Unload beatmap storyboard background when no longer present

osu.Game/Graphics/Backgrounds/BeatmapBackgroundWithStoryboard.cs

@@ -1,15 +1,21 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Collections.Generic;
+using System.Diagnostics;
+using System.Threading;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
+using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Threading;
 using osu.Framework.Timing;
 using osu.Game.Beatmaps;
 using osu.Game.Overlays;
 using osu.Game.Rulesets.Mods;
+using osu.Game.Screens;
 using osu.Game.Storyboards.Drawables;
 
 namespace osu.Game.Graphics.Backgrounds
@@ -18,6 +24,10 @@ namespace osu.Game.Graphics.Backgrounds
     {
         private readonly InterpolatingFramedClock storyboardClock;
 
+        private AudioContainer storyboardContainer = null!;
+        private DrawableStoryboard? drawableStoryboard;
+        private CancellationTokenSource? loadCancellationSource = new CancellationTokenSource();
+
         [Resolved(CanBeNull = true)]
         private MusicController? musicController { get; set; }
 
@@ -33,18 +43,48 @@ namespace osu.Game.Graphics.Backgrounds
         [BackgroundDependencyLoader]
         private void load()
         {
+            AddInternal(storyboardContainer = new AudioContainer
+            {
+                RelativeSizeAxes = Axes.Both,
+                Volume = { Value = 0 },
+            });
+
+            LoadStoryboard();
+        }
+
+        public void LoadStoryboard()
+        {
+            Debug.Assert(drawableStoryboard == null);
+
             if (!Beatmap.Storyboard.HasDrawable)
                 return;
 
             if (Beatmap.Storyboard.ReplacesBackground)
                 Sprite.Alpha = 0;
 
-            LoadComponentAsync(new AudioContainer
+            LoadComponentAsync(drawableStoryboard = new DrawableStoryboard(Beatmap.Storyboard, mods.Value)
             {
-                RelativeSizeAxes = Axes.Both,
+                Clock = storyboardClock
-                Volume = { Value = 0 },
+            }, s =>
-                Child = new DrawableStoryboard(Beatmap.Storyboard, mods.Value) { Clock = storyboardClock }
+            {
-            }, AddInternal);
+                storyboardContainer.FadeInFromZero(BackgroundScreen.TRANSITION_LENGTH, Easing.OutQuint);
+                storyboardContainer.Add(s);
+            }, (loadCancellationSource = new CancellationTokenSource()).Token);
+        }
+
+        public void UnloadStoryboard(Action<DrawableStoryboard> scheduleStoryboardRemoval)
+        {
+            Debug.Assert(drawableStoryboard != null);
+
+            loadCancellationSource.AsNonNull().Cancel();
+            loadCancellationSource = null;
+
+            DrawableStoryboard s = drawableStoryboard;
+
+            storyboardContainer.FadeOut(BackgroundScreen.TRANSITION_LENGTH, Easing.OutQuint);
+            scheduleStoryboardRemoval(s);
+
+            drawableStoryboard = null;
         }
 
         protected override void LoadComplete()

osu.Game/Screens/BackgroundScreen.cs

@@ -13,7 +13,8 @@ namespace osu.Game.Screens
 {
     public abstract partial class BackgroundScreen : Screen, IEquatable<BackgroundScreen>
     {
-        protected const float TRANSITION_LENGTH = 500;
+        public const float TRANSITION_LENGTH = 500;
+
         private const float x_movement_amount = 50;
 
         private readonly bool animateOnEnter;

osu.Game/Screens/BackgroundScreenStack.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using osu.Framework.Graphics;
 using osu.Framework.Screens;
+using osu.Game.Storyboards.Drawables;
 
 namespace osu.Game.Screens
 {
@@ -33,5 +34,7 @@ namespace osu.Game.Screens
             base.Push(screen);
             return true;
         }
+
+        public void ScheduleStoryboardDisposal(DrawableStoryboard storyboard) => Scheduler.AddDelayed(storyboard.RemoveAndDisposeImmediately, BackgroundScreen.TRANSITION_LENGTH);
     }
 }

osu.Game/Screens/Backgrounds/BackgroundScreenDefault.cs

@@ -3,11 +3,14 @@
 
 #nullable disable
 
+using System.Diagnostics;
 using System.Threading;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
+using osu.Framework.Screens;
 using osu.Framework.Threading;
 using osu.Framework.Utils;
 using osu.Game.Beatmaps;
@@ -71,6 +74,25 @@ namespace osu.Game.Screens.Backgrounds
             void next() => Next();
         }
 
+        public override void OnSuspending(ScreenTransitionEvent e)
+        {
+            var backgroundScreenStack = Parent as BackgroundScreenStack;
+            Debug.Assert(backgroundScreenStack != null);
+
+            if (background is BeatmapBackgroundWithStoryboard storyboardBackground)
+                storyboardBackground.UnloadStoryboard(backgroundScreenStack.ScheduleStoryboardDisposal);
+
+            base.OnSuspending(e);
+        }
+
+        public override void OnResuming(ScreenTransitionEvent e)
+        {
+            if (background is BeatmapBackgroundWithStoryboard storyboardBackground)
+                storyboardBackground.LoadStoryboard();
+
+            base.OnResuming(e);
+        }
+
         private ScheduledDelegate nextTask;
         private CancellationTokenSource cancellationTokenSource;