如何使用MPF创建虚拟节点?

我想创建一种类型的节点,该节点的支持实际上不存在于任何地方。为了简单起见,我只想动态生成标题。

我的问题是它不起作用。具体地说,当我点击“展开这个文件夹”图标时,它会变成蓝色(所以点击正在注册),但它会保持蓝色并且节点不会展开。调试显示,尝试展开文件夹时,确实会碰到GetProperty请求first child,并且会返回第一个子文件夹的id。之后,将查询VirtualNode两次,以查看它是否可展开。然后查询标题。然后是图标。那就没什么了。

public class AndroidFolderNode : FolderNode
{
    public enum FolderType
    {
        Normal,
        JavaSource
    }

    public string[] VirtualNodes = new[]
                                    {
                                        "Virtual Node One",
                                        "Virtual Node Two",
                                        "Virtual Node Three"
                                    };

    private FolderType mFolderType;
    public FolderType Type
    {
        get
        {
            return mFolderType;
        }
        set
        {
            if (mFolderType != value)
            {
                mFolderType = value;
                OnInvalidateItems(this);
            }
        }
    }

    private HierarchyNode mVirtualChild;

    public AndroidFolderNode(ProjectNode root, string relativePath, ProjectElement element)
        : base(root, relativePath, element)
    {
        var t = element.GetMetadata("Type");
        if (string.IsNullOrWhiteSpace(t))
        {
            Type = FolderType.Normal;
        }
        else
        {
            FolderType tempType;
            if (Enum.TryParse(t, true, out tempType))
            {
                Type = tempType;
            }
        }
    }

    protected override NodeProperties CreatePropertiesObject()
    {
        return new AndroidFolderNodeProperties(this);
    }


    public override object GetProperty(int propId)
    {
        object result = null;
        switch ((__VSHPROPID) propId)
        {
            case __VSHPROPID.VSHPROPID_FirstChild:
                goto case __VSHPROPID.VSHPROPID_FirstVisibleChild;

            case __VSHPROPID.VSHPROPID_FirstVisibleChild:
                if (Type == FolderType.Normal)
                {
                    result = (int)((this.FirstChild != null) ? this.FirstChild.ID : VSConstants.VSITEMID_NIL);
                }
                else
                {
                    if (mVirtualChild == null)
                    {
                        mVirtualChild = new VirtualFolderNode(this, 0);
                    }
                    result = mVirtualChild.ID;
                }
                break;
            default:
                result = base.GetProperty(propId);
                break;
        }
        return result;
    }
}

这是我的虚拟代码:

class VirtualFolderNode : HierarchyNode
{
    private static Guid _guid = new Guid("DD264E51-2E66-4BCC-A8A6-DE3BDE890DED");

    private int mIdx;
    private AndroidFolderNode mParent;
    private VirtualFolderNode mSibling;

    public VirtualFolderNode(AndroidFolderNode parent, int idx)
        : base(parent.ProjectMgr)
    {
        mParent = parent;
        mIdx = idx;
        Parent = parent;

        if (idx < parent.VirtualNodes.Length)
        {
            mSibling = new VirtualFolderNode(parent, idx + 1);
            NextSibling = mSibling;
        }
    }

    public override string Url
    {
        get { return Parent.Url + "\\VNode" + mIdx; }
    }

    public override string Caption
    {
        get { return mParent.VirtualNodes[mIdx]; }
    }

    public override Guid ItemTypeGuid
    {
        get { return _guid; }
    }
}