fake_gravity_bounce_animation.dart

import 'package:flutter/material.dart';
import 'package:flutter/physics.dart';
import 'package:flutter_hooks/flutter_hooks.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(primarySwatch: Colors.blue),
      home: const Home(),
    );
  }
}

class Home extends StatelessWidget {
  const Home({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Animation')),
      body: const Center(child: _Animation()),
    );
  }
}

const kRestitution = 0.6;

class _Animation extends HookWidget {
  const _Animation({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    const boxSize = 20.0;
    final barHeight = MediaQuery.of(context).size.height * 0.8;

    final controller =
        useAnimationController(duration: const Duration(seconds: 3));

    final animation =
        CurvedAnimation(parent: controller, curve: Curves.bounceOut);

    return Stack(
      children: [
        Container(
          decoration: BoxDecoration(
            border: Border.all(color: Colors.black54, width: 2.0),
          ),
          height: barHeight,
          width: boxSize,
        ),
        AnimatedBuilder(
            animation: controller,
            builder: (context, _) {
              return Positioned(
                top: animation.value * (barHeight - boxSize),
                left: 0,
                child: GestureDetector(
                  onTap: () => controller.animateWith(
                    GravitySimulation(1.0, 0.0, barHeight, 0.0),
                  ),
                  child: Container(
                    height: boxSize,
                    width: boxSize,
                    color: Colors.red.withOpacity(0.54),
                  ),
                ),
              );
            }),
      ],
    );
  }
}