When and where should I add my own controller?

[tagerjump]

Very good package but I'm a kind of confused about how to add my own player controller.

I declear YoutubePlayer as final inside of parent widget's build() and set hideControls to true. But I don't know when and where to init my own controller. Now my code is something like

final YoutubePlayer youtubePlayer = YoutubePlayer(
...
onPlayerInitialized: (controller) {
_player = PlayerPage(controller, true);
setState(() {
_stackList.add(_player);
});
},
};

_stackList.add(youtubePlayer);

return Stack(
children: _stackList,
);

However, I get error for using setState() inside onPlayerInitialized().

I/flutter (13939): setState() or markNeedsBuild() called during build.
I/flutter (13939): This VideoPage widget cannot be marked as needing to build because the framework is already in the
I/flutter (13939): process of building widgets. A widget can be marked as needing to be built during the build phase
I/flutter (13939): only if one of its ancestors is currently building. This exception is allowed because the framework
I/flutter (13939): builds parent widgets before children, which means a dirty descendant will always be built.
I/flutter (13939): Otherwise, the framework might not visit this widget during this build phase.
I/flutter (13939): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (13939): VideoPage(state: _VideoPageState#af93c)
I/flutter (13939): The widget which was currently being built when the offending call was made was:
I/flutter (13939): NotificationListener
I/flutter (13939):
I/flutter (13939): When the exception was thrown, this was the stack:
...

Seems the onPlayerInitialized run before parent build done. But I can't refer to _controller either inside the parent build() because it's null at that time.

Could you tell me how to do that correctly? Or even better if you've got a example about adding a custom controller. Thank you.

[tagerjump]

Solved... Just need another build function like
Widget _buildPlayer(YoutubePlayerController controller) {
return PlayerPage(controller, true);
}
to build the controller. But I don't know why.