void GetEntityExtents()
    {
        ads_name entName;
        ads_point pt;
        if(acedEntSel(_T("选择实体:"),entName,pt) != RTNORM)
        {
            return;
        }

        AcDbObjectId objId;
        if(acdbGetObjectId(objId,entName) != Acad::eOk)
            return;

        McDbObjectPointer<McDbEntity> spEntity(objId,AcDb::kForRead);
        if(spEntity.openStatus() != Acad::eOk)
        {
            return;
        }

        // 得到实体的外包
        McDbExtents extents;
        if(spEntity->getGeomExtents(extents) == Mcad::eOk)
        {
            // 得到外包成功
            CString sT;
            sT.Format(_T("外包框左下角点:%lf,%lf,右上角点:%lf,%lf"),
                extents.minPoint().x,extents.minPoint().y,
                extents.maxPoint().x,extents.maxPoint().y
                );
            AfxMessageBox(sT);
        }
    }