startPreview method

@override Future<void> startPreview({ required String imgset, required String streamKey, IvsQuality quality = IvsQuality.q720, CameraType cameraType = CameraType.BACK, void onData(dynamic)?, void onError(dynamic)?, })

Starts the camera preview for the broadcast with the specified settings.

• imgset: The image set identifier for the broadcast.
• streamKey: The stream key for the broadcast.
• quality: The desired broadcast quality, default is IvsQuality.q720.
• cameraType: The camera to use for the preview, default is CameraType.BACK.
• onData: A callback function to handle real-time data from the event stream.
• onError: A callback function to handle errors from the event stream.

Throws an Exception if the preview cannot start due to missing permissions, invalid parameters, or native platform issues.

Implementation

@override
Future<void> startPreview({
  required String imgset,
  required String streamKey,
  IvsQuality quality = IvsQuality.q720,
  CameraType cameraType = CameraType.BACK,
  void Function(dynamic)? onData,
  void Function(dynamic)? onError,
}) async {
  try {
    // Request permissions before starting the preview.
    final permissionStatus = await requestPermissions();
    if (!permissionStatus) {
      throw Exception(
        "Please Grant Camera and Microphone Permission [Start Preview]",
      );
    }
    // Ensure imgset and streamKey are not empty.
    if (imgset.isEmpty || streamKey.isEmpty) {
      throw Exception('imgset or streamKey is empty [Start Preview]');
    }
    // Invoke the native platform method to start the preview.
    await methodChannel.invokeMethod<void>('startPreview', <String, dynamic>{
      'imgset': imgset,
      'streamKey': streamKey,
      'cameraType': cameraType.index.toString(),
      "quality": quality.description,
    });
    // Cancel any existing event stream before starting a new one.
    try {
      eventStream?.cancel();
    } catch (e) {
      log("Error Cancelling Event Stream: $e");
    }
    // Start listening to the event stream for real-time data and errors.
    eventStream = eventChannel
        .receiveBroadcastStream()
        .listen(onData, onError: onError);
  } catch (e) {
    throw Exception("$e [Start Preview]");
  }
}