Flutter bug

gistfile1.txt

import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage>  with TickerProviderStateMixin {
  late AnimationController _controller;

  static const _animationDuration = Duration(milliseconds: 100);
  static const _curve = Curves.easeIn;
  final _curveFlipped = _curve.flipped;

  Animation<double> get _scale => Tween<double>(
    begin: 1.0,
    end: 0.76,
  ).animate(
    CurvedAnimation(
      parent: _controller,
      curve: _curve,
      reverseCurve: _curveFlipped,
    ),
  );
  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      vsync: this,
      duration: _animationDuration,
    );
  }
  final scrollController = ScrollController();

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: CustomScrollView(
          controller: scrollController,
          cacheExtent: double.maxFinite,
          slivers: [
             SliverToBoxAdapter(
              child:  Listener(
                onPointerDown: _handleOnPointerDown,
                onPointerUp: _handleOnPointerUp,
                child: AnimatedBuilder(
                  builder: _buildAnimation,
                  animation: _controller,
                  child: Text('hello'),
                ),
              )
            ),
          ],
        ),
      ),
    );
  }
 
  void _handleOnPointerDown(_) {
    setState(() {
      _isPointerDown = true;
    });
    _controller.forward().whenComplete(() {
      if (!_isPointerDown) _controller.reverse();
    });
  }
  bool _isPointerDown = false;
  bool get _isAnimating => _controller.isAnimating;

  void _handleOnPointerUp(_) {
    setState(() {
      _isPointerDown = false;
    });
    if (!_isAnimating) _controller.reverse();
  }

  Widget _buildAnimation(BuildContext context, Widget? child){
    return Transform.scale(
      scale: _scale.value,
      child:Container(
          decoration: const ShapeDecoration(
            shape: RoundedRectangleBorder(
              side: BorderSide(color: Colors.red, width: 1),
              borderRadius: BorderRadius.all(Radius.circular(8)
              ),
            ),
            color: Colors.white,
          ),
        child: Transform.scale(
          scale: 1 + (1 - _scale.value),
          child: child,
        ),
      )
    );
  }
}