[Gimp-developer] proposal for libgimpmetadata API

[Kevin Cozens]

Raphaël Quinet wrote:
> /* decode the given XMP packet (read from a file) and merge it into the metadata parasite. */
> gboolean
> gimp_metadata_decode_xmp  (gint32        image_ID,
>                            const gchar  *xmp_packet);
> 
> /* generate an XMP packet from the metadata parasite */
> const gchar *
> gimp_metadata_encode_xmp  (gint32        image_ID);
> 
> /* decode the given EXIF block (read from a file) and merge it into the metadata parasite. */
> gboolean
> gimp_metadata_decode_exif (gint32        image_ID,
>                            guint         exif_size,
>                            const gchar  *exif_block);
> 
> /* generate an EXIF block from the EXIF-compatible parts of the metadata parasite */
> gboolean
> gimp_metadata_encode_exif (gint32        image_ID,
>                            guint        *exif_size,
>                            const gchar **exif_block);

The prototype for gimp_metadata_encode_xmp() seems inconsistent to the pattern
of the other functions you listed. I would have expected it to be:

gboolean
gimp_metadata_encode_xmp (gint32        image_ID,
                           guint        *xmp_size,
                           const gchar **xmp_block);

> Example of use:
> - An image containing both XMP and EXIF information is loaded
> - Call gimp_metadata_encode_exif (image, exif_size, exif_block) to
>   load the EXIF block into the gimp metadata parasite.
> - Call gimp_metadata_encode_xmp (image, xmp_packet) to merge the XMP
>   information into the gimp metadata parasite.  If some properties are
>   present in both XMP and EXIF (this is very likely), the old EXIF
>   information is overwritten: XMP always takes precedence.

Are you proposing in step 2 of your "Example of use" above that it be done 
automatically in the file load plug-ins? I think that would make sense. Any 
XMP/EXIF data for an image should be converted to parasites on file load and 
coverted back to XMP/EXIF data on file save.

-- 
Cheers!

Kevin.

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