date_picker_example.dart

// Non-confidential feedback for Posse

import 'dart:async';
import 'package:intl/intl.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:meta/meta.dart';
import 'package:numberpicker/numberpicker.dart';

class _BirthDatePickerDialog extends StatefulWidget {
  const _BirthDatePickerDialog({
    Key key,
    @required this.initialDate,
    @required this.firstYear,
    @required this.lastYear,
  }) : super(key: key);

  final DateTime initialDate;
  final int firstYear;
  final int lastYear;

  @override
  _BirthDatePickerDialogState createState() =>
      new _BirthDatePickerDialogState();
}

class _BirthDatePickerDialogState extends State<_BirthDatePickerDialog> {
  @override
  void initState() {
    super.initState();
    _selectedYear = widget.initialDate.year;
    _selectedMonth = widget.initialDate.month;
    _selectedDay = widget.initialDate.day;
  }

  int _selectedYear;
  int _selectedMonth;
  int _selectedDay;

  void _vibrate() {
    switch (Theme
        .of(context)
        .platform) {
      case TargetPlatform.android:
      case TargetPlatform.fuchsia:
        HapticFeedback.vibrate();
        break;
      case TargetPlatform.iOS:
        break;
    }
  }

  void _handleYearChanged(int value) {
    if (value < widget.firstYear || value > widget.lastYear)
      return;
    _vibrate();
    setState(() {
      _selectedYear = value;
    });
  }

  void _handleMonthChanged(int value) {
    if (value < 1 || value > 12)
      return;
    _vibrate();
    setState(() {
      _selectedMonth = value;
    });
  }

  void _handleDayChanged(int value) {
    if (value < 1 || value > 31)
      return;
    _vibrate();
    setState(() {
      _selectedDay = value;
    });
  }

  void _handleCancel() {
    Navigator.pop(context);
  }

  void _handleOk() {
    Navigator.pop(
        context, new DateTime(_selectedYear, _selectedMonth, _selectedDay));
  }

  @override
  Widget build(BuildContext context) {
    TextStyle headerStyle = Theme.of(context).textTheme.headline;
    return new AlertDialog(
      actions: <Widget>[
        new FlatButton(
          child: const Text('CANCEL'),
          onPressed: _handleCancel,
        ),
        new FlatButton(
          child: const Text('OK'),
          onPressed: _handleOk,
        ),
      ],
      content: new Row(
        mainAxisAlignment: MainAxisAlignment.spaceEvenly,
        children: <Widget>[
          new Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.center,
            children: <Widget>[
              new Text('Year', style: headerStyle),
              new NumberPicker.integer(
                initialValue: _selectedYear,
                minValue: widget.firstYear,
                maxValue: widget.lastYear ?? new DateTime.now().year,
                onChanged: _handleYearChanged,
              ),
            ],
          ),
          new Flexible(
            child: new Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.center,
              children: [
                new Text('Month', style: headerStyle),
                new NumberPicker.integer(
                  initialValue: _selectedMonth,
                  minValue: 1,
                  maxValue: 12,
                  onChanged: _handleMonthChanged,
                ),
              ],
            ),
          ),
          new Column(
            mainAxisSize: MainAxisSize.min,
            crossAxisAlignment: CrossAxisAlignment.center,
            children: <Widget>[
              new Text('Day', style: headerStyle),
              new NumberPicker.integer(
                initialValue: _selectedDay,
                minValue: 1,
                maxValue: 31,
                onChanged: _handleDayChanged,
              ),
            ],
          ),
        ],
      ),
    );
  }
}

/// Shows a dialog containing a birth date picker.
///
/// The returned [Future] resolves to the date selected by the user when the
/// user closes the dialog. If the user cancels the dialog, null is returned.
///
/// See also:
///
///  * [showTimePicker]
///  * [showDatePicker]
///  * <https://material.google.com/components/pickers.html#pickers-date-pickers>
Future<DateTime> showBirthDatePicker({
  @required BuildContext context,
  @required DateTime initialDate,
  @required int firstYear,
  int lastYear,
}) async {
  assert(lastYear == null ||
      lastYear >= firstYear, 'lastYear must be on or after firstYear');
  assert(initialDate.year >= firstYear, 'initialDate must be after firstYear');
  assert(lastYear == null ||
      initialDate.year <= lastYear, 'initialDate must be before lastYear');
  return await showDialog(
      context: context,
      child: new _BirthDatePickerDialog(
        initialDate: initialDate,
        firstYear: firstYear,
        lastYear: lastYear,
      )
  );
}

// Example usage:

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

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

class MyHomePage extends StatefulWidget {

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

class _MyHomePageState extends State<MyHomePage> {
  DateTime _birthDate;

  Future<Null> _showBirthDateDialog(BuildContext context) async {
    DateTime birthDate = await showBirthDatePicker(
      context: context,
      firstYear: 1900,
      initialDate: _birthDate ?? new DateTime(1999, 6, 15),
    );
    if (mounted && birthDate != null) {
      setState(() {
        _birthDate = birthDate;
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text('Birthdate Example'),
      ),
      body: new Center(
        child: new Column(

          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new Text(
              _birthDate == null
                  ? 'You have not yet set your birthdate.'
                  : 'Your birthdate is ${new DateFormat.yMMMd().format(
                  _birthDate)}.',
              style: Theme
                  .of(context)
                  .textTheme
                  .subhead,
            ),
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        onPressed: () => _showBirthDateDialog(context),
        tooltip: 'Edit',
        child: new Icon(Icons.edit),
      ),
    );
  }
}