Scanner infrastructure in freedesktop

Étienne Bersac bersace03 at
Sun Jan 21 09:51:13 PST 2007


> Isn't TWAIN a Windows library?

TWAIN ( is a producted by a non profit organisation (a
kind of consortium) that define the TWAIN standard, provide a .h and let
members implementing it. TWAIN is « An image capture API for Microsoft
Windows and Apple Macintosh operating systems. » (stolen from the
official FAQ). AFAIK TWAIN is not libre. Technically, TWAIN is not that
bad, but seems far less simple and extensible than SANE.

> Is there any significant advantage to TWAIN?

Maybe software support by adding f* proprietary driver. So that's not a
good advantage, and SANE has a lot of reverse-engineering work in its
code base. (I currently reverse engineering Q-Scan scanner for adding
support in plustek backend).

I won't defend TWAIN that much. But TWAIN might change things in the

> Right, that's why I thought SANE should have dbus support so it can do
> that in the backend.  It could do all that with a library, but having
> a scanner daemon might make it easier to do the stuff you mention and
> would be fine as long as it's run on demand (the typical desktop has
> way too many daemons running as it is), and in that case a dbus API
> would be more useful.  Honestly, I really like the idea of a dbus API
> (adding endpoints on the system message bus is much more flexible than
> adding calls in a new library), I just thought that there wasn't much
> use for it since linking to libsane was a simpler way.  But if there's
> a daemon running to keep track of scanners, button press events, etc.
> and SANE is used more as the backend, then I'm all for a dbus API, as
> long as everything is kept as simple and straightforward as possible -
> otherwise it'll turn into something like the mess we've got with
> printing (n+1 libraries, daemons, and abstractions on top of
> abstractions on top of even more abstractions).

Agree. I don't mean abstraction, i mean features. Vista handle very well
scanner buttons. What's in free desktop ? It just sucks. Luckily, there
is an effort from Jean-Christophe Cardot (KScannerButton

> Ah, thanks for bringing that up, I didn't know it was supposed to be
> portable.  That changes things a bit, but then it should just have a
> set of Linux/BSD routines which interface with HAL and dbus, a set of
> Windows routines which interface with the Windows hardware system,.

Yes, that would be a good starting point.

> I'll have to download the SANE
> source and look over it. 

Good luck. You should read SANE standard before. .

> Verso l'Alto !
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