# Re: Does CANCEL_PREVIEW work?

Matto Marjanovic (maddog@mir.com)
Fri, 24 Jul 1998 13:28:23 -0400 (EDT)

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>Date: Tue, 21 Jul 1998 18:03:28 +0200
>From: Oliver Rauch <oliver.rauch@Wolfsburg.DE>

>Matto Marjanovic wrote:
>
>> The not-yet-released (soon!) v0.9 of the microtek backend does work
>> correctly if "CANCEL PREVIEW" is pressed; I just tried it out.
>> (Previous versions have a generally broken sane_cancel implementation.)
>
>Hi Matt,
>
>what did you do that it works?

I don't know --- it just worked when I tried it.

I haven't looked at how xscanimage handles the preview-cancel button,
so I don't have any idea what snags could happen.

What little I do know:
o the new implementation of sane_cancel for the microtek backend
sticks to the API -- so that it is safe to call it even while
in the middle of sane_start or sane_read (i.e. in case it's
called by a signal handler). The current or following sane_read
will return a cancelled status.
o the microtek backend doesn't do any forking (and has not non-blocking
i/o), so there is less room for locking/signalling/sync problems.

-matt m.

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