cad.net objectarx 后台打开dwg

 参考：https://spiderinnet1.typepad.com/blog/2013/03/autocad-net-safely-create-new-database-and-saveas.html

        [CommandMethod("testdata")]
        public static void testdata()
        {
            Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;
            string path = @"c:\temp\test.dwg";
            
            try
            {
                using (Database db = new Database(false, true))
                {
                    db.ReadDwgFile(path, FileOpenMode.OpenForReadAndAllShare, false, null);
                    db.CloseInput(true);
                    using (Transaction tr = db.TransactionManager.StartTransaction())
                    {
                        BlockTableRecord btr = (BlockTableRecord)tr.GetObject(SymbolUtilityServices.GetBlockModelSpaceId(db), OpenMode.ForRead);
                        foreach (ObjectId id in btr)
                        {
                            Entity ent = (Entity)tr.GetObject(id, OpenMode.ForWrite);
                            ent.ColorIndex = 1;
                        }

                        tr.Commit();
                    }
                    db.SaveAs(@"c:\temp\test_2red.dwg", DwgVersion.Current);


                    MessageBox.Show("保存完毕！");
                }
            }
            catch (System.Exception ex)
            {
                ed.WriteMessage(ex.ToString());
            }
        }