13 Flutter UI 之 对话框

一  SimpleDialog

1 显示对话框 

// 显示对话框
              showDialog(
                  context: context,
                  builder: (BuildContext context) {
                    // 选择对话框的样式
                    return SimpleDialog(
                      title: Text(
                        "this is simple",
                        style: TextStyle(color: Colors.red),
                      ),
                      // 可以定义很多选项
                      children: [
                        SimpleDialogOption(
                          child: Text('OptionA'),
                          // 点击关闭对话框
                          onPressed: () {
                            Navigator.of(context).pop();
                          },
                        ),
                        SimpleDialogOption(
                          child: Text('Option B'),
                          // 点击关闭对话框
                          onPressed: () {
                            Navigator.of(context).pop();
                          },
                        )
                      ],
                    );

2 获取对话框的选项的值

// 异步的回调
  Future _openOneDialog() async {
    //
    final option = await showDialog(
        context: context,
        builder: (BuildContext context) {
          // 选择对话框的样式
          return SimpleDialog(
            title: Text(
              "this is simple",
              style: TextStyle(color: Colors.red),
            ),
            // 可以定义很多选项
            children: [
              SimpleDialogOption(
                child: Text('OptionA'),
                // 点击关闭对话框
                onPressed: () {
                  // 这里把选择的值传递过去
                  Navigator.of(context).pop(Option.A);
                },
              ),
              SimpleDialogOption(
                child: Text('Option B'),
                // 点击关闭对话框
                onPressed: () {
                  // 这里把选择的值传递过去
                  Navigator.of(context).pop(Option.B);
                },
              )
            ],
          );
        });        
    print(option);
  }

二 AlertDialog

  
enum AlertOption { Ok, Cancel }

_openAlertDialog() async {
    final alertOption = await showDialog(
        context: context,
        builder: (BuildContext context) {
          return AlertDialog(
            // 标题
            title: Text(
              "This is Alert",
              style: TextStyle(color: Colors.red),
            ),
            // 内容
            content: Text(
                "It will not make much difference whether you go today or tomorrow,do you want cancel your plan?"),
            // 动作
            actions: [
              ElevatedButton(
                  onPressed: () {
                    Navigator.of(context).pop(AlertOption.Cancel);
                  },
                  child: Text("Close")),
              ElevatedButton(
                  onPressed: () {
                    Navigator.of(context).pop(AlertOption.Ok);
                  },
                  child: Text("Ok"))
            ],
          );
        });
    print(alertOption);
  }

三 BottomSheet

注意，定义的key 一定要在scafford 组件的key 中赋值，否则会报错 

key: _bottomSheetScaffordKey

// 这个key值必须赋给Scafford 中的key 字段，否则下面会报错
  final _bottomSheetScaffordKey = GlobalKey();

  _openBottomSheet() {
    _bottomSheetScaffordKey.currentState!
        .showBottomSheet((BuildContext context) {
      return BottomAppBar(
        child: Container(
          child: Center(
            child: Text("Put Many Widget"),
          ),
          height: 300,
          width: double.infinity,
        ),
      );
    });
  }

四 ModalBottomSheet

 Future _openModalBottomSheet() async {
    final options = await showModalBottomSheet(
        context: context,
        builder: (BuildContext context) {
          return Container(
            width: double.infinity,
            height: 250,
            child: Column(
              children: [
                ListTile(
                  title: Text("Option A"),
                  subtitle: Text(
                      "Sorry to be so direct,but how much did you pay for this ?"),
                  // 点击的时候关闭Modal
                  onTap: () {
                    Navigator.of(context).pop("OptionA");
                  },
                ),
                ListTile(
                  title: Text("Option B"),
                  subtitle: Text(
                      "this medicine,properly used,will do you a lot of good "),
                  onTap: () {
                    Navigator.of(context).pop("OptionB");
                  },
                ),
                ListTile(
                  title: Text("Option C"),
                  subtitle: Text(
                      "just as food feeds the body,so reading feeds the mind"),
                  onTap: () {
                    Navigator.of(context).pop("OptionC");
                  },
                ),
              ],
            ),
          );
        });
    // 打印用户选择
    print(options);
  }

  _openBottomSheet() {
    _bottomSheetScaffordKey.currentState!
        .showBottomSheet((BuildContext context) {
      return BottomAppBar(
        child: Container(
          child: Center(
            child: Text(
                "In the absence of better idea i had to choose this method"),
          ),
          height: 300,
          width: double.infinity,
        ),
      );
    });
  }