[sane-devel] Canon PIXMA MX330 working, with -x auto and -y auto bug; data here

[m. allan noah]

standard says:

Backends must attach a unit of either pixels (SANE_UNIT_PIXEL) or
millimeters (SANE_UNIT_MM) to these options. The unit of all four
options must be identical.

I dont think 'auto' qualifies as either of those units. Try stating
that 0 or -1 is auto.

allan

On Sun, Dec 6, 2009 at 8:45 AM, Nicolas Martin <nicolas0martin at gmail.com> wrote:
> Le dimanche 06 décembre 2009 à 10:50 +0100, Nicolas Martin a écrit :
>> - There's an error with scanimage/pixma backend when setting explicitly
>> -x or -y options to "auto". This is the same for all pixma devices, so
>> probably something the pixma backend rejects for now, and that needs to
>> be checked.
>
> Just tried  with another scanner (Canon N656U handled by the plustek
> backend) and got the same message when setting scanimage -x option to
> "auto"
>
> Looking more deeply at scanimage.c source code, I notice this:
>
> In main():
>
> ...
>    case 'x':
>      window_val_user[0] = 1;
>      parse_vector (&window_option[0], optarg, &window_val[0], 1);
>      break;
>
>    case 'y':
>      window_val_user[1] = 1;
>      parse_vector (&window_option[1], optarg, &window_val[1], 1);
>      break;
>
>    case 'l':           /* tl-x */
>      process_backend_option (device, window[2], optarg);
>      break;
> ...
>
> So here, (x, y) and (l, t) do not use obviously the same functions to be
> processed.
>
> Then, looking in parse_vector():
>
> ...
>      /* read value */
>      str = parse_scalar (opt, str, &value);
> ...
>
> and finally in parse_scalar():
>
> v = strtol (str, &end, 10);
>
> if (str == end)
>  {
>    fprintf (stderr,
>       "%s: option --%s: bad option value (rest of option: %s)\n",
>       prog_name, opt->name, str);
>    exit (1);
>  }
>
>
> So if -x value is "auto", the strtol will fail, and trig the error
> message:  scanimage: option --x: bad option value (rest of option: auto)
>
> More evidence of that if I enter the scanimage command like this:
>
> $ scanimage --format pnm -x foo  > output.pnm
> scanimage: option --x: bad option value (rest of option: foo)
>
> In conclusion: the -x auto limitation seems to be due to scanimage.
>
> => And now the questions, before changing anything:
>
> - Is there any reason for that, should the -x auto and -y auto options
> be valid ?
> - Does this need to be fixed, or is it working as designed ?
> - Should we process (x, y) values as (l, t) are processed ?
>
> All suggestions welcome.
>
> Nicolas
>
>
>
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