Deleting photos from database

[harri]

Currently it is not possible to delete photos from database using UI. This should be part of basic functionality.

Use case:

• User decides to delete a picture (or several picture) and selects "Delete" from menu or presser <DEL> key.
• Photovault asks for confirmation
  • If there are instances of the photo in external volume, Photovault must notify user that she is going to delete files that are outside Photovault database.
• If user accepts deletion, Photovault deletes all instance files of this photo as well as related DB records. The photo is also removed from all folders it belongs to.

Open issues:

• In future, plan is to support synchronization between several Photovault databases. This can lead to a situation in which there is a synchronization conflict in which photo is deleted in one database but changed in another. Resolving this conflict may require "Undoing" deletion of database records.
  • Should the "delete" be soft operation, i.e. that database record is marked as deleted and queries take this into account? But what if user really wants to hide the fact that she has ever possessed a certain photo?
  • Another way could be that the database record is copied from remote database as part of conflict resolution.
• What to do if some of the instance(s) are unaccessible or Photovault is otherwise not able to delete these?
  • If e.g. photo is on read-only external volume a new photo would be created every time this volume is indexed
  • One possibility: photo is deleted if Photovault is able to delete *all* instances. Otherwise only accessible instances are deleted and photo itself is preserved.

[harri]

Basic delete functionality added in r673. Still work do to:

• UI not finished (action icons, "Delete" command to all menus, dialog boxes in weird places, ...)
• Automatic test cases not implemented