Questions re Sane API digression & MF Scanner

Dave Restall - System Administrator (
Sun, 14 Nov 1999 18:18:59 +0000


I have started writing a backend for the Scanace 9630 scanner and
unfortunately I hit a brick wall at my first attempt. The brick wall
being :-

The API seems pretty clear to follow and relatively simple to
implement, however there are a few things that I don't understand in the
code that I've looked at for backends. I'm only dealing with sane_init
here, but the API says this :-

"The version code of the backend is returned in the value pointed to by
version_code. If the pointer is NULL, no version code is returned.
Argument authorize is either a pointer to a function that is invoked
when the backend requires authentication for a specific resource or NULL
if the frontend does not support authentication."

Regarding authorization, should "frontend" read "backend" ?

Apart from that this bit of the spec seems pretty clear, however when I
started to read the code for other backends, all sorts of stuff seems to
go on, especially when it comes to initialising the hardware. Surely
this belongs in sane_open ?

I also don't understand the following :-

stubs.c What is it for ?

I was hoping it would be a pile of function stubs with comments in like
"put code for function Y here" in it, e.g. a template for the backend
but it seems to have a more sinister use.

What does the ENTRY macro do in stubs.c ?

I'm not new to C but am new to the style used in the code development
for sane so all help will be greatly appreciated.

I'm also willing to create an empty template with the "Put code to do X
for your scanner here" if it will help and write the FAQ for writing a
backend but I'll need help and guidance, can I use the list for this ?

My other question, I'm looking for a film scanner and liked the look of
the Minolta Dimage series, Minolta don't seem to have any supported
scanners. Is this because nobody has tried or is it because Minolta
won't release any information ?

If Minolta won't play, can anybody recommend a suitable film scanner
that meets the following :-

Can scan :-

35mm Negatives (singly or in strips)
35mm Transparencies (Singly in frames, or in strips)
Medium Format Negatives (Singly, in strips would be nice to have)
Medium Format Transparencies (Singly, in strips would be nice to have)

Optionally APS negatives and transparencies.

Sorry about the length of the mail, lets hope you can help.


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