[sane-devel] Options that cannot be controlled

[m. allan noah]

Have you checked the 'cap' on the option descriptor? The three pass
option, for instance, is SANE_CAP_INACTIVE unless you are in color
mode.

allan

On Sat, Mar 29, 2014 at 3:30 PM, Ross Vandegrift <ross at kallisti.us> wrote:
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> Hello,
>
> I've been working with libsane, and have discovered that some options
> cannot be used to anything.  One cannot get, set or force them to
> auto.  For example, option 5 on the sane-test backend, "three-pass" is
> one such option.  Sample code demonstrating this is below.  Is this
> intentional?  If so, what is the point?
>
> Please keep me CCed, as I am not subscribed.
>
> Thanks,
> Ross
>
>
>
> #include <stdlib.h>
> #include <stdio.h>
> #include <sane/sane.h>
>
> int main(void) {
>   static SANE_Handle h;
>   const SANE_Option_Descriptor *desc;
>   const SANE_String_Const *x;
>   SANE_Status s;
>   char *buf;
>   SANE_Int i;
>
>   sane_init(NULL, NULL);
>   sane_open("test", &h);
>
>   /* "three-pass" is option index 5 for the sane-test backend */
>   desc = sane_get_option_descriptor(h, 5);
>   printf("name: %s\n", desc->name);
>   printf("title: %s\n", desc->title);
>   printf("desc: %s\n", desc->desc);
>
>   buf = (char *) malloc((size_t) desc->size);
>   s = sane_control_option(h, 5, SANE_ACTION_SET_AUTO, buf, &i);
>   printf("Set auto return: %s (info: %d)\n", sane_strstatus(s), i);
>   s = sane_control_option(h, 5, SANE_ACTION_GET_VALUE, buf, &i);
>   printf("Get value return: %s (info: %d)\n", sane_strstatus(s), i);
>   s = sane_control_option(h, 5, SANE_ACTION_SET_VALUE, buf, &i);
>   printf("Set value return: %s (info: %d)\n", sane_strstatus(s), i);
> }
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