macosx/MainWindow: fixed mute toggle and removed some minor code duplication

modules/gui/macosx/CoreInteraction.h

@@ -64,6 +64,7 @@
 
 - (void)volumeUp;
 - (void)volumeDown;
+- (void)toggleMute;
 
 - (BOOL)performDragOperation:(id <NSDraggingInfo>)sender;
 

modules/gui/macosx/CoreInteraction.m

@@ -446,6 +446,15 @@ static VLCCoreInteraction *_o_sharedInstance = nil;
     aout_VolumeDown( pl_Get( p_intf ), 1, NULL );
 }
 
+- (void)toggleMute
+{
+    intf_thread_t *p_intf = VLCIntf;
+    if( !p_intf )
+        return;
+
+    aout_MuteToggle( pl_Get( p_intf ) );
+}
+
 - (void)setMute:(BOOL)b_value
 {
     intf_thread_t *p_intf = VLCIntf;

modules/gui/macosx/MainWindow.m

@@ -1204,9 +1204,7 @@ static VLCMainWindow *_o_sharedInstance = nil;
     if (sender == o_volume_sld)
         [[VLCCoreInteraction sharedInstance] setVolume: [sender intValue]];
     else if (sender == o_volume_down_btn)
-    {
-        [[VLCCoreInteraction sharedInstance] setMute: YES];
-    }
+        [[VLCCoreInteraction sharedInstance] toggleMute];
     else
         [[VLCCoreInteraction sharedInstance] setVolume: AOUT_VOLUME_MAX];
 }
@@ -1568,8 +1566,7 @@ static VLCMainWindow *_o_sharedInstance = nil;
 
 - (void)updateVolumeSlider
 {
-    playlist_t * p_playlist = pl_Get( VLCIntf );
-    int i_volume = lroundf(aout_VolumeGet( p_playlist ) * AOUT_VOLUME_DEFAULT);
+    int i_volume = [[VLCCoreInteraction sharedInstance] volume];
     BOOL b_muted = [[VLCCoreInteraction sharedInstance] mute];
 
     if( !b_muted )