playlist: Create a way to get the current selected tracks

I do this as a generator so we can work with tracks as we find them.

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

playlist/__init__.py

@@ -29,3 +29,7 @@ class Panel(Gtk.Box):
     def jump_clicked(self, button):
         view = self.window.get_child()
         view.track_changed(audio.Player, None, audio.Player.track)
+
+    def selected_tracks(self):
+        for track in self.window.selected_tracks():
+            yield track

playlist/view.py

@@ -33,6 +33,12 @@ class PlaylistView(Gtk.ColumnView):
             if index := plist.get_track_index(track):
                 plist.current = index
 
+    def selected_tracks(self):
+        model = self.get_model()
+        selection = model.get_selection()
+        for n in range(selection.get_size()):
+            yield model.get_item(selection.get_nth(n))
+
     def track_changed(self, player, old, new):
         selection = self.get_model()
         adjustment = self.get_vadjustment()
@@ -56,6 +62,7 @@ class PlaylistWindow(Gtk.ScrolledWindow):
     def get_filter_model(self): return self.get_child().get_filter_model()
     def get_playlist(self): return self.get_child().get_playlist()
     def set_playlist(self, plist): self.get_child().set_playlist(plist)
+    def selected_tracks(self): return self.get_child().selected_tracks()
 
 
 class SortOrderView(Gtk.ListView):