[sane-devel] scanner buttons, was: Simplified installation procedure for Redhat Fedora Linux 1.0 and Epson 1670 scanner, also a report of a bug?

[Henning Meier-Geinitz]

Hi,

On Tue, Feb 10, 2004 at 05:10:31PM -0500, m. allan noah wrote:
> 1. we would like a backend to be able to signal a frontend when a button 
> or sensor is tripped.
> 
> 2. if the backend is polled, it needs a way to request the polling 
> interval.

Why? Shouldn't it be up to the frontend to decide how often it asks
for a button press? Is there a difference between the scanners how
often that should be done?

I'm asking because if you really need the intervall, you must use the
"name-encoded" options as I don't know any other way to provide that
information. You can't place bothe an int (msecs) and a bool (button
press) in one option.

> 3. the stati are generally not accessed via a separate command for each 
> sensor, but instead, there is one command that gets a bitmask from the 
> scanner.

But that's completely backend-specific. So it shouldn't stop us from
using single options (if there are no other disadvantages).

> 4. we would like as many of these sensors as possible to have well-known 
> names so that a front-end could set sane (pun intended) defaults.

Ok. But that can be done wither way (having well-known options like
"scanner-button-scan" or having a bitfield with 
#define SANE_BUTTON_SCAN 1

Bye,
  Henning