[ENHANCEMENT] Reduce volume when focus is lost

project.hxp

@@ -293,6 +293,13 @@ class Project extends HXProject
    */
   static final FEATURE_DISCORD_RPC:FeatureFlag = "FEATURE_DISCORD_RPC";
 
+  /**
+   * `-DFEATURE_LOST_FOCUS_VOLUME`
+   * If this flag is enabled, the game will reduce application volume, when lost focus.
+   * Allowed only on Desktop targets.
+   */
+  static final FEATURE_LOST_FOCUS_VOLUME:FeatureFlag = "FEATURE_LOST_FOCUS_VOLUME";
+
   /**
    * `-DFEATURE_FILE_DROP`
    * If this flag is enabled, the game will support dragging and dropping files onto it for various features.
@@ -857,6 +864,8 @@ class Project extends HXProject
     // We don't want testers to accidentally leak songs to their Discord friends!
     FEATURE_DISCORD_RPC.apply(this, isDesktop() && !FEATURE_DEBUG_FUNCTIONS.isEnabled(this));
 
+    FEATURE_LOST_FOCUS_VOLUME.apply(this, isDesktop());
+
     // Newgrounds features
     FEATURE_NEWGROUNDS.apply(this, !isMobile());
     FEATURE_NEWGROUNDS_DEBUG.apply(this, false);

source/funkin/InitState.hx

@@ -212,6 +212,10 @@ class InitState extends FlxState
       });
       #end
 
+      #if FEATURE_LOST_FOCUS_VOLUME
+      FlxG.signals.focusLost.add(onLostFocus);
+      FlxG.signals.focusGained.add(onGainFocus);
+      #end
       //
       // ANDROID SETUP
       //
@@ -287,6 +291,23 @@ class InitState extends FlxState
     #end
   }
 
+  #if FEATURE_LOST_FOCUS_VOLUME
+  @:noCompletion var _lastFocusVolume:Null<Float>;
+
+  function onLostFocus()
+  {
+    if (FlxG.sound.muted || FlxG.sound.volume == 0 || FlxG.autoPause) return;
+    _lastFocusVolume = FlxG.sound.volume;
+    FlxG.sound.volume *= Constants.LOST_FOCUS_VOLUME_MULTIPLIER;
+  }
+
+  function onGainFocus()
+  {
+    if (FlxG.sound.muted || FlxG.autoPause) return;
+    if (_lastFocusVolume != null) FlxG.sound.volume = _lastFocusVolume;
+  }
+  #end
+
   /**
    * Start the game.
    *

source/funkin/util/Constants.hx

@@ -570,6 +570,13 @@ class Constants
   public static final GHOST_TAP_DELAY:Float = 3 / 8;
   #end
 
+  #if FEATURE_LOST_FOCUS_VOLUME
+  /**
+   * How much volume should be reduced on Application Focus Lost.
+   */
+  public static final LOST_FOCUS_VOLUME_MULTIPLIER:Float = 0.5;
+  #end
+
   /**
    * Otherwise known as "The FuckCunt Variable"
    */