在 TextField Flutter 中垂直居中对齐文本

我尝试查找大量资源，但不幸的是我找不到一种方法来将文本在文本字段中垂直居中对齐。我也尝试使用 suffixIcon 而不是 suffix 但仍然不走运。这是我的代码：

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _HomePageState();
  }
}

class _HomePageState extends State<HomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        leading: Icon(
          Icons.menu,
          color: Colors.black,
        ),
        backgroundColor: Colors.white,
        title: Container(
          margin: EdgeInsets.only(bottom: 10),
          child: Image.asset(
            "icons/logo.png",
          ),
        ),
        bottom: PreferredSize(
          child: Padding(
            padding: EdgeInsets.only(
              left: 10,
              right: 10,
              bottom: 10,
            ),
            child: Container(
              height: 40,
              child: TextField(
                textAlignVertical: TextAlignVertical.center,
                textAlign: TextAlign.left,
                maxLines: 1,
                style: TextStyle(
                  fontSize: 13,
                ),
                decoration: InputDecoration(
                    suffixIcon: IconButton(icon: Icon(Icons.search, color: Colors.black,), onPressed: (){}),
                    border: OutlineInputBorder(
                      borderSide: BorderSide(
                        color: Colors.black,
                      ),
                      borderRadius: BorderRadius.all(Radius.circular(15)),
                    )
                ),
              ),
            ),
          ),
          preferredSize: Size(MediaQuery.of(context).size.width, 50),
        ),
      ),
      body: Container(
        margin: EdgeInsets.only(top: 11),
        child: Column(
          children: <Widget>[
            Carousel(),
          ],
        ),
      ),
    );
  }
}

class Carousel extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _CarouselState();
  }
}

class _CarouselState extends State<Carousel> {
  List<String> urls = [];

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: EdgeInsets.symmetric(horizontal: 10),
      child: Stack(
        children: <Widget>[
          Image.network(
              "someImageUrlHere."),
          Positioned(
            bottom: 5,
            width: MediaQuery.of(context).size.width - 20,
            child: Row(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text("•"),
                Text("•"),
                Text("•"),
                Text("•"),
                Text("•"),
              ],
            ),
          ),
        ],
      ),
    );
  }
}

导致此问题的可能是什么？我该如何解决这个问题？

TextField(
   textAlign: TextAlign.center,
   decoration: InputDecoration(
     hintText: "Centered Hint",
   ),
)

希望这会有所帮助。