[sane-devel] SANE2 and filmscanners

[Michael Herder]

Henning Meier-Geinitz, Dienstag, 24. Dezember 2002 15:15:
...
> > > True but closely related to this is the fact that scanning a single
> > > frame is a slow process; 10 minutes a frame is not unrealistic.
> > > Therefore if I only want one frame scanning the lot is a massive pain.
> > > If I have an APS film it will be horrendous if I just want frame 38
> > > say. So you also need a way to select individual frames from what ever
> > > is loaded. On my scanner I have a holder for negatives, which has up to
> > > six frames, a holder for slides which has four and an APS adaptor which
> > > can take an APS film cartridge. From memory depending on which you
> > > insert into the scanner Vuescan offers an appropriate list to scan
> > > from.
> >
> > Maybe we could allow an option value size > sizeof(SANE_Word) for options
> > of type SANE_TYPE_BOOL ? The frontends could then present e.g. a list of
> > checkboxes (or something similar) to the user, where (s)he can select the
> > desired frames from.
>
> I'm not sure, if this is the right approach. Can't this be done in the
> frontend entirely? I mean, the frontend must know about the option
> that selects the "frame" anyway so it can also provide a means to scan
> several different ones one after the other.

I actually thought, that the frontend mustn't know about the 
"frame-selection" option. E.g. there could be a "scan-source" option named
"Film (36 pictures)". When this option is selected, the backend enables a 
bool-option "select frames". When this option is selected too, the frontend 
displays a list with 36 items, from which one can select the desired frames.
The scanner/backend skips the frames that are not selected.
No need for the frontend to know about these options.
Of course, it's also possible to implement this in a different way.
I'm also not sure, whether I understand the requirements for such a scanner 
completely. Maybe someone who owns such a device can explain the requirements 
in more detail. (Another option is, that manufactures send me free devices 
for testing - it's Christmas, isn't it ? :-)

bb
Michael