[Digikam-devel] XMP to solve tags name and Tags Path record in pictures metadata...

Mikolaj Machowski mikmach at wp.pl
Mon Oct 1 18:46:48 BST 2007

Dnia poniedziałek 01 październik 2007, Gilles Caulier napisał:
>     xmlns:xap="http://ns.adobe.com/xap/1.0/"
>     xmlns:tiff="http://ns.adobe.com/tiff/1.0/"
>     xmlns:exif="http://ns.adobe.com/exif/1.0/"
>     xmlns:photoshop="http://ns.adobe.com/photoshop/1.0/"
>     xmlns:dc="http://purl.org/dc/elements/1.1/"
>     xmlns:digiKam="http://www.digikam.org/"

Shouldn't path be more precise?

> As Xmp use UTF-8 endoding nothing is lost ! Also, the strings size are
> not limited ! The only limitation (for JPEG only) is the JFIF APP1
> section used to store Xmp packet wich is limited to... 64Kb (PNG chunk
> and TIFF tag don't have this limitation.)
> Nota : With the new future Database structure, we will store certainly
> more private informations in Xmp digiKam namespace... Marcel, we can do
> what we want (:=))) Xmp rock...

Future looks very promising :)
> But i have a question about how to save the a tag path. Currently the
> separator is a '/'. This can be a problem if user use this character in
> a tag name because it will break the tags tree in a future import
> (backup/restore). If somebody has an alternative to prevent this
> problem, let's me hear...
> Thanks in advance for you constructive remarks...

Maybe some "phishing"?

Unicode provides several types of slash, among them:


Comparing to well known solidus:


Since XMP fully supports utf-8 we could use them. But there is one big
problem (as seen above): we may be not sure if user has font with proper
glyphs. Of course it is possible to do some display time substitute but
with that it would be probably better to use some special sequence of
chars, beginning eg with :: and ending with {%this is digikam tags path
separator%} :)

Well, after a moment of thinking... why stop at phishing-like solutions?
Just use real arrows:


I put it in some random string in libksirtet.po and works quite nice
on my system.  While I am working on KDE from SVN (3.5 branch), and Qt
3.4.3 the rest of my system is 2 years old - including fonts.

If you prefer good old ASCII:

:: - geek friendly, may be not so understandable for "masses"
\  - I hate this Win-path look ;)
|  - hmm, not bad but IMO suggests equality of terms on both sides
>  - risky

Feature wish: auto synchronisation of appropriate  digiKam tags with
more common XMP schemas like DC, or IPTC Core.


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