[sane-devel] scanbd with Fujitsu fi-7260 Scanner: need help

[Ralph Little]

Hi,

On Mon, Jun 9, 2025 at 11:27 AM m. allan noah <kitno455 at gmail.com> wrote:

>
> On Mon, Jun 9, 2025 at 12:11 PM Tricia via sane-devel <
> sane-devel at alioth-lists.debian.net> wrote:
>
>> Hi, Dirk.
>>
>> On Mon, Jun 09, 2025 at 01:57:28AM -0700, Dirk Meier via sane-devel wrote:
>>
>> And here, we find that `scan` is now `1` (in technical terms, this means
>> that _while checking_, scanbd found the scan button was being held down.
>> It's possible to press the button so quickly that scanbd misses it while
>> polling...)
>
>
> A point of clarification here- the fujitsu backend attempts to buffer the
> responses from the hardware and returns that buffered response so that
> presses are not lost. But, if the frontend is slow enough in its polling
> loop, I expect that could still happen. I'm not sure what the timing is for
> scanbd
>
>
Yeah, I have seem some machines capture button press events and latch them
in software for the next query, while others only report button presses
live. In the latter case, if you don't query while the button is being
physically pressed, then you just don't see it at all. This is poor design
I believe. It seems to me that it is unrealistic to expect that polling
rate is sufficiently high for reliable detection necessarily. I would
imagine that some Windows drivers are hammering USB ports at a fairly rapid
rate to make this sufficiently responsive which is a bit crazy.

Cheers,
Ralph
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