/// <summary>
        /// 添加一个函数框
        /// </summary>
        /// <param name="itbox"></param>
        public override void Add(IItemBox item)
        {
            LineItemBox itbox = item as LineItemBox;
            FunctionBox fb    = new FunctionBox();

            itbox.ContentX  = currentPosition.X;
            itbox.ContentY  = currentPosition.Y;
            fb.UIMain       = contentsCanvas;
            fb.DataContext  = itbox;
            itbox.Thickness = 6;
            Itemboxs.Add(itbox);
            fb.InitFunction();
            Add(fb);
        }
        /// <summary>
        /// 添加一个函数框
        /// </summary>
        /// <param name="itbox"></param>
        public void Add(IItemBox item, bool isaddposition)
        {
            LineItemBox itbox = item as LineItemBox;
            FunctionBox fb    = new FunctionBox();

            if (isaddposition == true)
            {
                itbox.ContentX = currentPosition.X;
                itbox.ContentY = currentPosition.Y;
            }
            fb.UIMain       = contentsCanvas;
            fb.DataContext  = itbox;
            itbox.Thickness = 6;
            Itemboxs.Add(itbox);
            fb.InitFunction();
            Add(fb);
        }