提问人:An Tran 提问时间:7/15/2022 最后编辑:An Tran 更新时间:7/15/2022 访问量:432
如何在listview.builder中的项目之间添加延迟?
How can i add delay between items in listview.builder?
问:
我有一个包含字符串项的 ListView。我想使ListView的项目延迟一个接一个地显示。在每个项目出现后,我想用打字指示器等待大约 2 秒钟,然后下一个项目就会出现。我该怎么办?请给我解决方案。谢谢!
答:
0赞
Muni
7/15/2022
#1
尝试将你的小部件包裹在这个小部件周围 https://pub.dev/packages/delayed_display。请确认这是否有效。
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An Tran
7/15/2022
这是行不通的。2 秒后,将出现所有项目。
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Hamid Musayev
7/15/2022
#2
您可以像下面的代码一样使用AnimatedListView
https://www.youtube.com/watch?v=ZtfItHwFlZ8
// main.dart
import 'package:flutter/material.dart';
void main() {
runApp(const MyApp());
}
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
title: 'Test',
theme: ThemeData(
primaryColor: Colors.green,
colorScheme:
ColorScheme.fromSwatch().copyWith(secondary: Colors.greenAccent)),
home: const HomePage(),
);
}
}
class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);
@override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
// Items in the list
final _items = ["Item 0"];
// The key of the list
final GlobalKey<AnimatedListState> _key = GlobalKey();
// Add a new item to the list
// This is trigger when the floating button is pressed
void _addItem() {
_items.insert(0, "Item ${_items.length + 1}");
_key.currentState!.insertItem(0, duration: const Duration(seconds: 1));
}
// Remove an item
// This is trigger when an item is tapped
void _removeItem(int index, BuildContext context) {
AnimatedList.of(context).removeItem(index, (_, animation) {
return FadeTransition(
opacity: animation,
child: SizeTransition(
sizeFactor: animation,
child: SizedBox(
height: 150,
child: Card(
margin: const EdgeInsets.symmetric(vertical: 20),
elevation: 10,
color: Colors.red[400],
child: const Center(
child: Text("I am going away",
style: const TextStyle(fontSize: 28)),
),
),
),
),
);
}, duration: const Duration(seconds: 1));
_items.removeAt(index);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Test list'),
actions: [
IconButton(
onPressed: _addItem,
icon: const Icon(Icons.plus_one_outlined),
)
],
),
body: AnimatedList(
key: _key,
initialItemCount: 1,
padding: const EdgeInsets.all(10),
itemBuilder: (context, index, animation) {
return SlideTransition(
key: UniqueKey(),
position: Tween<Offset>(
begin: const Offset(-1, -0.5),
end: const Offset(0, 0),
).animate(animation),
child: RotationTransition(
turns: animation,
child: SizeTransition(
axis: Axis.vertical,
sizeFactor: animation,
child: SizedBox(
height: 150,
child: InkWell(
onTap: () => _removeItem(index, context),
child: Card(
margin: const EdgeInsets.symmetric(vertical: 20),
elevation: 10,
color: Colors.primaries[
(index * 100) % Colors.primaries.length][300],
child: Center(
child: Text(_items[index],
style: const TextStyle(fontSize: 28)),
),
),
),
),
),
),
);
},
),
);
}
}
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