[Digikam-devel] Image history in metadata

[Marcel Wiesweg]

Andreas,

for the GSoc project about non-destructive image editing we have come up with 
an XML format in which we would like to store the image history.

Now thinking about storing this in metadata, we have crossed the problem of 
storing XML in XMP's XML. Alternatively, the structure could be inserted 
directly in XMP, but it is not easily mapped to a single list or map, so using 
bag or other XMP structures appears not easy.
For reference, see some example XML at the bottom of this mail.

What is the best way to put this into metadata?

Thanks, Marcel


> 
> We are indeed using XML formatted directly in digikam. The purpose of this
> XML creation is not primarly for storing this in the metadata, but rather
> as a specified format that can describe the changes, slightly inspired by
> OpenRaster's XML. We can add attributes to all nodes and extend it in the
> future.
> The XML will also be used in other places, and it's a bit more complex than
> a simple map, which would be too limiting. We will also store the XML in
> the database.
> 
> So far I did not think about the implication that XMP is also based on XML,
> and we now have the purpose of storing XML in XML. Hm.
> So we either really store it as a string, or we try to integrate it into
> XMP. Is XMP flexible enough to carry a custom chunk of xml?


history>
        <file type="raw">
                <filename>pict1234.nef</filename>
                <originaluuid>asdf-1234-ghjk-5678-tzui</originaluuid>
                <creationdate>2010-05-05.16:23:56</creationdate>
        </file>
        <filter name="digikam:rawimport" version=1 category="reproducible">
                <description>"Manual Raw import"</description>
                <param name="interpolationMethod">Bilinear</param>
                ... // many more params
        </filter>
        <file type="intermediate">
                <filename>pict1234-1.jpg</filename>
                <fileuuid>ertz-3456-sdfg-1234-fghj</fileuuid>
        </file>
        <filter name="digikam:crop" version=1 category="reproducible">
                <param name="rect" x="10" y="10" width="90" height="40" />
        </filter>
        <file type="current">
                <filename>pict1234.jpg</filename>
                <fileuuid>dfgh-4567-2345-rtzu</fileuuid>
        </file>
</history>