今天接到这样一个需求，需要自定义弹窗，所以就有了如下的代码：

通过分析，一切皆widget 所以可以这样实现：

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_screenutil/flutter_screenutil.dart';





 showDialog(
                  barrierDismissible: true, //表示点击灰色背景的时候是否消失弹出框
                  context: context,
                  builder: (context) {
                    return MyDialogWidget();
                  });
                  




                  
                  class MyDialogWidget extends StatelessWidget {
  const MyDialogWidget({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Material(
      type: MaterialType.transparency,
      child: Center(
          child: Container(
        height: 245.w,
        width: 564.w,
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(
            24.w,
          ),
          color: Colors.white,
        ),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.start,
          children: <Widget>[
            Padding(
              padding: EdgeInsets.only(
                  top: 52.w, left: 120.w, right: 120.w, bottom: 52.w),
              child: Text(
                '退出将不保留此次编辑',
                style: TextStyle(
                  fontSize: 32.w,
                  color: Color(0xFF000000),
                  fontWeight: FontWeight.bold,
                ),
              ),
            ),
            SizedBox(
              width: 564.w,
              height: 1.w,
              child: DecoratedBox(
                decoration: BoxDecoration(color: Color(0xFFDDDDDD)),
              ),
            ),
            Row(
              mainAxisAlignment: MainAxisAlignment.center,
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Container(
                  padding: EdgeInsets.only(right: 60.w),
                  child: FlatButton(
                    child: Center(
                      child: new Text(
                        '不保留',
                        style:
                            TextStyle(fontSize: 32.w, color: Color(0xFF999999)),
                      ),
                    ),
                    onPressed: () {
                      Navigator.of(context).pop();
                      Navigator.of(context).pop();
                    },
                  ),
                ),
                SizedBox(
                  width: 1.w,
                  height: 94.w,
                  child: DecoratedBox(
                    decoration: BoxDecoration(color: Color(0xFFDDDDDD)),
                  ),
                ),
                Container(
                  padding: EdgeInsets.only(
                    left: 60.w,
                  ),
                  child: FlatButton(
                      onPressed: () {
                        Navigator.of(context).pop();
                      },
                      child: Text(
                        "继续编辑",
                        style:
                            TextStyle(fontSize: 32.w, color: Color(0xFF23A427)),
                      )),
                )
              ],
            )
          ],
        ),
      )),
    );
  }
}