Le 6 août 2022 18:17:12 GMT+02:00, Ralph Little <[email protected]> a écrit :
>Hi,
>I'm having a go at writing my first SANE backend for a learning exercise.
>
>I notice that a few backends that use the functions:
>sanei_usb_attach_matching_devices() and sanei_usb_find_devices() require some
>context information in the callback function to complete the find function.
>This is typically because the backend is looping through a list of known
>device configurations and calling the sanei_* function on each one: the
>callback needs to know the element in that loop to complete the attach
>function in the callback.
>
>This is typically achieved with setting some global variables to be picked up
>by the callback function, or searching again through the original loop using
>information gleaned from the devicename (such as vendor and product), both of
>which are messy and ugly hacks.
>
>I propose that we change the function signature of the functions and the
>callback to include a (void *) context pointer:
>
>SANE_Status
>sanei_usb_find_devices (SANE_Int vendor, SANE_Int product, void *context,
> SANE_Status (*attach) (SANE_String_Const dev, void *context));
>
>void
>sanei_usb_attach_matching_devices (const char *name, void *context,
> SANE_Status (*attach) (const char *dev, void *context));
>
Hi Ralph,
Your change may impact proprietary backends (Brother, Canon, ...).
Thierry
>I would have to change existing backends that rely on this function but I feel
>that it would be an improvement and clean up the processing of USB device
>detection.
>
>Comments?
>
>Cheers,
>Ralph
>
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