From https://specifications.freedesktop.org/mpris-spec/latest/ :
> The Media Player Remote Interfacing Specification is a standard D-Bus interface which aims to provide a common programmatic API for controlling media players.
> It provides a mechanism for discovery, querying and basic playback control of compliant media players, as well as a tracklist interface which is used to add context to the active media item.
It is actually a nice fit for slideshows, with Gwenview adding support to it lately: https://www.kde.org/announcements/announce-applications-18.04.0.php
Most controls are not mandatory, including the ones that are not a good fit to a slideshow: play/pause/stop/seek (though I guess they could be enabled if there is a video playing? I am not sure every mpris client supports this).
A nice touch would be to add a slideshow miniature trough the mpris:artUrl metadata :)
This would allow the following:
* Control via media keys son some desktop environments (includes gestures, remote controls, hardware buttons, etc)
* Control via widgets on some desktop environments (including the ones that could be on a lock screen, for example)
* Control via any MPRIS controller (including remote ones, such as KDE Connect's)
* Progress on Okular: https://phabricator.kde.org/D11250
* Blog post by the creator of the gwenview patch: https://frinring.wordpress.com/2018/03/15/present-your-images-from-the-couch-with-gwenview-mpris-kde-connect/
Sounds good -> NEW