清除图层中的图元【原】

     /// <summary>
    /// Summary description for PinPointCommand.
    /// </summary>
    [Serializable]
    public class ClearPinPointCommand : MapInfo.WebControls.MapBaseCommand
    {
        /// <summary>
        /// Constructor for this command, sets the name of the command
        /// </summary>
        /// <remarks>None</remarks>
        public ClearPinPointCommand()
        {
            Name = "ClearPinPointCommand";
        }
        /// <summary>
        /// This method gets the map object out of the mapfactory with given mapalias
        /// and This method delete the pin point features added by AddPinPointCommand in a given point
        /// and then streams the image back to client.
        /// </summary>
        /// <remarks>None</remarks>
        public override void Process()
        {
            System.Drawing.Point[] points = ExtractPoints(DataString);
            MapControlModel model = MapControlModel.GetModelFromSession();
            model.SetMapSize(MapAlias, MapWidth, MapHeight);
            MapInfo.Mapping.Map map = model.GetMapObj(MapAlias);
            if (map == null) return;
            PointDeletion(map, points[0]);
            MemoryStream ms = model.GetMap(MapAlias, MapWidth, MapHeight, ExportFormat);
            StreamImageToClient(ms);
        }
        /// <summary>
        /// Delete a feature in the temporary layer.
        /// </summary>
        /// <param name="mapAlias">MapAlias of the map</param>
        /// <param name="point">Point in pixels</param>
        private void PointDeletion(Map map, System.Drawing.Point point)
        {
            // Do the search and show selections
            SearchInfo si = MapInfo.Mapping.SearchInfoFactory.SearchNearest(map, point, 10);
            (si.SearchResultProcessor as ClosestSearchResultProcessor).Options = ClosestSearchOptions.StopAtFirstMatch;
            MapInfo.Data.Table table = MapInfo.Engine.Session.Current.Catalog["kb"];
            if (table != null)
            {
                IResultSetFeatureCollection ifc = MapInfo.Engine.Session.Current.Catalog.Search(table, si);
                foreach (Feature f in ifc)
                {
                    table.DeleteFeature(f);
                }
                ifc.Close();
            }
        }
    }