【Flutter/Dart】カレンダーを表示する

dependencies:
  flutter:
    sdk: flutter
  table_calendar: ^3.0.9 // 追加

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Calendar View Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: CalendarView(),
    );
  }
}

class CalendarView extends StatefulWidget {
  @override
  _CalendarViewState createState() => _CalendarViewState();
}

class _CalendarViewState extends State<CalendarView> {
  CalendarFormat _calendarFormat = CalendarFormat.month;
  DateTime _focusedDay = DateTime.now();
  DateTime? _selectedDay;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Calendar View'),
      ),
      body: Center(
        child: TableCalendar(
          calendarFormat: _calendarFormat,
          focusedDay: _focusedDay,
          firstDay: DateTime.utc(2021, 1, 1),
          lastDay: DateTime.utc(2030, 12, 31),
          selectedDayPredicate: (day) {
            // Use this predicate to determine if a day is selected
            return isSameDay(_selectedDay, day);
          },
          onFormatChanged: (format) {
            setState(() {
              _calendarFormat = format;
            });
          },
          onPageChanged: (focusedDay) {
            _focusedDay = focusedDay;
          },
          onDaySelected: (selectedDay, focusedDay) {
            setState(() {
              _selectedDay = selectedDay;
              _focusedDay = focusedDay;
            });
          },
        ),
      ),
    );
  }
}