[sane-devel] ADF support in SANE API

[Jürgen Mellinger]

Hi Alex,

nice to hear from you in person, I’m quite impressed by the work you have done in sane-airscan.
At some point, I wanted to include WSD support in AirSane but had to give up because Windows was never
willing to create a device node for the announced device, even if the metadata xml closely matched that from a real scanner.
So I concluded Windows has a whitelist for devices it is willing to accept, or some other undocumented mechanism designed to obstruct efforts like mine, or maybe I simply made a silly mistake that I was unable to see, despite I spent quite some time on this.
Do you have any insights into that complementary side of your code?

> It would be enough, if in a case of empty ADF,
> ScanJobs will fail with, say, HTTP 409 status, and subsequent ScannerStatus will return the reason of this failure.

OK, that sounds reasonable. So I have to report scan:AdfState as ScannerAdfLoaded all times, except once after scan failure.
BTW, would you bother to omit scan:AdfState for scanners that don’t have an ADF? I’ve noticed that Vuescan complains about an empty ADF when used with AirSane, even though the scanner has no ADF. This would suggest that scan:AdfState == ScannerAdfLoaded is not optional but expected for all scanners, with or without ADF?

Best,
Jürgen