attach method
Called when an output should be attached to a CameraController.
This should not need to be called by a user directly unless implementing their own CameraOutput.
Implementation
@override
Future<void> attach(covariant CameraController controller) {
super.attach(controller);
_controller = controller;
capturePhotoOutput = CapturePhotoOutput();
return controller.session.addOutput(capturePhotoOutput);
}