listener method
Implementation
Future<void> listener() async {
if (widget.controller.isFullScreen && !_isFullScreen) {
_isFullScreen = true;
widget.controller.setVolume(1.0);
await _pushFullScreenWidget(context);
} else if (_isFullScreen) {
Navigator.of(context, rootNavigator: true).pop();
widget.controller.setVolume(0.0);
_isFullScreen = false;
}
}