我认为CopsOnRoad的解决方案对于不想使用第三方库的人来说更好、更简单。然而，由于没有动画，我在查看卡片（展开）和滑动上一个卡片（缩小）时使用了索引添加了比例动画。所以当页面首次加载时，第一张和第二张卡片将没有任何动画效果，而当卡片被滑动时，只有前一个和当前卡片具有比例动画。这是我的实现：
class MyHomePage extends StatefulWidget {
const MyHomePage({super.key, required this.title});
final String title;
@override
State<MyHomePage> createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int currentIndex = -1, previousIndex = 0;
double getAnimationValue(int currentIndex, int widgetIndex, int previousIndex,
{bool begin = true}) {
if (widgetIndex == currentIndex) {
return begin ? 0.9 : 1;
} else {
return begin ? 1 : 0.9;
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
SizedBox(
height: 200,
child: PageView.builder(
itemCount: 10,
controller: PageController(viewportFraction: 0.7),
onPageChanged: (int index) {
setState(() {
if (currentIndex != -1) {
previousIndex = currentIndex;
}
currentIndex = index;
});
},
itemBuilder: (_, widgetIndex) {
return (currentIndex != -1 &&
(previousIndex == widgetIndex ||
widgetIndex == currentIndex))
? TweenAnimationBuilder(
duration: const Duration(milliseconds: 400),
tween: Tween<double>(
begin: getAnimationValue(
currentIndex,
widgetIndex,
previousIndex,
),
end: getAnimationValue(
currentIndex,
widgetIndex,
previousIndex,
begin: false,
),
),
builder: (context, value, child) {
return Transform.scale(
scale: value,
child: Card(
elevation: 6,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(20)),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
"Card${widgetIndex + 1}",
style: const TextStyle(fontSize: 30),
),
Text(
"$widgetIndex >> Widget Index << $widgetIndex",
style: const TextStyle(fontSize: 22),
),
Text(
"$currentIndex >> Current Index << $currentIndex",
style: const TextStyle(fontSize: 22),
),
Text(
"$previousIndex >> Previous Index << $previousIndex",
style: const TextStyle(fontSize: 22),
),
],
),
),
);
},
)
: Transform.scale(
scale:
(widgetIndex == 0 && currentIndex == -1) ? 1 : 0.9,
child: Card(
elevation: 6,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(20)),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
"Card${widgetIndex + 1}",
style: const TextStyle(fontSize: 30),
),
Text(
"$widgetIndex >> Widget Index << $widgetIndex",
style: const TextStyle(fontSize: 22),
),
Text(
"$currentIndex >> Init Index << $currentIndex",
style: const TextStyle(fontSize: 22),
),
Text(
"$previousIndex >> Previous Index << $previousIndex",
style: const TextStyle(fontSize: 22),
),
],
),
),
);
},
),
),
],
),
);
}
}
我在这个动画中使用了TweenAnimationBuilder并硬编码了小部件。您可以为您的小部件使用方法，或者在需要时使用flutter_animate包进行简单的动画。
