On Mon, Nov 1, 2010 at 8:53 PM, Olaf Meeuwissen <olaf.meeuwissen at avasys.jp> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 2010?11?01? 23:45, stef wrote: >> Le Monday 01 November 2010 14:51:59 m. allan noah, vous avez ?crit : >>> We need a way for authors of button handling programs to figure out >>> what sensors a scanner exposes. Yes, they can use libsane to query the >>> options, but then a third user would have to install the button >>> daemon, just to find out if there are any sensors. I'd rather that >>> scanimage could tell us. > > Not sure I understand the scenario you have in mind. ?Care to explain? > Within that scenario: > > ?- How would one use scanimage to figure out what sensors a scanner exposes?
In this case- scanimage --all-options > ?- How would one use libsane to do that for that matter? get options and check the CAP bits. > ?- Why would a button handling program need a button daemon to find out > if there are any sensors when using libsane if scanimage can do the same > thing using libsane without that button daemon? It does not- but as I said above- the third party end user might like to know if his scanner exposes sensors BEFORE he installs the button daemon. We have no other program installed as part of sane-backends which can do this. > ?- How does this relate to button handling for non-button sensors such > as, for example, a paper tray empty sensor? A sensor is a sensor, regardless of type- look at the fujitsu, canon_dr, genesys backends. > >> ? ? ? I think there are different points to answer. First there is a bug to >> fix: the --help argument (which is geared to scanimage command line usage) >> shouldn't print command line options that cannot be used. > > Agreed. ?Read-only SANE options aren't command line options. > >> ? ? ? Second listing all the options a backend provides including buttons is >> useful. It will better served with a specific argument (--list-options / -- >> list-buttons / --show-options ?). I'll submit a patch that brings such an >> argument for everyone to review. > > Read-only SANE options are just a somewhat odd way for a backend to > inform the user about some aspect of the device it controls and the > information may even change over time. ?Having a means to show this > information is definitely required but I doubt this should be made > scanimage's responsibility. It is a perfectly logical place, given that it is the only thing installed as a part of sane-backends... allan -- "The truth is an offense, but not a sin"
