CAD二次开发之“添加对象到模型空间”

模型空间是一条名为BlockTableRecord.ModelSpace的特殊块表记录(添加到其中的对象会在模型空间图纸中绘制出其形状)，
将对象添加到模型空间的方法与将对象添加到块表记录的方法一样。

using System;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
[assembly: CommandClass(typeof(Sample.AddToModelSpace))]
namespace Sample
{
    class AddToModelSpace
    {
        [CommandMethod("ToModelSpace")]
        public void ModelSpace()
        {
            Database db = HostApplicationServices.WorkingDatabase;
            DBText txt = new DBText(); txt.Position = new Point3d();
            txt.TextString = "BimCAD.org"; ToModelSpace(txt, db);
        }
        /// <summary> 
        /// 将一个图形对象加入到指定的Database的模型空间 
        /// </summary> 
        /// <param name="ent">实体对象</param> 
        /// <param name="db">数据库</param> 
        /// <returns></returns>
        public static ObjectId ToModelSpace(Entity ent, Database db)
        {
            ObjectId entId; using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                BlockTable bt = (BlockTable)trans.GetObject(db.BlockTableId, OpenMode.ForRead);

                BlockTableRecord btr = (BlockTableRecord)trans.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
                entId = btr.AppendEntity(ent); trans.AddNewlyCreatedDBObject(ent, true); trans.Commit();
            }
            return entId;
        }
    }
}

 加载程序后运行"ToModelSpace"模型空间显示如下：

end