mopidy/mopidy/backends/base/playback.py
Stein Magnus Jodal fae469cca3 Merge branch 'develop' into feature/mpris-frontend
Conflicts:
	docs/changes.rst
2011-06-10 19:30:00 +02:00

594 lines
18 KiB
Python

import logging
import random
import time
from pykka.registry import ActorRegistry
from mopidy.frontends.base import BaseFrontend
logger = logging.getLogger('mopidy.backends.base')
class PlaybackController(object):
"""
:param backend: the backend
:type backend: :class:`mopidy.backends.base.Backend`
:param provider: provider the controller should use
:type provider: instance of :class:`BasePlaybackProvider`
"""
# pylint: disable = R0902
# Too many instance attributes
pykka_traversable = True
#: Constant representing the paused state.
PAUSED = u'paused'
#: Constant representing the playing state.
PLAYING = u'playing'
#: Constant representing the stopped state.
STOPPED = u'stopped'
#: :class:`True`
#: Tracks are removed from the playlist when they have been played.
#: :class:`False`
#: Tracks are not removed from the playlist.
consume = False
#: The currently playing or selected track.
#:
#: A two-tuple of (CPID integer, :class:`mopidy.models.Track`) or
#: :class:`None`.
current_cp_track = None
#: :class:`True`
#: Tracks are selected at random from the playlist.
#: :class:`False`
#: Tracks are played in the order of the playlist.
random = False
#: :class:`True`
#: The current playlist is played repeatedly. To repeat a single track,
#: select both :attr:`repeat` and :attr:`single`.
#: :class:`False`
#: The current playlist is played once.
repeat = False
#: :class:`True`
#: Playback is stopped after current song, unless in :attr:`repeat`
#: mode.
#: :class:`False`
#: Playback continues after current song.
single = False
def __init__(self, backend, provider):
self.backend = backend
self.provider = provider
self._state = self.STOPPED
self._shuffled = []
self._first_shuffle = True
self.play_time_accumulated = 0
self.play_time_started = None
def destroy(self):
"""
Cleanup after component.
"""
self.provider.destroy()
def _get_cpid(self, cp_track):
if cp_track is None:
return None
return cp_track.cpid
def _get_track(self, cp_track):
if cp_track is None:
return None
return cp_track.track
@property
def current_cpid(self):
"""
The CPID (current playlist ID) of the currently playing or selected
track.
Read-only. Extracted from :attr:`current_cp_track` for convenience.
"""
return self._get_cpid(self.current_cp_track)
@property
def current_track(self):
"""
The currently playing or selected :class:`mopidy.models.Track`.
Read-only. Extracted from :attr:`current_cp_track` for convenience.
"""
return self._get_track(self.current_cp_track)
@property
def current_playlist_position(self):
"""
The position of the current track in the current playlist.
Read-only.
"""
if self.current_cp_track is None:
return None
try:
return self.backend.current_playlist.cp_tracks.index(
self.current_cp_track)
except ValueError:
return None
@property
def track_at_eot(self):
"""
The track that will be played at the end of the current track.
Read-only. A :class:`mopidy.models.Track` extracted from
:attr:`cp_track_at_eot` for convenience.
"""
return self._get_track(self.cp_track_at_eot)
@property
def cp_track_at_eot(self):
"""
The track that will be played at the end of the current track.
Read-only. A two-tuple of (CPID integer, :class:`mopidy.models.Track`).
Not necessarily the same track as :attr:`cp_track_at_next`.
"""
# pylint: disable = R0911
# Too many return statements
cp_tracks = self.backend.current_playlist.cp_tracks
if not cp_tracks:
return None
if self.random and not self._shuffled:
if self.repeat or self._first_shuffle:
logger.debug('Shuffling tracks')
self._shuffled = cp_tracks
random.shuffle(self._shuffled)
self._first_shuffle = False
if self.random and self._shuffled:
return self._shuffled[0]
if self.current_cp_track is None:
return cp_tracks[0]
if self.repeat and self.single:
return cp_tracks[self.current_playlist_position]
if self.repeat and not self.single:
return cp_tracks[
(self.current_playlist_position + 1) % len(cp_tracks)]
try:
return cp_tracks[self.current_playlist_position + 1]
except IndexError:
return None
@property
def track_at_next(self):
"""
The track that will be played if calling :meth:`next()`.
Read-only. A :class:`mopidy.models.Track` extracted from
:attr:`cp_track_at_next` for convenience.
"""
return self._get_track(self.cp_track_at_next)
@property
def cp_track_at_next(self):
"""
The track that will be played if calling :meth:`next()`.
Read-only. A two-tuple of (CPID integer, :class:`mopidy.models.Track`).
For normal playback this is the next track in the playlist. If repeat
is enabled the next track can loop around the playlist. When random is
enabled this should be a random track, all tracks should be played once
before the list repeats.
"""
cp_tracks = self.backend.current_playlist.cp_tracks
if not cp_tracks:
return None
if self.random and not self._shuffled:
if self.repeat or self._first_shuffle:
logger.debug('Shuffling tracks')
self._shuffled = cp_tracks
random.shuffle(self._shuffled)
self._first_shuffle = False
if self.random and self._shuffled:
return self._shuffled[0]
if self.current_cp_track is None:
return cp_tracks[0]
if self.repeat:
return cp_tracks[
(self.current_playlist_position + 1) % len(cp_tracks)]
try:
return cp_tracks[self.current_playlist_position + 1]
except IndexError:
return None
@property
def track_at_previous(self):
"""
The track that will be played if calling :meth:`previous()`.
Read-only. A :class:`mopidy.models.Track` extracted from
:attr:`cp_track_at_previous` for convenience.
"""
return self._get_track(self.cp_track_at_previous)
@property
def cp_track_at_previous(self):
"""
The track that will be played if calling :meth:`previous()`.
A two-tuple of (CPID integer, :class:`mopidy.models.Track`).
For normal playback this is the previous track in the playlist. If
random and/or consume is enabled it should return the current track
instead.
"""
if self.repeat or self.consume or self.random:
return self.current_cp_track
if self.current_playlist_position in (None, 0):
return None
return self.backend.current_playlist.cp_tracks[
self.current_playlist_position - 1]
@property
def state(self):
"""
The playback state. Must be :attr:`PLAYING`, :attr:`PAUSED`, or
:attr:`STOPPED`.
Possible states and transitions:
.. digraph:: state_transitions
"STOPPED" -> "PLAYING" [ label="play" ]
"STOPPED" -> "PAUSED" [ label="pause" ]
"PLAYING" -> "STOPPED" [ label="stop" ]
"PLAYING" -> "PAUSED" [ label="pause" ]
"PLAYING" -> "PLAYING" [ label="play" ]
"PAUSED" -> "PLAYING" [ label="resume" ]
"PAUSED" -> "STOPPED" [ label="stop" ]
"""
return self._state
@state.setter
def state(self, new_state):
(old_state, self._state) = (self.state, new_state)
logger.debug(u'Changing state: %s -> %s', old_state, new_state)
# FIXME play_time stuff assumes backend does not have a better way of
# handeling this stuff :/
if (old_state in (self.PLAYING, self.STOPPED)
and new_state == self.PLAYING):
self._play_time_start()
elif old_state == self.PLAYING and new_state == self.PAUSED:
self._play_time_pause()
elif old_state == self.PAUSED and new_state == self.PLAYING:
self._play_time_resume()
@property
def time_position(self):
"""Time position in milliseconds."""
if self.state == self.PLAYING:
time_since_started = (self._current_wall_time -
self.play_time_started)
return self.play_time_accumulated + time_since_started
elif self.state == self.PAUSED:
return self.play_time_accumulated
elif self.state == self.STOPPED:
return 0
def _play_time_start(self):
self.play_time_accumulated = 0
self.play_time_started = self._current_wall_time
def _play_time_pause(self):
time_since_started = self._current_wall_time - self.play_time_started
self.play_time_accumulated += time_since_started
def _play_time_resume(self):
self.play_time_started = self._current_wall_time
@property
def _current_wall_time(self):
return int(time.time() * 1000)
def change_track(self, cp_track, on_error_step=1):
"""
Change to the given track, keeping the current playback state.
:param cp_track: track to change to
:type cp_track: two-tuple (CPID integer, :class:`mopidy.models.Track`)
or :class:`None`
:param on_error_step: direction to step at play error, 1 for next
track (default), -1 for previous track
:type on_error_step: int, -1 or 1
"""
old_state = self.state
self.stop()
self.current_cp_track = cp_track
if old_state == self.PLAYING:
self.play(on_error_step=on_error_step)
elif old_state == self.PAUSED:
self.pause()
def on_end_of_track(self):
"""
Tell the playback controller that end of track is reached.
Typically called by :class:`mopidy.process.CoreProcess` after a message
from a library thread is received.
"""
if self.state == self.STOPPED:
return
original_cp_track = self.current_cp_track
if self.cp_track_at_eot:
self.play(self.cp_track_at_eot)
else:
self.stop(clear_current_track=True)
if self.consume:
self.backend.current_playlist.remove(cpid=original_cp_track.cpid)
def on_current_playlist_change(self):
"""
Tell the playback controller that the current playlist has changed.
Used by :class:`mopidy.backends.base.CurrentPlaylistController`.
"""
self._first_shuffle = True
self._shuffled = []
if (not self.backend.current_playlist.cp_tracks or
self.current_cp_track not in
self.backend.current_playlist.cp_tracks):
self.stop(clear_current_track=True)
def next(self):
"""
Change to the next track.
The current playback state will be kept. If it was playing, playing
will continue. If it was paused, it will still be paused, etc.
"""
if self.cp_track_at_next:
self.change_track(self.cp_track_at_next)
else:
self.stop(clear_current_track=True)
def pause(self):
"""Pause playback."""
if self.provider.pause():
self.state = self.PAUSED
def play(self, cp_track=None, on_error_step=1):
"""
Play the given track, or if the given track is :class:`None`, play the
currently active track.
:param cp_track: track to play
:type cp_track: two-tuple (CPID integer, :class:`mopidy.models.Track`)
or :class:`None`
:param on_error_step: direction to step at play error, 1 for next
track (default), -1 for previous track
:type on_error_step: int, -1 or 1
"""
if cp_track is not None:
assert cp_track in self.backend.current_playlist.cp_tracks
elif cp_track is None:
if self.state == self.PAUSED:
return self.resume()
elif self.current_cp_track is not None:
cp_track = self.current_cp_track
elif self.current_cp_track is None:
cp_track = self.cp_track_at_next
if cp_track is not None:
self.stop()
self.current_cp_track = cp_track
self.state = self.PLAYING
if not self.provider.play(cp_track.track):
# Track is not playable
if self.random and self._shuffled:
self._shuffled.remove(cp_track)
if on_error_step == 1:
self.next()
elif on_error_step == -1:
self.previous()
if self.random and self.current_cp_track in self._shuffled:
self._shuffled.remove(self.current_cp_track)
self._trigger_started_playing_event()
def previous(self):
"""
Change to the previous track.
The current playback state will be kept. If it was playing, playing
will continue. If it was paused, it will still be paused, etc.
"""
if self.cp_track_at_previous is None:
self.stop()
else:
self.change_track(self.cp_track_at_previous, on_error_step=-1)
def resume(self):
"""If paused, resume playing the current track."""
if self.state == self.PAUSED and self.provider.resume():
self.state = self.PLAYING
def seek(self, time_position):
"""
Seeks to time position given in milliseconds.
:param time_position: time position in milliseconds
:type time_position: int
:rtype: :class:`True` if successful, else :class:`False`
"""
if not self.backend.current_playlist.tracks:
return False
if self.state == self.STOPPED:
self.play()
elif self.state == self.PAUSED:
self.resume()
if time_position < 0:
time_position = 0
elif time_position > self.current_track.length:
self.next()
return True
self.play_time_started = self._current_wall_time
self.play_time_accumulated = time_position
return self.provider.seek(time_position)
def stop(self, clear_current_track=False):
"""
Stop playing.
:param clear_current_track: whether to clear the current track _after_
stopping
:type clear_current_track: boolean
"""
if self.state != self.STOPPED:
self._trigger_stopped_playing_event()
if self.provider.stop():
self.state = self.STOPPED
if clear_current_track:
self.current_cp_track = None
def _trigger_started_playing_event(self):
"""
Notifies frontends that a track has started playing.
For internal use only. Should be called by the backend directly after a
track has started playing.
"""
if self.current_track is None:
return
frontend_refs = ActorRegistry.get_by_class(BaseFrontend)
for frontend_ref in frontend_refs:
frontend_ref.send_one_way({
'command': 'started_playing',
'track': self.current_track,
})
def _trigger_stopped_playing_event(self):
"""
Notifies frontends that a track has stopped playing.
For internal use only. Should be called by the backend before a track
is stopped playing, e.g. at the next, previous, and stop actions and at
end-of-track.
"""
if self.current_track is None:
return
frontend_refs = ActorRegistry.get_by_class(BaseFrontend)
for frontend_ref in frontend_refs:
frontend_ref.send_one_way({
'command': 'stopped_playing',
'track': self.current_track,
'stop_position': self.time_position,
})
class BasePlaybackProvider(object):
"""
:param backend: the backend
:type backend: :class:`mopidy.backends.base.Backend`
"""
pykka_traversable = True
def __init__(self, backend):
self.backend = backend
def destroy(self):
"""
Cleanup after component.
*MAY be implemented by subclasses.*
"""
pass
def pause(self):
"""
Pause playback.
*MUST be implemented by subclass.*
:rtype: :class:`True` if successful, else :class:`False`
"""
raise NotImplementedError
def play(self, track):
"""
Play given track.
*MUST be implemented by subclass.*
:param track: the track to play
:type track: :class:`mopidy.models.Track`
:rtype: :class:`True` if successful, else :class:`False`
"""
raise NotImplementedError
def resume(self):
"""
Resume playback at the same time position playback was paused.
*MUST be implemented by subclass.*
:rtype: :class:`True` if successful, else :class:`False`
"""
raise NotImplementedError
def seek(self, time_position):
"""
Seek to a given time position.
*MUST be implemented by subclass.*
:param time_position: time position in milliseconds
:type time_position: int
:rtype: :class:`True` if successful, else :class:`False`
"""
raise NotImplementedError
def stop(self):
"""
Stop playback.
*MUST be implemented by subclass.*
:rtype: :class:`True` if successful, else :class:`False`
"""
raise NotImplementedError