[- Flutter基础篇 -] 聊聊那些弹框

对话框作为一个挺重要的东西，这里来说一下，细细一数也蛮多的，本文包括

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[1].SimpleDialog
[2].AlertDialog
[3].CupertinoAlertDialog
[4].Dialog中的组件状态更新
[5].SnackBar
[6].BottomSheet
[7].DatePicker
[8].TimePickerwTimePicker,
[9].CupertinoPicker
[10].CupertinoDatePicker
[11].CupertinoTimerPicker

0.搭个场子再说

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class DialogShow extends StatefulWidget {
  @override
  _DialogShowState createState() => _DialogShowState();
}

class _DialogShowState extends State {
  @override
  Widget build(BuildContext context) {
    var title = Container(
      alignment: AlignmentDirectional.center,
      child: Text(
        "Dialog Unit",
        style: TextStyle(fontSize: 30),
      ),
    );
    
    Map buttons = {
      "对话框SimpleDialog": _showSimpleDialog,
      "对话框AlertDialog": _showAlertDialog,
      "对话框CupertinoAlertDialog": _showCupertinoAlertDialog,
      "对话框显示自己": _showWidgetDialog,
      "对话框显示StatefulWidget": _showStatefulWidgetDialog,
      "Scaffold": _showScaffold,
      "BottomSheet": _showBottomSheet,
      "DatePicker": _showDatePicker,
      "TimePicker": _showTimePicker,
      "CupertinoPicker": _showCupertinoPicker,
      "CupertinoDatePicker": _showCupertinoDatePicker,
      "CupertinoTimerPicker": _showCupertinoTimerPicker,
    };
    
    var btns=  buttons.keys.toList().map((str){//构建按钮组件列表
      return RaisedButton(
        onPressed: () {
          buttons[str](context);
        },
        child: Text(str),
      );
    }).toList();

    var result =Column(children: [title,Column(
      children: btns,
    )],) ;
    return result;
  }
}

1.对话框:`SimpleDialog`

通过showDialog来创建对话框，传入BuildContext对象，通过builder构造器来创建组件简单的对话框，只要一条条的东西可以选择SimpleDialog，比如：

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_showSimpleDialog(BuildContext context) {
  var strs=['云深不知处内亥时息,卯时起',
    "云深不知处内不可挑食留剩,不可境内杀生",
    "云深不知处内不可私自斗殴,不可淫乱",
    "云深不知处禁止魏无羡入内,不可吹笛"];
  
  var title = Row(//标题
    children: [
      Image.asset("images/icon_lwj.png", width: 30,height: 30,),
      SizedBox(width: 10,),
      new Text("蓝氏家规")],
  );
  showDialog(
      context: context,
      builder: (context) {
        return SimpleDialog(
          title: title,
          children: strs.map((str){
            return SimpleDialogOption(
              child: Row(children: [
                Icon(Icons.turned_in_not,color: Colors.blue,),Text(str)],) ,
              onPressed: () {
                Navigator.of(context).pop(str);
                print(str);
              },
            );
          }).toList(),
        );
      });
}

3.对话框:`CupertinoAlertDialog`

Cupertino风格的对话框

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void _showCupertinoAlertDialog(BuildContext context) {
  var title = Row(//标题
    mainAxisAlignment: MainAxisAlignment.center,
    children: <Widget>[
      Image.asset("images/icon_wwx.png", width: 30,height: 30,),
      SizedBox(width: 10,),
      new Text("表白")],
  );
  var content = Row(
    children: <Widget>[
      Text("我?你，你是我的",style: TextStyle(fontSize: 20),),
      Image.asset("images/icon_ylm.png", width: 40, height: 40, ) ],
  );
  var dialog = CupertinoAlertDialog(
    content: content,
    title: title,
    actions: <Widget>[
      CupertinoButton( child: Text("不要闹"),
        onPressed: () {
          Navigator.pop(context);
        },
      ),
      CupertinoButton( child: Text("走开"),
        onPressed: () {
          Navigator.pop(context);
        },
      ),
    ],
  );
  showDialog(context: context, builder: (context) => dialog);
}
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4.瞎玩一下

既然对话框里面显示的是一个Widget，那我把它自己显示出了会怎么样? 现在Dialog应该不难玩了吧，既然什么Widget都能放进去，还有什么好怕的。

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_showWidgetDialog(BuildContext context) {
  showDialog(
      context: context,
      builder: (context) {
        return this.widget;
      });
}
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5.对话框中的StatefulWidget

想要更新对话框里的组件状态，可以用StatefulBuilder，里面回调的StateSetter对象

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_showStatefulWidgetDialog(BuildContext context) {
  var progress = 0.0;
  StateSetter stateSetter;

  Timer.periodic(Duration(milliseconds: 100), (timer) {//计时器模拟进度增加
    progress  = 0.1;
    if (stateSetter != null) {
      stateSetter(() {});
    }
    if (progress >= 1) {
      timer.cancel();
      stateSetter = null;
      Navigator.of(context).pop();
    }
  });

  var statefulBuilder = StatefulBuilder(
    builder: (ctx, state) {
      stateSetter = state;
      return Center(
        child: SizedBox(width: 150, height: 150,
          child: Card(elevation: 24.0,
            color: Colors.blue.withAlpha(240),
            child: Column(
              mainAxisSize: MainAxisSize.min,
              crossAxisAlignment: CrossAxisAlignment.center,
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                CircularProgressIndicator(
                  valueColor: AlwaysStoppedAnimation(Colors.white),
                  value: progress,
                ),
                SizedBox(height: 20,),
                Text("Loading...",
                  style: TextStyle(color: Colors.white),),
                SizedBox(height: 5,),
                Text("done ${((progress-0.1) * 100).toStringAsFixed(1)}%",
                  style: TextStyle(color: Colors.white),),
              ],
            ),
          ),
        ),
      );
    },
  );
  showDialog(context: context, builder: (ctx) => statefulBuilder);
}
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6.底部弹框:SnackBar

这个比较简单，使用Scaffold.of方法获取ScaffoldState调用showSnackBar

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_showScaffold(BuildContext context) {
      var snackBar = SnackBar(
      backgroundColor: Color(0xffFB6431),//颜色
      content: Text('Hello!'),//内容
      duration: Duration(seconds: 3),//持续时间
      action: SnackBarAction(
          label: '确定',
          onPressed: () {
            print("Flutter之旅");
          }));
      Scaffold.of(context).showSnackBar(snackBar);//这样就行了
}
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7.底部抽屉:BottomSheet

用法和SnackBar相似，更强的是底部栏的child你想放什么都可以。

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bool _showing=false;
_showBottomSheet(BuildContext context) {
  var bottomSheet = BottomSheet(
      onClosing: () {},
      builder: (context) => (Container(
            color: Color(0xdde3fbf6),
            height: 150,
            child: Center(
              child: Image.asset("images/wy_300x200_filter.jpg"),
            ),
          )));
  if(_showing){
    Navigator.of(context).pop();
  }else{
    Scaffold.of(context).showBottomSheet(bottomSheet.builder); //这样就行了
  }
  _showing=!_showing;
}
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8.日历选表：showDatePicker

返回一个DataTime泛型的Future对象

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void _showDatePicker(BuildContext cxt) {
  showDatePicker(
    context: cxt,
    initialDate: DateTime.now(),
    firstDate: DateTime(2018),
    lastDate: DateTime(2030),
    builder: (BuildContext context, Widget child) {
      return Theme(
        data: ThemeData.dark(),
        child: child,
      );
    },
  ).then((data){
    print(data);
  });
}
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9.时间选表：showDatePicker

返回一个TimeOfDay泛型的Future对象

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void _showTimePicker(BuildContext cxt) {
  showTimePicker(
    context: cxt,
    initialTime: TimeOfDay(hour: 11, minute: 45),
    builder: (BuildContext context, Widget child) {
      return Theme(
        data: ThemeData.dark(),
        child: child,
      );
    },
  ).then((data){
    print(data);
  });
}
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10.选择表：CupertinoPicker

ios风格的选择表，感觉还挺好看

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void _showCupertinoPicker(BuildContext context){
  var names=['魏祖','蓝二','江姐','江舅','瑶妹'];
  final picker  = CupertinoPicker(
      itemExtent: 40,
      onSelectedItemChanged: (position){
        print('The position is ${names[position]}');
      }, children: names.map((e){
        return Text(e);
  }).toList());
  showCupertinoModalPopup(context: context, builder: (cxt){
    return Container(
      height: 200,
      child: picker,
    );
  });
}
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11.日期选卡：CupertinoPicker

挺方便的

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_showCupertinoDatePicker(BuildContext context){
  final picker =CupertinoDatePicker(
    onDateTimeChanged: (date){
    print("当前日期、时间 ${date.toString()}");
  },
    initialDateTime: DateTime(1994),
  );
  showCupertinoModalPopup(context: context, builder: (cxt){
    return Container(
      height: 200,
      child: picker,
    );
  });
}
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12.日期选卡：CupertinoPicker

不多说，看效果

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void _showCupertinoTimerPicker(BuildContext cxt){
  final picker = CupertinoTimerPicker(onTimerDurationChanged: (duration){
    print('当前时间 $duration');
  });
  showCupertinoModalPopup(context: cxt, builder: (cxt){
    return Material(child: Container(
      height: 200,
      child: picker,
    ),);
  });
}
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