mydeltax和mydeltay为offset value
set mylayout mylayout.gds
set myoutfile myoutfile.gds
set mydeltax 12.0
set mydeltay 15.0
set L [layout create $mylayout -dt_expand]
set mytopcell [$L topcell]
$L cellname $mytopcell myoldtopcell
set mydbunits [$L units user]
$L create cell $mytopcell
$L create ref $mytopcell myoldtopcell \
[expr $mydeltax / $mydbunits] \
[expr $mydeltay / $mydbunits] 0 0 1
$L expand cell myoldtopcell
$L gdsout $myoutfile $mytopcell