[sane-standard] More device properties

[m. allan noah]

sorry for the weird forward from new account- having email troubles....

> On Wed, 17 Jan 2007, Étienne Bersac wrote:
>
> > Hi,
> >
> > Thanks for you comments. There are very useful.
> >
> >>   - alignment of original to scan origin or not (centered feeds)
> >
> > That's an important point. SANE should provide a "adf padding" option or
> > similar.
>
> >>   - limiting scan area to page size
> >
> > This can be done via {tl,br}-{x,y}. Isn't it ?
> >
> >>   - rotation of original
> >
> > Imo, this is post processing, device/sane/backend should not care this.
> >
> >>   - "ADF preview" (feed first page, do a preview scan, leave it on the
> >>     scan area so the user can fiddle with whatever other options before
> >>     starting a scan of a 100 page document.  You may even want to allow
> >>     for repeating the preview with the same page.)
> >
> > That makes sense.
>
but requires that the user understand that the page that has been
previewed cannot be rescanned without reloading the hopper.
>
> >
> > So, I propose the following options add:
> >
> >      * simplex/duplex document
> >              * name: "adf-duplex"
> >              * title: "Duplex/simplex"
> >              * desc: "Wether the document in the ADF is duplex or
> >                simplex."
> >              * type: string enum
> >              * values: none/long-edge/short-edge
>
i do not understand the need for this? what will the front-end do
differently with this info? why the need for long/short edge?
>
> >      * ADF introduced side
> >              * name: "adf-side"
> >              * title: "From which side of the scan area the document
> >                come from"
> >              * desc: ""
> >              * type: enum
> >              * values: right/left/top/bottom
>
maybe crazy, but why not have the backend just rotate to standard
orientation before returning data?
>
> >      * ADF document centered
> >              * name: "adf-centered"
> >              * title: "Document centered in ADF"
> >              * desc: "Expose wether document are centered in ADF."
> >              * type: Bool
>
what will a front-end do with this info? i feel like we are perhaps
exposing things that should be taken care of by backend...
>
> >      * ADF padding
> >              * name: "adf-padding"
> >              * title: "ADF padding"
> >              * desc: "Expose the padding of the document in the ADF,
> >                relative to scan area origin of the adf-side. If
> >                adf-centered is set to true, then the padding refer to
> >                the center of the document."
> >              * type: Fixed
> >              * unit: mm
> >              * readonly
> >
>
i just dont get this. i guess i am slow today :)

i propose another method which removes the need for this, i think:

add paper-width and paper-height options. the user can tell the scanner
what size the paper is, and the scanner can move the users scan area
coordinates so that they are always anchored in the upper left corner of
the paper. then the backend deals with centering, etc.

otherwise, you are potentially talking about extending all front-ends that
might ever use an adf scanner to understand all this centering
manipulations?

in the interest of full disclosure, this is how the fujitsu backend
already works, and it works pretty well, other than the overscanning
issues which i need to address.

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