Hi Alexander, What is the difference between sane-airscan and Sane's escl backend? I'm a little bit confused about that.
Cheers, Rolf Am 29.06.20 um 01:09 schrieb Alexander Pevzner: > Hi Jürgen, > > I'm the author of sane-airscan, the eSCL/WSD backend for SANE > (https://github.com/alexpevzner/sane-airscan) > > At some point, your AirSane was one of my knowledge sources to learn > the eSCL protocol :-) > >> I’m trying to incorporate ADF support into a SANE frontend that I >> have written >> (github.com/SimulPiscator/AirSane). >> The frontend is a web server that needs to report or announce the >> scanner’s status to its clients. >> Without an ADF, scanner status is just idle vs busy, and any error >> state is only temporary. >> With an ADF, the "ADF empty" state prevents scanning but needs to be >> monitored such that >> a client can know it may initiate a scan when it switches to "ADF >> loaded". > > 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. > > Hardware scanners are not very accurate in reporting current ADF > status, and actually all behave the slightly different way. > > My backend even doesn't bother to request ScannerStatus until ScanJobs > or NextDocument fails. > >> So my question is: What can I do in order to monitor ADF status? Call >> sane_start() after setting an empty >> scan region, so the scan is done at the first call to sane_read()? >> This is obviously not an option, as in the >> case of a loaded feeder this would consume the first original rather >> than just read ADF status. >> Cancel the scan immediately after sane_start() using sane_cancel()? I >> have no idea whether this is possible. > > There are actually no such API that will return ADF status before > actual scan attempt. > > BTW, some hardware scanners scan all pages loaded into ADF when > ScanJobs command is issues and requires multiple NextDocument to > gather all scanned pages, while others scan only one page. >
