Flutter响应式布局插件responsive_page的使用

开始使用

responsive_widget 包含了一些可以创建响应式用户界面的小部件。这个包主要用于为不同设备（或尺寸）创建页面结构。

在这个包中，你需要重写四个不同的构建方法：

• buildMobile
• buildWideMobileOrTablet
• buildWideTabletOrDesktop
• buildDesktop

这个包应该只在需要根据大小变化时改变整个结构的情况下使用。

保存状态

对于我创建这个包的目的来说： 在大小变化时（特别是在Web上），状态不会丢失。

导入包

import 'package:responsive_page/responsive_page.dart';

创建页面

设置全局断点

void main() {
  responsiveWidgetController.setDefaultBreakpoints(
    mobile: 500,
    wideMobileOrTablet: 800,
    wideTabletOrDesktop: 1150
  );
  runApp(const MyApp());
}

状态fulWidget

在这个包中，结构变化时状态不会消失。

只需要用 ResponsiveState 替换 State 即可。

然后创建缺失的覆盖方法。

class ResponsiveWelcomePage extends StatefulWidget {
  [@override](/user/override)
  _ResponsiveWelcomePageState createState() => _ResponsiveWelcomePageState();
}

// 使用 ResponsiveState 替换 State
class _ResponsiveWelcomePageState extends ResponsiveState<ResponsiveWelcomePage> {
  [@override](/user/override)
  Widget buildDesktop(BuildContext context) {}

  [@override](/user/override)
  Widget buildMobile(BuildContext context) {}

  [@override](/user/override)
  Widget buildWideMobileOrTablet(BuildContext context) {}

  [@override](/user/override)
  Widget buildWideTabletOrDesktop(BuildContext context) {}
}

无状态小部件

扩展 ResponsiveWidget 并创建缺失的覆盖方法。

// 扩展 ResponsiveWidget
class ResponsiveStatelessExample extends ResponsiveWidget {
  // 覆盖方法
}

减少种类

// 扩展 ResponsiveWidget
class ResponsiveStatelessExample extends ResponsiveWidget {
  // 覆盖方法
  [@override](/user/override)
  Widget buildMobile(BuildContext context) {
    return Container();
  }

  [@override](/user/override)
  Widget buildWideMobileOrTablet(BuildContext context) => buildMobile();
}

完整示例

以下是一个完整的示例，展示了如何使用 responsive_page 插件来创建一个响应式页面。

主文件

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

void main() {
  responsiveWidgetController.setDefaultBreakpoints(mobile: 500);
  runApp(ResponsivePageExampleApp());
}

///
class ResponsivePageExampleApp extends StatelessWidget {
  ///
  ResponsivePageExampleApp({Key key}) : super(key: key);

  [@override](/user/override)
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: AtoBExample(),
    );
  }
}

///
class AtoBExample extends StatefulWidget {
  [@override](/user/override)
  _AtoBExampleState createState() => _AtoBExampleState();
}

class _AtoBExampleState extends State<AtoBExample> {
  ScrollController scrollController = ScrollController();

  _toB() {
    scrollController.animateTo(MediaQuery.of(context).size.width,
        curve: Curves.easeIn, duration: const Duration(milliseconds: 500));
  }

  _toA() {
    scrollController.animateTo(0,
        curve: Curves.easeIn, duration: const Duration(milliseconds: 500));
  }

  [@override](/user/override)
  Widget build(BuildContext context) {
    var size = MediaQuery.of(context).size;
    return Scaffold(
      body: SingleChildScrollView(
        controller: scrollController,
        scrollDirection: Axis.horizontal,
        physics: const NeverScrollableScrollPhysics(),
        child: Row(
          children: [
            // A
            Builder(
              builder: (c) {
                print('GREEN BUILD');
                return InkWell(
                  onTap: () {
                    print('TO B');
                    _toB();
                  },
                  child: Container(
                    width: size.width,
                    height: size.height,
                    color: Colors.green,
                  ),
                );
              },
            ),
            Builder(
              builder: (c) {
                print('RED BUILD');
                return InkWell(
                  onTap: () {
                    print('TO A');
                    _toA();
                  },
                  child: Container(
                    width: size.width,
                    height: size.height,
                    color: Colors.red,
                  ),
                );
              },
            )
          ],
        ),
      ),
    );
  }
}

///
class MyHomePage extends StatefulWidget {
  ///
  MyHomePage({Key key, this.title}) : super(key: key);

  ///
  final String title;

  [@override](/user/override)
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends ResponsiveState<MyHomePage> {
  int _counter = 0;

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

  Widget redBox(Size size) {
    return Container(
      height: size.height,
      width: size.width,
      color: Colors.red,
    );
  }

  Widget greenBox(Size size) {
    return Container(
      height: size.height,
      width: size.width,
      color: Colors.green,
    );
  }

  Widget action(int i) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Text(
        'Action$i',
        style: const TextStyle(fontSize: 18),
      ),
    );
  }

  Widget countText() {
    return Text(
      '$_counter',
      style: Theme.of(context).textTheme.headline4,
    );
  }

  FloatingActionButton floatingActionButton() {
    return FloatingActionButton(
      onPressed: _incrementCounter,
      tooltip: 'Increment',
      child: const Icon(Icons.add),
    );
  }

  [@override](/user/override)
  Widget buildDesktop(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
          actions: [action(1), action(2), action(3)],
        ),
        body: Center(
          child: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Column(
                children: [
                  greenBox(Size(MediaQuery.of(context).size.width * 0.8,
                      MediaQuery.of(context).size.height * 0.4)),
                  redBox(Size(MediaQuery.of(context).size.width * 0.8,
                      MediaQuery.of(context).size.height * 0.4))
                ],
              ),
              countText(),
            ],
          ),
        ),
        floatingActionButton: floatingActionButton());
  }

  [@override](/user/override)
  Widget buildMobile(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: countText()),
        body: SingleChildScrollView(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              action(1),
              action(2),
              action(3),
              greenBox(Size(MediaQuery.of(context).size.width * 0.8,
                  MediaQuery.of(context).size.width * 0.5)),
              redBox(Size(MediaQuery.of(context).size.width * 0.8,
                  MediaQuery.of(context).size.width * 0.5))
            ],
          ),
        ),
        floatingActionButton: floatingActionButton());
  }

  [@override](/user/override)
  Widget buildWideMobileOrTablet(BuildContext context) {
    return Scaffold(
        appBar: AppBar(title: countText()),
        body: SingleChildScrollView(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Row(
                children: [
                  action(1),
                  action(2),
                  action(3),
                ],
              ),
              Row(
                children: [
                  greenBox(Size(MediaQuery.of(context).size.width * 0.4,
                      MediaQuery.of(context).size.width * 0.5)),
                  redBox(Size(MediaQuery.of(context).size.width * 0.4,
                      MediaQuery.of(context).size.width * 0.5))
                ],
              )
            ],
          ),
        ),
        floatingActionButton: floatingActionButton());
  }

  [@override](/user/override)
  Widget buildWideTabletOrDesktop(BuildContext context) => buildDesktop(context);
}