[sane-devel] plustek:libusb bugs on canon canoscan n1220U

[Étienne Bersac]

Hello,

> SANE standard 1 does not specify how to handle scanner buttons,
> but it is clear, that an option, which deals with a button has to deliver
> a value (button pressed or not). Regarding that requirement, you have either
> to use SANE_TYPE_BOOL or SANE_TYPE_INT - I choose BOOL.
> SANE_TYPE_BUTTON is maybe misleading. It is intended to be used by a backend
> to allow changes by pressing that button from the GUI and NOT to reflect
> the status of a scanner button. An option of type SANE_TYPE_BUTTON has no value.
> See also chapter 4.2.9.4 of the SANE Standard 
> http://www.sane-project.org/html/doc011.html

Okey, the strange part of this button handling is : how an app using
sane know an option reflect a button status ? Just in order to ignore
that option. For example, xsane advanced options dialog shows a fieldset
entitled "Buttons" with one option "Scanner button" which is inactive
and always false. That's useless. I don't know how multiple buttons are
handle. Do the app has to parse name or title or desc field in order to
find a "button" string and then treat the option as a button state
option ?

Thanks for all.

Étienne.

-- 
Verso l'Alto !