我试图实现的是保存小部件的状态,即在调用setState()方法时不应刷新它的状态。
class _GenderSelectionPageState extends State<GenderSelectionPage> {
bool isFemaleSelected = false;
AdmobBannerSize bannerSize;
GlobalKey _globalKey = new GlobalKey();
bool isLoaded = false;
@override
void initState() {
// TODO: implement initState
super.initState();
bannerSize = AdmobBannerSize.BANNER;
}
@override
Widget build(BuildContext context) {
double height = MediaQuery.of(context).size.height;
double width = MediaQuery.of(context).size.width;
return new Scaffold(
body: new Container(
width: width,
child: new Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Flexible(
child: new Hero(
tag: "gender",
child: Material(
child: new Row(
children: <Widget>[
InkWell(
onTap: () {
setState(() {
if (isFemaleSelected) {
isFemaleSelected = false;
} else {
isFemaleSelected = true;
}
});
},
child: Opacity(
child: Image.asset(
"assets/woman.png",
height: height / 4,
width: width / 2 - 12,
),
opacity: isFemaleSelected ? 1.0 : 0.30,
),
),
InkWell(
onTap: () {
setState(() {
if (isFemaleSelected) {
isFemaleSelected = false;
} else {
isFemaleSelected = true;
}
});
},
child: Opacity(
opacity: !isFemaleSelected ? 1.0 : 0.30,
child: Image.asset(
"assets/boy.png",
height: height / 4,
width: width / 2 - 12,
),
),
),
],
),
),
),
),
],
),
flex: 1,
),
InkWell(
onTap: () {
setState(() {
});
Navigator.push(
context,
MaterialPageRoute(
builder: (BuildContext) =>
new HeightWeightSelection(isFemaleSelected
? "assets/woman.png"
: "assets/boy.png")));
},
child: Container(
margin: EdgeInsets.only(bottom: 12.0),
child: new Image.asset(
"assets/next.png",
height: 64.0,
width: 64.0,
),
)),
new AdmobBannerWrapper(adUnitId: getBannerAdUnitId(),adSize: bannerSize,key: _globalKey,),
/* new AdmobBanner(
adUnitId: getBannerAdUnitId(),
adSize: bannerSize,
listener:
(AdmobAdEvent event, Map<String, dynamic> args) {
handleEvent(event, args, 'Banner');
},
),*/
],
),
)),
);
}
我不想每次按下底部的图像按钮时都调用AdmobBannerWrapper.AdmobBannerWrapper应该只加载一次,但是每次单击Next Image都会加载AdmobBannerWrapper方法。
最佳答案
用initState()
构建它,然后在需要时使用它的引用,直到父窗口小部件重新初始化后,它才可以再次构建。
var banner;
@override
void initState() {
// TODO: implement initState
super.initState();
bannerSize = AdmobBannerSize.BANNER;
banner = AdmobBannerWrapper(adUnitId: getBannerAdUnitId(),adSize: bannerSize,key:_globalKey,);
}
比在这里通过引用调用它
banner
@override
Widget build(BuildContext context) {
double height = MediaQuery.of(context).size.height;
double width = MediaQuery.of(context).size.width;
return new Scaffold(
body: new Container(
width: width,
child: new Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.end,
children: <Widget>[
Expanded(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.max,
children: <Widget>[
Flexible(
child: new Hero(
tag: "gender",
child: Material(
child: new Row(
children: <Widget>[
InkWell(
onTap: () {
setState(() {
if (isFemaleSelected) {
isFemaleSelected = false;
} else {
isFemaleSelected = true;
}
});
},
child: Opacity(
child: Image.asset(
"assets/woman.png",
height: height / 4,
width: width / 2 - 12,
),
opacity: isFemaleSelected ? 1.0 : 0.30,
),
),
InkWell(
onTap: () {
setState(() {
if (isFemaleSelected) {
isFemaleSelected = false;
} else {
isFemaleSelected = true;
}
});
},
child: Opacity(
opacity: !isFemaleSelected ? 1.0 : 0.30,
child: Image.asset(
"assets/boy.png",
height: height / 4,
width: width / 2 - 12,
),
),
),
],
),
),
),
),
],
),
flex: 1,
),
InkWell(
onTap: () {
setState(() {
});
Navigator.push(
context,
MaterialPageRoute(
builder: (BuildContext) =>
new HeightWeightSelection(isFemaleSelected
? "assets/woman.png"
: "assets/boy.png")));
},
child: Container(
margin: EdgeInsets.only(bottom: 12.0),
child: new Image.asset(
"assets/next.png",
height: 64.0,
width: 64.0,
),
)),
banner, /*this is our variable */
/* new AdmobBanner(
adUnitId: getBannerAdUnitId(),
adSize: bannerSize,
listener:
(AdmobAdEvent event, Map<String, dynamic> args) {
handleEvent(event, args, 'Banner');
},
),*/
],
),
)),
);
}