Flutter自定义扩展组件插件extension_widget的使用

Flutter自定义扩展组件插件extension_widget的使用

在本教程中，我们将学习如何使用extension_widget插件来创建具有CSS样式的自定义扩展组件。extension_widget插件允许我们通过链式调用的方式设置各种样式属性。

简介

extension_widget插件灵感来自于CSS的盒模型。通过使用该插件，我们可以轻松地为任何Widget添加内边距、外边距、背景颜色、圆角等样式。

// Container
Text('abc').div(DivStyle(
  height: 50,
  width: 50,
  paddingAll: 10,
  backgroundColor: Colors.blue,
  alignment: Alignment.center,
  radiusAll: 30,
)).div(DivStyle(
  paddingAll: 10,
  marginAll: 10,
  backgroundColor: Colors.green,
  alignment: Alignment.center,
  radiusAll: 50,
)).ink(() {
  print('clicked!');
});

开始使用

首先，我们需要在pubspec.yaml文件中添加extension_widget依赖：

dependencies:
  flutter:
    sdk: flutter
  extension_widget: ^1.0.0

然后，运行flutter pub get以获取依赖项。

接下来，我们创建一个简单的应用来演示extension_widget的使用方法。

示例代码

以下是一个完整的示例，展示了如何使用extension_widget插件来构建一个带有多种样式的文本组件。

import 'package:flutter/material.dart';
import 'package:extension_widget/extension_widget.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  double size = 50;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Colors.white,
        actions: [
          TextButton(
            onPressed: () {
              setState(() {
                size = 100;
              });
            },
            child: const Text('size 100'),
          ),
          TextButton(
            onPressed: () {
              setState(() {
                size = 50;
              });
            },
            child: const Text('size 50'),
          ),
        ],
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headlineMedium,
            )
                .div(
                    DivStyle(
                      width: size,
                      height: size,
                      backgroundColor: Colors.grey,
                      alignment: Alignment.center,
                      radiusAll: 25,
                    ),
                    true)
                .div(DivStyle(
                  paddingAll: 10,
                  backgroundColor: Colors.blue,
                  radiusAll: 50,
                ))
                .div(DivStyle(
                    marginAll: 10, border: Border.all(color: Colors.green)))
                .div(DivStyle(
                  paddingAll: 10,
                  backgroundColor: Colors.red,
                  radiusAll: 100,
                )),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

代码解释

1. 导入依赖：

   import 'package:flutter/material.dart';
   import 'package:extension_widget/extension_widget.dart';
   

2. 主应用类：

   class MyApp extends StatelessWidget {
     const MyApp({super.key});
   
     @override
     Widget build(BuildContext context) {
       return MaterialApp(
         title: 'Flutter Demo',
         theme: ThemeData(
           primarySwatch: Colors.blue,
         ),
         home: const MyHomePage(title: 'Flutter Demo Home Page'),
       );
     }
   }
   

3. 主页状态类：

   class MyHomePage extends StatefulWidget {
     const MyHomePage({super.key, required this.title});
   
     final String title;
   
     @override
     State<MyHomePage> createState() => _MyHomePageState();
   }
   

4. 主页状态实现类：

   class _MyHomePageState extends State<MyHomePage> {
     int _counter = 0;
     double size = 50;
   
     void _incrementCounter() {
       setState(() {
         _counter++;
       });
     }
   
     @override
     Widget build(BuildContext context) {
       return Scaffold(
         appBar: AppBar(
           backgroundColor: Colors.white,
           actions: [
             TextButton(
               onPressed: () {
                 setState(() {
                   size = 100;
                 });
               },
               child: const Text('size 100'),
             ),
             TextButton(
               onPressed: () {
                 setState(() {
                   size = 50;
                 });
               },
               child: const Text('size 50'),
             ),
           ],
         ),
         body: Center(
           child: Column(
             mainAxisAlignment: MainAxisAlignment.center,
             children: <Widget>[
               const Text(
                 'You have pushed the button this many times:',
               ),
               Text(
                 '$_counter',
                 style: Theme.of(context).textTheme.headlineMedium,
               )
                   .div(
                       DivStyle(
                         width: size,
                         height: size,
                         backgroundColor: Colors.grey,
                         alignment: Alignment.center,
                         radiusAll: 25,
                       ),
                       true)
                   .div(DivStyle(
                     paddingAll: 10,
                     backgroundColor: Colors.blue,
                     radiusAll: 50,
                   ))
                   .div(DivStyle(
                       marginAll: 10, border: Border.all(color: Colors.green)))
                   .div(DivStyle(
                     paddingAll: 10,
                     backgroundColor: Colors.red,
                     radiusAll: 100,
                   )),
             ],
           ),
         ),
         floatingActionButton: FloatingActionButton(
           onPressed: _incrementCounter,
           tooltip: 'Increment',
           child: const Icon(Icons.add),
         ),
       );
     }
   }