flutter给滚动内容添加粘性header组件

本文主要是介绍flutter给滚动内容添加粘性header组件，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

前言

Flutter是谷歌的移动UI框架，可以快速在iOS和Android上构建高质量的原生用户界面。

IT界著名的尼古拉斯·高尔包曾说：轮子是IT进步的阶梯！热门的框架千篇一律，好用轮子万里挑一！Flutter作为这两年开始崛起的跨平台开发框架，其第三方生态相比其他成熟框架还略有不足，但轮子的数量也已经很多了。本系列文章挑选日常app开发常用的轮子分享出来，给大家提高搬砖效率，同时也希望flutter的生态越来越完善，轮子越来越多。

本系列文章准备了超过50个轮子推荐，工作原因，尽量每1-2天出一篇文章。

tip:本系列文章合适已有部分flutter基础的开发者，入门请戳：flutter官网

正文

轮子

轮子名称：sticky_headers
轮子概述：flutter给滚动内容添加粘性header组件.
轮子作者：fluttercommunity.dev(官方)
推荐指数：★★★★
常用指数：★★★★
效果预览：
效果图

安装

yaml

1 2	dependencies:sticky_headers: ^0.1.8+1

dart

1	import 'package:sticky_headers/sticky_headers.dart';

使用方法

在列表项中，使用StickyHeader()，基本用法：（gif效果图中的默认效果）

dart

ListView.builder(itemCount: 12,itemBuilder: (context, index) {return StickyHeader(header: Container( //header组件height: 50.0,color: Colors.blueGrey[700],padding: EdgeInsets.symmetric(horizontal: 16.0),alignment: Alignment.centerLeft,child: Text('Header #$index',style: const TextStyle(color: Colors.white),),),content: Container(//内容组件child: Image.network(imgs[index], fit: BoxFit.cover,width: double.infinity, height: 200.0),),);}
)

在列表项中，使用StickyHeaderBuilder()来自定义更多的header效果和事件：（gif效果图中的自定义header效果）

dart

ListView.builder(itemCount: 12,itemBuilder: (context, index) {return StickyHeaderBuilder(builder: (BuildContext context, double stuckAmount) {stuckAmount = 1.0 - stuckAmount.clamp(0.0, 1.0);return new Container(height: 50.0,color: Color.lerp(Colors.blue[700], Colors.red[700], stuckAmount),padding: new EdgeInsets.symmetric(horizontal: 16.0),alignment: Alignment.centerLeft,child: new Row(children: <Widget>[new Expanded(child: new Text('Header #$index',style: const TextStyle(color: Colors.white),),),new Offstage(offstage: stuckAmount <= 0.0,child: new Opacity(opacity: stuckAmount,child: new IconButton(icon: new Icon(Icons.favorite, color: Colors.white),onPressed: () =>Scaffold.of(context).showSnackBar(new SnackBar(content: new Text('Favorite #$index'))),),),),],),);},content: new Container(child: new Image.network(imgs[index], fit: BoxFit.cover,width: double.infinity, height: 200.0),),);}
)

在列表项中，使用StickyHeaderBuilder()，overlapHeaders=true,使header悬浮在内容上：（gif效果图中的header浮动）

dart

ListView.builder(itemCount: 12,itemBuilder: (context, index) {return new StickyHeaderBuilder(overlapHeaders: true,builder: (BuildContext context, double stuckAmount) {stuckAmount = 1.0 - stuckAmount.clamp(0.0, 1.0);return new Container(height: 50.0,color: Colors.grey[900].withOpacity(0.6 + stuckAmount * 0.4),padding: new EdgeInsets.symmetric(horizontal: 16.0),alignment: Alignment.centerLeft,child: new Text('Header #$index',style: const TextStyle(color: Colors.white),),);},content: new Container(child: new Image.network(imgs[index], fit: BoxFit.cover,width: double.infinity, height: 200.0),),);}
)

数据分组，在content中渲染子列表，形成类似RN的SectionList：（gif效果图中的SectionList效果）

dart

class StickyHeadersDemo4 extends StatefulWidget {StickyHeadersDemo4({Key key}) : super(key: key);@override_demoState createState() => _demoState();
}class _demoState extends State<StickyHeadersDemo4> {List data=[{"latter":"A","group":["A分组1","A分组1","A分组1","A分组1","A分组1","A分组1"]},{"latter":"B","group":["B分组1","B分组1","B分组1","B分组1","B分组1","B分组1"]},{"latter":"C","group":["C分组1","C分组1","C分组1","C分组1","C分组1","C分组1"]},{"latter":"D","group":["D分组1","D分组1","D分组1","D分组1","D分组1","D分组1"]},{"latter":"E","group":["E分组1","E分组1","E分组1","E分组1","E分组1","E分组1"]}];@overrideWidget build(BuildContext context) {return Scaffold(appBar: AppBar(title: Text("sticky_headers"),actions: <Widget>[GoWeb(pluginName: 'sticky_headers')],),body: ListView.builder(itemCount: data.length,itemBuilder: (context, index) {return StickyHeader(header: Container(height: 50.0,color: Colors.blueGrey[700],padding: EdgeInsets.symmetric(horizontal: 16.0),alignment: Alignment.centerLeft,child: Text(data[index]['latter'],style: const TextStyle(color: Colors.white),),),content: Column(children: buildGroup(data[index]['group']),),);}));}List<Widget> buildGroup(List group){return group.map((item){return Container(height: 60,alignment: Alignment.centerLeft,padding: EdgeInsets.only(left: 20),child: Text(item),);}).toList();}
}