如图所示：增加一个图层“新图层”，颜色为红（1），当图层颜色定义为黄（2）时，直接覆盖之前图层颜色，图层名不变。

代码如下：

 

  /// </summary>/// <param name="数据库db"></param>/// <param name="图层名layname"></param>/// <param name="图层颜色colorindex"></param>/// <returns>图层名layname</returns>public static string AddLayer(this Database db, string layname, short colorindex){if ((colorindex < 0) || (colorindex > 256)){colorindex = 0;};//var pt = Point3d.Origin;//Application.DocumentManager.MdiActiveDocument.Editor.GetPoint(out pt, "asdf");// 获得当前文档和数据库   Get the current document and databaseDocument acDoc = Application.DocumentManager.MdiActiveDocument;//Database db = acDoc.Database;// 启动一个事务  Start a transactionusing (Transaction acTrans = db.TransactionManager.StartTransaction()){// 以只读方式打开图层表   Open the Layer table for readLayerTable acLyrTbl;acLyrTbl = acTrans.GetObject(db.LayerTableId,OpenMode.ForRead) as LayerTable;if (acLyrTbl.Has(layname) == false){LayerTableRecord acLyrTblRec = new LayerTableRecord();// Assign the layer the ACI color 1 and a nameacLyrTblRec.Color = Color.FromColorIndex(ColorMethod.ByAci, colorindex);acLyrTblRec.Name = layname;// Upgrade the Layer table for writeacLyrTbl.UpgradeOpen();// Append the new layer to the Layer table and the transactionacLyrTbl.Add(acLyrTblRec);acTrans.AddNewlyCreatedDBObject(acLyrTblRec, true);}else//已存在图层名{ObjectId layerId = acLyrTbl[layname];LayerTableRecord layerRecord = acTrans.GetObject(layerId, OpenMode.ForRead) as LayerTableRecord;layerRecord.UpgradeOpen();layerRecord.Color = Color.FromColorIndex(ColorMethod.ByAci, colorindex);// acTrans.AddNewlyCreatedDBObject(layerRecord, true);}以只读方式打开块表   Open the Block table for read//BlockTable acBlkTbl;//acBlkTbl = acTrans.GetObject(db.BlockTableId,//                             OpenMode.ForRead) as BlockTable;以写方式打开模型空间块表记录   Open the Block table record Model space for write//BlockTableRecord acBlkTblRec;//acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],//                                OpenMode.ForWrite) as BlockTableRecord;//Save the changes and dispose of the transactionacTrans.Commit();}return layname;}