为什么在使用flutter/dart中使用willpopscope时，返回按钮也可以工作？

Question

在我的代码中，有一个自动弹出对话框。当出现此弹出窗口时，我需要防止用户能够单击后按钮。

这是整个代码：

// New Game route
class NewGameRoute extends StatelessWidget {
  const NewGameRoute({key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'New Game',
      home: ListFromCSV(),
    );
  }
}

class ListFromCSV extends StatefulWidget {
  const ListFromCSV({Key? key}) : super(key: key);

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

class _ListFromCSVState extends State<ListFromCSV> {
  List<List<dynamic>> _listData = [
    [""]
  ];
  int _listCount = 0;
  bool _isFirstLoad = true;
  String assetPath = "files/main.jpg";
  bool shouldPop = true;

  @override
  void initState() {
    _loadCSV();
  }

  // This function is only triggered at init, so we only load csv once
  void _loadCSV() async {
    String rawData = await rootBundle.loadString("files/Text.csv");
    _listData = const CsvToListConverter().convert(rawData);
    assetPath = _listData[_listCount][1] == ""
        ? "files/main.jpg"
        : _listData[_listCount][1];
  }

  // This function is triggered when my button is pressed
  void _nextCSV() {
    setState(() {
      _listData = _listData;
      _listCount < _listData.length - 1
          ? _isFirstLoad
          ? _isFirstLoad = false
          : _listCount++
          : _listCount;
      assetPath =
      _listData[_listCount][1] == "" ? assetPath : _listData[_listCount][1];
      _listData[_listCount][2] == "" ? null : _showAlertDialog();
    });
  }

  // This function makes buttons visible/invisible
  bool isVisible = true; //will be visible for the first frame

  void _isVisible() {
    setState(() {
      isVisible = !isVisible;
    });
  }


  //Alert Dialog about questions and answers
  void _showAlertDialog() {

    // set up the buttons
    Widget Answer1Button = TextButton(
      child: Text(_listData[_listCount][3]),
      onPressed:  () {},
    );
    Widget Answer2Button = TextButton(
      child: Text(_listData[_listCount][4]),
      onPressed:  () {},
    );

    // set up the AlertDialog
    AlertDialog alert = AlertDialog(
      // title: Text(),
      content: Text(_listData[_listCount][2]),
      actions: [
        Answer1Button,
        Answer2Button,
      ],
    );

    // show the dialog
    showDialog(
      barrierDismissible: false,  //use to dismiss any tap on the background of the dialog
      context: context,
      builder: (BuildContext context) {
        return alert;
      },
    );
  }

  @override
  Widget build(BuildContext context) {
    return WillPopScope(
        onWillPop: () async {
          // await showDialog or Show add banners or whatever
          // return true if the route to be popped
          return false; // return false if you want to disable device back button click
        },
      child: Scaffold(
        appBar: AppBar(
          title: const Text('New Game'),
        ),
        body: Container(
          height: MediaQuery.of(context).size.height,
          decoration: BoxDecoration(
              image: DecorationImage(
                  image: AssetImage(assetPath),
                  fit: BoxFit.cover)),
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: <Widget>[
              Visibility(
                child: Column(
                  children: [
                    ClipRRect(
                      borderRadius: BorderRadius.circular(4),
                      child: Stack(
                        children: <Widget>[
                          Positioned.fill(
                            child: Container(
                              decoration: BoxDecoration(
                                  image: DecorationImage(
                                      image: AssetImage('files/sheet.jpg'),
                                      fit: BoxFit.cover)),
                            ),
                          ),
                          Text(_listData[_listCount][0]),
                        ],
                      ),
                    ),
                    Row(
                      mainAxisAlignment: MainAxisAlignment.spaceAround,
                      children: [
                        ImageButton(label: 'OK', onButtonTap: _nextCSV),
                        ImageButton(label: 'Hide', onButtonTap: _isVisible),
                        ImageButton(label: 'Test1', onButtonTap: _showAlertDialog),
                      ],
                    ),
                  ],
                ),
                visible: isVisible,
              ),
              // your other widgets
              Visibility(
                child: ImageButton(label: 'Show', onButtonTap: _isVisible),
                visible: !isVisible,
              )

            ],
          ),
        ),
      ),
    );
  }
}

这是包裹脚手架的部分：

  @override
  Widget build(BuildContext context) {
    return WillPopScope(
        onWillPop: () async {
          // await showDialog or Show add banners or whatever
          // return true if the route to be popped
          return false; // return false if you want to disable device back button click
        },
      child: Scaffold(

但是后面按钮仍然有效并取消对话框。我的错误是什么？提前致谢。

Answer 1

这应该有效：

showGeneralDialog(
      context: context,
      barrierDismissible: false,
      pageBuilder: (_, __, ___) {
        return WillPopScope(
          onWillPop: () async {
            return false;
          },
          child: Container(
            //Your popup's content goes here
          ));
      }
)