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