WIP: preview forward/back working

app/musicmuster.py

@@ -153,6 +153,24 @@ class PreviewManager:
         self.path: str = ""
         self.start_time: Optional[dt.datetime] = None
 
+    def back(self, ms: int) -> None:
+        """
+        Move play position back by 'ms' milliseconds
+        """
+
+        position = max(0, (self.get_playtime() - ms)) / 1000
+        mixer.music.set_pos(position)
+        self.start_time = dt.datetime.now() - dt.timedelta(seconds=position)
+
+    def forward(self, ms: int) -> None:
+        """
+        Move play position forward by 'ms' milliseconds
+        """
+
+        position = (self.get_playtime() + ms) / 1000
+        mixer.music.set_pos(position)
+        self.start_time = dt.datetime.now() - dt.timedelta(seconds=position)
+
     def get_playtime(self) -> int:
         """
         Return time since track started in milliseconds, 0 if not playing
@@ -1115,8 +1133,7 @@ class Window(QMainWindow, Ui_MainWindow):
     def preview_back(self) -> None:
         """Wind back preview file"""
 
-        # TODO
-        pass
+        self.preview_manager.back(5000)
 
     def preview_end(self) -> None:
         """Advance preview file to Config.PREVIEW_END_BUFFER_MS before end of intro"""
@@ -1127,8 +1144,7 @@ class Window(QMainWindow, Ui_MainWindow):
     def preview_fwd(self) -> None:
         """Advance preview file"""
 
-        # TODO
-        pass
+        self.preview_manager.forward(5000)
 
     def preview_mark(self) -> None:
         """Set intro time"""

app/trackmanager.py

@@ -328,7 +328,9 @@ class _Music:
         if self.player:
             self.player.set_position(position)
 
-    def set_volume(self, volume: Optional[int] = None, set_default: bool = True) -> None:
+    def set_volume(
+        self, volume: Optional[int] = None, set_default: bool = True
+    ) -> None:
         """Set maximum volume used for player"""
 
         if not self.player: