatGroup.unknown,
}) async {
  try {
    final Camera camera = getCamera(cameraId);

    await camera.initialize();

    // Add camera's video error events to the camera events stream.
    // The error event fires when the video element's source has failed to load, or can't be used.
    _cameraVideoErrorSubscriptions[cameraId] =
        camera.videoElement.onError.listen((html.Event _) {
      // The Event itself (_) doesn't contain information about the actual error.
      // We need to look at the HTMLMediaElement.error.
      // See: https://developer.mozilla.org/en-US/docs/Web/API/HTMLMediaElement/error
      final html.MediaError error = camera.videoElement.error!;
      final CameraErrorCode errorCode = CameraErrorCode.fromMediaError(error);
      final String? errorMessage =
          error.message != '' ? error.message : _kDefaultErrorMessage;

      cameraEventStreamController.add(
        CameraErrorEvent(
          cameraId,
          'Error code: $errorCode, error message: $errorMessage',
        ),
      );
    });

    // Add camera's video abort events to the camera events stream.
    // The abort event fires when the video element's source has not fully loaded.
    _cameraVideoAbortSubscriptions[cameraId] =
        camera.videoElement.onAbort.listen((html.Event _) {
      cameraEventStreamController.add(
        CameraErrorEvent(
          cameraId,
          "Error code: ${CameraErrorCode.abort}, error message: The video element's source has not fully loaded.",
        ),
      );
    });

    await camera.play();

    // Add camera's closing events to the camera events stream.
    // The onEnded stream fires when there is no more camera stream data.
    _cameraEndedSubscriptions[cameraId] =
        camera.onEnded.listen((html.MediaStreamTrack _) {
      cameraEventStreamController.add(
        CameraClosingEvent(cameraId),
      );
    });

    final Size cameraSize = camera.getVideoSize();

    cameraEventStreamController.add(
      CameraInitializedEvent(
        cameraId,
        cameraSize.width,
        cameraSize.height,
        // TODO(bselwe): Add support for exposure mode and point (https://github.com/flutter/flutter/issues/86857).
        ExposureMode.auto,
        false,
        // TODO(bselwe): Add support for focus mode and point (https://github.com/flutter/flutter/issues/86858).
        FocusMode.auto,
        false,
      ),
    );
  } on html.DomException catch (e) {
    throw PlatformException(code: e.name, message: e.message);
  } on CameraWebException catch (e) {
    _addCameraErrorEvent(e);
    throw PlatformException(code: e.code.toString(), message: e.description);
  }
}