效果

需求

• 数字切换时新数字从上往下进入，上个数字从上往下出
• 新数字进入时下落到位置并带有回弹效果
• 上个数字及新输入切换时带有透明度和缩放动画

实现

主要采用AnimatedSwitcher实现需求，代码比较简单，直接撸

import 'dart:math';import 'package:flutter/material.dart';
import 'package:flutter_xy/widgets/xy_app_bar.dart';class NumAnimPage extends StatefulWidget {const NumAnimPage({super.key});@overrideState<NumAnimPage> createState() => _NumAnimPageState();
}class _NumAnimPageState extends State<NumAnimPage> {int _currentNum = 0;// 数字文本随机颜色Color get _numColor {Random random = Random();int red = random.nextInt(256);int green = random.nextInt(256);int blue = random.nextInt(256);return Color.fromARGB(255, red, green, blue);}// 数字累加void _addNumber() {setState(() {_currentNum++;});}@overrideWidget build(BuildContext context) {return Scaffold(appBar: XYAppBar(title: "数字动画",),body: Center(child: _bodyWidget(),),);}Widget _bodyWidget() {return Column(mainAxisAlignment: MainAxisAlignment.center,children: [AnimatedSwitcher(duration: const Duration(milliseconds: 500),transitionBuilder: (Widget child, Animation<double> animation) {Offset startOffset = animation.status == AnimationStatus.completed? const Offset(0.0, 1.0): const Offset(0.0, -1.0);Offset endOffset = const Offset(0.0, 0.0);return SlideTransition(position: Tween(begin: startOffset, end: endOffset).animate(CurvedAnimation(parent: animation, curve: Curves.bounceOut),),child: FadeTransition(opacity: Tween(begin: 0.0, end: 1.0).animate(CurvedAnimation(parent: animation, curve: Curves.linear),),child: ScaleTransition(scale: Tween(begin: 0.5, end: 1.0).animate(CurvedAnimation(parent: animation, curve: Curves.linear),),child: child,),),);},child: Text('$_currentNum',key: ValueKey<int>(_currentNum),style: TextStyle(fontSize: 100, color: _numColor),),),const SizedBox(height: 80),ElevatedButton(onPressed: _addNumber,child: const Text('数字动画',style: TextStyle(fontSize: 25, color: Colors.white),),),],);}
}

具体见github：github.com/yixiaolunhui/flutter_xy