图层图例的展开与收缩

        /// <summary>
        /// 展开图层的图例（最后需要执行toc的Update方法）
        /// </summary>
        /// <param name="pLayer"></param>
        /// <param name="bExpand"></param>
        public static void ExpandLegend(ILayer pLayer, bool bExpand)
        {          
            ILegendInfo pLegendInfo = pLayer as ILegendInfo;

            int iLegendGroupCount = pLegendInfo.LegendGroupCount;
            ILegendGroup pLGroup;
            for (int i = 0; i < iLegendGroupCount; i++)
            {
                pLGroup = pLegendInfo.get_LegendGroup(i);
                pLGroup.Visible = false;
            }          
        }