Layout Builder

 /// Syntax:

///   LayoutBuilder(
///   builder: (BuildContext context, BoxConstraints constraints) {
///   return Widget();
///   }
///   ),


import "package:flutter/material.dart";

void main() {
  runApp(MyApp(),);
}
class MyApp extends StatelessWidget {
  MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: "LayoutBuilder in Flutter",
      theme: ThemeData(
        primarySwatch: Colors.indigo,
      ),
      home: LayoutBuilderExample(),
    );
  }
}
class LayoutBuilderExample extends StatelessWidget {
  LayoutBuilderExample({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("LayoutBuilder"),
      ),
      body: LayoutBuilder(
        builder: (BuildContext context, BoxConstraints constraints) {
          if(constraints.maxWidth > 600) {
            return _buildWideContainer();
          } else {
            return _buildNormalContainer();
          }
        },
      ),
    );
  }
}
Widget _buildNormalContainer() {
  return Center(
    child: Container(
      width: 200,
      height: 200,
      color: Colors.red,
    ),
  );
}
Widget _buildWideContainer() {
  return Center(
    child: Row(
      mainAxisAlignment: MainAxisAlignment.spaceEvenly,
      children: <Widget>[
        Container(
          height: 200.0,
          width: 200.0,
          color: Colors.indigo,
        ),
        Container(
          height: 200.0,
          width: 200.0,
          color: Colors.pink,
        ),
        Container(
          height: 200.0,
          width: 200.0,
          color: Colors.amber,
        ),
      ],
    ),
  );
}