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When I include the Tutorial class that I create inside the children of a Column class I get this error:

Launching lib/main.dart on iPhone XR in debug mode...

Starting Xcode build...

Xcode build done.                                           20.7s

Syncing files to device iPhone XR...

flutter: ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════

flutter: The following assertion was thrown during performResize():

flutter: Horizontal viewport was given unbounded height.

flutter: Viewports expand in the cross axis to fill their container and constrain their children to match

flutter: their extent in the cross axis. In this case, a horizontal viewport was given an unlimited amount of

flutter: vertical space in which to expand.

flutter:

flutter: When the exception was thrown, this was the stack:

flutter: #0      RenderViewport.performResize.<anonymous closure> (package:flutter/src/rendering/viewport.dart:1170:15)

flutter: #1      RenderViewport.performResize (package:flutter/src/rendering/viewport.dart:1182:6)

flutter: #2      RenderObject.layout (package:flutter/src/rendering/object.dart:1619:9)

flutter: #3      _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #4      RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #5      _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #6      RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #7      _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #8      RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #9      _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #10     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #11     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #12     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #13     RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)

flutter: #14     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #15     RenderFlex.performLayout (package:flutter/src/rendering/flex.dart:738:15)

flutter: #16     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #17     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #18     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #19     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #20     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #21     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #22     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #23     RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)

flutter: #24     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #25     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #26     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #27     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #28     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #29     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #30     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #31     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #32     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #33     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #34     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #35     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #36     RenderOffstage.performLayout (package:flutter/src/rendering/proxy_box.dart:2881:13)

flutter: #37     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #38     RenderStack.performLayout (package:flutter/src/rendering/stack.dart:510:15)

flutter: #39     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #40     __RenderTheatre&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #41     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #42     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #43     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #44     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #45     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #46     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #47     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #48     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #49     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #50     _RenderProxyBox&RenderBox&RenderObjectWithChildMixin&RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:104:13)

flutter: #51     RenderObject.layout (package:flutter/src/rendering/object.dart:1634:7)

flutter: #52     RenderView.performLayout (package:flutter/src/rendering/view.dart:147:13)

flutter: #53     RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1509:7)

flutter: #54     PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:768:18)

flutter: #55     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:281:19)

flutter: #56     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:677:13)

flutter: #57     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:219:5)

flutter: #58     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)

flutter: #59     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:930:9)

flutter: #60     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.scheduleWarmUpFrame.<anonymous closure> (package:flutter/src/scheduler/binding.dart:751:7)

flutter: #62     _Timer._runTimers (dart:isolate/runtime/libtimer_impl.dart:382:19)

flutter: #63     _Timer._handleMessage (dart:isolate/runtime/libtimer_impl.dart:416:5)

flutter: #64     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:171:12)

flutter: (elided one frame from package dart:async)

flutter:

flutter: The following RenderObject was being processed when the exception was fired:

flutter:   RenderViewport#64551 NEEDS-LAYOUT NEEDS-PAINT

flutter:   creator: Viewport ← _ScrollableScope ← IgnorePointer-[GlobalKey#608ab] ← Semantics ← Listener ←

flutter:   _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#19222] ←

flutter:   _ScrollSemantics-[GlobalKey#0390f] ← Scrollable ← NotificationListener<ScrollNotification> ←

flutter:   PageView ← Stack ← ⋯

flutter:   parentData: <none> (can use size)

flutter:   constraints: BoxConstraints(0.0<=w<=414.0, 0.0<=h<=Infinity)

flutter:   size: MISSING

flutter:   axisDirection: right

flutter:   crossAxisDirection: down

flutter:   offset: _PagePosition#edc3e(offset: null, range: null..null, viewport: null, ScrollableState,

flutter:   PageScrollPhysics -> AlwaysScrollableScrollPhysics -> BouncingScrollPhysics,

flutter:   IdleScrollActivity#95217, ScrollDirection.idle)

flutter:   anchor: 0.0

flutter: This RenderObject had the following child:

flutter:   RenderSliverFillViewport#5d322 NEEDS-LAYOUT NEEDS-PAINT

flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════

flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#64551 NEEDS-LAYOUT NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderViewport#64551 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderIgnorePointer#cca00 relayoutBoundary=up6 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#498e5 relayoutBoundary=up5 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderPointerListener#a32d0 relayoutBoundary=up4 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsGestureHandler#cbf64 relayoutBoundary=up3 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: _RenderScrollSemantics#11d99 relayoutBoundary=up2 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderStack#d9de7 relayoutBoundary=up1 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderFlex#554a3 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#1d6d0 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#b279d NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderIgnorePointer#e430d NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderStack#e8e8f NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderDecoratedBox#a3175 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderFractionalTranslation#4ca11 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderFractionalTranslation#0d592 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#6ed00 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#7d38e NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderOffstage#4e5b5 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderStack#4e841 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: _RenderTheatre#f534f NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#85a31 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderAbsorbPointer#a08a9 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderPointerListener#f45f1 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderCustomPaint#5f6ee NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#6ed00 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderCustomPaint#5f6ee

flutter: Another exception was thrown: NoSuchMethodError: The getter 'visible' was called on null.

flutter: Another exception was thrown: RenderBox was not laid out: RenderSemanticsAnnotations#5dcca

flutter: Another exception was thrown: RenderBox was not laid out: RenderRepaintBoundary#6ed00 NEEDS-PAINT

flutter: Another exception was thrown: RenderBox was not laid out: RenderCustomPaint#5f6ee

My code is:

import 'package:flutter/material.dart';

import 'Components/Tutorial.dart';



    class SplashScreen extends StatefulWidget {

      @override

      _SplashScreenState createState() => _SplashScreenState();

    }



    class _SplashScreenState extends State<SplashScreen> {

      @override

      Widget build(BuildContext context) {

        return Container(

          child: Column(

            children: <Widget>[

              Padding(

                padding: const EdgeInsets.all(38.0),

                child: Text(

                    'Title',

                    style: TextStyle(

                      color: Colors.white,

                      decoration: TextDecoration.none

                  ),

                ),

              ),

              Tutorial()

            ],

          ),

        );

      }

    }

This only happens when I insert Tutorial inside a Column. I try many things but I don't understand why the crash!

And the file with the Tutorial class:

Import 'dart:math';

import 'package:flutter/foundation.dart';

import 'package:flutter/material.dart';



class DotsIndicator extends AnimatedWidget {

  DotsIndicator({

    this.controller,

    this.itemCount,

    this.onPageSelected,

    this.color: Colors.white,

  }) : super(listenable: controller);



  /// The PageController that this DotsIndicator is representing.

  final PageController controller;



  /// The number of items managed by the PageController

  final int itemCount;



  /// Called when a dot is tapped

  final ValueChanged<int> onPageSelected;



  /// The color of the dots.

  ///

  /// Defaults to `Colors.white`.

  final Color color;



  // The base size of the dots

  static const double _kDotSize = 8.0;



  // The increase in the size of the selected dot

  static const double _kMaxZoom = 2.0;



  // The distance between the center of each dot

  static const double _kDotSpacing = 25.0;



  Widget _buildDot(int index) {

    double selectedness = Curves.easeOut.transform(

      max(

        0.0,

        1.0 - ((controller.page ?? controller.initialPage) - index).abs(),

      ),

    );

    double zoom = 1.0 + (_kMaxZoom - 1.0) * selectedness;

    return Container(

      width: _kDotSpacing,

      child: Center(

        child: Material(

          color: color,

          type: MaterialType.circle,

          child: Container(

            width: _kDotSize * zoom,

            height: _kDotSize * zoom,

            child: InkWell(

              onTap: () => onPageSelected(index),

            ),

          ),

        ),

      ),

    );

  }



  Widget build(BuildContext context) {

    return Row(

      mainAxisAlignment: MainAxisAlignment.center,

      children: List<Widget>.generate(itemCount, _buildDot),

    );

  }

}



class Tutorial extends StatefulWidget {

  @override

  State createState() => TutorialState();

}



class TutorialState extends State<Tutorial> {

  final _controller = PageController(viewportFraction: 0.5);



  static const _kDuration = const Duration(milliseconds: 300);



  static const _kCurve = Curves.ease;



  final _kArrowColor = Colors.black.withOpacity(0.8);



  static onTap(index) {

    print("$index selected.");

  }



  final List<Widget> _pages = <Widget>[

    FlutterLogo(colors: Colors.blue),

    FlutterLogo(style: FlutterLogoStyle.stacked, colors: Colors.red),

    FlutterLogo(style: FlutterLogoStyle.horizontal, colors: Colors.green),

  ];



  Widget _buildPageItem(BuildContext context, int index) {

    return Page(page: _pages[index], idx: index);

  }



  @override

  Widget build(BuildContext context) {

    return Stack(

      children: <Widget>[

        PageView.builder(

          physics: AlwaysScrollableScrollPhysics(),

          controller: _controller,

          itemCount: _pages.length,

          itemBuilder: (BuildContext context, int index) {

            return _buildPageItem(context, index % _pages.length);

          },

        ),

        Positioned(

          bottom: 0.0,

          left: 0.0,

          right: 0.0,

          child: Container(

            color: Colors.grey[800].withOpacity(0.5),

            padding: const EdgeInsets.all(20.0),

            child: Center(

              child: DotsIndicator(

                controller: _controller,

                itemCount: _pages.length,

                onPageSelected: (int page) {

                  _controller.animateToPage(

                    page,

                    duration: _kDuration,

                    curve: _kCurve,

                  );

                },

              ),

            ),

          ),

        ),

      ],

    );

  }

}



class Page extends StatelessWidget {

  final page;

  final idx;



  Page({

    @required this.page,

    @required this.idx,

  });



  onTap() {

    print("${this.idx} selected.");

  }



  @override

  Widget build(BuildContext context) {

    return Padding(

      padding: const EdgeInsets.all(8.0)

    );

  }

}

What is the error? What am I doing wrong?

try change column to listview

ListView(

      children: <Widget>[

        Padding(

          padding: const EdgeInsets.all(38.0),

          child: Text(

            'Title',

            style: TextStyle(

                color: Colors.white, decoration: TextDecoration.none),

          ),

        ),

        Tutorial()

      ],

    )

you need to use Expanded for the tutorial Widget

  Expanded(child: Tutorial())