编辑 -- 错误是用户未定义。
class _CheckInState extends State<CheckIn> {
double _value = 0;
String _emotionalStatus = 'Happy';
bool didStartDrag = false;
double updatedDragDelta;
bool didEndDrag = false;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: new LBAppBar().getAppBar(),
drawer: new LBDrawer().getDrawer(),
body:
SwipeDetector(
child: Container(
decoration: BoxDecoration(
gradient: new LinearGradient(
colors: [Color.fromRGBO(1,89,99, 1.0), Colors.grey],
begin: Alignment.bottomLeft,
end: Alignment.topRight
)
),
child: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.start,
children: <Widget>[
Container(
margin: EdgeInsets.only(left: 30.0,top: 30.0, bottom: 70.0, right:30.0),
child :
Text(
'How are you feeling today Sam?', style: new TextStyle( color: Colors.white, fontWeight: FontWeight.bold, fontSize: 21.0 ))
,
),
Text(
'${_emojis[_value.toInt()]}',
style: Theme.of(context).textTheme.display3,
),
Container(
margin: EdgeInsets.only(left: 30.0,top: 20.0, bottom: 20.0, right:30.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget> [
Container(
margin: EdgeInsets.all(10.0),
child: Text(
'$_emotionalStatus', style: new TextStyle( color: Colors.white, fontWeight: FontWeight.bold, fontSize: 21.0 ))
,
)
]
)
),
Padding(
padding: const EdgeInsets.symmetric(horizontal: 15.0),
child:
Container(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(_emojis[0], softWrap: true),
Expanded(
child: Slider(
value: _value,
// label: _emojis[_value.toInt()],
min: 0.0,
max: 4.0,
divisions: 4,
onChangeStart: (double value) {
print('Start value is ' + value.toString());
},
onChangeEnd: (double value) {
print('Finish value is ' + value.toString());
if (value.toString() == '0.0') {
_emotionalStatus = 'Happy';
}
if (value.toString() == '1.0') {
_emotionalStatus = 'Optimistic';
}
if (value.toString() == '2.0') {
_emotionalStatus = 'Neutral';
}
if (value.toString() == '3.0') {
_emotionalStatus = 'Pessimistic';
}
if (value.toString() == '4.0') {
_emotionalStatus = 'Sad';
}
setState(() {
});
},
onChanged: (double value) {
setState(() {
_value = value;
});
},
activeColor: Colors.white,
inactiveColor: Colors.white,
),
),
Text(_emojis[4], softWrap: true,)
],
),
),
),
Container(
margin: EdgeInsets.all(20.0),
child:OutlineButton(
child: Text('Tap to Continue'), textColor: Colors.white,
shape: new RoundedRectangleBorder(borderRadius: new BorderRadius.circular(30.0)),
onPressed: (){
Navigator.of(context).push(new MaterialPageRoute(builder: (BuildContext context) => new CheckInQ(user: user, emoji: _emojis[_value.toInt()], mood: _emotionalStatus))
);
}
)
)
我们有一个Flutter应用程序,在按钮按下时将用户对象传递给不同的屏幕。当传递给无状态小部件时,这很有效。我尝试在有状态的小部件中实现相同的模式,但它没有起作用。我认为由于我对Flutter还不熟悉,所以我的做法是错误的,有状态的小部件必须以不同的方式处理此对象。
以下是无状态小部件的代码:
class HomeMember extends StatelessWidget {
User user;
HomeMember({Key key, @required this.user}) : super(key: key);
@override
Widget build(BuildContext context){
bool isIOS = Theme.of(context).platform == TargetPlatform.iOS;
return new Scaffold(
appBar : LBAppBar().getAppBar(),
//drawer: new LBDrawer().getDrawer(),
body: Container(
decoration: BoxDecoration(
gradient: new LinearGradient(
colors: [Color.fromRGBO(1,89,99, 1.0), Colors.grey],
begin: Alignment.bottomLeft,
end: Alignment.topRight
)
),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children:[
Row(
children: [
Container(
margin: EdgeInsets.only(left: 20.0,top: 10.0, bottom: 10.0, right:30.0),
child: Column(
children: <Widget>[
Text("Hi ${user.firstName}, Today is " + formatDate(), style: new TextStyle( color: Colors.white70, fontWeight: FontWeight.bold, fontSize: 19.0 )),
],
我尝试使用这种将用户对象传递给有状态小部件的方法,但它并没有起作用。
class CheckIn extends StatefulWidget {
@override
_CheckInState createState() => _CheckInState();
User user;
CheckIn({Key key, @required this.user}) : super(key: key);
}
class _CheckInState extends State<CheckIn> {
double _value = 0;
String _emotionalStatus = 'Happy';
bool didStartDrag = false;
double updatedDragDelta;
bool didEndDrag = false;
_CheckInState
中只需引用widget.user
。 - Richard HeapState
类的任何地方需要它时,将其称为widget.user
。 - Richard Heap