我是Flutter的新手，我想使用“剪切路径”为自己的顶部栏创建自定义形状， 我正确地遵循了一些教程，但对我来说，我每个孩子必须准确地布置一次错误
这是我的代码
class MainPage extends StatefulWidget {
@override
_MainPageState createState() => _MainPageState();
}
class _MainPageState extends State<MainPage> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: <Widget>[
ClipPath(
clipper: TopBarClipper(),
child: Container(
width: double.infinity,
height: 300,
color: Colors.black26,
),
),
],
)
);
}
}
class TopBarClipper extends CustomClipper<Path> {
@override
Path getClip(Size size) {
var path = Path();
path.lineTo(0, size.height - 100);
path.quadraticBezierTo(
size.width / 5, size.height, size.width, size.height - 150);
//path.lineTo(size.width, size.height);
path.lineTo(size.width, 0);
path.close();
// TODO: implement getClip
return path;
}
@override
bool shouldReclip(covariant CustomClipper<Path> oldClipper) {
// TODO: implement shouldReclip
return null;
throw UnimplementedError();
}
}
这是我尝试跑步的时间
════════ Exception caught by rendering library ═════════════════════════════════════════════════════
The following assertion was thrown during performLayout():
Each child must be laid out exactly once.
The _ScaffoldLayout custom multichild layout delegate forgot to lay out the following child:
_ScaffoldSlot.body: RenderStack#57108 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
parentData: offset=Offset(0.0, 0.0); id=_ScaffoldSlot.body
constraints: MISSING
size: MISSING
alignment: AlignmentDirectional.topStart
textDirection: ltr
fit: loose
The relevant error-causing widget was:
Scaffold file:///C:/Users/****/AndroidStudioProjects/****/lib/main/MainPage.dart:14:12
When the exception was thrown, this was the stack:
#0 MultiChildLayoutDelegate._callPerformLayout.<anonymous closure> (package:flutter/src/rendering/custom_layout.dart:246:11)
#1 MultiChildLayoutDelegate._callPerformLayout (package:flutter/src/rendering/custom_layout.dart:259:8)
#2 RenderCustomMultiChildLayoutBox.performLayout (package:flutter/src/rendering/custom_layout.dart:402:14)
#3 RenderObject.layout (package:flutter/src/rendering/object.dart:1777:7)
#4 RenderProxyBoxMixin.performLayout (package:flutter/src/rendering/proxy_box.dart:113:14)
...
The following RenderObject was being processed when the exception was fired: RenderCustomMultiChildLayoutBox#e4670 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: <none> (can use size)
... constraints: BoxConstraints(w=360.0, h=702.0)
... size: Size(360.0, 702.0)
RenderObject: RenderCustomMultiChildLayoutBox#e4670 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
parentData: <none> (can use size)
constraints: BoxConstraints(w=360.0, h=702.0)
size: Size(360.0, 702.0)
... child 1: RenderStack#57108 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: offset=Offset(0.0, 0.0); id=_ScaffoldSlot.body
... constraints: MISSING
... size: MISSING
... alignment: AlignmentDirectional.topStart
... textDirection: ltr
... fit: loose
... child 1: RenderClipPath#ded0f NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: not positioned; offset=Offset(0.0, 0.0)
... constraints: MISSING
... size: MISSING
... child: RenderConstrainedBox#b2003 NEEDS-LAYOUT NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: <none>
... constraints: MISSING
... size: MISSING
... additionalConstraints: BoxConstraints(w=Infinity, h=300.0)
... child: _RenderColoredBox#a551f NEEDS-LAYOUT NEEDS-PAINT
... parentData: <none>
... constraints: MISSING
... size: MISSING
... behavior: opaque
... child 2: RenderStack#953d0 relayoutBoundary=up1 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: offset=Offset(0.0, 0.0); id=_ScaffoldSlot.body (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(360.0, 300.0)
... alignment: AlignmentDirectional.topStart
... textDirection: ltr
... fit: loose
... child 1: RenderClipPath#5d400 relayoutBoundary=up2 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: not positioned; offset=Offset(0.0, 0.0) (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(360.0, 300.0)
... child: RenderConstrainedBox#cb85b relayoutBoundary=up3 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: <none> (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(360.0, 300.0)
... additionalConstraints: BoxConstraints(w=Infinity, h=300.0)
... child: _RenderColoredBox#b00e1 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: <none> (can use size)
... constraints: BoxConstraints(w=360.0, h=300.0)
... size: Size(360.0, 300.0)
... behavior: opaque
... child 3: RenderStack#6c594 relayoutBoundary=up1 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: offset=Offset(344.0, 686.0); id=_ScaffoldSlot.floatingActionButton (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(0.0, 0.0)
... alignment: centerRight
... textDirection: ltr
... fit: loose
... child 1: RenderTransform#01581 relayoutBoundary=up2 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: not positioned; offset=Offset(0.0, 0.0) (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(0.0, 0.0)
... transform matrix: [0] 0.0,0.0,0.0,0.0
[1] 0.0,0.0,0.0,0.0
[2] 0.0,0.0,1.0,0.0
[3] 0.0,0.0,0.0,1.0
... origin: null
... alignment: center
... textDirection: ltr
... transformHitTests: true
... child: RenderTransform#56c78 relayoutBoundary=up3 NEEDS-PAINT NEEDS-COMPOSITING-BITS-UPDATE
... parentData: <none> (can use size)
... constraints: BoxConstraints(0.0<=w<=360.0, 0.0<=h<=702.0)
... size: Size(0.0, 0.0)
... transform matrix: [0] 0.7,0.7,0.0,0.0
[1] -0.7,0.7,0.0,0.0
[2] 0.0,0.0,1.0,0.0
[3] 0.0,0.0,0.0,1.0
... origin: null
... alignment: center
... textDirection: ltr
... transformHitTests: true
════════════════════════════════════════════════════════════════════════════════════════════════════
我在互联网上阅读，有人说这只是Flutter错误，我确实清理了Flutter，然后重新运行，但它仍然出现，
它只是在我使用ClipPath时出现。
为什么会这样？
谢谢
答案 0 :(得分：1)
我刚刚找到了答案，但是不知道这是否是一个好方法，
我刚刚将shouldReclip的返回值更改为true并解决了问题。