Karl Heinz Kremer wrote:
>
> I tried to send this to the list a few days ago, but so far I can not
> find it in the archives. Really strange: My last message to the list
> is in there twice, and this one never showed up ...
>
> ----- Forwarded message from Karl Heinz Kremer <khk@khk.net> -----
>
> Date: Sat, 19 Feb 2000 13:54:48 -0500
> From: Karl Heinz Kremer <khk@khk.net>
> To: sane-devel@mostang.com
> Subject: Scanner Button Status / Is there anyting we can do with the buttons?
> Mail-Followup-To: sane-devel@mostang.com
> X-Mailer: Mutt 1.0i
>
> Most of the scanners have one or more buttons that can be used to
> either start the scanning or cancel the scan process - at least when
> using the Windows driver.
>
> I don't see a way to use the "Scan" button with the current implenentation
> of SANE: Even if I create a thread that checks the button status every
> second, I still can not communicate with the frontend and let it know
> that received a scan request via the button. The frontend would need to
> provide a callback function in order to do that. I guess the cancel
> button could be handled internally in the backend. The frontend does not
> need to know that the button was pressed, it should be sufficient to just
> stop sending data (and report some kind of error instead).
>
> What we would need is a function that the frontend can call to find out
> how many buttons the scanner supports. In addition to that we would need
> to define a set of well known button "labels" so that the frontend could
> then register callback functions for e.g. "scan", "cancel", "fax", "email",
> ... The backend would default to no callback for all buttons, so that the
> "button watching thread" would not start until at least one callback is
> registered.
>
> My EPSON scanner has only one button, so this wold be a pretty simple
> implementation: Once the button is pressed the frontend would do the
> same thing as if the scan-button in the GUI would have been pressed.
>
> What do you think?
>
> Karl Heinz
Karl,
I think it's a good idea.
Bill Thompson
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