[fprint] How to increase delay for reading the fingerprint ?

[Bastien Nocera]

On Thu, 2018-08-30 at 11:10 +0000, Kleyson de Sousa Rios wrote:
> Hi Bastian,
> 
> Is the below possible ?
> Keep the finger on the reader for more time before the image be
> taken.

It depends on the driver. Most devices will send us a message when a
finger has been set down, for us to take the image through
fpi_imgdev_report_finger_status().

That might be where you want to try adding a delay, though you'd
probably ultimately want the device to keep capturing new images until
the libfprint core is happy with the amount of minutiae provided.

That process could also be used to provide continuous capture on
"press" (as opposed to "swipe") devices, so they behave like the
fingerprint sensors on mobile phones, where you press the sensor until
enough data has been captured.

This would require quite extensive changes to the core though, so it
might not be a short-term change.

Cheers