[sane-devel] Interactive use of scanner buttons

[m. allan noah]

There is a great deal of variation between scanners and backends regarding
what buttons are available and how they are exposed. You also have the
exclusive device access problem. In the end, I think you need a new
frontend, or modifications to an existing one, rather than a separate
monitor.

allan

On Thu, Dec 2, 2021 at 5:35 PM Paul Wolneykien <manowar at altlinux.org> wrote:

>
>   Hi!
>
>   As I can see, XSane doesn't poll the scanner's hardware buttons.
> And if I understand the scanbd manual right, the daemon locks the SANE
> interface to the scanner until a button is pressed, and then gives
> exclusive access to the scanner for the frontend. So, the daemon is
> primarily for launching a frontend, but not for controlling the
> frontend while it is running. Am I right?
>
>   I've grep'ed the mailing list archives a little and it seems that the
> main purpose of various button daemons (scanbuttond, scanbd) is to
> implement such a facility as "push scan": the user goes to a remote
> (possibly, network) scanner, places a standard material into it,
> presses a button on the scanner and the system performes an automatic
> (that's important!) scan.
>   It also seems that in other situations, when a user wants to use an
> interactive frontend (for making previews, selecting the scan
> area, adjusting black and white points and gamma) the scanner is
> expected to be placed on the table near PC. Or, at least, that the
> material for scan can be placed into the scanner without a need for
> further attention (i.e. a sheet material), so the user can set it up
> and then back to his/her keyboard and mouse to make a scan or a number
> of scans with different settings using the GUI frontend.
>
>   These two stories (the "push story" and the "desktop story") are nice
> and simple, but are more or less unapplicable in the world of book
> scanning!
>
>   Firstly, books are all different, so you need to make previews,
> select areas and adjust things for each one. Secondly, books aren't
> flat, so even if you use a special hardware you almost always need
> to handle the book with both your hands!
>
>   So, for scanning books, it would be nice to be able to control such a
> frontend as XSane with the scanner's hardware buttons. Because most of
> the time you can reach the hardware button even if you handle the book
> using both hands (however, a configurable delay after the button is
> pressed may be helpful option).
>
>   (The other possible way to solve the described problem is to use a
> separate triggering device. May be a pedal! But that's another story...)
>
>   I want to know/discuss, what a design of a button monitor for
> use with interactive frontends would fit into SANE better. Any ideas?
>
>

-- 
"well, I stand up next to a mountain- and I chop it down with the edge of
my hand"
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