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

[Jef D. <jef...@ho...>]

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.