Point3d pt1 = Autodesk.AutoCAD.Internal.Utils.UcsToDisplay(item.MinPoint, false);
Point3d pt2 = Autodesk.AutoCAD.Internal.Utils.UcsToDisplay(item.MaxPoint, false);
Point2d pStart = Point3dToPoint2d(pt1);
Point2d pEnd = Point3dToPoint2d(pt2);
//设置打印范围
Extents2d exWin = new Extents2d(pStart, pEnd);