[sane-devel] Sane API (sane-devel Digest, Vol 184, Issue 24)

Charles Lindsey chl at clerew.man.ac.uk
Wed Oct 21 13:56:44 BST 2020

On 20/10/2020 19:43, Alexander Pevzner wrote:

> BTW, some users missing push-mode scan, totally missed from SANE. But it 
> requires the whole image logistics to be rethought: user presses some buttons at 
> scanner, scanner connects the computer, some daemon accepts this connection, 
> then somehow GUI popup should occur with a question, how to handle received image.
> It doesn't fit well the UNIX multiuser model. At what desktop this popup should 
> be open? (unlike UNIX, on Windows current terminal session has a very special 
> role in respect to other system).
The obvious use for this facility is to use a scanner and some nearby printer.

So Bob marches up to some scanner, places his sheet, and presses the button 
marked 'Copy'.

Now the scanner belongs to Alice, so we must presume that, when Alice logs in, 
it automatically starts a daemon which listens for signals from that button, and 
starts some shell script (or maybe Alice keeps a daemon running on her computer 
and started on reboot or wakeup).

The shell script can do anything it likes. Perhaps it starts a frontend (if not 
already started). Perhaps something appears on Alice's screen (xsane), perhaps 
not (xscanimage). The script knows which printer to use, so it gets on with it.

If the printer jams, or runs out of paper, there is no way to warn Bob (unless 
the scanner can be made to "beep") so sensibly they should be in the same room. 
The advantage is that Bob (or even Alice herself) can stand by the scanner and 
feed in successive sheets, pressing the Button after each one, rather than 
having to move over to the computer to click on the Scan button in the xsane window.

Come to think of it, you can probably do all this already using 'scanbd'.

Charles H. Lindsey ---------At my New Home, still doing my own thing------
Tel: +44 161 488 1845                    Web: http://www.cs.man.ac.uk/~chl
Email: chl at clerew.man.ac.uk              Snail-mail: Apt 40, SK8 5BF, U.K.
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