Overflowing Widget inside a Row

main.dart

import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
          appBar: AppBar(title: Text("hello!")),
          body: BasicWidget(),
    ));
  }
}

class BasicWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ListView(children: [
      Container(
          color: Colors.green,
          padding: EdgeInsets.only(top: 20, left: 20, right: 20, bottom: 10),
          child: Container(
              decoration: BoxDecoration(
                border: Border.all(color: Colors.blueAccent),
              ),
              child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Expanded(child: Text('hello')),
                    Expanded(child: Text('b')),
                    Expanded(child: Text('c')),
                  ]))),
      Container(
          color: Colors.green,
          padding: EdgeInsets.only(top: 10, left: 20, right: 20, bottom: 10),
          child: Container(
              decoration: BoxDecoration(
                border: Border.all(color: Colors.blueAccent),
              ),
              child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Expanded(
                        child: Row(mainAxisSize: MainAxisSize.max, children: [
                      Text('hello'),
                      Expanded(
                          child: OverlayWidget(
                              child: Text('*',
                                  style: TextStyle(
                                      color: Colors.red, fontSize: 34)),
                              keepHeight: false,
                              keepWidth: true)),
                    ])),
                    Expanded(child: Text('b')),
                    Expanded(child: Text('c')),
                  ]))),
      Container(
          color: Colors.green,
          padding: EdgeInsets.only(top: 10, left: 20, right: 20, bottom: 20),
          child: Container(
              decoration: BoxDecoration(
                border: Border.all(color: Colors.blueAccent),
              ),
              child: Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    Expanded(child: Text('hello')),
                    Expanded(child: Text('b')),
                    Expanded(child: Text('c')),
                  ]))),
      Container(color: Colors.red, height: 700),
    ]);
  }
}

class OverlayWidget extends SingleChildRenderObjectWidget {
  const OverlayWidget({
    Key? key,
    this.keepHeight = true,
    this.keepWidth = true,
    required Widget child,
  }) : super(key: key, child: child);

  final bool keepHeight;
  final bool keepWidth;

  @override
  RenderObject createRenderObject(BuildContext context) {
    return _OverlayWidgetRenderObject(
      keepHeight: keepHeight,
      keepWidth: keepWidth,
    );
  }
}

/// An element that notifies whenever its size changes.
class _OverlayWidgetRenderObject extends RenderProxyBox {
  _OverlayWidgetRenderObject({
    required this.keepHeight,
    required this.keepWidth,
  });

  final bool keepHeight;
  final bool keepWidth;

  Size? _size;

  @override
  void paint(PaintingContext context, Offset offset) {
    super.paint(
        context,
        offset.translate(
          0,
          keepHeight ? 0 : -_size!.height / 2,
        ));
  }

  @override
  void performLayout() {
    super.performLayout();

    _size = child!.size;

    size = constraints.constrain(Size(
      constraints.biggest.width,
      keepHeight ? size.height : 0,
    ));
  }
}