Another exception was thrown: 'package:flutter/src/animation/curves.dart': Failed assertion: line 182 pos 12: 'begin <= 1.0': is not true.
════════小部件库捕获到异常══════════════════════════════════ ═════════════════════ 'package：flutter / src / animation / curves.dart'：失败的断言：第182行pos 12：'begin <= 1.0'：不正确。 相关的引起错误的小部件是： MyHomeWidget文件：/// C：/Users/Alfred%20J.%20Stanley/FlutterProjects/flutter_app_test/lib/main.dart：21：13
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_app_test/DrawerClass.dart';
import 'package:flutter_app_test/widgets/category_widget.dart';
import 'package:flutter_app_test/widgets/search_bar.dart';
import 'constants.dart';
class MyHomeWidget extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return MyHomeWidgetState();
}
}
class MyHomeWidgetState extends State<MyHomeWidget>
with SingleTickerProviderStateMixin {
AnimationController animationController;
Animation animationcolor;
Animation animationsize;
Animation animationsizeText;
@override
void initState() {
super.initState();
animationController = AnimationController(vsync: this, duration: Duration(seconds:4));
animationsizeText=Tween<double>(begin: 10.0,end: 30.0).animate(CurvedAnimation(parent:
animationController,curve: Interval(1.75,2.75)));
animationsize = TweenSequence(
[
TweenSequenceItem(tween: Tween(begin: 50.0, end: 30.0), weight: 1),
TweenSequenceItem(tween: Tween(begin: 30.0, end: 50.0), weight: 1)
],).animate(CurvedAnimation(parent: animationController,curve: Interval(3.0,4.0)));
animationcolor = ColorTween(begin: Colors.grey, end: Colors.black)
.animate(animationController);
animationController.forward();
animationController.addListener(() {
setState(() {});
});
}
@override
Widget build(BuildContext context) {
var screen_size = MediaQuery.of(context).size;
return Scaffold(
drawer: DrawerClass(),
appBar: AppBar(
title: Text("App Bar Title"),
),
bottomNavigationBar: BottomNavigationBar(
currentIndex: 0,
backgroundColor: Colors.blue,
items: [
BottomNavigationBarItem(
icon: Image.asset(
'assets/images/cloud.png',
height: 30,
),
title: Text(
'item1',
style: TextStyle(color: Colors.white),
),
),
BottomNavigationBarItem(
icon: Image.asset(
'assets/images/cloud.png',
height: 30,
),
title: Text(
'item2',
style: TextStyle(color: Colors.white),
),
),
BottomNavigationBarItem(
icon: Image.asset(
'assets/images/cloud.png',
height: 30,
),
title: Text(
'item3',
style: TextStyle(color: Colors.white),
),
),
],
),
body:Stack(
children: <Widget>[
Container(
width: screen_size.width,
height: screen_size.height * 0.4,
decoration: BoxDecoration(
color: Colors.lightBlueAccent,
image: DecorationImage(
image: AssetImage('assets/images/cloud.png'),
alignment: Alignment.centerLeft,
)),
child: Column(
children: [
Align(
alignment: Alignment.topRight,
child: Container(
width: animationsize.value,
height: animationsize.value,
decoration: BoxDecoration(
shape: BoxShape.circle,
color: Colors.white,
image: DecorationImage(
image: AssetImage('assets/images/cloud.png'),
),
),
),
),
Center(
child: Text(
"Good Morning, Faiz Ahammed",
style: TextStyle(
fontSize: animationsizeText.value,
fontWeight: FontWeight.w100,
color: animationcolor.value),
),
),
],
),
),
SafeArea(
child: Padding(
padding: EdgeInsets.fromLTRB(20.0, 120.0, 20.0,5.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
SearchBar(),
Expanded(
child: GridView.count(
mainAxisSpacing: 20.0,
crossAxisSpacing: 20.0,
childAspectRatio: 0.85,
crossAxisCount: 2,
children: <Widget>[
Category(
title: "Meditation",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Yoga",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Karatte",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Kunfu",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Swimming",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Cycling",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Trekking",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
Category(
title: "Sailing",
svgsrc: "assets/images/cloud.png",
onPress: () {},
),
],
),
),
],
),
),
),
],
),
);
} }
答案 0 :(得分：0)
如果您在Interval Class documentation阅读，将会看到：
直到开始时为0.0的曲线，然后从开始时的0.0弯曲到结束时的1.0（然后根据曲线），然后在结束时保持1.0。
因此begin和end参数都必须是0.0<=begin<end<=1.0之类的值。
在您的代码中有以下内容时，您无需关注此问题：
Interval(1.75,2.75)
如果不深入查看完整代码，我将无法理解您的意图，但是这些值没有意义。 Interval是一条曲线，仅表示值如何变化，因此数字本身的缩放比例不应该有任何区别。
从技术上讲，曲线是一种将值从0.0-> 1.0映射到0.0-> 1.0的函数。也就是说，它可以使动画在其过程的不同部分加速或减速。顾名思义，它仅指动画的曲线。有关常见动画曲线的示例，请参见此page。