Move parallax logic out of BackgroundScreenStack

osu.Game/OsuGame.cs

@@ -86,6 +86,9 @@ namespace osu.Game
         public readonly Bindable<OverlayActivation> OverlayActivationMode = new Bindable<OverlayActivation>();
 
         private BackgroundScreenStack backgroundStack;
+
+        private ParallaxContainer backgroundParallax;
+
         private ScreenStack screenStack;
         private VolumeOverlay volume;
         private OnScreenDisplay onscreenDisplay;
@@ -353,7 +356,11 @@ namespace osu.Game
                     ActionRequested = action => volume.Adjust(action),
                     ScrollActionRequested = (action, amount, isPrecise) => volume.Adjust(action, amount, isPrecise),
                 },
-                backgroundStack = new BackgroundScreenStack { RelativeSizeAxes = Axes.Both },
+                backgroundParallax = new ParallaxContainer
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Child = backgroundStack = new BackgroundScreenStack { RelativeSizeAxes = Axes.Both },
+                },
                 screenContainer = new ScalingContainer(ScalingMode.ExcludeOverlays)
                 {
                     RelativeSizeAxes = Axes.Both,
@@ -766,6 +773,8 @@ namespace osu.Game
 
             if (newScreen is IOsuScreen newOsuScreen)
             {
+                backgroundParallax.ParallaxAmount = ParallaxContainer.DEFAULT_PARALLAX_AMOUNT * newOsuScreen.BackgroundParallaxAmount;
+
                 OverlayActivationMode.Value = newOsuScreen.InitialOverlayActivationMode;
 
                 if (newOsuScreen.HideOverlaysOnEnter)

osu.Game/Screens/BackgroundScreenStack.cs

@@ -3,50 +3,30 @@
 
 using System.Collections.Generic;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
 using osu.Framework.Screens;
-using osu.Game.Graphics.Containers;
 using osuTK;
 
 namespace osu.Game.Screens
 {
-    public class BackgroundScreenStack : CompositeDrawable
+    public class BackgroundScreenStack : ScreenStack
     {
-        public BackgroundScreen Current => (BackgroundScreen)stack.CurrentScreen;
-
-        private readonly ParallaxContainer parallax;
-        private readonly ScreenStack stack;
-
         public BackgroundScreenStack()
         {
-            InternalChild = parallax = new ParallaxContainer
+            Scale = new Vector2(1.06f);
-            {
+            RelativeSizeAxes = Axes.Both;
-                RelativeSizeAxes = Axes.Both,
-                Child = stack = new ScreenStack
-                {
-                    RelativeSizeAxes = Axes.Both,
-                    Scale = new Vector2(1.06f)
-                }
-            };
         }
 
-        public float ParallaxAmount { set => parallax.ParallaxAmount = ParallaxContainer.DEFAULT_PARALLAX_AMOUNT * value; }
+        //public float ParallaxAmount { set => parallax.ParallaxAmount = ParallaxContainer.DEFAULT_PARALLAX_AMOUNT * value; }
 
-        public void Push(BackgroundScreen screen)
+        public new void Push(BackgroundScreen screen)
         {
             if (screen == null)
                 return;
 
-            if (EqualityComparer<BackgroundScreen>.Default.Equals(Current, screen))
+            if (EqualityComparer<BackgroundScreen>.Default.Equals((BackgroundScreen)CurrentScreen, screen))
                 return;
 
-            stack.Push(screen);
+            base.Push(screen);
-        }
-
-        public void Exit(BackgroundScreen screen)
-        {
-            if (stack.CurrentScreen == screen)
-                stack.Exit();
         }
     }
 }

osu.Game/Screens/IOsuScreen.cs

@@ -30,5 +30,10 @@ namespace osu.Game.Screens
         /// Whether overlays should be able to be opened once this screen is entered or resumed.
         /// </summary>
         OverlayActivation InitialOverlayActivationMode { get; }
+
+        /// <summary>
+        /// The amount of parallax to be applied while this screen is displayed.
+        /// </summary>
+        float BackgroundParallaxAmount { get; }
     }
 }

osu.Game/Screens/Multi/Multiplayer.cs

@@ -35,6 +35,8 @@ namespace osu.Game.Screens.Multi
         public bool HideOverlaysOnEnter => false;
         public OverlayActivation InitialOverlayActivationMode => OverlayActivation.All;
 
+        public float BackgroundParallaxAmount => 1;
+
         public bool ValidForResume { get; set; } = true;
         public bool ValidForPush { get; set; } = true;
 

osu.Game/Screens/Multi/MultiplayerSubScreen.cs

@@ -22,6 +22,8 @@ namespace osu.Game.Screens.Multi
         public bool HideOverlaysOnEnter => false;
         public OverlayActivation InitialOverlayActivationMode => OverlayActivation.All;
 
+        public float BackgroundParallaxAmount => 1;
+
         public bool ValidForResume { get; set; } = true;
         public bool ValidForPush { get; set; } = true;
 

osu.Game/Screens/OsuScreen.cs

@@ -60,7 +60,7 @@ namespace osu.Game.Screens
 
         private SampleChannel sampleExit;
 
-        protected BackgroundScreen Background => backgroundStack?.Current;
+        protected BackgroundScreen Background => backgroundStack?.CurrentScreen as BackgroundScreen;
 
         private BackgroundScreen localBackground;
 
@@ -137,7 +137,8 @@ namespace osu.Game.Screens
             if (base.OnExiting(next))
                 return true;
 
-            backgroundStack?.Exit(localBackground);
+            if (localBackground != null && backgroundStack?.CurrentScreen == localBackground)
+                backgroundStack?.Exit();
 
             Beatmap.UnbindAll();
             return false;
@@ -157,9 +158,6 @@ namespace osu.Game.Screens
             {
                 if (this.IsCurrentScreen()) LogoArriving(logo, isResuming);
             }, true);
-
-            if (backgroundStack != null)
-                backgroundStack.ParallaxAmount = BackgroundParallaxAmount;
         }
 
         /// <summary>