Querying the RGB and Color Index values of a layer using C#

By Stephen Preston

Here’s a simple C# code snippet showing how to access the RGB color and color index values for a layer. The code iterates all LayerTableRecords in the drawing and prints the values we’re querying to the command line.

using System;    using Autodesk.AutoCAD.Runtime;    using Autodesk.AutoCAD.DatabaseServices;    using Autodesk.AutoCAD.ApplicationServices;    using Autodesk.AutoCAD.EditorInput;    using Autodesk.AutoCAD.Colors;         namespace LayerColor    {      public class GetRGBValuesClass      {        public GetRGBValuesClass()        {        }             [CommandMethod("GetRGB")]        public void GetRGB()        {          Database dBase =                    Application.DocumentManager.MdiActiveDocument.Database;          Autodesk.AutoCAD.DatabaseServices.TransactionManager tm =                                       dBase.TransactionManager;          Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;               using (Transaction myT = tm.StartTransaction())          {            try            {                   LayerTable lt = (LayerTable)tm.GetObject(dBase.LayerTableId,                                                       OpenMode.ForRead);              //Iterate all records in table              foreach (ObjectId ltrId in lt)              {                LayerTableRecord ltr = (LayerTableRecord)tm.GetObject(ltrId, OpenMode.ForRead);                Color colour = ltr.Color;                ed.WriteMessage("nThe name of the layer is: " +                           &#160
;                         ltr.Name.ToString());                ed.WriteMessage("nRed: " + colour.ColorValue.R.ToString());                ed.WriteMessage("nGreen: " + colour.ColorValue.G.ToString());                ed.WriteMessage("nBlue: " + colour.ColorValue.B.ToString());                ed.WriteMessage("nColor Index value of the layer is:" +                                     colour.ColorIndex.ToString() + "n");              }              myT.Commit();            }            catch (Autodesk.AutoCAD.Runtime.Exception e1)            {              //Handle errors            }          }        }      }    }