This fix syncs up the AudioPlayer's internal state for showing
playlist information with the AudioPlayer's GUI. Before, if the
AudioPlayer was opened with a playlist file (.m3u or .m3u8) it would
automatically show the playlist information in the GUI and set the
loop mode to playlist, but the menu options would be unchecked. In
order to hide the playlist information, the menu option would then
have to be toggled twice -- once on and again off.
Previously, a libc-like out-of-line error information was used in the
loader and its plugins. Now, all functions that may fail to do their job
return some sort of Result. The universally-used error type ist the new
LoaderError, which can contain information about the general error
category (such as file format, I/O, unimplemented features), an error
description, and location information, such as file index or sample
index.
Additionally, the loader plugins try to do as little work as possible in
their constructors. Right after being constructed, a user should call
initialize() and check the errors returned from there. (This is done
transparently by Loader itself.) If a constructor caused an error, the
call to initialize should check and return it immediately.
This opportunity was used to rework a lot of the internal error
propagation in both loader classes, especially FlacLoader. Therefore, a
couple of other refactorings may have sneaked in as well.
The adoption of LibAudio users is minimal. Piano's adoption is not
important, as the code will receive major refactoring in the near future
anyways. SoundPlayer's adoption is also less important, as changes to
refactor it are in the works as well. aplay's adoption is the best and
may serve as an example for other users. It also includes new buffering
behavior.
Buffer also gets some attention, making it OOM-safe and thereby also
propagating its errors to the user.
The path returned by GUI:FilePicker is stored on the stack when the
callback is executed. The player only stored a StringView to the path
however it should take ownership of the path instead since the path is
accessed even after the file menu open action has returned.
The shuffling algorithm uses a naïve bloom filter to provide random
uniformity, avoiding items that were recently played. With 32 bits,
double hashing, and an error rate of ~10%, this bloom filter should
be able to hold around ~16 keys, which should be sufficient to give the
illusion of fairness to the shuffling algorithm.
This avoids having to shuffle the playlist itself (user might have
spent quite a bit of time to sort them, so it's not a good idea to mess
with it), or having to create a proxy model that shuffles (that could
potentially use quite a bit of memory).
This is a first pass at refactoring SoundPlayer so that the View widget
is decoupled from the player itself.
In doing so, this fixed a couple of issues, including possibly
inconsistent states (e.g. player could be paused and stopped at the
same time).
With the change, Player actually controls the show, and calls methods
overriden by its subclasses to perform actions, such as update the Seek
bar; the hard work of massaging the raw data is done by the Player
class, so subclasses don't need to reimplement any of these things.
This also removes some copies of playlist management code that happened
to be copied+pasted inside callbacks of buttons -- it now lives inside
a neatly packaged Playlist class, and the Player only asks for the next
song to play.
In addition, the menu bar has been slightly rearranged.
