Re: [Libexif-devel] Need some help with adding support for extra canon makernotes

[Jan P. <pa...@pi...>]

Apparently the data associated to tag MNOTE_CANON_TAG_FOCAL_LENGTH have
four short int values (because entry->components is 4).
The first value is 2 (you get 1 after dividing by 2). Is this what
you expect? Are you familiar with the format of the data
of this tag (I am not)?

 -- Jan

 Apparent
> Jan Patera wrote:
>>> case MNOTE_CANON_TAG_FOCAL_LENGTH:
>>>     CF (entry->format, EXIF_FORMAT_SHORT, val, maxlen);
>>>     n = exif_get_short (data, entry->order) / 2;
>>>     if (t >= n) return NULL;
>>>     CC (entry->components, n, val, maxlen);
>>>     vs = exif_get_short (entry->data + 2 + t * 2, entry->order);
>>> snprintf (buf, sizeof (buf), "0x%04x", vs);
>>>     strncpy (val, buf, maxlen - strlen (val));
>>>     break;
>>>
>>> But when I run the exif commandline utility, an error is reported for
>>> the new tag:
>>>
>>> Focal type          |Invalid number of components (4, expected 1).
>>>
>>> What am I doing wrong here?
>>
>>
>> this message is printed by the CC macro. It checks whether
>> 1st & 2nd arguments are equal. apparently entry->components is 4, but
>> n is only 1.
>
> I knew it was reported by the CC macro, but I don't understand why it is
> happening. It is exactly the same code as is used for
> MNOTE_CANON_TAG_SETTINGS_1 (which also has multiple components), but no
> error there! Probably I forgot to add some code somewhere else, but I
> don't see it.