小编Sun*_*nny的帖子

我是颤振新手。

所以我尝试在颤动中使用曲线动画，但它给了我一个标题中提到的类型错误。我在下面分享了我的 main.dart 和welcome_screen.dart。在文档 https://flutter.dev/docs/development/ui/animations/tutorial中，他们还使用了动画控制器和曲线（以及 Tween），我想我也做了同样的事情。怎么解决这个问题呢？

主程序.dart

import 'package:flutter/material.dart'; import 'package:flash_chat/screens/welcome_screen.dart'; import 'package:flash_chat/screens/login_screen.dart'; import 'package:flash_chat/screens/registration_screen.dart'; import 'package:flash_chat/screens/chat_screen.dart';

void main() => runApp(FlashChat());

class FlashChat extends StatelessWidget {   @override   Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        textTheme: TextTheme(bodyText1: TextStyle(color: Colors.black54)),
      ),
      initialRoute: WelcomeScreen.id,
      routes: {
        WelcomeScreen.id: (context) => WelcomeScreen(),
        LoginScreen.id: (context) => LoginScreen(),
        RegistrationScreen.id: (context) => RegistrationScreen(),
        ChatScreen.id: (context) => ChatScreen(),
      },
    );   } }

欢迎屏幕.dart

import 'package:flutter/material.dart'; import 'package:flash_chat/screens/login_screen.dart'; import 'package:flash_chat/screens/registration_screen.dart';

class WelcomeScreen extends StatefulWidget {   static const …