我正在使用 Flutter 开发我的第一个应用程序。有时我想知道：我是否正确地开发了 UX 部分？意思是我使用了正确的小部件，有没有更好的方法来做到这一点等等。我在 Intellj Idea 上发现了 Flutter Performance，我看到我开发的大部分页面都是红色的...
仅供参考：我为一个简单页面创建的代码
Flutter 检查器结果 => radio-btn-aligned
import 'package:flutter/material.dart';
import 'package:testapp/my_theme.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: MyAppTheme(ctx: context).defaultTheme,
home: new Scaffold(
appBar: new AppBar(
title: new Text("Title"),
),
body: AddDailyTaskPage()),
);
}
}
enum Options { goal, category }
class AddDailyTaskPage extends StatefulWidget {
@override
_AddDailyTaskPageState createState() => new _AddDailyTaskPageState();
}
class _AddDailyTaskPageState extends State<AddDailyTaskPage> {
Options _options = Options.goal;
@override
Widget build(BuildContext context) {
return Container(
child: Column(
children: [
Container(
child: Text("Task Description"),
),
Container(child: Row(
children: [
Expanded(
child: Row(
children: [
Radio<Options>(
value: Options.goal,
groupValue: _options,
onChanged: (Options value) {
setState(() {
_options = value;
});
},
),
Text(
'Goal',
style: new TextStyle(fontSize: 16.0),
)
]
)
),
Expanded(
child: Row(
children: [
Container(
child: Radio(
value: Options.category,
groupValue: _options,
onChanged: (Options value) {
setState(() {
_options = value;
});
},
),
),
Container(
child: Text(
'Category',
style: new TextStyle(
fontSize: 16.0,
),
),
)
],
)
)
],
),)
// Container(
// child: TextField(
// maxLines: 10,
// decoration: InputDecoration(
// // suffixIcon:
// focusedBorder: OutlineInputBorder(
// borderSide: BorderSide(color: Colors.grey, width: 5.0),
// ),
// enabledBorder: OutlineInputBorder(
// borderSide: BorderSide(color: Colors.black, width: 5.0),
// ),
// hintText: 'Description task',
// ),
// ),
// )
],
),
);
}
}
为了查看差异，我查看了创建flutter项目时提供的示例代码
仅供参考： 颤振性能结果：auto-increment 正如我们在上一张图片中看到的那样，它似乎没有优化.. :/
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this
// case the title) provided by the parent (in this case the App widget) and
// used by the build method of the State. Fields in a Widget subclass are
// always marked "final".
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
// This call to setState tells the Flutter framework that something has
// changed in this State, which causes it to rerun the build method below
// so that the display can reflect the updated values. If we changed
// _counter without calling setState(), then the build method would not be
// called again, and so nothing would appear to happen.
_counter++;
});
}
@override
Widget build(BuildContext context) {
// This method is rerun every time setState is called, for instance as done
// by the _incrementCounter method above.
//
// The Flutter framework has been optimized to make rerunning build methods
// fast, so that you can just rebuild anything that needs updating rather
// than having to individually change instances of widgets.
return Scaffold(
appBar: AppBar(
// Here we take the value from the MyHomePage object that was created by
// the App.build method, and use it to set our appbar title.
title: Text(widget.title),
),
body: Center(
// Center is a layout widget. It takes a single child and positions it
// in the middle of the parent.
child: Column(
// Column is also a layout widget. It takes a list of children and
// arranges them vertically. By default, it sizes itself to fit its
// children horizontally, and tries to be as tall as its parent.
//
// Invoke "debug painting" (press "p" in the console, choose the
// "Toggle Debug Paint" action from the Flutter Inspector in Android
// Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
// to see the wireframe for each widget.
//
// Column has various properties to control how it sizes itself and
// how it positions its children. Here we use mainAxisAlignment to
// center the children vertically; the main axis here is the vertical
// axis because Columns are vertical (the cross axis would be
// horizontal).
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
几个问题： 1/ 有没有人/知道一个很好的 Flutter 存储库，其中包含大量基于性能的示例？
2/ 你的性能标准是什么？我的意思是在我的虚拟设备上，用户体验似乎很流畅，但如果 Flutter Perf 是“红色”，那么我猜我做错了什么，有更好的方法吗？
3/ 你们知道一个网站/论坛/愿意每周进行一次核心审查以帮助我在我的 Flutter 应用程序中实现良好模式的人吗？
4/ 我目前的设计有什么问题？默认设计有什么问题？为什么性能似乎不太好？我开始阅读 perf 的官方文档，但我怎么知道 UX 本身是否具有良好的性能？实际上通过测试一些东西，我发现把所有东西都放在容器/行或列小部件中，提高了很多性能，但即使有这个小部件，这还不够：/
有什么建议吗？
感谢您的帮助
答案 0 :(得分：0)
您对整个页面使用 StatefulWidget。这意味着当您调用 setState() 时，整个页面都会重建。
一个例子是：
Radio<Options>(
value: Options.goal,
groupValue: _options,
onChanged: (Options value) {
setState(() {
_options = value;
});
},
),
设置选项时无需重建整个页面。如果您将该代码提取到它自己的 StatefulWidget 中，则只会重建这部分。
您可以点击“跟踪小部件重建”以查看您的应用中哪些小部件会重建，然后考虑这些小部件是否真的应该重建。
一旦您制作较小的 Widget，您就会遇到一个问题，即一个 Widget 中的事件应该会影响其他 Widget。这就是状态管理解决方案发挥作用的时候。 Bloc 包的 weather example 展示了您可以复制的良好应用结构。