Question

我正在播放视频，但是没有问题，但是导航到另一个页面时，控制台会这样说。
我尝试了所有我想出的方法，例如检查mounted，但没有一个起作用。
我想念什么？有人知道如何解决吗？

flutter：调度VideoPlayerController的通知时引发了以下断言：
  flutter：在构建期间调用setState（）或markNeedsBuild（）。
  flutter：此VideoProgressIndicator小部件无法标记为需要构建，因为框架是
  颤动：已经在构建小部件的过程中。可以将小部件标记为需要在
期间构建   颤动：仅当其祖先之一正在构建时才构建阶段。允许此例外是因为
  flutter：该框架在子代之前构建父代小部件，这意味着肮脏的后代将永远是
  颤动：内置。否则，框架在此构建阶段可能不会访问此小部件。
  flutter：调用了setState（）或markNeedsBuild（）的小部件是：
  颤振：VideoProgressIndicator（状态：_VideoProgressIndicatorState＃09ac7）

代码：

class _VideoScreenState extends State<VideoScreen> {
      VideoPlayerController _controller;
      FadeAnimation imageFadeAnim =
          new FadeAnimation(child: const Icon(Icons.play_arrow, size: 100.0));
      VoidCallback listener;
      bool _isPlaying = false;
      List<String> videos = [
        'http://www.sample-videos.com/video/mp4/720/big_buck_bunny_720p_20mb.mp4',
      ];

      _VideoScreenState() {
        listener = () {
          if (mounted) setState(() {});
        };
      }

      Future _videoOnTap() async {
        if (!_controller.value.initialized) {
          return;
        }
        if (_controller.value.isPlaying) {
          imageFadeAnim = new FadeAnimation(
              child: Icon(Icons.pause,
                  color: Colors.white.withOpacity(0.3), size: 75.0));
          await _controller.pause();
        } else {
          imageFadeAnim = new FadeAnimation(
              child: Icon(Icons.play_arrow,
                  color: Colors.white.withOpacity(0.3), size: 75.0));
          await _controller.play();
        }
      }

      Future _startVideoPlayer(int index) async {
        if (_controller != null) {
          await _controller.dispose();
        }
        _controller = VideoPlayerController.network(videos[index])
          ..addListener(() {
            final bool isPlaying = _controller.value.isPlaying;
            if (isPlaying != _isPlaying) {
              if (mounted)
                setState(() {
                  _isPlaying = isPlaying;
                });
            }
          })
          ..initialize().then((_) async {
            await _controller.play();
            if (mounted) setState(() {});
          });
      }

      @override
      void initState() {
        SystemChrome.setEnabledSystemUIOverlays([]);
        _startVideoPlayer(0);
        super.initState();
      }

      @override
      void deactivate() {
        _controller?.setVolume(0.0);
        _controller?.removeListener(listener);
        super.deactivate();
      }

      @override
      void dispose() {
        _controller?.dispose();
        super.dispose();
      }

      @override
      Widget build(BuildContext context) {
         final List<Widget> children = <Widget>[
      new GestureDetector(
        child: new Center(
          child: _controller.value.initialized
              ? new AspectRatio(
                  aspectRatio: _controller.value.aspectRatio,
                  child: new VideoPlayer(_controller))
              : new Container(),
        ),
        onTap: _videoOnTap,
      ),
      new Align(
        alignment: Alignment.topCenter,
        child: new VideoProgressIndicator(
          _controller,
          allowScrubbing: false,
          colors: VideoProgressColors(
              backgroundColor: Colors.black.withOpacity(0.5),
              playedColor: Colors.white),
        ),
      ),
      new Center(child: imageFadeAnim),
    ];

        return new Scaffold(
          backgroundColor: Colors.black,
          body: new SafeArea(
            top: true,
            left: false,
            right: false,
            bottom: false,
            child: new Stack(
              fit: StackFit.passthrough,
              children: children,
            ),
          ),
        );
      }
    }

    class FadeAnimation extends StatefulWidget {
      final Widget child;
      final Duration duration;

      FadeAnimation({this.child, this.duration: const Duration(milliseconds: 300)});

      @override
      _FadeAnimationState createState() => new _FadeAnimationState();
    }

    class _FadeAnimationState extends State<FadeAnimation>
        with SingleTickerProviderStateMixin {
      AnimationController animationController;

      @override
      void initState() {
        super.initState();
        animationController =
            new AnimationController(duration: widget.duration, vsync: this);
        animationController.addListener(() {
          if (mounted) {
            setState(() {});
          }
        });
        animationController.forward(from: 0.0);
      }

      @override
      void deactivate() {
        animationController.stop();
        super.deactivate();
      }

      @override
      void didUpdateWidget(FadeAnimation oldWidget) {
        super.didUpdateWidget(oldWidget);
        if (oldWidget.child != widget.child) {
          animationController.forward(from: 0.0);
        }
      }

      @override
      void dispose() {
        animationController.dispose();
        super.dispose();
      }

      @override
      Widget build(BuildContext context) {
        return animationController.isAnimating
            ? new Container(
                width: 75.0,
                height: 75.0,
                decoration: new BoxDecoration(
                  color: Colors.black.withOpacity(0.01),
                  shape: BoxShape.circle,
                ),
                child: widget.child,
              )
            : new Container();
      }
    }

Answer 1

在 initState 中初始化你的 animationController 并将监听器添加到 didchangeDependencies

 @override
      void initState() {
        super.initState();
        animationController =
            new AnimationController(duration: widget.duration, vsync: this);
        
      }

@override
void didChangeDependencies(
{
super.didChangeDependencies();
animationController.addListener(() {
          if (mounted) {
            setState(() {});
          }
        });
        animationController.forward(from: 0.0);
})

“ Flutter VideoPlayerController”在构建过程中调用了setState（）或markNeedsBuild（）。

1 个答案: