一些滚动后颤动ListView KeepAlive [英] flutter ListView KeepAlive after some scroll

问题描述

我想keepAlive 已经在 ListView 中呈现的小部件.我尝试使用由 ListView 类提供的 addAutomaticKeepAlives:true 属性.

I want to keepAlive my widgets which are already rendered in ListView. I was tried with addAutomaticKeepAlives:true properties which provide by ListView class.

这是我使用的示例代码.SliverChildBuilderDelegate 委托中的相同问题，由 SliverList 提供.

Here is my sample code which I was used. Same issue in SliverChildBuilderDelegate delegate which provide by SliverList.

ListView.builder(
    itemBuilder: (context,index){
      return Card(
        child: Container(
          child: Image.asset("images/${index+1}.jpg",fit: BoxFit.cover,),
          height: 250.0,
        ),
      );
    },
    addAutomaticKeepAlives: true,
    itemCount:40 ,
);

推荐答案

为了使 automaticKeepAlive 工作，每个需要保持活动的项目都必须发送特定的通知.

For automaticKeepAlive to work, each item that needs to be kept alive must send a specific notification.

触发此类通知的典型方法是使用 AutomaticKeepAliveClientMixinp>

A typical way to fire such notification is using AutomaticKeepAliveClientMixin

class Foo extends StatefulWidget {
  @override
  FooState createState() {
    return new FooState();
  }
}

class FooState extends State<Foo> with AutomaticKeepAliveClientMixin {
  @override
  Widget build(BuildContext context) {
    return Container(

    );
  }

  @override
  bool get wantKeepAlive => true;
}

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