// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'package:flutter/material.dart'; /// Flutter code sample for [ScrollMetricsNotification]. void main() => runApp(const ScrollMetricsDemo()); class ScrollMetricsDemo extends StatefulWidget { const ScrollMetricsDemo({super.key}); @override State<ScrollMetricsDemo> createState() => ScrollMetricsDemoState(); } class ScrollMetricsDemoState extends State<ScrollMetricsDemo> { double windowSize = 200.0; @override Widget build(BuildContext context) { return MaterialApp( home: Scaffold( appBar: AppBar( title: const Text('ScrollMetrics Demo'), ), floatingActionButton: FloatingActionButton( child: const Icon(Icons.add), onPressed: () => setState(() { windowSize += 10.0; }), ), body: NotificationListener<ScrollMetricsNotification>( onNotification: (ScrollMetricsNotification notification) { ScaffoldMessenger.of(notification.context).showSnackBar( const SnackBar( content: Text('Scroll metrics changed!'), ), ); return false; }, child: Scrollbar( thumbVisibility: true, child: SizedBox( height: windowSize, width: double.infinity, child: const SingleChildScrollView( primary: true, child: FlutterLogo( size: 300.0, ), ), ), ), ), ), ); } }