Flutter制作自己的第一个全平台APP学习之Popup篇

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摘要

这一篇文章主要是学习Popup，就是页面中的各种提示，包括但不限于弹出框，弹出提示，底部提示等，该项功能类似于Javascript中的alert，当然在App中，表现的形式也是千变万化，本篇文章介绍几种带有普遍性的弹出框，以便快速掌握入手，分享给大家……
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Flutter制作自己的第一个全平台APP学习之Popup篇

开篇寄语

这一篇文章主要是学习Popup，就是页面中的各种提示，包括但不限于弹出框，弹出提示，底部提示等，该项功能类似于Javascript中的alert，当然在App中，表现的形式也是千变万化，本篇文章介绍几种带有普遍性的弹出框，以便快速掌握入手，分享给大家。

前情提要

内容详情

以下内容大多是更改lib下的main.dart文件内容，删掉里面的内容，复制粘贴代码，开启调试就可以出现了。

Alert Dialog

  • 有点类似于Javascript中的alert，警告弹出提示，用到的是AlertDialog这个类，试举一例，如下所示：
import 'dart:async';
import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Trial',
        home: Scaffold(
            appBar: AppBar(title: Text('Hello World')), body: new MyHome()));
  }
}

class MyHome extends StatelessWidget {
  // Wrapper Widget
  @override
  Widget build(BuildContext context) {
    Future.delayed(Duration.zero, () => showAlert(context));
    return Container(
      child: Text("Hello world"),
    );
  }

  void showAlert(BuildContext context) {
    showDialog(
        context: context,
        builder: (context) => AlertDialog(
              content: Text("hi"),
            ));
  }
}

效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇

更高级版的则是有取消或者确定等按钮，然后在底部生成提示返回框，代码如下：

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

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: 'Trial',
        home: Scaffold(
            appBar: AppBar(title: Text('Hello World')), body: new MyHome()));
  }
}

class MyHome extends StatelessWidget {
  // Wrapper Widget
  @override
  Widget build(BuildContext context) {
    Future.delayed(Duration.zero, () => showAlert(context));
    return Container(
      child: Text("Hello world"),
    );
  }

  void showAlert(BuildContext context) {
    showDialog(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Dialog title'),
        content: const Text(
          'Sample alert',
        ),
        actions: <Widget>[
          TextButton(
            onPressed: () => Navigator.pop(context, 'Cancel'),
            child: const Text('Cancel'),
          ),
          TextButton(
            onPressed: () => Navigator.pop(context, 'OK'),
            child: const Text('OK'),
          ),
        ],
      ),
    ).then((returnVal) {
      if (returnVal != null) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: Text('You clicked: $returnVal'),
            action: SnackBarAction(label: 'OK', onPressed: () {}),
          ),
        );
      }
    });
  }
}

效果如下图所示：

  • Flutter制作自己的第一个全平台APP学习之Popup篇
    展示弹窗
  • Flutter制作自己的第一个全平台APP学习之Popup篇
    点击后

date picker timeline

  • 显示时间轴控件，可以进行时间的选择，试举一例：

首先是安装date_picker_timeline这个flutter第三方资料库，具体可以参看这个官网介绍：

代码如下：

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

void main() => runApp(MyApp());

// ignore: use_key_in_widget_constructors
class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      // ignore: prefer_const_constructors
      home: MyHomePage(title: 'Date Picker Timeline Demo'),
    );
  }
}

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

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

class _MyHomePageState extends State<MyHomePage> {
  // ignore: prefer_final_fields
  DatePickerController _controller = DatePickerController();

  DateTime _selectedValue = DateTime.now();

  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        floatingActionButton: FloatingActionButton(
          // ignore: prefer_const_constructors
          child: Icon(Icons.replay),
          onPressed: () {
            _controller.animateToSelection();
          },
        ),
        appBar: AppBar(
          title: Text(widget.title!),
        ),
        body: Container(
          // ignore: prefer_const_constructors
          padding: EdgeInsets.all(20.0),
          color: Colors.blueGrey[100],
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              // ignore: prefer_const_constructors
              Text('You Selected:'),
              const Padding(
                padding: EdgeInsets.all(10),
              ),
              Text(_selectedValue.toString()),
              const Padding(
                padding: EdgeInsets.all(20),
              ),
              // ignore: avoid_unnecessary_containers
              Container(
                child: DatePicker(
                  DateTime.now(),
                  width: 60,
                  height: 80,
                  controller: _controller,
                  initialSelectedDate: DateTime.now(),
                  selectionColor: Colors.black,
                  selectedTextColor: Colors.white,
                  onDateChange: (DateTime date) {
                    setState(() {
                      _selectedValue = date;
                    });
                  },
                ),
              ),
            ],
          ),
        ));
  }
}

效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇

DatePickerDialog

  • 日期选择内置语法，选择一个时间，试举例如下：
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      restorationScopeId: 'app',
      title: _title,
      home: MyStatefulWidget(restorationId: 'main'),
    );
  }
}
class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key, this.restorationId}) : super(key: key);

  final String? restorationId;

  @override
  _MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget>
    with RestorationMixin {
  @override
  String? get restorationId => widget.restorationId;

  final RestorableDateTime _selectedDate = RestorableDateTime(DateTime.now());
  late final RestorableRouteFuture<DateTime?> _restorableDatePickerRouteFuture =
      RestorableRouteFuture<DateTime?>(
    onComplete: _selectDate,
    onPresent: (NavigatorState navigator, Object? arguments) {
      return navigator.restorablePush(
        _datePickerRoute,
        arguments: _selectedDate.value.millisecondsSinceEpoch,
      );
    },
  );

  static Route<DateTime> _datePickerRoute(
    BuildContext context,
    Object? arguments,
  ) {
    return DialogRoute<DateTime>(
      context: context,
      builder: (BuildContext context) {
        return DatePickerDialog(
          restorationId: 'date_picker_dialog',
          initialEntryMode: DatePickerEntryMode.calendarOnly,
          initialDate: DateTime.fromMillisecondsSinceEpoch(arguments! as int),
          firstDate: DateTime(2021, 1, 1),
          lastDate: DateTime(2050, 1, 1),
        );
      },
    );
  }

  @override
  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
    registerForRestoration(_selectedDate, 'selected_date');
    registerForRestoration(
        _restorableDatePickerRouteFuture, 'date_picker_route_future');
  }

  void _selectDate(DateTime? newSelectedDate) {
    if (newSelectedDate != null) {
      setState(() {
        _selectedDate.value = newSelectedDate;
        ScaffoldMessenger.of(context).showSnackBar(SnackBar(
          content: Text(
              'Selected: ${_selectedDate.value.day}/${_selectedDate.value.month}/${_selectedDate.value.year}'),
        ));
      });
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: OutlinedButton(
          onPressed: () {
            _restorableDatePickerRouteFuture.present();
          },
          child: const Text('Open Date Picker'),
        ),
      ),
    );
  }
}

生成效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇

showDateRangePicker

  • 选择一段时间区域，由用户选择，试举一例：
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      restorationScopeId: 'app',
      title: _title,
      home: MyStatefulWidget(restorationId: 'main'),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key, this.restorationId}) : super(key: key);

  final String? restorationId;

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

class _MyStatefulWidgetState extends State<MyStatefulWidget>
    with RestorationMixin {
  @override
  String? get restorationId => widget.restorationId;

  final RestorableDateTimeN _startDate =
      RestorableDateTimeN(DateTime(2021, 1, 1));
  final RestorableDateTimeN _endDate =
      RestorableDateTimeN(DateTime(2021, 1, 5));
  late final RestorableRouteFuture<DateTimeRange?>
      _restorableDateRangePickerRouteFuture =
      RestorableRouteFuture<DateTimeRange?>(
    onComplete: _selectDateRange,
    onPresent: (NavigatorState navigator, Object? arguments) {
      return navigator
          .restorablePush(_dateRangePickerRoute, arguments: <String, dynamic>{
        'initialStartDate': _startDate.value?.millisecondsSinceEpoch,
        'initialEndDate': _endDate.value?.millisecondsSinceEpoch,
      });
    },
  );

  void _selectDateRange(DateTimeRange? newSelectedDate) {
    if (newSelectedDate != null) {
      setState(() {
        _startDate.value = newSelectedDate.start;
        _endDate.value = newSelectedDate.end;
      });
    }
  }

  @override
  void restoreState(RestorationBucket? oldBucket, bool initialRestore) {
    registerForRestoration(_startDate, 'start_date');
    registerForRestoration(_endDate, 'end_date');
    registerForRestoration(
        _restorableDateRangePickerRouteFuture, 'date_picker_route_future');
  }

  static Route<DateTimeRange?> _dateRangePickerRoute(
    BuildContext context,
    Object? arguments,
  ) {
    return DialogRoute<DateTimeRange?>(
      context: context,
      builder: (BuildContext context) {
        return DateRangePickerDialog(
          restorationId: 'date_picker_dialog',
          initialDateRange:
              _initialDateTimeRange(arguments! as Map<dynamic, dynamic>),
          firstDate: DateTime(2021, 1, 1),
          currentDate: DateTime(2021, 1, 25),
          lastDate: DateTime(2022, 1, 1),
        );
      },
    );
  }

  static DateTimeRange? _initialDateTimeRange(Map<dynamic, dynamic> arguments) {
    if (arguments['initialStartDate'] != null &&
        arguments['initialEndDate'] != null) {
      return DateTimeRange(
        start: DateTime.fromMillisecondsSinceEpoch(
            arguments['initialStartDate'] as int),
        end: DateTime.fromMillisecondsSinceEpoch(
            arguments['initialEndDate'] as int),
      );
    }

    return null;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: OutlinedButton(
          onPressed: () {
            _restorableDateRangePickerRouteFuture.present();
          },
          child: const Text('Open Date Range Picker'),
        ),
      ),
    );
  }
}

生成效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇

showTimePicker

  • 选定24小时时钟时间，试举例如下：
import 'package:flutter/material.dart';

void main() => runApp(MyApp());

// ignore: use_key_in_widget_constructors
class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      builder: (BuildContext context, Widget? child) => MediaQuery(
          data: MediaQuery.of(context).copyWith(alwaysUse24HourFormat: true),
          child: child!),
      home: Container(
        color: Colors.white,
        child: Center(
          child: Builder(
            builder: (BuildContext context) => ElevatedButton(
              onPressed: () => showTimePicker(
                  context: context, initialTime: TimeOfDay.now()),
              child: const Text('Show Time Picker'),
            ),
          ),
        ),
      ),
    );
  }
}

生成效果如下图所示：

  • Flutter制作自己的第一个全平台APP学习之Popup篇
  • Flutter制作自己的第一个全平台APP学习之Popup篇

SnackBar

  • 底部弹出的信息框，试举一例：
import 'package:flutter/material.dart';

void main() => runApp(SnackBarDemo());

class SnackBarDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'SnackBar Demo',
      home: Scaffold(
        appBar: AppBar(
          title: Text('SnackBar Demo'),
        ),
        body: SnackBarPage(),
      ),
    );
  }
}

class SnackBarPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: ElevatedButton(
        onPressed: () {
          final snackBar = SnackBar(
            content: Text('Yay! A SnackBar!'),
            action: SnackBarAction(
              label: 'Undo',
              onPressed: () {
                // Some code to undo the change.
              },
            ),
          );

          // Find the ScaffoldMessenger in the widget tree
          // and use it to show a SnackBar.
          ScaffoldMessenger.of(context).showSnackBar(snackBar);
        },
        child: Text('Show SnackBar'),
      ),
    );
  }
}

生成效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇

showAboutDialog

  • 显示App关于页面，这个基本上每个App都是需要的，试举一例：
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: _MyAppContent(),
    );
  }
}

class _MyAppContent extends StatefulWidget {
  @override
  _MyAppContentState createState() => new _MyAppContentState();
}

class _MyAppContentState extends State<_MyAppContent> {
  @override
  void initState() {
    super.initState();
    this.initMyLibrary();
  }

  void initMyLibrary() {
    // ignore: invalid_use_of_visible_for_testing_member
    LicenseRegistry.reset();
    LicenseRegistry.addLicense(() async* {
      yield LicenseEntryWithLineBreaks(<String>['ACustomLibrary'], '''
  Copyright 2016 Woolha.com. All rights reserved.
  
     * Redistributions of source code must retain the above copyright
  notice, this list of conditions and the following disclaimer.
   
  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS''');
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Flutter Demo'),
      ),
      body: Center(
        child: ElevatedButton(
          child: Text('Show AboutDialog'),
          onPressed: () {
            showAboutDialog(
              context: context,
              applicationIcon: FlutterLogo(),
              applicationName: 'Flutter Demo',
              applicationVersion: '0.0.1',
              applicationLegalese: '©2020 Flutter.dev',
              children: <Widget>[
                Padding(
                    padding: EdgeInsets.only(top: 15),
                    child: Text('This is an about dialog in Flutter'))
              ],
            );
          },
        ),
      ),
    );
  }
}

生成效果如下图所示：

  • Flutter制作自己的第一个全平台APP学习之Popup篇
  • Flutter制作自己的第一个全平台APP学习之Popup篇

showModalBottomSheet

  • 这个是从底部弹出，类似于snack bar但是可以展现的内容则更加丰富，试举例如下：
// main.dart
import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      // Remove the debug banner
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: HomeScreen(),
    );
  }
}

class HomeScreen extends StatelessWidget {
  const HomeScreen({Key? key}) : super(key: key);
  void _show(BuildContext ctx) {
    showModalBottomSheet(
        elevation: 10,
        backgroundColor: Colors.amber,
        context: ctx,
        builder: (ctx) => Container(
              width: 300,
              height: 250,
              color: Colors.white54,
              alignment: Alignment.center,
              child: const Text('Hello World!'),
            ));
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter Demo'),
      ),
      body: SafeArea(
        child: Center(
          child: ElevatedButton(
            child: const Text('Click Me'),
            onPressed: () => _show(context),
          ),
        ),
      ),
    );
  }
}

生成效果如下图所示：

Flutter制作自己的第一个全平台APP学习之Popup篇
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