如何在flutter中设置谷歌地图的底部表单？

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

class MapPage extends StatefulWidget {
  @override
  _MapPageState createState() => _MapPageState();
}

class _MapPageState extends State<MapPage> {
  GoogleMapController _mapController;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Google Map'),
      ),
      body: Stack(
        children: [
          GoogleMap(
            initialCameraPosition: CameraPosition(
              target: LatLng(37.422, -122.084),
              zoom: 10,
            ),
            onMapCreated: (controller) {
              setState(() {
                _mapController = controller;
              });
            },
            onTap: (position) {
              // Handle map tap event
            },
          ),
          Positioned(
            bottom: 0,
            left: 0,
            right: 0,
            child: Container(
              padding: EdgeInsets.all(16),
              color: Colors.white,
              child: Column(
                children: [
                  TextField(
                    decoration: InputDecoration(
                      labelText: 'Name',
                    ),
                  ),
                  SizedBox(height: 16),
                  RaisedButton(
                    child: Text('Submit'),
                    onPressed: () {
                      // Handle form submission
                    },
                  ),
                ],
              ),
            ),
          ),
        ],
      ),
    );
  }
}