添加 Material 触摸水波效果

在设计应遵循Material Design指南的应用程序时，我们希望在点击时将水波动画添加到Widgets。

Flutter提供了InkWellWidget来实现这个效果。

步骤

1. 创建一个可点击的Widget。
2. 将它包裹在一个InkWell中来管理点击回调和水波动画。

// The InkWell Wraps our custom flat button Widget
new InkWell(
  // When the user taps the button, show a snackbar
  onTap: () {
    Scaffold.of(context).showSnackBar(new SnackBar(
      content: new Text('Tap'),
    ));
  },
  child: new Container(
    padding: new EdgeInsets.all(12.0),
    child: new Text('Flat Button'),
  ),
);

完整的例子

import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    final title = 'InkWell Demo';
    return new MaterialApp(
      title: title,
      home: new MyHomePage(title: title),
    );
  }
}
class MyHomePage extends StatelessWidget {
  final String title;
  MyHomePage({Key key, this.title}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text(title),
      ),
      body: new Center(child: new MyButton()),
    );
  }
}
class MyButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    // The InkWell Wraps our custom flat button Widget
    return new InkWell(
      // When the user taps the button, show a snackbar
      onTap: () {
        Scaffold.of(context).showSnackBar(new SnackBar(
          content: new Text('Tap'),
        ));
      },
      child: new Container(
        padding: new EdgeInsets.all(12.0),
        child: new Text('Flat Button'),
      ),
    );
  }
}