1 files changed, 12 insertions, 2 deletions

diff --git a/helpers/mapping.py b/helpers/mapping.py
index 9420acf..3622f9d 100644
--- a/helpers/mapping.py
+++ b/helpers/mapping.py
@@ -10,6 +10,7 @@ import sys
 from .music_file import *
 from .mixer import Mixer
 from . import Config, gain, error_print
+from .music_effect import GainEffect
 
 class Mapping(RelativeLayout):
     expected_keys = NumericProperty(0)
@@ -32,13 +33,22 @@ class Mapping(RelativeLayout):
     def master_gain(self):
         return gain(self.master_volume)
 
-    def set_master_volume(self, value, delta=False):
+    def set_master_volume(self, value, delta=False, fade=0):
         [db_gain, self.master_volume] = gain(
                 value + int(delta) * self.master_volume,
                 self.master_volume)
 
         for music in self.open_files.values():
-            music.set_gain(db_gain)
+            if fade > 0:
+                music.gain_effects.append(GainEffect(
+                    "fade",
+                    music.current_audio_segment,
+                    music.current_loop,
+                    music.sound_position,
+                    music.sound_position + fade,
+                    gain=db_gain))
+            else:
+                music.set_gain(db_gain)
 
     def _keyboard_closed(self):
         self._keyboard.unbind(on_key_down=self._on_keyboard_down)