packages/flutter/lib/src/material/date_picker_deprecated.dart - external/github.com/flutter/flutter - Git at Google

 // Copyright 2014 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:async';
 import 'dart:math' as math;

 import 'package:flutter/gestures.dart' show DragStartBehavior;
 import 'package:flutter/rendering.dart';
 import 'package:flutter/widgets.dart';

 import 'date.dart';
 import 'icon_button.dart';
 import 'icons.dart';
 import 'material_localizations.dart';
 import 'theme.dart';

 // This is the original implementation for the Material Date Picker.
 // These classes are deprecated and the whole file can be removed after
 // this has been on stable for long enough for people to migrate to the new
 // CalendarDatePicker (if needed, as showDatePicker has already been migrated
 // and it is what most apps would have used).


 // Examples can assume:
 // // @dart = 2.9
 // BuildContext context;

 const Duration _kMonthScrollDuration = Duration(milliseconds: 200);
 const double _kDayPickerRowHeight = 42.0;
 const int _kMaxDayPickerRowCount = 6; // A 31 day month that starts on Saturday.
 // Two extra rows: one for the day-of-week header and one for the month header.
 const double _kMaxDayPickerHeight = _kDayPickerRowHeight * (_kMaxDayPickerRowCount + 2);

 class _DayPickerGridDelegate extends SliverGridDelegate {
   const _DayPickerGridDelegate();

   @override
   SliverGridLayout getLayout(SliverConstraints constraints) {
     const int columnCount = DateTime.daysPerWeek;
     final double tileWidth = constraints.crossAxisExtent / columnCount;
     final double viewTileHeight = constraints.viewportMainAxisExtent / (_kMaxDayPickerRowCount + 1);
     final double tileHeight = math.max(_kDayPickerRowHeight, viewTileHeight);
     return SliverGridRegularTileLayout(
       crossAxisCount: columnCount,
       mainAxisStride: tileHeight,
       crossAxisStride: tileWidth,
       childMainAxisExtent: tileHeight,
       childCrossAxisExtent: tileWidth,
       reverseCrossAxis: axisDirectionIsReversed(constraints.crossAxisDirection),
     );
   }

   @override
   bool shouldRelayout(_DayPickerGridDelegate oldDelegate) => false;
 }

 const _DayPickerGridDelegate _kDayPickerGridDelegate = _DayPickerGridDelegate();

 /// Displays the days of a given month and allows choosing a day.
 ///
 /// The days are arranged in a rectangular grid with one column for each day of
 /// the week.
 ///
 /// The day picker widget is rarely used directly. Instead, consider using
 /// [showDatePicker], which creates a date picker dialog.
 ///
 /// See also:
 ///
 ///  * [showDatePicker], which shows a dialog that contains a material design
 ///    date picker.
 ///  * [showTimePicker], which shows a dialog that contains a material design
 ///    time picker.
 ///
 @Deprecated(
   'Use CalendarDatePicker instead. '
   'This feature was deprecated after v1.15.3.'
 )
 class DayPicker extends StatelessWidget {
   /// Creates a day picker.
   ///
   /// Rarely used directly. Instead, typically used as part of a [MonthPicker].
   DayPicker({
     Key? key,
     required this.selectedDate,
     required this.currentDate,
     required this.onChanged,
     required this.firstDate,
     required this.lastDate,
     required this.displayedMonth,
     this.selectableDayPredicate,
     this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(selectedDate != null),
        assert(currentDate != null),
        assert(onChanged != null),
        assert(displayedMonth != null),
        assert(dragStartBehavior != null),
        assert(!firstDate.isAfter(lastDate)),
        assert(selectedDate.isAfter(firstDate) || selectedDate.isAtSameMomentAs(firstDate)),
        super(key: key);

   /// The currently selected date.
   ///
   /// This date is highlighted in the picker.
   final DateTime selectedDate;

   /// The current date at the time the picker is displayed.
   final DateTime currentDate;

   /// Called when the user picks a day.
   final ValueChanged<DateTime> onChanged;

   /// The earliest date the user is permitted to pick.
   final DateTime firstDate;

   /// The latest date the user is permitted to pick.
   final DateTime lastDate;

   /// The month whose days are displayed by this picker.
   final DateTime displayedMonth;

   /// Optional user supplied predicate function to customize selectable days.
   final SelectableDayPredicate? selectableDayPredicate;

   /// Determines the way that drag start behavior is handled.
   ///
   /// If set to [DragStartBehavior.start], the drag gesture used to scroll a
   /// date picker wheel will begin upon the detection of a drag gesture. If set
   /// to [DragStartBehavior.down] it will begin when a down event is first
   /// detected.
   ///
   /// In general, setting this to [DragStartBehavior.start] will make drag
   /// animation smoother and setting it to [DragStartBehavior.down] will make
   /// drag behavior feel slightly more reactive.
   ///
   /// By default, the drag start behavior is [DragStartBehavior.start].
   ///
   /// See also:
   ///
   ///  * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
   final DragStartBehavior dragStartBehavior;

   /// Builds widgets showing abbreviated days of week. The first widget in the
   /// returned list corresponds to the first day of week for the current locale.
   ///
   /// Examples:
   ///
   /// ```
   /// ┌ Sunday is the first day of week in the US (en_US)
   /// |
   /// S M T W T F S  <-- the returned list contains these widgets
   /// _ _ _ _ _ 1 2
   /// 3 4 5 6 7 8 9
   ///
   /// ┌ But it's Monday in the UK (en_GB)
   /// |
   /// M T W T F S S  <-- the returned list contains these widgets
   /// _ _ _ _ 1 2 3
   /// 4 5 6 7 8 9 10
   /// ```
   List<Widget> _getDayHeaders(TextStyle? headerStyle, MaterialLocalizations localizations) {
     final List<Widget> result = <Widget>[];
     for (int i = localizations.firstDayOfWeekIndex; true; i = (i + 1) % 7) {
       final String weekday = localizations.narrowWeekdays[i];
       result.add(ExcludeSemantics(
         child: Center(child: Text(weekday, style: headerStyle)),
       ));
       if (i == (localizations.firstDayOfWeekIndex - 1) % 7)
         break;
     }
     return result;
   }

   // Do not use this directly - call getDaysInMonth instead.
   static const List<int> _daysInMonth = <int>[31, -1, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

   /// Returns the number of days in a month, according to the proleptic
   /// Gregorian calendar.
   ///
   /// This applies the leap year logic introduced by the Gregorian reforms of
   /// 1582. It will not give valid results for dates prior to that time.
   static int getDaysInMonth(int year, int month) {
     if (month == DateTime.february) {
       final bool isLeapYear = (year % 4 == 0) && (year % 100 != 0) || (year % 400 == 0);
       if (isLeapYear)
         return 29;
       return 28;
     }
     return _daysInMonth[month - 1];
   }

   /// Computes the offset from the first day of week that the first day of the
   /// [month] falls on.
   ///
   /// For example, September 1, 2017 falls on a Friday, which in the calendar
   /// localized for United States English appears as:
   ///
   /// ```
   /// S M T W T F S
   /// _ _ _ _ _ 1 2
   /// ```
   ///
   /// The offset for the first day of the months is the number of leading blanks
   /// in the calendar, i.e. 5.
   ///
   /// The same date localized for the Russian calendar has a different offset,
   /// because the first day of week is Monday rather than Sunday:
   ///
   /// ```
   /// M T W T F S S
   /// _ _ _ _ 1 2 3
   /// ```
   ///
   /// So the offset is 4, rather than 5.
   ///
   /// This code consolidates the following:
   ///
   /// - [DateTime.weekday] provides a 1-based index into days of week, with 1
   ///   falling on Monday.
   /// - [MaterialLocalizations.firstDayOfWeekIndex] provides a 0-based index
   ///   into the [MaterialLocalizations.narrowWeekdays] list.
   /// - [MaterialLocalizations.narrowWeekdays] list provides localized names of
   ///   days of week, always starting with Sunday and ending with Saturday.
   int _computeFirstDayOffset(int year, int month, MaterialLocalizations localizations) {
     // 0-based day of week, with 0 representing Monday.
     final int weekdayFromMonday = DateTime(year, month).weekday - 1;
     // 0-based day of week, with 0 representing Sunday.
     final int firstDayOfWeekFromSunday = localizations.firstDayOfWeekIndex;
     // firstDayOfWeekFromSunday recomputed to be Monday-based
     final int firstDayOfWeekFromMonday = (firstDayOfWeekFromSunday - 1) % 7;
     // Number of days between the first day of week appearing on the calendar,
     // and the day corresponding to the 1-st of the month.
     return (weekdayFromMonday - firstDayOfWeekFromMonday) % 7;
   }

   @override
   Widget build(BuildContext context) {
     final ThemeData themeData = Theme.of(context);
     final MaterialLocalizations localizations = MaterialLocalizations.of(context);
     final int year = displayedMonth.year;
     final int month = displayedMonth.month;
     final int daysInMonth = getDaysInMonth(year, month);
     final int firstDayOffset = _computeFirstDayOffset(year, month, localizations);
     final List<Widget> labels = <Widget>[
       ..._getDayHeaders(themeData.textTheme.caption, localizations),
     ];
     for (int i = 0; true; i += 1) {
       // 1-based day of month, e.g. 1-31 for January, and 1-29 for February on
       // a leap year.
       final int day = i - firstDayOffset + 1;
       if (day > daysInMonth)
         break;
       if (day < 1) {
         labels.add(Container());
       } else {
         final DateTime dayToBuild = DateTime(year, month, day);
         final bool disabled = dayToBuild.isAfter(lastDate)
             || dayToBuild.isBefore(firstDate)
             || (selectableDayPredicate != null && !selectableDayPredicate!(dayToBuild));

         BoxDecoration? decoration;
         TextStyle? itemStyle = themeData.textTheme.bodyText2;

         final bool isSelectedDay = selectedDate.year == year && selectedDate.month == month && selectedDate.day == day;
         if (isSelectedDay) {
           // The selected day gets a circle background highlight, and a contrasting text color.
           itemStyle = themeData.accentTextTheme.bodyText1;
           decoration = BoxDecoration(
             color: themeData.accentColor,
             shape: BoxShape.circle,
           );
         } else if (disabled) {
           itemStyle = themeData.textTheme.bodyText2!.copyWith(color: themeData.disabledColor);
         } else if (currentDate.year == year && currentDate.month == month && currentDate.day == day) {
           // The current day gets a different text color.
           itemStyle = themeData.textTheme.bodyText1!.copyWith(color: themeData.accentColor);
         }

         Widget dayWidget = Container(
           decoration: decoration,
           child: Center(
             child: Semantics(
               // We want the day of month to be spoken first irrespective of the
               // locale-specific preferences or TextDirection. This is because
               // an accessibility user is more likely to be interested in the
               // day of month before the rest of the date, as they are looking
               // for the day of month. To do that we prepend day of month to the
               // formatted full date.
               label: '${localizations.formatDecimal(day)}, ${localizations.formatFullDate(dayToBuild)}',
               selected: isSelectedDay,
               sortKey: OrdinalSortKey(day.toDouble()),
               child: ExcludeSemantics(
                 child: Text(localizations.formatDecimal(day), style: itemStyle),
               ),
             ),
           ),
         );

         if (!disabled) {
           dayWidget = GestureDetector(
             behavior: HitTestBehavior.opaque,
             onTap: () {
               onChanged(dayToBuild);
             },
             child: dayWidget,
             dragStartBehavior: dragStartBehavior,
           );
         }

         labels.add(dayWidget);
       }
     }

     return Padding(
       padding: const EdgeInsets.symmetric(horizontal: 8.0),
       child: Column(
         children: <Widget>[
           Container(
             height: _kDayPickerRowHeight,
             child: Center(
               child: ExcludeSemantics(
                 child: Text(
                   localizations.formatMonthYear(displayedMonth),
                   style: themeData.textTheme.subtitle1,
                 ),
               ),
             ),
           ),
           Flexible(
             child: GridView.custom(
               gridDelegate: _kDayPickerGridDelegate,
               childrenDelegate: SliverChildListDelegate(labels, addRepaintBoundaries: false),
               padding: EdgeInsets.zero,
             ),
           ),
         ],
       ),
     );
   }
 }

 /// A scrollable list of months to allow picking a month.
 ///
 /// Shows the days of each month in a rectangular grid with one column for each
 /// day of the week.
 ///
 /// The month picker widget is rarely used directly. Instead, consider using
 /// [showDatePicker], which creates a date picker dialog.
 ///
 /// See also:
 ///
 ///  * [showDatePicker], which shows a dialog that contains a material design
 ///    date picker.
 ///  * [showTimePicker], which shows a dialog that contains a material design
 ///    time picker.
 ///
 @Deprecated(
   'Use CalendarDatePicker instead. '
   'This feature was deprecated after v1.15.3.'
 )
 class MonthPicker extends StatefulWidget {
   /// Creates a month picker.
   ///
   /// Rarely used directly. Instead, typically used as part of the dialog shown
   /// by [showDatePicker].
   MonthPicker({
     Key? key,
     required this.selectedDate,
     required this.onChanged,
     required this.firstDate,
     required this.lastDate,
     this.selectableDayPredicate,
     this.dragStartBehavior = DragStartBehavior.start,
   }) : assert(selectedDate != null),
        assert(onChanged != null),
        assert(!firstDate.isAfter(lastDate)),
        assert(selectedDate.isAfter(firstDate) || selectedDate.isAtSameMomentAs(firstDate)),
        super(key: key);

   /// The currently selected date.
   ///
   /// This date is highlighted in the picker.
   final DateTime selectedDate;

   /// Called when the user picks a month.
   final ValueChanged<DateTime> onChanged;

   /// The earliest date the user is permitted to pick.
   final DateTime firstDate;

   /// The latest date the user is permitted to pick.
   final DateTime lastDate;

   /// Optional user supplied predicate function to customize selectable days.
   final SelectableDayPredicate? selectableDayPredicate;

   /// {@macro flutter.widgets.scrollable.dragStartBehavior}
   final DragStartBehavior dragStartBehavior;

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

 class _MonthPickerState extends State<MonthPicker> with SingleTickerProviderStateMixin {
   static final Animatable<double> _chevronOpacityTween = Tween<double>(begin: 1.0, end: 0.0)
     .chain(CurveTween(curve: Curves.easeInOut));

   @override
   void initState() {
     super.initState();
     // Initially display the pre-selected date.
     final int monthPage = _monthDelta(widget.firstDate, widget.selectedDate);
     _dayPickerController = PageController(initialPage: monthPage);
     _handleMonthPageChanged(monthPage);
     _updateCurrentDate();

     // Setup the fade animation for chevrons
     _chevronOpacityController = AnimationController(
       duration: const Duration(milliseconds: 250), vsync: this,
     );
     _chevronOpacityAnimation = _chevronOpacityController.drive(_chevronOpacityTween);
   }

   @override
   void didUpdateWidget(MonthPicker oldWidget) {
     super.didUpdateWidget(oldWidget);
     if (widget.selectedDate != oldWidget.selectedDate) {
       final int monthPage = _monthDelta(widget.firstDate, widget.selectedDate);
       _dayPickerController = PageController(initialPage: monthPage);
       _handleMonthPageChanged(monthPage);
     }
   }

   MaterialLocalizations? localizations;
   TextDirection? textDirection;

   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
     localizations = MaterialLocalizations.of(context);
     textDirection = Directionality.of(context);
   }

   late DateTime _todayDate;
   late DateTime _currentDisplayedMonthDate;
   Timer? _timer;
   late PageController _dayPickerController;
   late AnimationController _chevronOpacityController;
   late Animation<double> _chevronOpacityAnimation;

   void _updateCurrentDate() {
     _todayDate = DateTime.now();
     final DateTime tomorrow = DateTime(_todayDate.year, _todayDate.month, _todayDate.day + 1);
     Duration timeUntilTomorrow = tomorrow.difference(_todayDate);
     timeUntilTomorrow += const Duration(seconds: 1); // so we don't miss it by rounding
     _timer?.cancel();
     _timer = Timer(timeUntilTomorrow, () {
       setState(() {
         _updateCurrentDate();
       });
     });
   }

   static int _monthDelta(DateTime startDate, DateTime endDate) {
     return (endDate.year - startDate.year) * 12 + endDate.month - startDate.month;
   }

   /// Add months to a month truncated date.
   DateTime _addMonthsToMonthDate(DateTime monthDate, int monthsToAdd) {
     return DateTime(monthDate.year + monthsToAdd ~/ 12, monthDate.month + monthsToAdd % 12);
   }

   Widget _buildItems(BuildContext context, int index) {
     final DateTime month = _addMonthsToMonthDate(widget.firstDate, index);
     return DayPicker(
       key: ValueKey<DateTime>(month),
       selectedDate: widget.selectedDate,
       currentDate: _todayDate,
       onChanged: widget.onChanged,
       firstDate: widget.firstDate,
       lastDate: widget.lastDate,
       displayedMonth: month,
       selectableDayPredicate: widget.selectableDayPredicate,
       dragStartBehavior: widget.dragStartBehavior,
     );
   }

   void _handleNextMonth() {
     if (!_isDisplayingLastMonth) {
       SemanticsService.announce(localizations!.formatMonthYear(_nextMonthDate), textDirection!);
       _dayPickerController.nextPage(duration: _kMonthScrollDuration, curve: Curves.ease);
     }
   }

   void _handlePreviousMonth() {
     if (!_isDisplayingFirstMonth) {
       SemanticsService.announce(localizations!.formatMonthYear(_previousMonthDate), textDirection!);
       _dayPickerController.previousPage(duration: _kMonthScrollDuration, curve: Curves.ease);
     }
   }

   /// True if the earliest allowable month is displayed.
   bool get _isDisplayingFirstMonth {
     return !_currentDisplayedMonthDate.isAfter(
         DateTime(widget.firstDate.year, widget.firstDate.month));
   }

   /// True if the latest allowable month is displayed.
   bool get _isDisplayingLastMonth {
     return !_currentDisplayedMonthDate.isBefore(
         DateTime(widget.lastDate.year, widget.lastDate.month));
   }

   late DateTime _previousMonthDate;
   late DateTime _nextMonthDate;

   void _handleMonthPageChanged(int monthPage) {
     setState(() {
       _previousMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage - 1);
       _currentDisplayedMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage);
       _nextMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage + 1);
     });
   }

   @override
   Widget build(BuildContext context) {
     return SizedBox(
       // The month picker just adds month navigation to the day picker, so make
       // it the same height as the DayPicker
       height: _kMaxDayPickerHeight,
       child: Stack(
         children: <Widget>[
           Semantics(
             sortKey: _MonthPickerSortKey.calendar,
             child: NotificationListener<ScrollStartNotification>(
               onNotification: (_) {
                 _chevronOpacityController.forward();
                 return false;
               },
               child: NotificationListener<ScrollEndNotification>(
                 onNotification: (_) {
                   _chevronOpacityController.reverse();
                   return false;
                 },
                 child: PageView.builder(
                   dragStartBehavior: widget.dragStartBehavior,
                   key: ValueKey<DateTime>(widget.selectedDate),
                   controller: _dayPickerController,
                   scrollDirection: Axis.horizontal,
                   itemCount: _monthDelta(widget.firstDate, widget.lastDate) + 1,
                   itemBuilder: _buildItems,
                   onPageChanged: _handleMonthPageChanged,
                 ),
               ),
             ),
           ),
           PositionedDirectional(
             top: 0.0,
             start: 8.0,
             child: Semantics(
               sortKey: _MonthPickerSortKey.previousMonth,
               child: FadeTransition(
                 opacity: _chevronOpacityAnimation,
                 child: IconButton(
                   icon: const Icon(Icons.chevron_left),
                   tooltip: _isDisplayingFirstMonth ? null : '${localizations!.previousMonthTooltip} ${localizations!.formatMonthYear(_previousMonthDate)}',
                   onPressed: _isDisplayingFirstMonth ? null : _handlePreviousMonth,
                 ),
               ),
             ),
           ),
           PositionedDirectional(
             top: 0.0,
             end: 8.0,
             child: Semantics(
               sortKey: _MonthPickerSortKey.nextMonth,
               child: FadeTransition(
                 opacity: _chevronOpacityAnimation,
                 child: IconButton(
                   icon: const Icon(Icons.chevron_right),
                   tooltip: _isDisplayingLastMonth ? null : '${localizations!.nextMonthTooltip} ${localizations!.formatMonthYear(_nextMonthDate)}',
                   onPressed: _isDisplayingLastMonth ? null : _handleNextMonth,
                 ),
               ),
             ),
           ),
         ],
       ),
     );
   }

   @override
   void dispose() {
     _timer?.cancel();
     _chevronOpacityController.dispose();
     _dayPickerController.dispose();
     super.dispose();
   }
 }

 // Defines semantic traversal order of the top-level widgets inside the month
 // picker.
 class _MonthPickerSortKey extends OrdinalSortKey {
   const _MonthPickerSortKey(double order) : super(order);

   static const _MonthPickerSortKey previousMonth = _MonthPickerSortKey(1.0);
   static const _MonthPickerSortKey nextMonth = _MonthPickerSortKey(2.0);
   static const _MonthPickerSortKey calendar = _MonthPickerSortKey(3.0);
 }
	// Copyright 2014 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:async';
	import 'dart:math' as math;

	import 'package:flutter/gestures.dart' show DragStartBehavior;
	import 'package:flutter/rendering.dart';
	import 'package:flutter/widgets.dart';

	import 'date.dart';
	import 'icon_button.dart';
	import 'icons.dart';
	import 'material_localizations.dart';
	import 'theme.dart';

	// This is the original implementation for the Material Date Picker.
	// These classes are deprecated and the whole file can be removed after
	// this has been on stable for long enough for people to migrate to the new
	// CalendarDatePicker (if needed, as showDatePicker has already been migrated
	// and it is what most apps would have used).


	// Examples can assume:
	// // @dart = 2.9
	// BuildContext context;

	const Duration _kMonthScrollDuration = Duration(milliseconds: 200);
	const double _kDayPickerRowHeight = 42.0;
	const int _kMaxDayPickerRowCount = 6; // A 31 day month that starts on Saturday.
	// Two extra rows: one for the day-of-week header and one for the month header.
	const double _kMaxDayPickerHeight = _kDayPickerRowHeight * (_kMaxDayPickerRowCount + 2);

	class _DayPickerGridDelegate extends SliverGridDelegate {
	const _DayPickerGridDelegate();

	@override
	SliverGridLayout getLayout(SliverConstraints constraints) {
	const int columnCount = DateTime.daysPerWeek;
	final double tileWidth = constraints.crossAxisExtent / columnCount;
	final double viewTileHeight = constraints.viewportMainAxisExtent / (_kMaxDayPickerRowCount + 1);
	final double tileHeight = math.max(_kDayPickerRowHeight, viewTileHeight);
	return SliverGridRegularTileLayout(
	crossAxisCount: columnCount,
	mainAxisStride: tileHeight,
	crossAxisStride: tileWidth,
	childMainAxisExtent: tileHeight,
	childCrossAxisExtent: tileWidth,
	reverseCrossAxis: axisDirectionIsReversed(constraints.crossAxisDirection),
	);
	}

	@override
	bool shouldRelayout(_DayPickerGridDelegate oldDelegate) => false;
	}

	const _DayPickerGridDelegate _kDayPickerGridDelegate = _DayPickerGridDelegate();

	/// Displays the days of a given month and allows choosing a day.
	///
	/// The days are arranged in a rectangular grid with one column for each day of
	/// the week.
	///
	/// The day picker widget is rarely used directly. Instead, consider using
	/// [showDatePicker], which creates a date picker dialog.
	///
	/// See also:
	///
	/// * [showDatePicker], which shows a dialog that contains a material design
	/// date picker.
	/// * [showTimePicker], which shows a dialog that contains a material design
	/// time picker.
	///
	@Deprecated(
	'Use CalendarDatePicker instead. '
	'This feature was deprecated after v1.15.3.'
	)
	class DayPicker extends StatelessWidget {
	/// Creates a day picker.
	///
	/// Rarely used directly. Instead, typically used as part of a [MonthPicker].
	DayPicker({
	Key? key,
	required this.selectedDate,
	required this.currentDate,
	required this.onChanged,
	required this.firstDate,
	required this.lastDate,
	required this.displayedMonth,
	this.selectableDayPredicate,
	this.dragStartBehavior = DragStartBehavior.start,
	}) : assert(selectedDate != null),
	assert(currentDate != null),
	assert(onChanged != null),
	assert(displayedMonth != null),
	assert(dragStartBehavior != null),
	assert(!firstDate.isAfter(lastDate)),
	assert(selectedDate.isAfter(firstDate) \|\| selectedDate.isAtSameMomentAs(firstDate)),
	super(key: key);

	/// The currently selected date.
	///
	/// This date is highlighted in the picker.
	final DateTime selectedDate;

	/// The current date at the time the picker is displayed.
	final DateTime currentDate;

	/// Called when the user picks a day.
	final ValueChanged<DateTime> onChanged;

	/// The earliest date the user is permitted to pick.
	final DateTime firstDate;

	/// The latest date the user is permitted to pick.
	final DateTime lastDate;

	/// The month whose days are displayed by this picker.
	final DateTime displayedMonth;

	/// Optional user supplied predicate function to customize selectable days.
	final SelectableDayPredicate? selectableDayPredicate;

	/// Determines the way that drag start behavior is handled.
	///
	/// If set to [DragStartBehavior.start], the drag gesture used to scroll a
	/// date picker wheel will begin upon the detection of a drag gesture. If set
	/// to [DragStartBehavior.down] it will begin when a down event is first
	/// detected.
	///
	/// In general, setting this to [DragStartBehavior.start] will make drag
	/// animation smoother and setting it to [DragStartBehavior.down] will make
	/// drag behavior feel slightly more reactive.
	///
	/// By default, the drag start behavior is [DragStartBehavior.start].
	///
	/// See also:
	///
	/// * [DragGestureRecognizer.dragStartBehavior], which gives an example for the different behaviors.
	final DragStartBehavior dragStartBehavior;

	/// Builds widgets showing abbreviated days of week. The first widget in the
	/// returned list corresponds to the first day of week for the current locale.
	///
	/// Examples:
	///
	/// ```
	/// ┌ Sunday is the first day of week in the US (en_US)
	/// \|
	/// S M T W T F S <-- the returned list contains these widgets
	/// _ _ _ _ _ 1 2
	/// 3 4 5 6 7 8 9
	///
	/// ┌ But it's Monday in the UK (en_GB)
	/// \|
	/// M T W T F S S <-- the returned list contains these widgets
	/// _ _ _ _ 1 2 3
	/// 4 5 6 7 8 9 10
	/// ```
	List<Widget> _getDayHeaders(TextStyle? headerStyle, MaterialLocalizations localizations) {
	final List<Widget> result = <Widget>[];
	for (int i = localizations.firstDayOfWeekIndex; true; i = (i + 1) % 7) {
	final String weekday = localizations.narrowWeekdays[i];
	result.add(ExcludeSemantics(
	child: Center(child: Text(weekday, style: headerStyle)),
	));
	if (i == (localizations.firstDayOfWeekIndex - 1) % 7)
	break;
	}
	return result;
	}

	// Do not use this directly - call getDaysInMonth instead.
	static const List<int> _daysInMonth = <int>[31, -1, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];

	/// Returns the number of days in a month, according to the proleptic
	/// Gregorian calendar.
	///
	/// This applies the leap year logic introduced by the Gregorian reforms of
	/// 1582. It will not give valid results for dates prior to that time.
	static int getDaysInMonth(int year, int month) {
	if (month == DateTime.february) {
	final bool isLeapYear = (year % 4 == 0) && (year % 100 != 0) \|\| (year % 400 == 0);
	if (isLeapYear)
	return 29;
	return 28;
	}
	return _daysInMonth[month - 1];
	}

	/// Computes the offset from the first day of week that the first day of the
	/// [month] falls on.
	///
	/// For example, September 1, 2017 falls on a Friday, which in the calendar
	/// localized for United States English appears as:
	///
	/// ```
	/// S M T W T F S
	/// _ _ _ _ _ 1 2
	/// ```
	///
	/// The offset for the first day of the months is the number of leading blanks
	/// in the calendar, i.e. 5.
	///
	/// The same date localized for the Russian calendar has a different offset,
	/// because the first day of week is Monday rather than Sunday:
	///
	/// ```
	/// M T W T F S S
	/// _ _ _ _ 1 2 3
	/// ```
	///
	/// So the offset is 4, rather than 5.
	///
	/// This code consolidates the following:
	///
	/// - [DateTime.weekday] provides a 1-based index into days of week, with 1
	/// falling on Monday.
	/// - [MaterialLocalizations.firstDayOfWeekIndex] provides a 0-based index
	/// into the [MaterialLocalizations.narrowWeekdays] list.
	/// - [MaterialLocalizations.narrowWeekdays] list provides localized names of
	/// days of week, always starting with Sunday and ending with Saturday.
	int _computeFirstDayOffset(int year, int month, MaterialLocalizations localizations) {
	// 0-based day of week, with 0 representing Monday.
	final int weekdayFromMonday = DateTime(year, month).weekday - 1;
	// 0-based day of week, with 0 representing Sunday.
	final int firstDayOfWeekFromSunday = localizations.firstDayOfWeekIndex;
	// firstDayOfWeekFromSunday recomputed to be Monday-based
	final int firstDayOfWeekFromMonday = (firstDayOfWeekFromSunday - 1) % 7;
	// Number of days between the first day of week appearing on the calendar,
	// and the day corresponding to the 1-st of the month.
	return (weekdayFromMonday - firstDayOfWeekFromMonday) % 7;
	}

	@override
	Widget build(BuildContext context) {
	final ThemeData themeData = Theme.of(context);
	final MaterialLocalizations localizations = MaterialLocalizations.of(context);
	final int year = displayedMonth.year;
	final int month = displayedMonth.month;
	final int daysInMonth = getDaysInMonth(year, month);
	final int firstDayOffset = _computeFirstDayOffset(year, month, localizations);
	final List<Widget> labels = <Widget>[
	..._getDayHeaders(themeData.textTheme.caption, localizations),
	];
	for (int i = 0; true; i += 1) {
	// 1-based day of month, e.g. 1-31 for January, and 1-29 for February on
	// a leap year.
	final int day = i - firstDayOffset + 1;
	if (day > daysInMonth)
	break;
	if (day < 1) {
	labels.add(Container());
	} else {
	final DateTime dayToBuild = DateTime(year, month, day);
	final bool disabled = dayToBuild.isAfter(lastDate)
	\|\| dayToBuild.isBefore(firstDate)
	\|\| (selectableDayPredicate != null && !selectableDayPredicate!(dayToBuild));

	BoxDecoration? decoration;
	TextStyle? itemStyle = themeData.textTheme.bodyText2;

	final bool isSelectedDay = selectedDate.year == year && selectedDate.month == month && selectedDate.day == day;
	if (isSelectedDay) {
	// The selected day gets a circle background highlight, and a contrasting text color.
	itemStyle = themeData.accentTextTheme.bodyText1;
	decoration = BoxDecoration(
	color: themeData.accentColor,
	shape: BoxShape.circle,
	);
	} else if (disabled) {
	itemStyle = themeData.textTheme.bodyText2!.copyWith(color: themeData.disabledColor);
	} else if (currentDate.year == year && currentDate.month == month && currentDate.day == day) {
	// The current day gets a different text color.
	itemStyle = themeData.textTheme.bodyText1!.copyWith(color: themeData.accentColor);
	}

	Widget dayWidget = Container(
	decoration: decoration,
	child: Center(
	child: Semantics(
	// We want the day of month to be spoken first irrespective of the
	// locale-specific preferences or TextDirection. This is because
	// an accessibility user is more likely to be interested in the
	// day of month before the rest of the date, as they are looking
	// for the day of month. To do that we prepend day of month to the
	// formatted full date.
	label: '${localizations.formatDecimal(day)}, ${localizations.formatFullDate(dayToBuild)}',
	selected: isSelectedDay,
	sortKey: OrdinalSortKey(day.toDouble()),
	child: ExcludeSemantics(
	child: Text(localizations.formatDecimal(day), style: itemStyle),
	),
	),
	),
	);

	if (!disabled) {
	dayWidget = GestureDetector(
	behavior: HitTestBehavior.opaque,
	onTap: () {
	onChanged(dayToBuild);
	},
	child: dayWidget,
	dragStartBehavior: dragStartBehavior,
	);
	}

	labels.add(dayWidget);
	}
	}

	return Padding(
	padding: const EdgeInsets.symmetric(horizontal: 8.0),
	child: Column(
	children: <Widget>[
	Container(
	height: _kDayPickerRowHeight,
	child: Center(
	child: ExcludeSemantics(
	child: Text(
	localizations.formatMonthYear(displayedMonth),
	style: themeData.textTheme.subtitle1,
	),
	),
	),
	),
	Flexible(
	child: GridView.custom(
	gridDelegate: _kDayPickerGridDelegate,
	childrenDelegate: SliverChildListDelegate(labels, addRepaintBoundaries: false),
	padding: EdgeInsets.zero,
	),
	),
	],
	),
	);
	}
	}

	/// A scrollable list of months to allow picking a month.
	///
	/// Shows the days of each month in a rectangular grid with one column for each
	/// day of the week.
	///
	/// The month picker widget is rarely used directly. Instead, consider using
	/// [showDatePicker], which creates a date picker dialog.
	///
	/// See also:
	///
	/// * [showDatePicker], which shows a dialog that contains a material design
	/// date picker.
	/// * [showTimePicker], which shows a dialog that contains a material design
	/// time picker.
	///
	@Deprecated(
	'Use CalendarDatePicker instead. '
	'This feature was deprecated after v1.15.3.'
	)
	class MonthPicker extends StatefulWidget {
	/// Creates a month picker.
	///
	/// Rarely used directly. Instead, typically used as part of the dialog shown
	/// by [showDatePicker].
	MonthPicker({
	Key? key,
	required this.selectedDate,
	required this.onChanged,
	required this.firstDate,
	required this.lastDate,
	this.selectableDayPredicate,
	this.dragStartBehavior = DragStartBehavior.start,
	}) : assert(selectedDate != null),
	assert(onChanged != null),
	assert(!firstDate.isAfter(lastDate)),
	assert(selectedDate.isAfter(firstDate) \|\| selectedDate.isAtSameMomentAs(firstDate)),
	super(key: key);

	/// The currently selected date.
	///
	/// This date is highlighted in the picker.
	final DateTime selectedDate;

	/// Called when the user picks a month.
	final ValueChanged<DateTime> onChanged;

	/// The earliest date the user is permitted to pick.
	final DateTime firstDate;

	/// The latest date the user is permitted to pick.
	final DateTime lastDate;

	/// Optional user supplied predicate function to customize selectable days.
	final SelectableDayPredicate? selectableDayPredicate;

	/// {@macro flutter.widgets.scrollable.dragStartBehavior}
	final DragStartBehavior dragStartBehavior;

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

	class _MonthPickerState extends State<MonthPicker> with SingleTickerProviderStateMixin {
	static final Animatable<double> _chevronOpacityTween = Tween<double>(begin: 1.0, end: 0.0)
	.chain(CurveTween(curve: Curves.easeInOut));

	@override
	void initState() {
	super.initState();
	// Initially display the pre-selected date.
	final int monthPage = _monthDelta(widget.firstDate, widget.selectedDate);
	_dayPickerController = PageController(initialPage: monthPage);
	_handleMonthPageChanged(monthPage);
	_updateCurrentDate();

	// Setup the fade animation for chevrons
	_chevronOpacityController = AnimationController(
	duration: const Duration(milliseconds: 250), vsync: this,
	);
	_chevronOpacityAnimation = _chevronOpacityController.drive(_chevronOpacityTween);
	}

	@override
	void didUpdateWidget(MonthPicker oldWidget) {
	super.didUpdateWidget(oldWidget);
	if (widget.selectedDate != oldWidget.selectedDate) {
	final int monthPage = _monthDelta(widget.firstDate, widget.selectedDate);
	_dayPickerController = PageController(initialPage: monthPage);
	_handleMonthPageChanged(monthPage);
	}
	}

	MaterialLocalizations? localizations;
	TextDirection? textDirection;

	@override
	void didChangeDependencies() {
	super.didChangeDependencies();
	localizations = MaterialLocalizations.of(context);
	textDirection = Directionality.of(context);
	}

	late DateTime _todayDate;
	late DateTime _currentDisplayedMonthDate;
	Timer? _timer;
	late PageController _dayPickerController;
	late AnimationController _chevronOpacityController;
	late Animation<double> _chevronOpacityAnimation;

	void _updateCurrentDate() {
	_todayDate = DateTime.now();
	final DateTime tomorrow = DateTime(_todayDate.year, _todayDate.month, _todayDate.day + 1);
	Duration timeUntilTomorrow = tomorrow.difference(_todayDate);
	timeUntilTomorrow += const Duration(seconds: 1); // so we don't miss it by rounding
	_timer?.cancel();
	_timer = Timer(timeUntilTomorrow, () {
	setState(() {
	_updateCurrentDate();
	});
	});
	}

	static int _monthDelta(DateTime startDate, DateTime endDate) {
	return (endDate.year - startDate.year) * 12 + endDate.month - startDate.month;
	}

	/// Add months to a month truncated date.
	DateTime _addMonthsToMonthDate(DateTime monthDate, int monthsToAdd) {
	return DateTime(monthDate.year + monthsToAdd ~/ 12, monthDate.month + monthsToAdd % 12);
	}

	Widget _buildItems(BuildContext context, int index) {
	final DateTime month = _addMonthsToMonthDate(widget.firstDate, index);
	return DayPicker(
	key: ValueKey<DateTime>(month),
	selectedDate: widget.selectedDate,
	currentDate: _todayDate,
	onChanged: widget.onChanged,
	firstDate: widget.firstDate,
	lastDate: widget.lastDate,
	displayedMonth: month,
	selectableDayPredicate: widget.selectableDayPredicate,
	dragStartBehavior: widget.dragStartBehavior,
	);
	}

	void _handleNextMonth() {
	if (!_isDisplayingLastMonth) {
	SemanticsService.announce(localizations!.formatMonthYear(_nextMonthDate), textDirection!);
	_dayPickerController.nextPage(duration: _kMonthScrollDuration, curve: Curves.ease);
	}
	}

	void _handlePreviousMonth() {
	if (!_isDisplayingFirstMonth) {
	SemanticsService.announce(localizations!.formatMonthYear(_previousMonthDate), textDirection!);
	_dayPickerController.previousPage(duration: _kMonthScrollDuration, curve: Curves.ease);
	}
	}

	/// True if the earliest allowable month is displayed.
	bool get _isDisplayingFirstMonth {
	return !_currentDisplayedMonthDate.isAfter(
	DateTime(widget.firstDate.year, widget.firstDate.month));
	}

	/// True if the latest allowable month is displayed.
	bool get _isDisplayingLastMonth {
	return !_currentDisplayedMonthDate.isBefore(
	DateTime(widget.lastDate.year, widget.lastDate.month));
	}

	late DateTime _previousMonthDate;
	late DateTime _nextMonthDate;

	void _handleMonthPageChanged(int monthPage) {
	setState(() {
	_previousMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage - 1);
	_currentDisplayedMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage);
	_nextMonthDate = _addMonthsToMonthDate(widget.firstDate, monthPage + 1);
	});
	}

	@override
	Widget build(BuildContext context) {
	return SizedBox(
	// The month picker just adds month navigation to the day picker, so make
	// it the same height as the DayPicker
	height: _kMaxDayPickerHeight,
	child: Stack(
	children: <Widget>[
	Semantics(
	sortKey: _MonthPickerSortKey.calendar,
	child: NotificationListener<ScrollStartNotification>(
	onNotification: (_) {
	_chevronOpacityController.forward();
	return false;
	},
	child: NotificationListener<ScrollEndNotification>(
	onNotification: (_) {
	_chevronOpacityController.reverse();
	return false;
	},
	child: PageView.builder(
	dragStartBehavior: widget.dragStartBehavior,
	key: ValueKey<DateTime>(widget.selectedDate),
	controller: _dayPickerController,
	scrollDirection: Axis.horizontal,
	itemCount: _monthDelta(widget.firstDate, widget.lastDate) + 1,
	itemBuilder: _buildItems,
	onPageChanged: _handleMonthPageChanged,
	),
	),
	),
	),
	PositionedDirectional(
	top: 0.0,
	start: 8.0,
	child: Semantics(
	sortKey: _MonthPickerSortKey.previousMonth,
	child: FadeTransition(
	opacity: _chevronOpacityAnimation,
	child: IconButton(
	icon: const Icon(Icons.chevron_left),
	tooltip: _isDisplayingFirstMonth ? null : '${localizations!.previousMonthTooltip} ${localizations!.formatMonthYear(_previousMonthDate)}',
	onPressed: _isDisplayingFirstMonth ? null : _handlePreviousMonth,
	),
	),
	),
	),
	PositionedDirectional(
	top: 0.0,
	end: 8.0,
	child: Semantics(
	sortKey: _MonthPickerSortKey.nextMonth,
	child: FadeTransition(
	opacity: _chevronOpacityAnimation,
	child: IconButton(
	icon: const Icon(Icons.chevron_right),
	tooltip: _isDisplayingLastMonth ? null : '${localizations!.nextMonthTooltip} ${localizations!.formatMonthYear(_nextMonthDate)}',
	onPressed: _isDisplayingLastMonth ? null : _handleNextMonth,
	),
	),
	),
	),
	],
	),
	);
	}

	@override
	void dispose() {
	_timer?.cancel();
	_chevronOpacityController.dispose();
	_dayPickerController.dispose();
	super.dispose();
	}
	}

	// Defines semantic traversal order of the top-level widgets inside the month
	// picker.
	class _MonthPickerSortKey extends OrdinalSortKey {
	const _MonthPickerSortKey(double order) : super(order);

	static const _MonthPickerSortKey previousMonth = _MonthPickerSortKey(1.0);
	static const _MonthPickerSortKey nextMonth = _MonthPickerSortKey(2.0);
	static const _MonthPickerSortKey calendar = _MonthPickerSortKey(3.0);
	}