* Macro to correct errors in the internal SHIFT command
* syntax : shift image x y
* install by adding the following line to startup.cmd
* cli rename shift old_shift

* handle degenerate cases where x is 0
if $1 == 0
  if $2 == 0
    i= $0
  else
    old_shift $0 0 $2
  endif
  return
endif

* handle degenerate cases where y is 0
if $2 == 0
  if $1 == 0
    i= $0
  else
    old_shift $0 $1 0
  endif
  return
endif

* handle dual shift case
vdef xs i.cols
vdef ys i.rows
vdef ci i.name

icreate sh_tmp @xs @ys
ci sh_tmp
old_shift $0 $1 0
ci "@ci"
old_shift sh_tmp 0 $2

iremove sh_tmp
vkill xs ys ci