Flutterで角を丸くする

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;

  void _incrementCounter() {
    setState(() {
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    String dropdownValue = 'One';
    return Scaffold(
      backgroundColor: Colors.grey,
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            ClipRRect(
              borderRadius: BorderRadius.all(Radius.circular(30)),
              child: Container(
                width: 200,
                height: 100,
                color: Colors.yellow,
                child: Padding(
                  padding: const EdgeInsets.all(8),
                  child: const TextField(
                    obscureText: true,
                    decoration: InputDecoration(
                      border: InputBorder.none,
                      labelText: 'Pass',
                    ),
                  ),
                ),
              ),
            ),
            Gap(20),
            Container(
              padding: const EdgeInsets.symmetric(horizontal: 5),
              width: 200,
              decoration: BoxDecoration(
                border: Border.all(color: Colors.blue),
                borderRadius: BorderRadius.circular(20),
              ),
              child: const TextField(
                obscureText: true,
                decoration: InputDecoration(
                  border: InputBorder.none,
                  labelText: 'Pass',
                ),
              ),
            ),
            Gap(20),
            Container(
              padding: const EdgeInsets.symmetric(horizontal: 5),
              width: 200,
              decoration: BoxDecoration(
                border: Border.all(color: Colors.blue),
                borderRadius: BorderRadius.circular(20),
              ),
              child: DropdownButton<String>(
                value: dropdownValue,
                icon: const Icon(Icons.arrow_downward),
                iconSize: 24,
                elevation: 16,
                style: const TextStyle(color: Colors.deepPurple),
                onChanged: (String? newValue) {},
                items: <String>['One', 'Two', 'Free', 'Four']
                    .map<DropdownMenuItem<String>>((String value) {
                  return DropdownMenuItem<String>(
                    value: value,
                    child: Text(value),
                  );
                }).toList(),
              ),
            ),
            Gap(20),
            Text(
              'You have pushed the button this many times:',
              style: TextStyle(color: Colors.white),
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}