[sane-standard] More device properties

Étienne Bersac bersace03 at laposte.net
Wed Jan 17 23:45:37 CET 2007


Hi,

> > > That makes sense.
> >
> but requires that the user understand that the page that has been
> previewed cannot be rescanned without reloading the hopper.

ACK. That's not very important since the purpose of adding option is to
avoid preview by computing almost all paramaters by the frontend.

> 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?

You're right. A boolean value should be enough.

> > >      * ADF introduced side
> maybe crazy, but why not have the backend just rotate to standard
> orientation before returning data?

This option help the frontend computing right scan-area. This is not
about rotation. And, yeah, rotating in the backend is crazy, imho :).

> > >      * 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?

Again, the purpose of this option is for frontend to compute scan-area
using ADF.

> > >      * ADF padding
> i just dont get this. i guess i am slow today :)

think "offset" or "document-offset" if you prefer.

> 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.

That makes sense.

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

There is far more backends than frontends, and frontends are almost all
maintained. Also, user can teach almost all those info if the backend
does not provide them. If the backend do not take care of paper-width
and paper-height, we get back to the current situation.

> 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.

I don't think that implemented that in all backends is a good solution.
Let the frontent do that one for all.

Étienne.
-- 
Verso l'Alto !
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