【发布时间】：2019-05-26 10:08:13
【问题描述】：
我是 Flutter 的初学者，但由于“布局问题”而无法得到我想要的结果。我尝试了好几个小时...
技术问题：
当我单击“添加播放器按钮”以添加新的 TextField 以设置更多播放名称时，出现错误：“BoxConstraints 强制无限宽度”。所以，TextField 没有显示出来。
其他我不知道如何实现的功能：
- 我有一个“下拉菜单”来选择难度游戏。为什么不显示默认文本（难度：正常）？
- 怎么做：当用户点击图标“remove”（见TextField上的suffixIcon），那么对应的fieldText就被删除了？
- 如何做到这一点：当用户单击添加播放器时，默认提示文本会增加（播放器 2、播放器 3、播放器 4 ......）？
- 为什么当用户滚动页面时我的背景渐变没有修复？ （就像在 HTML/CSS '背景附件：固定'）？
import 'package:flutter/material.dart';
/// Styles
///
class Homepage extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return _MyHomePageState();
}
}
class _MyHomePageState extends State<Homepage> {
String dropdownValue = 'Normal';
List<TextField> _playerList = new List(); //_playerList is my List name
int playerListIndex = 0; //Count the number of times "Add" button clicked
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(children: <Widget>[
// To have a gradient background
new Container(
height: MediaQuery.of(context).size.height,
width: MediaQuery.of(context).size.width,
decoration: new BoxDecoration(
gradient: new LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [0.1, 1],
colors: [
Colors.redAccent[200],
Colors.red[300],
],
tileMode:
TileMode.repeated,
),
),
//I need SingleChildScrollView to haven't "Overflow yellow bar on bottom screen"
child: SingleChildScrollView(
child: Container(
padding: EdgeInsets.fromLTRB(20, 0, 20, 0),
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
// Box to add big image
SizedBox(
height: 450,
),
// DROP DOWN MENU to choose difficulty modes
InputDecorator(
decoration: InputDecoration(
prefixIcon: const Icon(Icons.games),
filled: true,
),
child: DropdownButtonHideUnderline(
child: new DropdownButton<String>(
value: dropdownValue,
hint: Text('Difficulty normal'),
isDense: true,
items: <String>['Normal', 'Easy', 'Hard']
.map<DropdownMenuItem<String>>((String value) {
return DropdownMenuItem<String>(
value: value,
child: Text(value),
);
}).toList(),
onChanged: (String newValue) {
setState(() {
dropdownValue = newValue;
});
},
),
),
),
//Field player name 1. At least I need 1 player
new TextField(
maxLength: 20,
decoration: InputDecoration(
prefixIcon: const Icon(Icons.person),
filled: true,
hintText:"Player 1",
counterText: "",
),
),
//Field for other player name 2, 3, 4, ...
new ListView.builder(
padding: EdgeInsets.all(0),
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
itemCount: _playerList.length,
itemBuilder: (context, index) {
TextField widget = _playerList.elementAt(index);
return widget;
}),
//Button to add other field text to set player name. The user can delete a player on click on "clear icon button"
new Align(
alignment: Alignment.centerRight,
child: FlatButton.icon(
color: Colors.black,
icon: Icon(
Icons.add,
color: Colors.white,
size: 18,
),
label: Text('Add player',
style:
TextStyle(fontSize: 12, color: Colors.white)),
onPressed: () {
setState(() {
playerListIndex++;
_playerList.add(
new TextField(
maxLength: 20,
decoration: InputDecoration(
prefixIcon: const Icon(Icons.person),
suffixIcon: new IconButton(
icon: Icon(Icons.clear),
onPressed: () {
_playerList.removeAt(playerListIndex); //Doesn't work
}),
filled: true,
hintText: "Player $playerListIndex", //Doesn't work i would like Player 2, Player 3, ...
counterText: "",
),
),
);
print(playerListIndex);
print(_playerList);
print(_playerList[0]);
});
}),
),
new ButtonTheme(
minWidth: 350,
height: 45,
child: FlatButton(
color: Colors.black,
child: Text('Play',
style:
TextStyle(fontSize: 18, color: Colors.white)),
onPressed: () {
// Perform some action
},
),
),
],
),
),
),
),
),
]),
);
}
}
【问题讨论】：
标签： flutter