// 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'; class CullOpacityPage extends StatefulWidget { const CullOpacityPage({super.key}); @override State<StatefulWidget> createState() => _CullOpacityPageState(); } class _CullOpacityPageState extends State<CullOpacityPage> with SingleTickerProviderStateMixin { late Animation<double> _offsetY; late AnimationController _controller; @override void initState() { super.initState(); _controller = AnimationController(vsync: this, duration: const Duration(seconds: 2)); // Animations are typically implemented using the AnimatedBuilder widget. // This code uses a manual listener for historical reasons and will remain // in order to preserve compatibility with the history of measurements for // this benchmark. _offsetY = Tween<double>(begin: 0, end: -1000.0).animate(_controller)..addListener(() { setState(() {}); }); _controller.repeat(); } @override void dispose() { _controller.dispose(); super.dispose(); } @override Widget build(BuildContext context) { return Stack(children: List<Widget>.generate(50, (int i) => Positioned( left: 0, top: (200 * i).toDouble() + _offsetY.value, child: Opacity( opacity: 0.5, child: RepaintBoundary( child: Container( // Slightly change width to invalidate raster cache. width: 1000 - (_offsetY.value / 100), height: 100, color: Colors.red, ), ), ), ))); } }