def op_subtract {
label Subtract
active { expr { [bases] == 2 } }
setup_image {
show
}
setup {
variable scale 1
variable offset 0
proc show {args} {
variable scale
variable offset
show_image [crimp alpha opaque \
[crimp subtract [base 0] [base 1] $scale $offset]]
return
}
scale .left.s -variable ::DEMO::scale -from 1 -to 255 -orient vertical -command ::DEMO::show
scale .left.o -variable ::DEMO::offset -from 0 -to 255 -orient vertical -command ::DEMO::show
pack .left.s -side left -expand 1 -fill both
pack .left.o -side left -expand 1 -fill both
}
}