Comment 3 for bug 1326653

Hi Shwan,

cool!

First you should make sure you environment is prepared. Are you able to build the latest master and are you able to single step though the code?
This link may help getting you up http://www.mixxx.org/wiki/doku.php/bugfix_workflow otherwise just ask.

I think the MPRIS clients expect a single player like all other media players. For your requirements it seams to be the best to let the clients believe that Mixxx is such a player.
We can only predict the next track reliable when Auto DJ is enabled. In this state, the next tracks is loaded to a deck but still on top of the Auto DJ play list. So there is no need to deal with four decks.

The current playing deck, you will get from the PlayerInfo::getCurrentPlayingTrack a singelton class in src/playerinfo.cpp
To implement only this seams to be a reasonable fist step.

For the following tracks you may interface somehow with the AutoDJ src/library/autodj/autodjprocessor.cpp
the tracks are located in m_pAutoDJTableModel

I have not much experience with DBus, but this seams to be a good tutorial:
https://techbase.kde.org/Development/Tutorials#D-Bus

Hope that helps.