[sane-devel] option size = 0 allowed ?

[Michael Herder]

Henning Meier-Geinitz, Mittwoch, 18. Dezember 2002 11:55:
...
> > The umax backend defines an option "halftone pattern" with size 0. Is
> > this allowed?
>
> I don't think so. While one could argue if 0 is positive (or negative,
> or both or neither positive nor negative) the intention here is clear
> for me: size > 0. There was a similar discussion on sane-devel years
> (?) ago, but I don't remember the conclusion.
> > Furthermore, the umax backend changes the option size later. IMHO, that
> > at least isn't allowed, because only the availablity or value of an
> > option may change.
>
> It's not allowed. But at least the mustek backend does it also. And I
> don't know an easy work-around if you don't want to specify options
> for every combination of halftone pattern dimensions.

I'm just wondering, how one would present such an option to the user ... 
(Maybe you can integrate all known backend hacks in your test backend :-)

> Changing constraints is also not allowed in SANE1, but it's done by
> quite some backends.

.. for extensions to the SANE standard, read the source code ?

bb
Michael