我创建了一个基本OverlyEntry。

我创建了一个基本的OverlyEntry来显示一些类似搜索的想法，当我仍然在textfromfield中写入时，仍然重建overlyEntry构建器，当尝试打开dropDownButton时，重建。

• 我试图修复它，但任何想法，它没有工作。*

final FocusNode _focusNode = FocusNode();
final GlobalKey globalKey = LabeledGlobalKey('OverlayEntry');

--

@override
  void initState() {
    _focusNode.addListener(() {
      if (_focusNode.hasFocus) {
        print('showed');
        _overlayEntry = _createOverlayEntry();
        Overlay.of(context)!.insert(_overlayEntry);
      } else {
        _overlayEntry.remove();
      }
    });
  }

--

OverlayEntry _createOverlayEntry() {
    RenderBox renderBox = globalKey.currentContext!.findRenderObject() as RenderBox;
    var size = renderBox.size;
    var offset = renderBox.localToGlobal(Offset.zero);

    return OverlayEntry(
      maintainState: true,
      builder: (context) {
      print('OverlayEntry');
      return Builder( 
        builder: (context) {
          return Positioned(
            left: offset.dx,
            top: offset.dy + size.height + 5.0,
            width: size.width,
            child: Material(
              elevation: 4.0,
              child: ListView(
                padding: EdgeInsets.zero,
                shrinkWrap: true,
                children: const [
                  ListTile(
                    title: Text('Syria'),
                  ),
                  ListTile(
                    title: Text('Lebanon'),
                  ),
                  ListTile(
                    title: Text('Lebanon'),
                  ),ListTile(
                    title: Text('Lebanon'),
                  )
                ],
              ),
            ),
          );
        }
      );
    });
  }

--

@override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        widthFactor: 50,
        child: TextFormField(
          key: globalKey,
          focusNode: _focusNode,
          decoration: const InputDecoration(labelText: 'Country'),
        ),
      ),
    );
  }