flutter_intro

main.dart

import 'package:flutter/material.dart';

final Color darkBlue = Color.fromARGB(255, 18, 32, 47);

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(scaffoldBackgroundColor: darkBlue),
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  OverlayEntry overlayEntry;
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          RaisedButton(
            onPressed: () {
              overlayEntry = OverlayEntry(
                builder: (context) => Container(
                  color: Colors.white.withOpacity(.4),
                  child: Center(
                    child: RaisedButton(
                      onPressed: () {
                        overlayEntry.remove();
                      },
                      child: Text('点我关闭 OverlayEntry'),
                    ),
                  ),
                ),
              );
              Overlay.of(context).insert(overlayEntry);
            },
            child: Text('点我康康 Overlay 的用法'),
          ),
        ],
      ),
    );
  }
}