LearnGodot/Utils/FileDirSelector.cs

using System.Threading.Tasks;
using Godot;

public partial class FileDirSelector : FileDialog
{
	private bool _isRequestPending;
	
	public override void _Ready()
	{
		FileMode = FileModeEnum.OpenDir;
		Title = "请选择一个文件夹";
		Access = AccessEnum.Filesystem;
	}

    public async Task<string> SelectFolderAsync()
    {
	    if (_isRequestPending)
	    {
		    GD.PrintErr("错误：另一个文件对话框请求正在进行中。本次请求被忽略。");
		    return null; // 直接返回 null 或抛出异常
	    }
        
	    _isRequestPending = true;
	    
        var tcs = new TaskCompletionSource<string>();

        void OnDirSelected(string dir)
        {
            DirSelected -= OnDirSelected;
            Canceled -= OnCanceled;
            tcs.SetResult(dir);
            _isRequestPending = false;
        }

        void OnCanceled()
        {
            DirSelected -= OnDirSelected;
            Canceled -= OnCanceled;
            tcs.SetResult(null);
            _isRequestPending = false;
        }

        DirSelected += OnDirSelected;
        Canceled += OnCanceled;

        PopupCentered();

        return await tcs.Task;
    }
}