嗨，我想在所有小部件顶部的屏幕中心显示CircularProgressIndicator。它应该像叠加。
现在，当CircularProgressIndicator可见时，所有小部件都会向下移动一点以显示CircularProgressIndicator。我希望它应该覆盖。有人知道怎么做吗？
import 'package:flutter/material.dart';
import 'package:roomie/auth/Auth.dart';
class ForgotPasswordScreen extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return ForgotPasswordScreenState();
}
}
class ForgotPasswordScreenState extends State<ForgotPasswordScreen> {
var emailController = new TextEditingController();
var authHandler = new Auth();
bool isLoading = false;
@override
Widget build(BuildContext context) {
return new Scaffold(
body: Container(
height: MediaQuery.of(context).size.height,
decoration: BoxDecoration(
color: Colors.white,
),
child: new Column(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Row(
children: <Widget>[
new Expanded(
child: isLoading
? Center(child: CircularProgressIndicator())
: new Container()),
],
),
new Row(
children: <Widget>[
new Expanded(
child: new Padding(
padding: const EdgeInsets.only(left: 40.0),
child: new Text(
"EMAIL",
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.redAccent,
fontSize: 15.0,
),
),
),
),
],
),
new Container(
width: MediaQuery.of(context).size.width,
margin:
const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
alignment: Alignment.center,
decoration: BoxDecoration(
border: Border(
bottom: BorderSide(
color: Colors.redAccent,
width: 0.5,
style: BorderStyle.solid),
),
),
padding: const EdgeInsets.only(left: 0.0, right: 10.0),
child: new Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
new Expanded(
child: TextField(
controller: emailController,
textAlign: TextAlign.left,
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'PLEASE ENTER YOUR EMAIL',
hintStyle: TextStyle(color: Colors.grey),
),
),
),
],
),
),
Divider(
height: 24.0,
),
new Container(
width: MediaQuery.of(context).size.width,
margin:
const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
alignment: Alignment.center,
child: new Row(
children: <Widget>[
new Expanded(
child: new FlatButton(
shape: new RoundedRectangleBorder(
borderRadius: new BorderRadius.circular(30.0),
),
color: Colors.redAccent,
onPressed: () {
setState(() {
isLoading = true;
});
authHandler
.sendPasswordResetEmail(emailController.text)
.then((void nothing) async {
await showDialog(
context: context,
builder: (BuildContext context) {
// return object of type Dialog
return AlertDialog(
content: new Text(
"Password reset email has been sent."),
actions: <Widget>[
// usually buttons at the bottom of the dialog
new FlatButton(
child: new Text("OK"),
onPressed: () {
Navigator.pop(context);
},
),
],
);
},
);
Navigator.pop(context);
setState(() {
isLoading = false;
});
}).catchError((e) => print(e));
},
child: new Container(
padding: const EdgeInsets.symmetric(
vertical: 20.0,
horizontal: 20.0,
),
child: new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Expanded(
child: Text(
"FORGOT PASSWORD",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold),
),
),
],
),
),
),
),
],
),
),
],
)));
}
}
答案 0 :(得分：4)
堆栈就是您想要的：
https://docs.flutter.io/flutter/widgets/Stack-class.html
@override
Widget build(BuildContext context) {
return new Scaffold(
body: Stack(
children:<Widget>[ Container(
height: MediaQuery.of(context).size.height,
decoration: BoxDecoration(
color: Colors.white,
),
child: new Column(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Row(
children: <Widget>[
new Expanded(
child: new Padding(
padding: const EdgeInsets.only(left: 40.0),
child: new Text(
"EMAIL",
style: TextStyle(
fontWeight: FontWeight.bold,
color: Colors.redAccent,
fontSize: 15.0,
),
),
),
),
],
),
new Container(
width: MediaQuery.of(context).size.width,
margin:
const EdgeInsets.only(left: 40.0, right: 40.0, top: 10.0),
alignment: Alignment.center,
decoration: BoxDecoration(
border: Border(
bottom: BorderSide(
color: Colors.redAccent,
width: 0.5,
style: BorderStyle.solid),
),
),
padding: const EdgeInsets.only(left: 0.0, right: 10.0),
child: new Row(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
new Expanded(
child: TextField(
controller: emailController,
textAlign: TextAlign.left,
decoration: InputDecoration(
border: InputBorder.none,
hintText: 'PLEASE ENTER YOUR EMAIL',
hintStyle: TextStyle(color: Colors.grey),
),
),
),
],
),
),
Divider(
height: 24.0,
),
new Container(
width: MediaQuery.of(context).size.width,
margin:
const EdgeInsets.only(left: 30.0, right: 30.0, top: 20.0),
alignment: Alignment.center,
child: new Row(
children: <Widget>[
new Expanded(
child: new FlatButton(
shape: new RoundedRectangleBorder(
borderRadius: new BorderRadius.circular(30.0),
),
color: Colors.redAccent,
onPressed: () {
setState(() {
isLoading = true;
});
authHandler
.sendPasswordResetEmail(emailController.text)
.then((void nothing) async {
await showDialog(
context: context,
builder: (BuildContext context) {
// return object of type Dialog
return AlertDialog(
content: new Text(
"Password reset email has been sent."),
actions: <Widget>[
// usually buttons at the bottom of the dialog
new FlatButton(
child: new Text("OK"),
onPressed: () {
Navigator.pop(context);
},
),
],
);
},
);
Navigator.pop(context);
setState(() {
isLoading = false;
});
}).catchError((e) => print(e));
},
child: new Container(
padding: const EdgeInsets.symmetric(
vertical: 20.0,
horizontal: 20.0,
),
child: new Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Expanded(
child: Text(
"FORGOT PASSWORD",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold),
),
),
],
),
),
),
),
],
),
),
],
)),
isLoading ? Container(
color: Colors.black.withOpacity(0.5),
child: Center(
child: CircularProgressIndicator(),
),
) : Container()
],
));
}
答案 1 :(得分：0)
2021 年：尽管 Stack 是一个非凡的选择，但简单的 showDialog 就可以解决问题。它干净、高效，并且会给你一个淡入/淡出动画。代码：
onEvent: () {
showDialog(
barrierDismissible: false,
builder: (ctx) {
return Center(
child: CircularProgressIndicator(
strokeWidth: 2,
),
)
},
context: context,
);
},
事件完成后，调用 Navigator.of(context).pop();。如果您希望用户能够点击屏幕并手动关闭对话框，请删除 barrierDismissable: false 代码。如果您对 .pop() 有问题，您可能需要在关闭时专门使用对话框的 context。