Oliver> the sane standard defines of how much frames an image
Oliver> consists. After the last frame - that means if the image is
Oliver> transferred completly - the frontend has to call
Oliver> sane_cancel.
Actually, IIRC, our intent was indeed to allow the call sequence that
Tom describes. Note that in 4.4 it says:
"If the frontend expects additional frames (e.g., the individual channels
in of a red/green/blue image or multiple images), it can call sane_start()
^^^^^^^^^^^^^^^^^^
again."
Also, note that xcam does acquire multiple images without calling
sane_cancel(). (It's an amusing exercise to test a scanner with xcam,
actually ;-)
In other words, the idea is to have sane_start() be called, and
collect as many images as the frontend wants (which could in turn
consist of multiple frames each as indicated by frame-type) and when
the frontend is done, it should call sane_cancel(). Sometimes it's
better to think of sane_cancel() as "sane_stop()" but that name would
have had some misleading connotations as well, that's why we stuck
with "cancel".
--david
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