Question 75486 in Flutter Question posted in
The official Flutter documentation can be found here.

How to wrap a page view builder with a singlechildscrollview widget in flutter

I am trying to wrap a my Column widget which houses an expanded widget wrapping a Pageview builder, but keep getting error. This is an onboarding screen with a page view builder that automatically animates the scroll every 5 seconds.

I have tried wrapping the whole column with a singlechildscrollview widget but nothing works, just errors

body: SafeArea(
          child: Stack(
        alignment: AlignmentDirectional.center,
        children: [
          Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Expanded(
                child: PageView.builder(
                  controller: _pageController,
                  scrollDirection: Axis.horizontal,
                  onPageChanged: (index) {
                    setState(() {
                      _pageIndex = index % demo_data.length;
                    });
                  },
                  itemBuilder: (context, index) => OnboardingContents(
                    image: demo_data[index % demo_data.length].image,
                    title: demo_data[index % demo_data.length].title,
                  ),
                ),
              ),
              Padding(
                padding: const EdgeInsets.symmetric(horizontal: 20.0),
                child: Column(
                  children: [
                    Row(
                      children: [
                        ...List.generate(
                            demo_data.length,
                            (index) => Padding(
                                  padding: const EdgeInsets.all(5.0),
                                  child: DotIndicator(
                                    isActive: index == _pageIndex,
                                  ),
                                ))
                      ],
                    ),
                    const SizedBox(
                      height: 30,
                    ),
                    InkWell(
                      onTap: () {
                        Navigator.push(
                            context,
                            MaterialPageRoute(
                                builder: (context) => const LoginScreen()));
                      },
                      child: Container(
                        decoration: BoxDecoration(
                          color: primaryColor,
                          borderRadius: BorderRadius.circular(8),
                        ),
                        width: MediaQuery.of(context).size.width,
                        height: 60,
                        child: const Center(
                          child: Text(
                            'Log In',
                            style: TextStyle(
                              fontSize: 20,
                              color: Colors.white,
                              fontFamily: 'Futura',
                            ),
                          ),
                        ),
                      ),
                    ),
                    const SizedBox(
                      height: 15,
                    ),
                    InkWell(
                      onTap: () {
                        Navigator.push(
                            context,
                            MaterialPageRoute(
                                builder: (context) => const WelcomeScreen()));
                      },
                      child: Container(
                        decoration: BoxDecoration(
                          border: Border.all(
                            color: primaryColor,
                            width: 2,
                          ),
                          color: Colors.white,
                          borderRadius: BorderRadius.circular(8),
                        ),
                        width: MediaQuery.of(context).size.width,
                        height: 60,
                        child: Center(
                          child: Text(
                            'Sign Up',
                            style: TextStyle(
                              fontSize: 20,
                              color: primaryColor,
                              fontFamily: 'Futura',
                            ),
                          ),
                        ),
                      ),
                    ),
                    const SizedBox(
                      height: 30,
                    ),
                  ],
                ),
              )
            ],
          ),
          Padding(
            padding: const EdgeInsets.symmetric(
              horizontal: 20.0,
            ),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: [
                SizedBox(
                  height: 50,
                  width: 50,
                  child: ElevatedButton(
                      onPressed: () {
                        _pageController.previousPage(
                          curve: Curves.ease,
                          duration: const Duration(milliseconds: 300),
                        );
                      },
                      style: ElevatedButton.styleFrom(
                          backgroundColor: primaryColor,
                          shape: const CircleBorder()),
                      child: Image.asset('assets/images/backward.png')),
                ),
                SizedBox(
                  height: 50,
                  width: 50,
                  child: ElevatedButton(
                      onPressed: () {
                        _pageController.nextPage(
                          curve: Curves.ease,
                          duration: const Duration(milliseconds: 300),
                        );
                      },
                      style: ElevatedButton.styleFrom(
                          backgroundColor: primaryColor,
                          shape: const CircleBorder()),
                      child: Image.asset('assets/images/forward.png')),
                ),
              ],
            ),
          )
        ],
      )),


class OnboardingContents extends StatelessWidget {
  const OnboardingContents({
    super.key,
    required this.image,
    required this.title,
  });

  final String image, title;

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        const Spacer(),
        Image.asset(
          image,
        ),
        SizedBox(
          height: MediaQuery.of(context).size.height * 0.03,
        ),
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 20.0),
          child: Text(
            title,
            style: const TextStyle(
              fontFamily: 'Futura',
              fontWeight: FontWeight.w800,
              color: Colors.black,
              fontSize: 55,
            ),
          ),
        ),
        SizedBox(
          height: MediaQuery.of(context).size.height * 0.03,
        ),
      ],
    );
  }
}

The error log:

Error: Unexpected null value.
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49      throw_
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 561:63  nullCheck
packages/flutter/src/widgets/scroll_position.dart 177:53                                                                       get viewportDimension
packages/flutter/src/widgets/page_view.dart 390:19                                                                             getPixelsFromPage
packages/flutter/src/widgets/page_view.dart 203:15                                                                             animateToPage
packages/lantern_andriod/view/Pages/onboarding_screen.dart 32:23                                                               <fn>
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/isolate_helper.dart 80:17           <fn>
Restarted application in 848ms.
══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
RenderFlex children have non-zero flex but incoming height constraints are unbounded.
When a column is in a parent that does not provide a finite height constraint, for example if it is
in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
space in the vertical direction.
These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
cannot simultaneously expand to fit its parent.
Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
children (using Flexible rather than Expanded). This will allow the flexible children to size
themselves to less than the infinite remaining space they would otherwise be forced to take, and
then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
constraints provided by the parent.
If this message did not help you determine the problem, consider using debugDumpRenderTree():
  https://flutter.dev/debugging/#rendering-layer
  http://api.flutter.dev/flutter/rendering/debugDumpRenderTree.html
The affected RenderFlex is:
  RenderFlex#1030d relayoutBoundary=up17 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE(creator: Column ← _SingleChildViewport ← IgnorePointer-[GlobalKey#7a9b8] ← Semantics ← Listener ← _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#9d09e] ← Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#5bb31] ← NotificationListener<ScrollMetricsNotification> ← RepaintBoundary ← ⋯, parentData: <none> (can use size), constraints: BoxConstraints(0.0<=w<=500.0, 0.0<=h<=Infinity), size: MISSING, direction: vertical, mainAxisAlignment: start, mainAxisSize: min, crossAxisAlignment: center, verticalDirection: down)
The creator information is set to:
  Column ← _SingleChildViewport ← IgnorePointer-[GlobalKey#7a9b8] ← Semantics ← Listener ←
  _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#9d09e] ←
  Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#5bb31] ←
  NotificationListener<ScrollMetricsNotification> ← RepaintBoundary ← ⋯
The nearest ancestor providing an unbounded width constraint is: _RenderSingleChildViewport#7fdc8 relayoutBoundary=up16 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE:
  needs compositing
  creator: _SingleChildViewport ← IgnorePointer-[GlobalKey#7a9b8] ← Semantics ← Listener ←
    _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#9d09e] ←
    Listener ← _ScrollableScope ← _ScrollSemantics-[GlobalKey#5bb31] ←
    NotificationListener<ScrollMetricsNotification> ← RepaintBoundary ← CustomPaint-[GlobalKey#fe817]
    ← ⋯
  parentData: <none> (can use size)
  constraints: BoxConstraints(0.0<=w<=500.0, 0.0<=h<=620.0)
  size: MISSING
  offset: Offset(0.0, -0.0)
See also: https://flutter.dev/layout/
If none of the above helps enough to fix this problem, please don't hesitate to file a bug:
  https://github.com/flutter/flutter/issues/new?template=2_bug.md
The relevant error-causing widget was:
  Column
Column:file:///C:/Users/hp/StudioProjects/latern_mobile/lib/view/Pages/onboarding_screen.dart:56:20
When the exception was thrown, this was the stack:
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 266:49  throw_
packages/flutter/src/rendering/flex.dart 933:9                                                                             <fn>
packages/flutter/src/rendering/flex.dart 935:14                                                                            performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/widgets/single_child_scroll_view.dart 502:7                                                           performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/custom_paint.dart 552:11                                                                    performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/layout_helper.dart 56:10                                                                    layoutChild
packages/flutter/src/rendering/stack.dart 595:43                                                                           [_computeSize]
packages/flutter/src/rendering/stack.dart 622:12                                                                           performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/shifted_box.dart 240:5                                                                      performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/custom_layout.dart 171:10                                                                   layoutChild
packages/flutter/src/material/scaffold.dart 1080:7                                                                         performLayout
packages/flutter/src/rendering/custom_layout.dart 240:7                                                                    [_callPerformLayout]
packages/flutter/src/rendering/custom_layout.dart 410:14                                                                   performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/proxy_box.dart 1467:11                                                                      performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/proxy_box.dart 3815:13                                                                      performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/widgets/overlay.dart 856:14                                                                           performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11                                                                            layout
packages/flutter/src/rendering/proxy_box.dart 120:7                                                                        performLayout
packages/flutter/src/rendering/object.dart 2189:7                                                                          layout
packages/flutter/src/rendering/box.dart 2430:11
Tags:

2

Answers


  1. 0

    What you need to wrap around the SingleChildScrollView is the content of the itemBuilder or put it inside OnboardingContents widget.

    itemBuilder: (context, index) => SingleChildScrollView(
     child: OnboardingContents(
         image: demo_data[index % demo_data.length].image
         title: demo_data[index % demo_data.length].title,
)),

    UPDATE:

    On your OnboardingContents you just need to remove the spacer, because when wrapping with a Column inside a SingleChildScrollView it would try to occupy the most space posible (and that would be infinite). This code is working fine:

    class OnboardingContents extends StatelessWidget {
  const OnboardingContents({
    super.key,
    required this.image,
    required this.title,
  });

  final String image, title;

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
     child: Column(
      children: [
        //const Spacer(), //<-- This is the problem
        Image.asset(
          image,
        ),
        SizedBox(
          height: MediaQuery.of(context).size.height * 0.03,
        ),
        Padding(
          padding: const EdgeInsets.symmetric(horizontal: 20.0),
          child: Text(
            title,
            style: const TextStyle(
              fontFamily: 'Futura',
              fontWeight: FontWeight.w800,
              color: Colors.black,
              fontSize: 55,
            ),
          ),
        ),
        SizedBox(
          height: MediaQuery.of(context).size.height * 0.03,
        ),
      ],
     ),
    );
  }
}
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  2. 0

    You could try using the plugin ExpandablePageView

    EDIT: You could used ExpandablePageView.builder like you did in PageView

    ExpandablePageView

    Implementation:

    Widget build(BuildContext context) {
  return Column(
    children: [
      Expanded(
    child: SingleChildScrollView(
      child: Column(
        children: [
          Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              ExpandablePageView(
                physics: const NeverScrollableScrollPhysics(),
                scrollDirection: Axis.horizontal,
                controller: pageController,
                onPageChanged: (id) {},
                children: [
                  //Add your pages here
                ],
              ),
            ],
          ),
        ],
      ),
    ),
  ),
 ],
);
}
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