I made a carousel that retrieves the link of the images on Firebase Firestore. The recuperation of the images works but when the position changes the image does not change it displays only the first image, same as when I automate it. It's been a long time that I'm stuck on it and I don't know where the problem is. Here is the error I have in the console:

[VERBOSE-2:ui_dart_state.cc(198)] Unhandled Exception: 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 107 pos 12: '_positions.isNotEmpty': ScrollController not attached to any scroll views.
#0      _AssertionError._doThrowNew (dart:core-patch/errors_patch.dart:51:61)
#1      _AssertionError._throwNew (dart:core-patch/errors_patch.dart:40:5)
#2      ScrollController.position (package:flutter/src/widgets/scroll_controller.dart:107:12)
#3      PageController.animateToPage (package:flutter/src/widgets/page_view.dart:197:41)
#4      _CarouselWidgetState.initState.<anonymous closure> (package:flyzik/widgets/carousel_widget.dart:36:23)
#5      _rootRunUnary (dart:async/zone.dart:1434:47)
#6      _CustomZone.runUnary (dart:async/zone.dart:1335:19)
#7      _CustomZone.runUnaryGuarded (dart:async/zone.dart:1244:7)
#8      _CustomZone.bindUnaryCallbackGuarded.<anonymous closure> (dart:async/zone.dart:1281:26)
#9      _rootRunUnary (dart:async/zone.dart:1442:13)
#10     _CustomZone.<…>

Here is all my source code of carousel:

class CarouselWidget extends StatefulWidget {
  const CarouselWidget({Key? key}) : super(key: key);

  @override
  State<CarouselWidget> createState() => _CarouselWidgetState();
}

class _CarouselWidgetState extends State<CarouselWidget> {
  int _currentIndex = 0;
  late PageController _pageController;
  late Timer _timer;
  @override
  void initState() {
    _pageController = PageController(initialPage: 0);
    _timer = Timer.periodic(const Duration(seconds: 4), (Timer timer) {
      if (_currentIndex < 5 - 1) {
        _currentIndex  ;
      } else {
        _currentIndex = 0;
      }

      _pageController.animateToPage(
        _currentIndex,
        duration: const Duration(milliseconds: 350),
        curve: Curves.easeOutCubic,
      );
    });
    super.initState();
  }

  @override
  void dispose() {
    _pageController.dispose();
    _timer.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return StreamBuilder<List<CarouselModel>>(
        stream: DBServices().getCarousels,
        builder: (context, snapshot) {
          if (snapshot.hasError) {
            return Center(
              child: Text('Erreur: '   snapshot.error.toString()),
            );
          }
          if (snapshot.connectionState == ConnectionState.waiting) {
            return Shimmer.fromColors(
              baseColor: kShimmerBaseColor,
              highlightColor: kShimmerHifhtLightColor,
              child: Container(
                width: double.infinity,
                height: 220,
                decoration: BoxDecoration(
                    borderRadius: BorderRadius.circular(10),
                    color: Colors.grey),
              ),
            );
          }
          final carousels = snapshot.data;
          return AspectRatio(
                  aspectRatio: 1.81,
                  child: Stack(
                    alignment: Alignment.bottomRight,
                    children: [
                      PageView.builder(
                        itemCount: carousels!.length,
                        controller: _pageController,
                        onPageChanged: (value) {
                          setState(() {
                            _currentIndex = value;
                            print("current index: $value");
                            print("current index2: $_currentIndex");
                          });
                        },
                        itemBuilder: (context, index) => ClipRRect(
                          borderRadius: BorderRadius.all(Radius.circular(12)),
                          child: CachedNetworkImage(
                            imageUrl: carousels[index].imageUrl,
                            fit: BoxFit.cover,
                          ),
                        ),
                      ),
                      Positioned(
                        bottom: defaultPadding,
                        right: defaultPadding,
                        child: Padding(
                          padding:
                              const EdgeInsets.only(left: defaultPadding / 4),
                          child: Row(
                            children: List.generate(
                                carousels.length,
                                (index) => IndicatorDot(
                                    isActive: index == _currentIndex)),
                          ),
                        ),
                      ),
                    ],
                  ),
                );
        });
  }
}

class IndicatorDot extends StatelessWidget {
  const IndicatorDot({
    Key? key,
    required this.isActive,
  }) : super(key: key);
  final bool isActive;

  @override
  Widget build(BuildContext context) {
    return Container(
      height: getProportionateScreenHeight(4),
      width: getProportionateScreenWidth(8),
      decoration: BoxDecoration(
        color: isActive ? kBlack : Colors.white38,
        borderRadius: BorderRadius.all(
          Radius.circular(getProportionateScreenWidth(12)),
        ),
      ),
    );
  }
}

CodePudding user response：

To avoid such type of errors use the getter

ScrollController.hasClient

If this is false, then members that interact with the [ScrollPosition],such as [position], [offset], [animateTo], and [jumpTo], must not be called.

for example:

 if (_controller.hasClients) {
      _controller.animateTo(
      ...
    }

CodePudding user response：

You are trying to call _pageController.animatePage without giving the controller to the PageView. that's mentioned in the error log.

Failed assertion: line 107 pos 12: '_positions.isNotEmpty': ScrollController not attached to any scroll views.