[sane-standard] More device properties

[m. allan noah]

On 1/18/07, abel deuring <adeuring at gmx.net> wrote:
> Olaf Meeuwissen wrote:
> > abel deuring <adeuring at gmx.net> writes:
> >> Étienne Bersac wrote:

> >>>>   - alignment of original to scan origin or not (centered feeds)
> >>> That's an important point. SANE should provide a "adf padding" option or
> >>> similar.
> >> Some hints how the alignment of the paper width in the feeder
> >> affects the scan window settings may be useful, but I think this is
> >> too simple.
> >>
> >> I see several "scanner parameters" that can affect the scan window
> >> settings:
> >>
> >> (1) the paper can be centered/left aligned/right aligned in the
> >>     feeder
> >> (2) some scanners know about the parameters "page width" and "page
> >>     length"
> >> (3) the origin of the scan window coordinates is fixed, or it is at
> >>     the "corner" of the selected page size.
> >>
> >> Another question is, if a frontend really needs to know about all
> >> these details: If a user does not properly adjust the paper width of
> >> the  feeder, the scan results will anyway be a bit messy. And if we
> >> assume that the feeder is properly aligned, I think that (1) is no
> >> longer important.
> >
> > In the most extreme case a frontend doesn't need to know anything:
> > just scan at the default settings.  The thing is that some users want
> > to do things that require access to the very last little bit of
> > configurability.  That doesn't automatically imply that every little
> > option should be in the standard, of course.
>
> Agree. But I had a hard time to figure out, how and why a frontend
> should deal with the parameter "ADF centers/left aligns/right aligns
> documents".
>
> >>>>   - limiting scan area to page size
> >>> This can be done via {tl,br}-{x,y}. Isn't it ?
> >> right.
> >
> > True, but I was thinking of an advanced boolean option where user
> > could turn this behaviour off if they want to.
>
> Couldn't this be left to the frontend, like a button "set scan
> window size to page size"?

i think all this can be addressed by the backend. presumably it knows
how the paper guides are designed, so it will know the centering.
presumably it will either be able to auto-detect the paper size, or
the user will tell via the 'paper-width/height' options. the scan area
can be clamped to this paper size.

allan

-- 
"The truth is an offense, but not a sin"