Save and restore playback progress

data/music.gschema.xml

@@ -22,6 +22,11 @@
       <summary>The last song played by Music</summary>
       <description>A string representing the uri of the last played music file</description>
     </key>
+    <key type="i" name="progression-last-played">
+      <default>0</default>
+      <summary>Playback progression of the last song played by Music</summary>
+      <description>Number of seconds elapsed since the beginning of the last track that was played</description>
+    </key>
 
     <key name="window-height" type="i">
       <default>475</default>

src/PlaybackManager.vala

@@ -42,7 +42,6 @@ public class Music.PlaybackManager : Object {
     private PlaybackManager () {}
 
     construct {
-        settings = new Settings ("io.elementary.music");
         queue_liststore = new ListStore (typeof (AudioObject));
 
         playbin = Gst.ElementFactory.make ("playbin", "playbin");
@@ -87,8 +86,12 @@ public class Music.PlaybackManager : Object {
         bind_property ("has-items", clear_action, "enabled", SYNC_CREATE);
     }
 
+    public void seek_to_progress_nano_seconds (int64 progress) {
+        playbin.seek_simple (Gst.Format.TIME, Gst.SeekFlags.FLUSH, progress);
+    }
+
     public void seek_to_progress (double percent) {
-        playbin.seek_simple (Gst.Format.TIME, Gst.SeekFlags.FLUSH, (int64)(percent * current_audio.duration));
+        seek_to_progress_nano_seconds ((int64)(percent * current_audio.duration));
     }
 
     // Files[] must not contain any null entries
@@ -185,6 +188,13 @@ public class Music.PlaybackManager : Object {
                         playbin.query_position (Gst.Format.TIME, out position);
                         playback_position = position.clamp (0, current_audio.duration);
 
+                        int playback_position_seconds = (int)(playback_position / 1000000000);
+                        // Save progress every other second, to reduce disk writes
+                        if (playback_position_seconds % 2 == 0) {
+                            debug ("setting progress: " + (playback_position_seconds).to_string () + "s");
+                            settings.set_int ("progression-last-played", playback_position_seconds);
+                        }
+
                         return Source.CONTINUE;
                     });
                 } else {
@@ -380,6 +390,27 @@ public class Music.PlaybackManager : Object {
             }
 
             current_audio = (AudioObject) queue_liststore.get_item (position);
+
+            // Read then restore saved progress
+            var progression_last_played_seconds = settings.get_int ("progression-last-played");
+            if (progression_last_played_seconds > 0) {
+                int64 progression_last_played = (int64)progression_last_played_seconds * 1000000000;
+
+                // Wait for current_audio.duration to be set by the object responsible for setting it
+                GLib.Timeout.add (50, () => {
+                    if (current_audio.duration != 0) {
+                        // Do not seek if duration is inferior to seeking position
+                        if (current_audio.duration > progression_last_played) {
+                            info ("saved progress found and valid, restoring it: %i", progression_last_played_seconds);
+                            seek_to_progress_nano_seconds (progression_last_played);
+                        }
+                        return Source.REMOVE;
+                    }
+
+                    // Track metadata are not set yet, continue to wait before restoring playback position
+                    return Source.CONTINUE;
+                });
+            }
         }
     }
 }