main.dart

import 'package:flutter/material.dart';

void main() => runApp(const LogoApp());

double? first = null;

class AnimatedLogo extends AnimatedWidget {
  const AnimatedLogo({super.key, required Animation<double> animation})
      : super(listenable: animation);

  @override
  Widget build(BuildContext context) {
    final animation = listenable as Animation<double>;
    if (first == null) {
      // Log the first value
      first = animation.value;
      print(first);
    }
    return Center(
      child: Container(
        margin: const EdgeInsets.symmetric(vertical: 10),
        height: animation.value + 100,
        width: animation.value + 100,
        child: const FlutterLogo(),
      ),
    );
  }
}

class LogoApp extends StatefulWidget {
  const LogoApp({super.key});

  @override
  State<LogoApp> createState() => _LogoAppState();
}

class _LogoAppState extends State<LogoApp> with SingleTickerProviderStateMixin {
  late Animation<double> animation;
  late AnimationController controller;

  @override
  void initState() {
    super.initState();
    controller = AnimationController(
        duration: const Duration(seconds: 2),
        vsync: this,
        lowerBound: -100,
        upperBound: 200);
    // Swap the two lines above with the two below to see the other issue
//         lowerBound: 100,
//         upperBound: 300);
    controller.repeat();
  }

  @override
  Widget build(BuildContext context) => AnimatedLogo(animation: controller);

  @override
  void dispose() {
    controller.dispose();
    super.dispose();
  }
}