示例 1 ：使用搜索表单创建全屏模式
我们要构建的小应用程序有一个应用程序栏，右侧有一个搜索按钮。按下此按钮时，将出现一个全屏模式对话框。它不会突然跳出来，而是带有淡入淡出动画和幻灯片动画（从上到下）。在圆形搜索字段旁边，有一个取消按钮，可用于关闭模式。在搜索字段下方，我们会显示一些搜索历史记录（您可以添加其他内容，如建议、类别等）。
编码
我们通过定义一个扩展 ModalRoute 类的名为FullScreenSearchModal的类来创建完整模式。
main.dart中的完整源代码及说明：
// 大前端之旅
// 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(
// remove the debug banner
debugShowCheckedModeBanner: false,
title: '大前端之旅',
theme: ThemeData(
primarySwatch: Colors.green,
),
home: const KindaCodeDemo(),
);
}
}
// this class defines the full-screen search modal
// by extending the ModalRoute class
class FullScreenSearchModal extends ModalRoute {
@override
Duration get transitionDuration => const Duration(milliseconds: 500);
@override
bool get opaque => false;
@override
bool get barrierDismissible => false;
@override
Color get barrierColor => Colors.black.withOpacity(0.6);
@override
String? get barrierLabel => null;
@override
bool get maintainState => true;
@override
Widget buildPage(
BuildContext context,
Animation<double> animation,
Animation<double> secondaryAnimation,
) {
return Scaffold(
body: SafeArea(
child: Padding(
padding: const EdgeInsets.symmetric(vertical: 10, horizontal: 15),
child: Column(
mainAxisSize: MainAxisSize.min,
crossAxisAlignment: CrossAxisAlignment.start,
children: [
// implement the search field
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Expanded(
child: TextField(
autofocus: true,
decoration: InputDecoration(
contentPadding: const EdgeInsets.symmetric(
vertical: 0, horizontal: 20),
filled: true,
fillColor: Colors.grey.shade300,
suffixIcon: const Icon(Icons.close),
hintText: 'Search 大前端之旅',
border: OutlineInputBorder(
borderSide: BorderSide.none,
borderRadius: BorderRadius.circular(30)),
),
),
),
const SizedBox(
width: 10,
),
// This button is used to close the search modal
TextButton(
onPressed: () => Navigator.of(context).pop(),
child: const Text('Cancel'))
],
),
// display other things like search history, suggestions, search results, etc.
const SizedBox(
height: 20,
),
const Padding(
padding: EdgeInsets.only(left: 5),
child: Text('Recently Searched',
style:
TextStyle(fontSize: 18, fontWeight: FontWeight.bold)),
),
const ListTile(
title: Text('Flutter tutorials'),
leading: Icon(Icons.search),
trailing: Icon(Icons.close),
),
const ListTile(
title: Text('How to fry a chicken'),
leading: Icon(Icons.search),
trailing: Icon(Icons.close),
),
const ListTile(
title: Text('大前端之旅'),
leading: Icon(Icons.search),
trailing: Icon(Icons.close),
),
const ListTile(
title: Text('Goodbye World'),
leading: Icon(Icons.search),
trailing: Icon(Icons.close),
),
const ListTile(
title: Text('Cute Puppies'),
leading: Icon(Icons.search),
trailing: Icon(Icons.close),
)
],
),
),
),
);
}
// animations for the search modal
@override
Widget buildTransitions(BuildContext context, Animation<double> animation,
Animation<double> secondaryAnimation, Widget child) {
// add fade animation
return FadeTransition(
opacity: animation,
// add slide animation
child: SlideTransition(
position: Tween<Offset>(
begin: const Offset(0, -1),
end: Offset.zero,
).animate(animation),
child: child,
),
);
}
}
// This is the main screen of the application
class KindaCodeDemo extends StatelessWidget {
const KindaCodeDemo({Key? key}) : super(key: key);
void _showModal(BuildContext context) {
Navigator.of(context).push(FullScreenSearchModal());
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('大前端之旅'), actions: [
// this button is used to open the search modal
IconButton(
icon: const Icon(Icons.search),
onPressed: () => _showModal(context),
)
]),
body: Container(),
);
}
}示例 2：AppBar 内的搜索字段（最常见于娱乐应用程序）
通常，许多娱乐应用程序（包括 Facebook、Youtube、Spotify 等大型应用程序）默认不显示搜索字段，而是显示搜索图标按钮。按下此按钮时，将显示搜索字段。
我们要制作的演示应用程序包含 2 个屏幕（页面）：HomePage和SearchPage。用户可以通过点击搜索图标按钮从主页移动到搜索页面。搜索字段将通过使用SearchPage 的 AppBar的title参数来实现。
让我们看看它是如何工作的：
编码
./lib/main.dart中的完整源代码及说明：
// 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(
// Remove the debug banner
debugShowCheckedModeBanner: false,
title: '大前端之旅',
theme: ThemeData(
primarySwatch: Colors.indigo,
),
home: const HomePage());
}
}
// Home Page
class HomePage extends StatelessWidget {
const HomePage({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('大前端之旅'),
actions: [
// Navigate to the Search Screen
IconButton(
onPressed: () => Navigator.of(context)
.push(MaterialPageRoute(builder: (_) => const SearchPage())),
icon: const Icon(Icons.search))
],
),
);
}
}
// Search Page
class SearchPage extends StatelessWidget {
const SearchPage({Key? key}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
// The search area here
title: Container(
width: double.infinity,
height: 40,
decoration: BoxDecoration(
color: Colors.white, borderRadius: BorderRadius.circular(5)),
child: Center(
child: TextField(
decoration: InputDecoration(
prefixIcon: const Icon(Icons.search),
suffixIcon: IconButton(
icon: const Icon(Icons.clear),
onPressed: () {
/* Clear the search field */
},
),
hintText: 'Search...',
border: InputBorder.none),
),
),
)),
);
}
}示例 3：搜索字段和 SliverAppBar
广告搜索是许多电子商务应用程序最重要的功能之一，因此它们通常以最容易识别的方式显示搜索字段，并且从一开始就占用大量空间（亚马逊、Shopee 等）。
编码
// 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(
// Remove the debug banner
debugShowCheckedModeBanner: false,
title: '大前端之旅',
theme: ThemeData(
primarySwatch: Colors.deepPurple,
),
home: const HomePage());
}
}
class HomePage extends StatefulWidget {
const HomePage({Key? key}) : super(key: key);
@override
State<HomePage> createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: CustomScrollView(
slivers: [
SliverAppBar(
floating: true,
pinned: true,
snap: false,
centerTitle: false,
title: const Text('大前端之旅'),
actions: [
IconButton(
icon: const Icon(Icons.shopping_cart),
onPressed: () {},
),
],
bottom: AppBar(
title: Container(
width: double.infinity,
height: 40,
color: Colors.white,
child: const Center(
child: TextField(
decoration: InputDecoration(
hintText: 'Search for something',
prefixIcon: Icon(Icons.search),
suffixIcon: Icon(Icons.camera_alt)),
),
),
),
),
),
// Other Sliver Widgets
SliverList(
delegate: SliverChildListDelegate([
const SizedBox(
height: 400,
child: Center(
child: Text(
'This is an awesome shopping platform',
),
),
),
Container(
height: 1000,
color: Colors.pink,
),
]),
),
],
),
);
}
}结论
您已经研究了在 Flutter 中实现全屏搜索框的端到端示例。这种搜索方式如今非常流行，您可以在许多大型应用程序和移动网站中注意到它。
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