AnimatedOpacity

main.dart

import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  @override
  State<MyApp> createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  var opacityLevel = 0.1;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('FlutterZero'),
        ),
        body: Center(
          child: GestureDetector(
            child: AnimatedOpacity(
              child: FlutterLogo(size: 150),
              duration: Duration(seconds: 2),
              opacity: opacityLevel,
            ),
            onTap: () => setState(
              () => opacityLevel = opacityLevel == 0.1 ? 1 : 0.1,
            ),
          ),
        ),
      ),
    );
  }
}