[sane-devel] More front end developer Q's

abel deuring a.deuring at satzbau-gmbh.de
Mon Sep 22 14:49:32 BST 2003

Guy Brooker wrote:

> The Image Capture API also wants the the TWAIN DS to implement DEVICEONLINE
> status, presumably for some UI indicator.
> Checking if the scanner is in the device list isn't really going to work, as
> that will only determine if the device is plugged in. Infact, the way the
> API works on OS X, the data source will only ever be called if the device is
> plugged in, and it will be pulled down if the device is unplugged, so it
> will always be in the device list.
> I could just return TRUE for that call, but I assume there may be some
> scanners which won't scan until the lid is closed, or something like that.
> Would sane_start() be enough to make sure the scanner is ready, or will it
> only fail on the first call to sane_read() ?

I'm afraid that calling sane_start can be a bit "expensive": the
sane_start call may take a few seconds, if the scanner performs for
example a CCD line calibration. 


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