Implement mpris support for Netflix (fixes #45)

[petrmanek]

Here's a TL;DR:

• QtWebFlix now supports D-Bus MPRIS v.2 interface for media players. This can be used to display media playback information in some WMs, WM widgets or even mobile apps (e.g. KDE connect). Furthermore, MPRIS allows to conveniently control some basic media playback features remotely (e.g. through media keys) without having to interact with the player's UI.
• The supported MPRIS features are:
  • play,
  • pause,
  • toggle play/pause,
  • get/set volume,
  • get/set full screen state,
  • get video duration,
  • get current position in the video,
  • get video artwork/backdrop,
  • get video title,
  • get D-Bus-compatible track ID.
• Remote control and state inquiry of the web-based player is implemented by issuing JavaScript instructions to specific DOM elements in the rendered website. Since the IDs of these elements and their architecture are completely dependent on the service provider, and may thus be changed at any point in time without prior warning or backward compatibility,
• For future support of other streaming services, the MPRIS interface implementation uses dynamic polymorphism, wherein common generic features are implemented in a base class, and provider-specific features are implemented in derived classes.
• To achieve this functionality, qtmpris and qtdbusextended (dependency of qtmpris) were added as submodules to the repo, and are compiled together with the rest of the project. Since no distribution packages for these libraries were found at the time of integration, they are statically linked into the QtWebFlix's binary.

More information can be found in the discussion related to the referenced issue.

[petrmanek]

OK, check it out.

The latest implementation can switch between various MPRIS interfaces based on the hostname. Currently, only two interfaces are available -- one for Netflix and the other as a fallback for other service providers.

When the page loading is finished, hostname is matched against very simple string criteria and a MprisInterface subclass is proposed. If that class differs from the current interface (this is detected courtesy of std::type_index), it becomes the current interface and gets set up. However, this doesn't occur before the destructor of the previous interface is called -- this way, at most one instance of MprisPlayer exists in the scope at all times and no clashes occur.

[gort818]

@petrmanek Awesome! Thanks again. I am writing the amazon interface as we speak. will merge shortly

[gort818]

@petrmanek How would you like to credited in the authors file?

[petrmanek]

@gort818 Sure, thank you! :+1: