从另一个类的函数调用时如何停止视频onPageChanged函数

Question

我想知道如何在从另一个类调用函数时停止视频onPageChanged函数，所以我很陌生，所以想在从另一个类调用函数时了解小部件通信。

下面是我的代码实际上未与该函数一起使用，实际上我直接调用了一个函数，这就是为什么我认为它不起作用，但实际上我不知道如何使用有状态或无状态来做到这一点。

class TutorialScreen extends StatefulWidget {
  @override

_HomePageState createState() => _HomePageState();
}

class _HomePageState extends State<TutorialScreen>
with SingleTickerProviderStateMixin {

  PageController _pageController;
  @override
  void initState() {
// TODO: implement initState
getDataByJson();
_pageController = PageController();
super.initState();

 }

  @override
  void dispose() {
  // TODO: implement dispose
  super.dispose();
  }

  @override
Widget build(BuildContext context) {

return FutureBuilder(
  future: getDataByJson(),
  builder: (context, snapshot) {
    if (complexTutorial == null) return Center(
        child: CircularProgressIndicator()
    );

    return getBody();
  },
);
}

  Widget getBody() {
var size = MediaQuery.of(context).size;
return PageView(
    children: [
        PageView(
          onPageChanged: (){
            _VideoPlayerItemState _videoPlayerItemState = _VideoPlayerItemState();
            _videoPlayerItemState.callToAnotherClassOnPageChanged();
          },
          controller: _pageController,
          scrollDirection: Axis.horizontal,
          children: List.generate(complexTutorial.data.length, (index) {
            return VideoPlayerItem(
              videoUrl: complexTutorial.data[index].tutorialLink,
              size: size,
              name: complexTutorial.data[index].titorialText,
            );
          }),
        ),
      Container(child: Center(child: Text("USER OLD TUTORIALS"),),)
    ]
);
}
}

class VideoPlayerItem extends StatefulWidget {
  final String videoUrl;
final String name;
VideoPlayerItem(
  {Key key,
    @required this.size,
    this.name,
    this.videoUrl})
  : super(key: key);
  final Size size;

  @override
 _VideoPlayerItemState createState() => _VideoPlayerItemState();
}

class _VideoPlayerItemState extends State<VideoPlayerItem> with AutomaticKeepAliveClientMixin,TickerProviderStateMixin{

  // this is my videoPlayerController declared here
  VideoPlayerController _videoController;

  @override


void initState() {

// TODO: implement initState
super.initState();

_videoController = VideoPlayerController.network(widget.videoUrl)
  ..initialize().then((value) {
    if(widget.pageControllerinsider.page.toInt() == 0) {
      _videoController.play();
    }
    setState(() {
      isShowPlaying = false;
    });
  });
}

  @override
  void dispose() {
// TODO: implement dispose
super.dispose();
_videoController.dispose();
  }

  Widget isPlaying(){
return _videoController.value.isPlaying && !isShowPlaying  ? Container() : Icon(Icons.play_arrow,size: 80,color: Colors.white.withOpacity(0.5),);
}

 @override
  Widget build(BuildContext context) {
return InkWell(
  onTap: () {
    setState(() {
      _videoController.value.isPlaying
          ? _videoController.pause()
          : _videoController.play();
    });
  },
  child: Container(
        height: widget.size.height,
        width: widget.size.width,
        child: Stack(
          children: <Widget>[
            Container(
              height: widget.size.height,
              width: widget.size.width,
              decoration: BoxDecoration(color: Colors.black),
              child: Stack(
                children: <Widget>[
                  FittedBox(
                    fit: BoxFit.cover,
                    child: SizedBox(
                      width: _videoController.value.aspectRatio,
                      height: 1,
                      child: VideoPlayer(_videoController),
                    ),
                  ),
                  Center(
                    child: Container(
                      decoration: BoxDecoration(
                      ),
                      child: isPlaying(),
                    ),
                  )
                ],
              ),
            ),
          ],
        )),
);
  }

//这是我从上面的类中调用的函数 //我想从上面的onPageChanged函数中暂停调用此函数时的视频

    callToAnotherClassOnPageChanged(){
print("VALUE GETTER");
print(_videoController.value);
if(_videoController.value.isPlaying){
  _videoController.pause();
}else{
  _videoController.play();
}
 }

  @override
  // TODO: implement wantKeepAlive

bool get wantKeepAlive => true;
}

请帮助我，这要感谢StackOverFlow团队。