[KPhotoAlbum] Extending the database schema

[Johannes Zarl]

Hi,

I have been thinking about a few wishlist items that would need to extend the 
current database schema in one way or the other.

The first group of wishes is about tagging a certain region inside the 
database (e.g. tagging a person and his/her location in the photo, marking a 
landmark/sight/plant/whatever):

https://bugs.kde.org/show_bug.cgi?id=292900
and its more popular duplicate:
https://bugs.kde.org/show_bug.cgi?id=170801
and another duplicate:
https://bugs.kde.org/show_bug.cgi?id=223053
(I can't find the "mark as duplicate" button for some reason)

The same mechanism could also be used in principle to create text-annotations 
or some type of hyperlink inside the description ("Look closely at that detail 
in [Region A]...").

Speaking in terms of the XML document, I guess this would be most easily 
accomplished by adding some type of annotation sub-elements to the image 
elements?

E.g:
<image file="foo.jpg" Persons="100,8"/>
could become
<image file="foo.jpg" Persons="100,8">
  <annotation Persons="8" boundingbox="10,10,30,30"/>
  <!-- or maybe more fancy: -->
  <annotation text="Look here!" type="svg">
    <svg>....</svg>
  </annotation>
</image>


The second type of extra information would be to add information to whole 
categories, as would be required for associating gps information with 
locations:

https://bugs.kde.org/show_bug.cgi?id=110974

Similiar to the above example, I guess the easiest way would be to add a sub-
element to add to the "value" tag of the category. A geotagged location would 
then look like this:

<Category name="Locations">
  <value value="Some Place" id="42">
    <!-- a simple point -->
    <geodata type="coordinates" lat="..." long="..." acc="..."/>
  </value>
  <value value="Some Region" id="43">
    <!-- could be handy if deriving geodata from gps coordinates of already 
tagged images, or when getting the data from an external source (marble?): -->
    <geodata type="region">
    ... 
    </geodata>
  </value>
</Category>

Drawback: The "coordinates" type could certainly be done without adding 
external dependencies, but more complicated stuff would probably need Marble-
support to be compiled in.


So now to my questions:

Would these changes to the database-file be acceptable? Did I overlook 
something / would you do the changes differently? Is somebody already working 
on the wishlist items mentioned above?

And regarding the SQL backend:
Does anybody use it? Is there somebody who maintains it? If the answer to both 
questions is "no": Should we disable this feature for now and avoid potential 
confusion in the KPA versions shipped with the various distributions?

  Johannes