[sane-devel] Scanner buttons (kind of RFC)

[Matto Marjanovic]

 > has an ADF, we're all set (assuming ADF's are handled properly, which they
 > aren't quite).
 ...
 >The user still has to initiate the whole process ("start ADF scan") from
 > the frontend, but then she slides her chair over to the scanner for the
 > duration of her document.

Furthermore (last thoughts before I go to work)...

The ADF problem could be fixed with the addition of a single, new, kind-of-
 -well-known-option.  It would be a boolean called "USE_ADF":

  o If the scanner/backend supports ADF scanning (either via a real and
     installed feeder, or via the user's button pushing) then the backend
     should provide this option.
    If the scanner doesn't support such scanning, then the backend does
     not provide this option, and everything works just as it does now.

  o If the option is set to FALSE, the scanner should do a regular
     single-sheet manual scan.
    If the option is set to TRUE, the backend should to into ADF mode,
     i.e. tell the scanner to use the ADF, or in the case of a front-panel
     button, the backend should wait for the button before scans.

Current frontends can be oblivious to this option, and the world will not
 be harmed.

scanadf can be modified to require this option, since it would now identify
 which scanners actually support an ADF mode.

xscanimage/xsane can be modified to finally do multi-page scans.  If the
 USE_ADF option exists, they could provide a "Scan Multiple" button in
 addition to "Scan" --- this would automatically scan & save pages until
 a NO_DOCS condition from the scanner, or the user presses a Cancel button.

-matt m.