Flutter 另一个例外是:RenderBox 没有布局:RenderRepaintBoundary#eaea6 NE

Question

我正在使用SingleChildScrollView和Column来显示滑动器和网格视图。

如果我在我的列中使用其他一些小部件，如文本、图像，应用程序会显示正常。 但是我的滑动器和网格视图无法显示，并报告错误：

I/flutter ( 4687): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter ( 4687): The following assertion was thrown during performLayout():
I/flutter ( 4687): RenderFlex children have non-zero flex but incoming height constraints are unbounded.
I/flutter ( 4687): When a column is in a parent that does not provide a finite height constraint, for example if it is
I/flutter ( 4687): in a vertical scrollable, it will try to shrink-wrap its children along the vertical axis. Setting a
I/flutter ( 4687): flex on a child (e.g. using Expanded) indicates that the child is to expand to fill the remaining
I/flutter ( 4687): space in the vertical direction.
I/flutter ( 4687): These two directives are mutually exclusive. If a parent is to shrink-wrap its child, the child
I/flutter ( 4687): cannot simultaneously expand to fit its parent.
I/flutter ( 4687): Consider setting mainAxisSize to MainAxisSize.min and using FlexFit.loose fits for the flexible
I/flutter ( 4687): children (using Flexible rather than Expanded). This will allow the flexible children to size
I/flutter ( 4687): themselves to less than the infinite remaining space they would otherwise be forced to take, and
I/flutter ( 4687): then will cause the RenderFlex to shrink-wrap the children rather than expanding to fit the maximum
I/flutter ( 4687): constraints provided by the parent.
I/flutter ( 4687): The affected RenderFlex is:
I/flutter ( 4687):   RenderFlex#1f4de relayoutBoundary=up14 NEEDS-LAYOUT NEEDS-PAINT
I/flutter ( 4687): The creator information is set to:
I/flutter ( 4687):   Column ← _SingleChildViewport ← IgnorePointer-[GlobalKey#ae070] ← Semantics ← Listener ←
I/flutter ( 4687):   _GestureSemantics ← RawGestureDetector-[LabeledGlobalKey<RawGestureDetectorState>#e4f77] ←
I/flutter ( 4687):   _ScrollableScope ← _ScrollSemantics-[GlobalKey#4bb86] ← RepaintBoundary ← CustomPaint ←
I/flutter ( 4687):   RepaintBoundary ← ⋯

我曾经是一名 uwp 开发人员，并且是 Flutter 的新手。 谁能帮忙？ 这是代码：

class _HomePageState extends State<HomePage> {
final List<ListItem> _children;
@override
Widget build(BuildContext context) {
return Scaffold(
body:SingleChildScrollView(
child: Column(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Expanded(
child: Container(
height: 200,
child: Swiper(
itemBuilder: (BuildContext context, int index) {
return Image.network(
"http://via.placeholder.com/350x150",
fit: BoxFit.fitHeight,
);
},
itemCount: 5,
pagination: SwiperPagination(),
control: SwiperControl(),
),
)),
Expanded(
child: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4, childAspectRatio: 1.0),
itemBuilder: (BuildContext context, int index) {
return ListItemWidget(_children[index]);
},
itemCount: _children.length,
),
),
],
),
),
);
}
}

Answer 1

SingleChildScrollView中不能有具有无限垂直维度的Expanded小部件。

class _HomePageState extends State<HomePage> {
final List<ListItem> _children;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
mainAxisSize: MainAxisSize.min,
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
Expanded(
child: Container(
height: 200,
child: Swiper(
itemBuilder: (BuildContext context, int index) {
return Image.network(
"http://via.placeholder.com/350x150",
fit: BoxFit.fitHeight,
);
},
itemCount: 5,
pagination: SwiperPagination(),
control: SwiperControl(),
),
)),
Expanded(
child: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4, childAspectRatio: 1.0),
itemBuilder: (BuildContext context, int index) {
return ListItemWidget(_children[index]);
},
itemCount: _children.length,
),
),
],
),
);
}
}

Answer 2

您可以将列放在 SsizeBox 中，然后使用 SingleChildScrollView 包装 SsizeBox

例如：

new Scaffold(
body: SingleChildScrollView(
child: Sizedbox(
child: new Column(
children: <Widget>[
header,
new Padding(
child: GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4, childAspectRatio: 1.0),
itemBuilder: (BuildContext context, int index) {
return ListItemWidget(_children[index]);
},
itemCount: _children.length,
),
),
],
),
),
),

Answer 3

我遇到了完全相同的问题，对我来说，有效的方法是先用扩展的小部件包装滑动器，然后用所需的大小用容器包装扩展的滑动器 1.容器 2. 扩展 3. 刷卡器