[sane-devel] scanbd vs scangear and the need to poll

[Jozef Riha]

Hello,

I can see that scanbd regularly generates USB traffic towards the scanner
in order to retrieve the state of the buttons which corresponds to the
statement in its manpage:

scanbd polls the scanner regularly (the interval can be set in scanbd.conf
) and monitors for any scanner button to be  pressed.

Out of curiosity I installed Win10 into VirtualBox together with original
software from Canon. It was a bit of a surprise that I see no regular
polling - yet pressing the button immediately generates a traffic on the
bus and ScanGear application opens shortly after.

My guess is that this approach also means that the device is not locked
during interaction with the buttons.

Can someone explain why the scanner works different in both OSes?

Test device: CanoScan LiDE 400

Thank you,

jose
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