AnimationController 停止工作,因为不知何故 vsync 不再是命名参数。
这行代码停止工作。
controller = AnimationController(duration: Duration(seconds: 3), vsync: this);
它现在显示一条错误消息:
The named parameter 'vsync' isn't defined.
Try correcting the name to an existing named parameter's name, or defining a named parameter with the name 'vsync'.dartundefined_named_parameter
我在两个不同的应用程序中使用了完全相同的代码,在其中一个应用程序中,我只是将淡入淡出的文本动画作为热修复删除,但在另一个应用程序中,我需要一个真正的修复。最近有没有人看到这个问题?
笔记:
- 这个完全相同的代码已经工作了几个月,并且在更新后停止工作。
- 周围的班级确实有:with TickerProviderStateMixin
class FadingText extends StatefulWidget {
final String text;
final int seconds;
final TextStyle style;
FadingText({this.text, this.seconds, this.style});
@override
_FadingTextState createState() => _FadingTextState();
}
class _FadingTextState extends State<FadingText> with TickerProviderStateMixin {
AnimationController controller;
Animation animation;
@override
Widget build(BuildContext context) {
return Container(
child: FadeTransition(
opacity: animation,
child: Text(widget.text, style: widget.style,),
),
);
}
@override
void initState() {
super.initState();
controller = AnimationController(duration: Duration(seconds: widget.seconds), vsync: this);
animation = Tween(begin: 0.5, end: 1.0).animate(controller);
animation.addStatusListener((status) {
if (status == AnimationStatus.completed) { controller.reverse(); }
else if (status == AnimationStatus.dismissed) { controller.forward(); }
});
controller.forward();
}
@override
void dispose() {
controller.dispose();
super.dispose();
}
}
Flutter Doctor
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