rind: Begin audio code

I don't yet have UI widgets, but this should cover the basics of audio
playback.

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

rind/gst.py

@@ -0,0 +1,55 @@
+# Copyright 2019 (c) Anna Schumaker.
+import curds
+import gi
+import sys
+gi.require_version("Gst", "1.0")
+from gi.repository import Gst, GLib
+
+class EmmentalAudio:
+    def __init__(self):
+        self.playbin = Gst.ElementFactory.make("playbin")
+        self.bus     = self.playbin.get_bus()
+        self.bus.add_signal_watch()
+        self.bus.connect("message", self.on_message)
+
+    def duration(self):
+        (res, cur) = self.playbin.query_duration(Gst.Format.TIME)
+        return cur / Gst.SECOND if res == True else 0.0
+
+    def load(self, track, play=True):
+        if track:
+            self.playbin.set_property("uri", f"file://{track.path}")
+            self.playbin.set_state(Gst.State.PLAYING if play  else Gst.State.PAUSED)
+
+    def next(self):
+        track = curds.PlaylistManager.next()
+        if track != None:
+            self.load(track)
+
+    def on_message(self, bus, message):
+        if message.type == Gst.MessageType.STATE_CHANGED:
+            (old, new, pending) = message.parse_state_changed()
+            curds.Notify.notify("state-changed", new)
+        elif message.type == Gst.MessageType.STREAM_START:
+            curds.Notify.notify("duration-changed", self.duration())
+        return True
+
+    def pause(self):
+        self.playbin.set_state(Gst.State.PAUSED)
+
+    def play(self):
+        self.playbin.set_state(Gst.State.PLAYING)
+
+    def position(self):
+        (res, cur) = self.playbin.query_position(Gst.Format.TIME)
+        return cur if res == True else 0
+
+    def progress(self):
+        pos = self.position()
+        dur = self.duration()
+        return (pos / dur) if dur > 0 else 0
+
+    def state(self):
+        return self.playbin.get_state(Gst.CLOCK_TIME_NONE)[1]
+
+Gst.init(sys.argv)

rind/test_gst.py

@@ -0,0 +1,90 @@
+# Copyright 2019 (c) Anna Schumaker.
+from . import gst
+import curds
+import os
+import time
+import unittest
+from gi.repository import Gst, GLib
+
+test_album = os.path.abspath("./trier/Test Library/Test Artist 01/Test Album 1")
+
+class TestGst(unittest.TestCase):
+    def setUp(self):
+        self.state = None
+        self.duration = None
+        curds.PlaylistManager["Collection"].list.clear()
+        curds.PlaylistManager["Library"].clear()
+        curds.Notify.notify_me("new-track", curds.PlaylistManager["Collection"].add)
+        if not curds.playlist.library.library_thread.is_alive():
+            curds.playlist.library.library_thread = curds.ThreadQueue()
+        curds.Notify.notify_me("state-changed", self.on_state_changed)
+        curds.Notify.notify_me("duration-changed", self.on_duration_changed)
+
+    def tearDown(self):
+        curds.playlist.library.library_thread.stop()
+
+    def main_loop(self):
+        events = GLib.main_context_default().iteration()
+        while events == True:
+            events = GLib.main_context_default().iteration(may_block=False)
+
+    def test_gst_init(self):
+        audio = gst.EmmentalAudio()
+        self.assertIsInstance(audio.playbin, Gst.Element)
+        self.assertIsInstance(audio.bus,     Gst.Bus)
+
+        self.assertEqual(audio.state(), Gst.State.NULL)
+        audio.load(None)
+        self.assertEqual(audio.state(), Gst.State.NULL)
+        audio.play()
+        self.assertEqual(audio.state(), Gst.State.READY)
+        audio.pause()
+        self.assertEqual(audio.state(), Gst.State.READY)
+        self.assertEqual(audio.position(), 0)
+        self.assertEqual(audio.duration(), 0)
+        self.assertEqual(audio.progress(), 0)
+
+    def on_state_changed(self, state):
+        self.state = state
+
+    def on_duration_changed(self, duration):
+        self.duration = duration
+
+    def test_gst_load(self):
+        audio = gst.EmmentalAudio()
+        track = curds.Track.lookup(os.path.join(test_album, "10 - Test Track 10.ogg"))
+
+        self.main_loop()
+        self.state = None
+        self.duration = None
+        audio.load(track)
+        while self.state == None or self.duration == None:
+            self.main_loop()
+
+        self.assertEqual(self.state, Gst.State.PAUSED)
+        self.assertEqual(audio.position(), 0)
+        self.assertEqual(audio.duration(), 10.0)
+        self.assertEqual(audio.progress(), 0)
+
+        while self.state != Gst.State.PLAYING:
+            self.main_loop()
+
+    def test_gst_controls(self):
+        audio = gst.EmmentalAudio()
+        self.assertEqual(audio.state(), Gst.State.NULL)
+        audio.next()
+        self.assertEqual(audio.state(), Gst.State.NULL)
+        self.assertIsNone(curds.PlaylistManager.track)
+
+        curds.PlaylistManager["Library"].add(test_album)
+        curds.playlist.library.library_thread.join()
+
+        self.state == None
+        audio.next()
+        self.assertIsNotNone(curds.PlaylistManager.track)
+        while self.state != Gst.State.PLAYING:
+            self.main_loop()
+
+        audio.pause()
+        while self.state != Gst.State.PAUSED:
+            self.main_loop()