intrstc Altrntv

test.dart

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

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

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

class _MyAppState extends State<MyApp> {

  var currentHeight = 0.0;

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: Material(
        color: Colors.red,
        child: Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.spaceBetween,
            children: <Widget>[
              Container(
                width: 50,
                height: currentHeight,
                color: Colors.yellow,
              ),
              MeasureSize(
                onChange: (size){
                  setState(() {
                    currentHeight = size.height;
                  });
                },
                child: Column(
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    Text('123', style: TextStyle(fontSize: 20)),
                    Text('123', style: TextStyle(fontSize: 20)),
                  ],
                ),
              ),
            ],
          ),
        ),
      ),
    );
  }
}

typedef void OnWidgetSizeChange(Size size);

class MeasureSize extends StatefulWidget {
  final Widget child;
  final OnWidgetSizeChange onChange;

  const MeasureSize({
    Key key,
    @required this.onChange,
    @required this.child,
  }) : super(key: key);

  @override
  _MeasureSizeState createState() => _MeasureSizeState();
}

class _MeasureSizeState extends State<MeasureSize> {
  @override
  Widget build(BuildContext context) {
    SchedulerBinding.instance.addPostFrameCallback(postFrameCallback);
    return Container(
      key: widgetKey,
      child: widget.child,
    );
  }

  var widgetKey = GlobalKey();
  var oldSize;

  void postFrameCallback(_) {
    var context = widgetKey.currentContext;
    if (context == null) return;

    var newSize = context.size;
    if (oldSize == newSize) return;

    oldSize = newSize;
    widget.onChange(newSize);
  }
}