[sane-devel] scanner buttons

[Henning Meier-Geinitz]

Hi,

On Fri, Jul 09, 2004 at 09:45:03AM -0400, m. allan noah wrote:
> > Hm - maybe callback stuff are too much changes for 1.x - maybe we
> > should finally start working on SANE 2?
> 
> can we do callbacks via options? thinking about a gui front-end:
> 
> what about an 'led' that is red while the lamp is off, yellow when 
> warming, and green when it is hot. this could be done via a read-only 
> option that has a polling capability set. the front end could just loop 
> thru all the options with poll set, and change the interface. if you gave 
> that option a well-known name, like 'lamp-status' then the front-ends 
> could do majic things like wait for it to become ready before displaying 
> the scan button.

That's an idea I like.

> > In my last mail I already wrote that the HP 74xx have buttons to
> > change the scan mode and copy count - this are also use cases where
> > the "option changed" callbacks come handy.
> 
> can you think of a case where a call-back is required? (i want to avoid 
> them, if possible.)

"Warm up time 30 seconds - [BUTTON: Cancel]". E.g. if you know that
the scanner is already warmed up.

In this case a more intelligent warm-up code may be better :-)

Bye,
  Henning