[Digikam-devel] Image history in metadata

[Martin Klapetek]

On Fri, Jun 11, 2010 at 11:28, Gilles Caulier <caulier.gilles at gmail.com>wrote:

> Hi Martin,
>
> The image history must follow XMP metadata.
>
> We have a digiKam XMP namespace. Image history must be recorded to this
> area :
>
> http://www.exiv2.org/tags-xmp-digiKam.html
> http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/XMP.html#digiKam<http://www.sno.phy.queensu.ca/%7Ephil/exiftool/TagNames/XMP.html#digiKam>
>
> You said that image history will be a QString. I think that we wil
> format XML data directly in digiKam. It's definitively a wrong way.
> You must delegate this point to libkexiv2/Exiv2
>

The image history is basically a QList containing another classes, which
holds info about used filters and their settings and also revisions. This
QList is transformed into XML (QXmlStreamWriter) when saving the image. And
to store the XML in metadata, it's converted to QString for easy
manipulation and that will go into metadata. Then it's read back when
opening the image as QString and parsed by QXmlStreamReader back into the
QList. That should be ok, no?


>
> Indeep, in digiKam core, the image history will be something like a
> QMap container, used to discribe :
>
> - the image revision.
> - the tool used to change image.
> - the tool settings.
>

Yes, that's how it's done right now.


>
> In XMP, there is a lots of map container available. Look in Metadata
> Properties section from this doc :
>
> http://www.adobe.com/devnet/xmp/pdfs/XMPSpecificationPart1.pdf
>
> To host image history to XMP, use Digikam::DMetadata class.
>
> Gilles Caulier
>

Ok, thanks.

Marty
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