audio: Add a Player class

I provide a way to load, play, and pause tracks. I also add functions
for picking the next and previous tracks from the tagdb.Stack

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

audio/__init__.py

@@ -0,0 +1,4 @@
+# Copyright 2021 (c) Anna Schumaker.
+from gi.repository import Gst
+import sys
+Gst.init(sys.argv)

audio/player.py

@@ -0,0 +1,51 @@
+# Copyright 2021 (c) Anna Schumaker.
+from gi.repository import Gst
+import trackdb
+
+class Player:
+    def __init__(self):
+        self.video = Gst.ElementFactory.make("fakesink")
+        self.playbin = Gst.ElementFactory.make("playbin")
+        self.playbin.set_property("video-sink", self.video)
+
+        self.bus = self.playbin.get_bus()
+        self.bus.add_signal_watch()
+
+        self.track = None
+
+    def get_state(self):
+        (ret, state, pending) = self.playbin.get_state(Gst.CLOCK_TIME_NONE)
+        if ret == Gst.StateChangeReturn.SUCCESS:
+            return state
+        return ret
+
+    def load_track(self, track):
+        self.track = track
+        if track is not None:
+            uri = track.filepath().absolute().as_uri()
+            self.playbin.set_property("uri", uri)
+
+    def load_set_state(self, track, state):
+        self.playbin.set_state(Gst.State.READY)
+        self.load_track(track)
+        self.playbin.set_state(state)
+
+    def next(self, *args):
+        (track, cont) = trackdb.Stack.next()
+        state = Gst.State.PLAYING if cont else Gst.State.PAUSED
+        self.load_set_state(track, state)
+
+    def pause(self, *args):
+        self.playbin.set_state(Gst.State.PAUSED)
+
+    def play(self, *args):
+        self.playbin.set_state(Gst.State.PLAYING)
+
+    def play_track(self, track):
+        if track == self.track:
+            return False
+        self.load_set_state(track, Gst.State.PLAYING)
+        return True
+
+    def previous(self, *args):
+        self.play_track(trackdb.Stack.previous())

audio/test_player.py

@@ -0,0 +1,70 @@
+# Copyright 2021 (c) Anna Schumaker.
+from . import player
+from gi.repository import Gst
+import pathlib
+import trackdb
+import unittest
+
+test_album = pathlib.Path("./trier/Test Album/")
+test_track = test_album / "01 - Test Track.ogg"
+
+
+class TestPlayer(unittest.TestCase):
+    def setUpClass():
+        trackdb.reset()
+        lib = trackdb.Library.add(test_album)
+        lib.scan().join()
+
+    def setUp(self):
+        self.library = trackdb.Library.store[test_album]
+        self.track = [ t for t in self.library.tracks if t.tracknumber == 1 ][0]
+
+    def tearDownClass():
+        trackdb.reset()
+
+    def test_player_init(self):
+        play = player.Player()
+        self.assertIsInstance(play.video, Gst.Element)
+        self.assertIsInstance(play.playbin, Gst.Element)
+        self.assertIsInstance(play.bus, Gst.Bus)
+        self.assertIsNone(play.track)
+
+        self.assertEqual(play.playbin.get_property("video-sink"), play.video)
+
+    def test_player_load_track(self):
+        play = player.Player()
+        uri = test_track.absolute().as_uri()
+
+        self.assertEqual(play.playbin.get_property("uri"), None)
+        play.load_track(self.track)
+        self.assertEqual(play.playbin.get_property("uri"), uri)
+        self.assertEqual(play.get_state(), Gst.State.NULL)
+        self.assertFalse(play.play_track(self.track))
+
+    def test_player_play_pause(self):
+        play = player.Player()
+
+        play.load_track(self.track)
+        self.assertEqual(play.track, self.track)
+        self.assertEqual(play.get_state(), Gst.State.NULL)
+
+        play.pause()
+        self.assertEqual(play.get_state(), Gst.State.PAUSED)
+
+        play.play()
+        self.assertEqual(play.get_state(), Gst.State.PLAYING)
+
+        play.pause()
+        self.assertEqual(play.get_state(), Gst.State.PAUSED)
+
+    def test_player_next_previous(self):
+        play = player.Player()
+
+        play.next()
+        self.assertEqual(play.track.trackid, 0)
+
+        play.next()
+        self.assertEqual(play.track.trackid, 1)
+
+        play.previous()
+        self.assertEqual(play.track.trackid, 0)

emmental-gtk4.py

@@ -2,6 +2,7 @@
 # Copyright 2021 (c) Anna Schumaker.
 import gi
 gi.require_version('Gtk', '4.0')
+gi.require_version('Gst', '1.0')
 
 import lib
 import trackdb