Неудачное утверждение: строка 423, позиция 16: «bodyMaxHeight <= I / flutter (29780): math.max (0.0 ,ooseConstraints.maxHeight - contentTop)»: не соответствует действительности - PullRequest
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Неудачное утверждение: строка 423, позиция 16: «bodyMaxHeight <= I / flutter (29780): math.max (0.0 ,ooseConstraints.maxHeight - contentTop)»: не соответствует действительности

1 голос
/ 04 июня 2019

У меня есть StatefullWidget, содержащий Scaffold, Scrollview в его теле, BottomAppBar с вырезом, содержащим FloatingActionButton.

При случайной прокрутке возникает следующая ошибка подтверждения: 

I/flutter (29780): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (29780): The following assertion was thrown during performLayout():
I/flutter (29780): 'package:flutter/src/material/scaffold.dart': Failed assertion: line 423 pos 16: 'bodyMaxHeight <=
I/flutter (29780): math.max(0.0, looseConstraints.maxHeight - contentTop)': is not true.
I/flutter (29780): 
I/flutter (29780): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (29780): more information in this error message to help you determine and fix the underlying cause.
I/flutter (29780): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (29780):   https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter (29780): 
I/flutter (29780): When the exception was thrown, this was the stack:
I/flutter (29780): #2      _ScaffoldLayout.performLayout (package:flutter/src/material/scaffold.dart:423:16)
I/flutter (29780): #3      MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:212:7)
I/flutter (29780): #4      RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:356:14)
I/flutter (29780): #5      RenderObject._layoutWithoutResize (package:flutter/src/rendering/object.dart:1519:7)
I/flutter (29780): #6      PipelineOwner.flushLayout (package:flutter/src/rendering/object.dart:766:18)
I/flutter (29780): #7      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding.drawFrame (package:flutter/src/rendering/binding.dart:347:19)
I/flutter (29780): #8      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:701:13)
I/flutter (29780): #9      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding&PaintingBinding&SemanticsBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:286:5)
I/flutter (29780): #10     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:1012:15)
I/flutter (29780): #11     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:952:9)
I/flutter (29780): #12     _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:864:5)
I/flutter (29780): #16     _invoke (dart:ui/hooks.dart:219:10)
I/flutter (29780): #17     _drawFrame (dart:ui/hooks.dart:178:3)
I/flutter (29780): (elided 5 frames from class _AssertionError and package dart:async)
I/flutter (29780): 
I/flutter (29780): The following RenderObject was being processed when the exception was fired:
I/flutter (29780):   RenderCustomMultiChildLayoutBox#0211b NEEDS-LAYOUT NEEDS-PAINT
I/flutter (29780):   creator: CustomMultiChildLayout ← AnimatedBuilder ← DefaultTextStyle ← AnimatedDefaultTextStyle ←
I/flutter (29780):   _InkFeatures-[GlobalKey#fe169 ink renderer] ← NotificationListener<LayoutChangedNotification> ←
I/flutter (29780):   PhysicalModel ← AnimatedPhysicalModel ← Material ← PrimaryScrollController ← _ScaffoldScope ←
I/flutter (29780):   Scaffold ← ⋯
I/flutter (29780):   parentData: <none> (can use size)
I/flutter (29780):   constraints: BoxConstraints(w=411.4, h=683.4)
I/flutter (29780):   size: Size(411.4, 683.4)
I/flutter (29780): This RenderObject had the following descendants (showing up to depth 5):
I/flutter (29780):   _RenderLayoutBuilder#c4759 relayoutBoundary=up1
I/flutter (29780):     RenderConstrainedBox#f3db9 relayoutBoundary=up2
I/flutter (29780):       RenderRepaintBoundary#7768d NEEDS-PAINT
I/flutter (29780):         RenderCustomPaint#4fd8f NEEDS-PAINT
I/flutter (29780):           RenderRepaintBoundary#3b2ce
I/flutter (29780):   RenderConstrainedBox#f158f relayoutBoundary=up1 NEEDS-PAINT
I/flutter (29780):     RenderPhysicalShape#9331d NEEDS-PAINT
I/flutter (29780):       RenderCustomPaint#26663 NEEDS-PAINT
I/flutter (29780):         _RenderInkFeatures#a489b NEEDS-PAINT
I/flutter (29780):           RenderPadding#db65e NEEDS-PAINT
I/flutter (29780):   RenderStack#80cab relayoutBoundary=up1
I/flutter (29780):     RenderTransform#033b9 relayoutBoundary=up2
I/flutter (29780):       RenderTransform#b621a relayoutBoundary=up3
I/flutter (29780):         RenderSemanticsAnnotations#56fe9 relayoutBoundary=up4
I/flutter (29780):           _RenderInputPadding#e9ac7 relayoutBoundary=up5
I/flutter (29780): ════════════════════════════════════════════════════════════════════════════════════════════════════

Поскольку мы используем BottomAppBar с надрезом и FloatingActionButton (FAB) внутри него, мы хотим, чтобы область за FAB, образуя надрез, была прозрачной, потому что мы скрываем BottomAppBar при прокрутке с помощьюанимированный контейнер.Поэтому мы установили следующий флаг в значение true в нашем Scaffold: 

extendBody: true

При удалении этого флага ошибка больше не возникает, но, как указано выше, это не вариант для нас.

Мы создали образец кода для репликации ошибки в минимально возможном масштабе: 

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  @override
  MyHomePageState createState() => MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  ScrollController _scrollController;
  bool _visible = true;

  @override
  void initState() {
    super.initState();

    _scrollController = ScrollController();
    _scrollController.addListener(() {
      if (_scrollController.position.userScrollDirection ==
          ScrollDirection.reverse) {
        setState(() {
          _visible = false;
        });
      }

      if (_scrollController.position.userScrollDirection ==
          ScrollDirection.forward) {
        setState(() {
          _visible = true;
        });
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    double _bottomAppBarHeight = MediaQuery.of(context).size.width * 0.1;

    return Scaffold(
      extendBody: true,
      body: Container(
        width: MediaQuery.of(context).size.width,
        height: MediaQuery.of(context).size.height,
        child: SingleChildScrollView(
          controller: _scrollController,
          child: Column(
            children: <Widget>[
              Text('Top'),
              Container(
                color: Colors.red,
                height: MediaQuery.of(context).size.height,
              ),
              Text('Bottom'),
            ],
          ),
        ),
      ),
      bottomNavigationBar: AnimatedContainer(
        duration: Duration(milliseconds: 300),
        curve: Curves.linear,
        height: _visible ? _bottomAppBarHeight : 0.0,
        child: BottomAppBar(
          color: Colors.green,
          shape: CircularNotchedRectangle(),
          child: IconButton(
            onPressed: () {},
            icon: Icon(Icons.menu),
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        child: Icon(Icons.add),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
    );
  }
}

Наша текущая версия флаттера: 

Flutter (Channel stable, v1.5.4-hotfix.2, on Microsoft Windows [Version 10.0.17134.799], locale de-DE)

Это на самом делепроблема самого флаттера, или мы просто упускаем что-то важное?

Обновление

Мы создали проблему в репозитории флаттера на GitHub: https://github.com/flutter/flutter/issues/34326

...