examples/flutter_gallery/lib/demo/cupertino/cupertino_picker_demo.dart

// Copyright 2017 The Chromium 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 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:intl/intl.dart';

import '../../gallery/demo.dart';
import 'cupertino_navigation_demo.dart' show coolColorNames;

const double _kPickerSheetHeight = 216.0;
const double _kPickerItemHeight = 32.0;

class CupertinoPickerDemo extends StatefulWidget {
  static const String routeName = '/cupertino/picker';

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

class _CupertinoPickerDemoState extends State<CupertinoPickerDemo> {
  int _selectedColorIndex = 0;

  Duration timer = Duration();

  // Value that is shown in the date picker in date mode.
  DateTime date = DateTime.now();

  // Value that is shown in the date picker in time mode.
  DateTime time = DateTime.now();

  // Value that is shown in the date picker in dateAndTime mode.
  DateTime dateTime = DateTime.now();

  Widget _buildMenu(List<Widget> children) {
    return Container(
      decoration: const BoxDecoration(
        color: CupertinoColors.white,
        border: Border(
          top: BorderSide(color: Color(0xFFBCBBC1), width: 0.0),
          bottom: BorderSide(color: Color(0xFFBCBBC1), width: 0.0),
        ),
      ),
      height: 44.0,
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 16.0),
        child: SafeArea(
          top: false,
          bottom: false,
          child: DefaultTextStyle(
            style: const TextStyle(
              letterSpacing: -0.24,
              fontSize: 17.0,
              color: CupertinoColors.black,
            ),
            child: Row(
              mainAxisAlignment: MainAxisAlignment.spaceBetween,
              children: children,
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildBottomPicker(Widget picker) {
    return Container(
      height: _kPickerSheetHeight,
      padding: const EdgeInsets.only(top: 6.0),
      color: CupertinoColors.white,
      child: DefaultTextStyle(
        style: const TextStyle(
          color: CupertinoColors.black,
          fontSize: 22.0,
        ),
        child: GestureDetector(
          // Blocks taps from propagating to the modal sheet and popping.
          onTap: () {},
          child: SafeArea(
            top: false,
            child: picker,
          ),
        ),
      ),
    );
  }

  Widget _buildColorPicker(BuildContext context) {
    final FixedExtentScrollController scrollController =
        FixedExtentScrollController(initialItem: _selectedColorIndex);

    return GestureDetector(
      onTap: () async {
        await showCupertinoModalPopup<void>(
          context: context,
          builder: (BuildContext context) {
            return _buildBottomPicker(
              CupertinoPicker(
                scrollController: scrollController,
                itemExtent: _kPickerItemHeight,
                backgroundColor: CupertinoColors.white,
                onSelectedItemChanged: (int index) {
                  setState(() => _selectedColorIndex = index);
                },
                children: List<Widget>.generate(coolColorNames.length, (int index) {
                  return Center(child:
                  Text(coolColorNames[index]),
                  );
                }),
              ),
            );
          },
        );
      },
      child: _buildMenu(
        <Widget>[
          const Text('Favorite Color'),
          Text(
            coolColorNames[_selectedColorIndex],
            style: const TextStyle(
                color: CupertinoColors.inactiveGray
            ),
          ),
        ],
      ),
    );
  }

  Widget _buildCountdownTimerPicker(BuildContext context) {
    return GestureDetector(
      onTap: () {
        showCupertinoModalPopup<void>(
          context: context,
          builder: (BuildContext context) {
            return _buildBottomPicker(
              CupertinoTimerPicker(
                initialTimerDuration: timer,
                onTimerDurationChanged: (Duration newTimer) {
                  setState(() => timer = newTimer);
                },
              ),
            );
          },
        );
      },
      child: _buildMenu(
        <Widget>[
          const Text('Countdown Timer'),
          Text(
            '${timer.inHours}:'
                '${(timer.inMinutes % 60).toString().padLeft(2,'0')}:'
                '${(timer.inSeconds % 60).toString().padLeft(2,'0')}',
            style: const TextStyle(color: CupertinoColors.inactiveGray),
          ),
        ],
      ),
    );
  }

  Widget _buildDatePicker(BuildContext context) {
    return GestureDetector(
      onTap: () {
        showCupertinoModalPopup<void>(
          context: context,
          builder: (BuildContext context) {
            return _buildBottomPicker(
              CupertinoDatePicker(
                mode: CupertinoDatePickerMode.date,
                initialDateTime: date,
                onDateTimeChanged: (DateTime newDateTime) {
                  setState(() => date = newDateTime);
                },
              ),
            );
          },
        );
      },
      child: _buildMenu(
        <Widget>[
          const Text('Date'),
          Text(
            DateFormat.yMMMMd().format(date),
            style: const TextStyle(color: CupertinoColors.inactiveGray),
          ),
        ]
      ),
    );
  }

  Widget _buildTimePicker(BuildContext context) {
    return GestureDetector(
      onTap: () {
        showCupertinoModalPopup<void>(
          context: context,
          builder: (BuildContext context) {
            return _buildBottomPicker(
              CupertinoDatePicker(
                mode: CupertinoDatePickerMode.time,
                initialDateTime: time,
                onDateTimeChanged: (DateTime newDateTime) {
                  setState(() => time = newDateTime);
                },
              ),
            );
          },
        );
      },
      child: _buildMenu(
        <Widget>[
          const Text('Time'),
          Text(
            DateFormat.jm().format(time),
            style: const TextStyle(color: CupertinoColors.inactiveGray),
          ),
        ],
      ),
    );
  }

  Widget _buildDateAndTimePicker(BuildContext context) {
    return GestureDetector(
      onTap: () {
        showCupertinoModalPopup<void>(
          context: context,
          builder: (BuildContext context) {
            return _buildBottomPicker(
              CupertinoDatePicker(
                mode: CupertinoDatePickerMode.dateAndTime,
                initialDateTime: dateTime,
                onDateTimeChanged: (DateTime newDateTime) {
                  setState(() => dateTime = newDateTime);
                },
              ),
            );
          },
        );
      },
      child: _buildMenu(
        <Widget>[
          const Text('Date and Time'),
          Text(
            DateFormat.yMMMd().add_jm().format(dateTime),
            style: const TextStyle(color: CupertinoColors.inactiveGray),
          ),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Cupertino Picker'),
        actions: <Widget>[MaterialDemoDocumentationButton(CupertinoPickerDemo.routeName)],
      ),
      body: DefaultTextStyle(
        style: const TextStyle(
          fontFamily: '.SF UI Text',
          fontSize: 17.0,
          color: CupertinoColors.black,
        ),
        child: DecoratedBox(
          decoration: const BoxDecoration(color: Color(0xFFEFEFF4)),
          child: ListView(
            children: <Widget>[
              const Padding(padding: EdgeInsets.only(top: 32.0)),
              _buildColorPicker(context),
              _buildCountdownTimerPicker(context),
              _buildDatePicker(context),
              _buildTimePicker(context),
              _buildDateAndTimePicker(context),
            ],
          ),
        ),
      ),
    );
  }
}