Flutter 如何使DropDownMenu宽度等于TextFormfield

我正在try 使下拉菜单具有与TextFormfield相同的大小.我怎么能这样做呢？

我试过使用MediaQuery，但它占据了整个屏幕.

我不确定该如何处理这种情况.

我也try 过使用Width，例如Width:300，但我不确定这是否适用于所有设备，所以我正在寻找一个通用的解决方案.

import 'package:flutter/material.dart';

const List<String> list = <String>['One', 'Two', 'Three', 'Four'];

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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: Text('Raporteaza o problema'),
        ),
        body: MyCustomForm(),
      ),
    );
  }
}

// Define a custom Form widget.
class MyCustomForm extends StatefulWidget {
  const MyCustomForm({super.key});

  @override
  MyCustomFormState createState() {
    return MyCustomFormState();
  }
}

// Define a corresponding State class.
// This class holds data related to the form.
class MyCustomFormState extends State<MyCustomForm> {
  // Create a global key that uniquely identifies the Form widget
  // and allows validation of the form.
  //
  // Note: This is a `GlobalKey<FormState>`,
  // not a GlobalKey<MyCustomFormState>.
  final _formKey = GlobalKey<FormState>();
  String dropdownValue = list.first;

  @override
  Widget build(BuildContext context) {
    // Build a Form widget using the _formKey created above.
    return Form(
      key: _formKey,
      child: Column(
        children: <Widget>[
          Padding(
            padding: EdgeInsets.symmetric(horizontal: 15, vertical: 10),
            child: TextFormField(
              // The validator receives the text that the user has entered.
              validator: (value) {
                if (value == null || value.isEmpty) {
                  return 'Please enter some text';
                }
                return null;
              },
              decoration: const InputDecoration(
                labelText: 'Nume și prenume',
                border: OutlineInputBorder(),
                hintText: 'Nume și prenume',
              ),
            ),
          ),
          Padding(
            padding: EdgeInsets.symmetric(horizontal: 15, vertical: 10),
            child: TextFormField(
              validator: (value) {
                if (value == null || value.isEmpty) {
                  return 'Te rog introdu o adresă de email.';
                } else if (!RegExp(
                        r"^[a-zA-Z0-9.a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9]+\.[a-zA-Z]+")
                    .hasMatch(value)) {
                  return 'Te rog introdu o adresă de email validă.';
                }
                return null;
              },
              decoration: const InputDecoration(
                labelText: 'Email',
                border: OutlineInputBorder(),
                hintText: 'example@example.com',
              ),
            ),
          ),
          Padding(
            padding: EdgeInsets.symmetric(horizontal: 0, vertical: 10),
            child: DropdownMenu<String>(,
              initialSelection: list.first,
              onSelected: (String? value) {
                // This is called when the user selects an item.
                setState(() {
                  dropdownValue = value!;
                });
              },
              dropdownMenuEntries:
                  list.map<DropdownMenuEntry<String>>((String value) {
                return DropdownMenuEntry<String>(value: value, label: value);
              }).toList(),
            ),
          ),
          ElevatedButton(
            onPressed: () {
              // Validate returns true if the form is valid, or false otherwise.
              if (_formKey.currentState!.validate()) {
                // If the form is valid, display a snackbar. In the real world,
                // you'd often call a server or save the information in a database.
                ScaffoldMessenger.of(context).showSnackBar(
                  const SnackBar(content: Text('Processing Data')),
                );
              }
            },
            child: const Text('Submit'),
          ),
        ],
      ),
    );
  }
}