如需轉載，請註明出處：Flutter學習筆記（20）--FloatingActionButton、PopupMenuButton、SimpleDialog、AlertDialog、SnackBar

• FloatingActionButton

FloatingActionButton對應一個圓形圖示按鈕，懸停在內容之上，以展示對應程式中的主要動作，所以非常醒目，類似於iOS系統裡的小白點按鈕。

FloatingActionButton元件屬性及描述如下：

1. child：child一般為icon，不推薦使用文字
2. tooltip：按鈕提示文字
3. foregroundColor：前景色
4. backgroundColor：背景色
5. elevation：未點選時陰影值，預設6.0
6. hignlightElevation：點選時陰影值
7. onPressed：點選事件回撥
8. shape：定義按鈕的shape，設定shape時，預設的elevation將會失效，預設為CircleBorder

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

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

class DemoApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new MaterialApp(
      title: 'FloatingButton Demo',
      debugShowCheckedModeBanner: false,
      home: new Scaffold(
        appBar: AppBar(
          title: new Text('FloatingButton Demo'),
        ),
        drawer: Drawer(
          child: ListView(
            children: <Widget>[
              UserAccountsDrawerHeader(
                  accountName: new Text('FloatingButton Demo'),
                  accountEmail: new Text('www.baidu.com'),
                  currentAccountPicture: new CircleAvatar(
                    backgroundImage: AssetImage('images/user.jpeg'),
                  ),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              )
            ],
          ),
        ),
        floatingActionButton: new Builder(builder: (BuildContext context){
          return new FloatingActionButton(
              child: Icon(Icons.album),
              foregroundColor: Colors.amberAccent,
              backgroundColor: Colors.deepPurple,
              elevation: 10.0,
              highlightElevation: 20.0,
              mini: false,
              onPressed: (){
                Scaffold.of(context).showSnackBar(new SnackBar(content: new Text('點選了FloatingButton')));
              }
          );
        }),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      ),
    );
  }

}

• PopupMenuButton

構造方法：

  const PopupMenuButton({
    Key key,
    @required this.itemBuilder,//item子項，可以為任意型別
    this.initialValue,//初始值
    this.onSelected,//選中其中一項時回撥
    this.onCanceled,//點選空白處，不選擇時回撥
    this.tooltip,//提示
    this.elevation = 8.0,//陰影大小
    this.padding = const EdgeInsets.all(8.0),//padding
    this.child,
    this.icon,
    this.offset = Offset.zero,
  }) : assert(itemBuilder != null),
        assert(offset != null),
        assert(!(child != null && icon != null)), // fails if passed both parameters
        super(key: key);

demo示例：

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

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

class DemoApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new MaterialApp(
      title: 'FloatingButton Demo',
      debugShowCheckedModeBanner: false,
      home: new Scaffold(
        body: new Center(
          child: _showPopupMenuButton(),
        ),
        appBar: AppBar(
          title: new Text('FloatingButton Demo'),
        ),
        drawer: Drawer(
          child: ListView(
            children: <Widget>[
              UserAccountsDrawerHeader(
                  accountName: new Text('FloatingButton Demo'),
                  accountEmail: new Text('www.baidu.com'),
                  currentAccountPicture: new CircleAvatar(
                    backgroundImage: AssetImage('images/user.jpeg'),
                  ),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              ),
              ListTile(
                title: new Text('我是主標題'),
                leading: Icon(Icons.add_circle_outline),
                subtitle: new Text('我是副標題'),
              )
            ],
          ),
        ),
        floatingActionButton: new Builder(builder: (BuildContext context){
          return new FloatingActionButton(
              child: Icon(Icons.album),
              foregroundColor: Colors.amberAccent,
              backgroundColor: Colors.deepPurple,
              elevation: 10.0,
              highlightElevation: 20.0,
              mini: false,
              onPressed: (){
              },
          );
        }),
        floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
      ),
    );
  }

  PopupMenuButton _showPopupMenuButton() {
    return PopupMenuButton(
      icon: Icon(Icons.menu),
        itemBuilder: (BuildContext context) => <PopupMenuEntry>[
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton1"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton2"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton3"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton4"),
            ),
          ),
        ]
    );
  }
}

效果截圖：

• SimpleDialog

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

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

class DemoApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'FloatingButton Demo',
      debugShowCheckedModeBanner: false,
      home: mHomePage(),
    );
  }
}

class mHomePage extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _mHomePage();
  }
}

class _mHomePage extends State {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
      body: new Center(
        child: _showPopupMenuButton(),
      ),
      appBar: AppBar(
        title: new Text('FloatingButton Demo'),
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            UserAccountsDrawerHeader(
              accountName: new Text('FloatingButton Demo'),
              accountEmail: new Text('www.baidu.com'),
              currentAccountPicture: new CircleAvatar(
                backgroundImage: AssetImage('images/user.jpeg'),
              ),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            )
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        child: Icon(Icons.album),
        foregroundColor: Colors.amberAccent,
        backgroundColor: Colors.deepPurple,
        elevation: 10.0,
        highlightElevation: 20.0,
        mini: false,
        onPressed: (){
            _showSimpleDialog(context);
        },
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
    );
  }

  PopupMenuButton _showPopupMenuButton() {
    return PopupMenuButton(
        icon: Icon(Icons.menu),
        itemBuilder: (BuildContext context) => <PopupMenuEntry>[
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton1"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton2"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton3"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton4"),
            ),
          ),
        ]
    );
  }

  void _showSimpleDialog(BuildContext context) {
    showDialog(
        context: context,
        builder: (BuildContext context){
          return SimpleDialog(
            title: new Text('SimpleDialog Demo'),
            children: <Widget>[
              SimpleDialogOption(
                child: Text('選項1'),
              ),
              SimpleDialogOption(
                child: Text('選項2'),
                onPressed: (){
                  Navigator.pop(context);
                },
              ),
            ],
          );
        }
    );
  }
}

效果截圖：

• AlertDialog

AlertDialog常用屬性：

  const AlertDialog({
    Key key,
    this.title,//對話方塊頂部提示文案
    this.titlePadding,
    this.titleTextStyle,//對話方塊頂部提示文案字型樣式
    this.content,//內容部分，對話方塊的提示內容，通常為文字
    this.contentPadding = const EdgeInsets.fromLTRB(24.0, 20.0, 24.0, 24.0),
    this.contentTextStyle,//對話方塊提示內容的字型樣式
    this.actions,//對話方塊底部操作按鈕
    this.backgroundColor,//對話方塊背景色
    this.elevation,
    this.semanticLabel,
    this.shape,
  }) : assert(contentPadding != null),
       super(key: key);

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

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

class DemoApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'FloatingButton Demo',
      debugShowCheckedModeBanner: false,
      home: mHomePage(),
    );
  }
}

class mHomePage extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _mHomePage();
  }
}

class _mHomePage extends State {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
      body: new Center(
        child: _showPopupMenuButton(),
      ),
      appBar: AppBar(
        title: new Text('FloatingButton Demo'),
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            UserAccountsDrawerHeader(
              accountName: new Text('FloatingButton Demo'),
              accountEmail: new Text('www.baidu.com'),
              currentAccountPicture: new CircleAvatar(
                backgroundImage: AssetImage('images/user.jpeg'),
              ),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            )
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        child: Icon(Icons.album),
        foregroundColor: Colors.amberAccent,
        backgroundColor: Colors.deepPurple,
        elevation: 10.0,
        highlightElevation: 20.0,
        mini: false,
        onPressed: (){
//            _showSimpleDialog(context);
          _showAlertDialog(context);
        },
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
    );
  }

  PopupMenuButton _showPopupMenuButton() {
    return PopupMenuButton(
        icon: Icon(Icons.menu),
        itemBuilder: (BuildContext context) => <PopupMenuEntry>[
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton1"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton2"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton3"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton4"),
            ),
          ),
        ]
    );
  }

  void _showSimpleDialog(BuildContext context) {
    showDialog(
        context: context,
        builder: (BuildContext context){
          return SimpleDialog(
            title: new Text('SimpleDialog Demo'),
            children: <Widget>[
              SimpleDialogOption(
                child: Text('選項1'),
              ),
              SimpleDialogOption(
                child: Text('選項2'),
                onPressed: (){
                  Navigator.pop(context);
                },
              ),
            ],
          );
        }
    );
  }

  void _showAlertDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (BuildContext context){
        return AlertDialog(
          title: new Text('提示'),
          content: new Text('這是提示框的內容'),
          actions: <Widget>[
            FlatButton(onPressed: null, child: new Text('確定'),disabledTextColor: Colors.blueAccent,),
            FlatButton(onPressed: null, child: new Text('取消'),disabledColor: Colors.deepPurple,),
          ],
        );
      }
    );
  }
}

效果截圖：

• SnackBar

SnackBar是一個輕量級訊息提示元件，在螢幕的底部顯示，SnackBar常用屬性如下：

  const SnackBar({
    Key key,
    @required this.content,//提示內容
    this.backgroundColor,//背景色
    this.action,
    this.duration = _kSnackBarDisplayDuration,//提示時常
    this.animation,//彈出動畫
  }) : assert(content != null),
       assert(duration != null),
       super(key: key);

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

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

class DemoApp extends StatelessWidget{
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'FloatingButton Demo',
      debugShowCheckedModeBanner: false,
      home: mHomePage(),
    );
  }
}

class mHomePage extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _mHomePage();
  }
}

class _mHomePage extends State {
  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return new Scaffold(
      body: new Center(
        child: _showPopupMenuButton(),
      ),
      appBar: AppBar(
        title: new Text('FloatingButton Demo'),
        actions: <Widget>[
          IconButton(icon: Icon(Icons.search), onPressed: (){
            Scaffold.of(context).showSnackBar(new SnackBar(content: new Text('SnackBar')));
          })
        ],
      ),
      drawer: Drawer(
        child: ListView(
          children: <Widget>[
            UserAccountsDrawerHeader(
              accountName: new Text('FloatingButton Demo'),
              accountEmail: new Text('www.baidu.com'),
              currentAccountPicture: new CircleAvatar(
                backgroundImage: AssetImage('images/user.jpeg'),
              ),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            ),
            ListTile(
              title: new Text('我是主標題'),
              leading: Icon(Icons.add_circle_outline),
              subtitle: new Text('我是副標題'),
            )
          ],
        ),
      ),
      floatingActionButton: new FloatingActionButton(
        child: Icon(Icons.album),
        foregroundColor: Colors.amberAccent,
        backgroundColor: Colors.deepPurple,
        elevation: 10.0,
        highlightElevation: 20.0,
        mini: false,
        onPressed: (){
//            _showSimpleDialog(context);
          _showAlertDialog(context);
        },
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
    );
  }

  PopupMenuButton _showPopupMenuButton() {
    return PopupMenuButton(
        icon: Icon(Icons.menu),
        itemBuilder: (BuildContext context) => <PopupMenuEntry>[
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton1"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton2"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton3"),
            ),
          ),
          const PopupMenuItem(
            child: ListTile(
              leading: Icon(Icons.add_circle_outline),
              title: Text("popupMenuButton4"),
            ),
          ),
        ]
    );
  }

  void _showSimpleDialog(BuildContext context) {
    showDialog(
        context: context,
        builder: (BuildContext context){
          return SimpleDialog(
            title: new Text('SimpleDialog Demo'),
            children: <Widget>[
              SimpleDialogOption(
                child: Text('選項1'),
              ),
              SimpleDialogOption(
                child: Text('選項2'),
                onPressed: (){
                  Navigator.pop(context);
                },
              ),
            ],
          );
        }
    );
  }

  void _showAlertDialog(BuildContext context) {
    showDialog(
      context: context,
      builder: (BuildContext context){
        return AlertDialog(
          title: new Text('提示'),
          content: new Text('這是提示框的內容'),
          actions: <Widget>[
            FlatButton(onPressed: null, child: new Text('確定'),disabledTextColor: Colors.blueAccent,),
            FlatButton(
              onPressed: (){
                Navigator.pop(context);
                Scaffold.of(context).showSnackBar(new SnackBar(content: new Text('SnackBar')));
              },
              child: new Text('取消'),disabledColor: Colors.deepPurple,),
          ],
          backgroundColor: Colors.amberAccent,
        );
      }
    );
  }
}

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