一、关于块的坐标转换

                    
//以块基点为起点，X轴方向镜像块
using (var plane = new Plane(reference.Position, Vector3d.XAxis.TransformBy(ed.CurrentUserCoordinateSystem)))
{
   reference.TransformBy(Matrix3d.Mirroring(plane));
}

//获取块内除标注外的图元的包围框，注意结果需要按照brf.BlockTransform 属性进行变换
//注意：extend必须初始化，否则变换结果不准确

            var btr = brf.BlockTableRecord.GetObject<BlockTableRecord>();
            //获取边界包围盒
            foreach (var itemId in btr)
            {
                var ent = itemId.GetObject();
                if (!(ent is RotatedDimension))
                    extend.AddExtents((ent as Entity).GeometricExtents);
                if (ent is Circle)
                    HasCircle = true;
                ent.Dispose();
            }
            extend.TransformBy(brf.BlockTransform);