If an item has multiple images, it would be great to make each file visible to users based on user role.
E.g. You have a series of postcards which have both a front and a back. Visitors and guest users should be able to view only the fronts. However, researchers, contributors, admins and supers should see both.
Another example could be 3D objects where you have a multitude of views, that you might not all want visible for visitors or guest users.
Interesting idea! I'm not entirely sure if/how a plugin could do that -- I don't think we have much in the way of permissions check for files on the items.
I'll also add another, even more complicated, use case that we're interested in: addressing cultural needs about access to different kinds of material, like Mukurtu is working on. Different content should be available based on more complex cultural criteria in those cases.
So, we're interested in the idea.
On first thought, those two appear to be separate issues. I am thinking that the access to materials based on cultural needs would most likely be resolved on the item (record) level, arguably extending that to collections and exhibits as well.
One way to do that is to introduce the ability to create custom ACL profiles with individualized permissions. I think Joomla has that capability, if I remember correctly. In addition, you would also have to introduce some form of category layer, to which you could assign items, collections, exhibits etc. in order to control access to those.
Viewing images / files based on user roles is below the item (record) level. To create this functionality, you could either expand the
files table, or create a
files_user_roles table, that simply holds the
file_id and an array with the allowed user rules, kind of like the Commenting plugin currently does.
In any case, I think both ideally should be solved within the Omeka Core and not as plugins.