[sane-devel] DUPLEX Scan

Olaf Meeuwissen paddy-hack at member.fsf.org
Tue Mar 5 11:21:48 GMT 2019

Hi sunjing,

孙静 writes:

>  But How The Frontends can find this 'source' option,
>  if different Frontends and Backends,How they be compatible?

That's all explained in the SANE API spec[1], but basically proper SANE
frontends ask the backend for a list of its options and build a user
interface from the information returned by the backend.

 [1]: http://sane-project.org/html/

In your case, that information would include your Duplex option, so a
proper SANE frontend will include that in it's user interface for your

Some SANE "frontends" have their own ideas of what they want to show
their users and try to adapt the backend information to those ideas
with various degrees of success.
Last time I looked, Simple Scan was one of those.

If you want your backend to "play nice" with such frontends, you would
do well to check their expectations and adjust your backend to them.
If you don't, your Duplex option may not be in the UI and you will have
to ask the frontend developers to fix things, wait for a fixed release
and wait again for the distributors to pick up the new release ... :-(

Hope this helps,
Olaf Meeuwissen, LPIC-2            FSF Associate Member since 2004-01-27
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