abstract class CameraEvent { const CameraEvent(); } class InitializeEvent extends CameraEvent { const InitializeEvent(); } class ZoomChangedEvent extends CameraEvent { final double value; const ZoomChangedEvent(this.value); } class ExposureOffsetChangedEvent extends CameraEvent { final double value; const ExposureOffsetChangedEvent(this.value); } class ExposureOffsetResetEvent extends CameraEvent { const ExposureOffsetResetEvent(); }