我在主屏幕上使用一个图标来向用户显示正在进行的某个过程。我希望这个图标在特定的时间内（比如100秒）可见。用户可能会导航到各种屏幕，但是当他回到主屏幕时，他应该能够看到这个图标，并且图标应该在100秒后消失。我该怎么做？
class AnimatedFlutterLogo extends StatefulWidget {
@override
State<StatefulWidget> createState() => new _AnimatedFlutterLogoState();
}
class _AnimatedFlutterLogoState extends State<AnimatedFlutterLogo> {
Timer _timer;
FlutterLogoStyle _logoStyle = FlutterLogoStyle.markOnly;
_AnimatedFlutterLogoState() {
_timer = new Timer(const Duration(milliseconds: 100), () {
setState(() {
_logoStyle = FlutterLogoStyle.horizontal;
});
});
}
@override
void dispose() {
super.dispose();
_timer.cancel();
}
@override
Widget build(BuildContext context) {
return new FlutterLogo(
size: 200.0,
textColor: Palette.white,
style: _logoStyle,
);
}
}
参考此链接如何在Flutter中运行一些延迟后的代码？
或者，您可以使用以下代码来实现延迟状态更新：
Future.delayed(const Duration(milliseconds: 100), () {
setState(() {
// Here you can write your code to update the state to show/hide the icon
});
});
bool _visibility = false;
---------------------------
Timer _timer;
int _start = 1;
--------------------------
void startTimer() {
const oneSec = const Duration(seconds: 1);
_timer = new Timer.periodic(
oneSec,
(Timer timer) => setState(() {
if (_start == 10) {
timer.cancel();
_changed(true);
} else {
_start = _start + 1;
}
}));
}
---------------------------------
void _changed(bool visibility) {
setState(()
if (_start == 10) {
_visibility = visibility;
}
});
}
---------------------------
@override
void initState() {
super.initState();
startTimer();
setState(() {});
}
-----------------------------
_visibility ? new Row(
// create Widget
)
