From e8e387b549d1f1caa50b790bf1633ece3d0b1b7e Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Mon, 16 Aug 2021 08:02:23 +0900
Subject: [PATCH] Cache buffered background to fix multiplayer lounge
 performance

Consider this a request for comment. It's the cleanest solution I can
come up with without dropping either the blur, or use of
`ModelBackedDrawable`.

Intended to resolve https://github.com/ppy/osu/issues/14276.
---
 .../Components/OnlinePlayBackgroundSprite.cs  |  6 +--
 .../Screens/OnlinePlay/OnlinePlayScreen.cs    | 48 +++++++++++++++----
 2 files changed, 42 insertions(+), 12 deletions(-)

diff --git a/osu.Game/Screens/OnlinePlay/Components/OnlinePlayBackgroundSprite.cs b/osu.Game/Screens/OnlinePlay/Components/OnlinePlayBackgroundSprite.cs
index d8dfac496d..e2ba0b03b0 100644
--- a/osu.Game/Screens/OnlinePlay/Components/OnlinePlayBackgroundSprite.cs
+++ b/osu.Game/Screens/OnlinePlay/Components/OnlinePlayBackgroundSprite.cs
@@ -10,12 +10,12 @@ namespace osu.Game.Screens.OnlinePlay.Components
 {
     public class OnlinePlayBackgroundSprite : OnlinePlayComposite
     {
-        private readonly BeatmapSetCoverType beatmapSetCoverType;
+        protected readonly BeatmapSetCoverType BeatmapSetCoverType;
         private UpdateableBeatmapBackgroundSprite sprite;
 
         public OnlinePlayBackgroundSprite(BeatmapSetCoverType beatmapSetCoverType = BeatmapSetCoverType.Cover)
         {
-            this.beatmapSetCoverType = beatmapSetCoverType;
+            BeatmapSetCoverType = beatmapSetCoverType;
         }
 
         [BackgroundDependencyLoader]
@@ -33,6 +33,6 @@ namespace osu.Game.Screens.OnlinePlay.Components
             sprite.Beatmap.Value = Playlist.FirstOrDefault()?.Beatmap.Value;
         }
 
-        protected virtual UpdateableBeatmapBackgroundSprite CreateBackgroundSprite() => new UpdateableBeatmapBackgroundSprite(beatmapSetCoverType) { RelativeSizeAxes = Axes.Both };
+        protected virtual UpdateableBeatmapBackgroundSprite CreateBackgroundSprite() => new UpdateableBeatmapBackgroundSprite(BeatmapSetCoverType) { RelativeSizeAxes = Axes.Both };
     }
 }
diff --git a/osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs b/osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs
index c2ad0285b1..72b63ab4d4 100644
--- a/osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs
+++ b/osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs
@@ -11,6 +11,7 @@ using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Logging;
 using osu.Framework.Screens;
+using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.Drawables;
 using osu.Game.Graphics.Containers;
 using osu.Game.Input;
@@ -104,14 +105,9 @@ namespace osu.Game.Screens.OnlinePlay
                         RelativeSizeAxes = Axes.Both,
                         Children = new Drawable[]
                         {
-                            new BufferedContainer
+                            new BeatmapBackgroundSprite
                             {
-                                RelativeSizeAxes = Axes.Both,
-                                BlurSigma = new Vector2(10),
-                                Child = new BeatmapBackgroundSprite
-                                {
-                                    RelativeSizeAxes = Axes.Both
-                                }
+                                RelativeSizeAxes = Axes.Both
                             },
                             new Box
                             {
@@ -306,11 +302,45 @@ namespace osu.Game.Screens.OnlinePlay
 
         private class BeatmapBackgroundSprite : OnlinePlayBackgroundSprite
         {
-            protected override UpdateableBeatmapBackgroundSprite CreateBackgroundSprite() => new BackgroundSprite { RelativeSizeAxes = Axes.Both };
+            protected override UpdateableBeatmapBackgroundSprite CreateBackgroundSprite() => new BlurredBackgroundSprite(BeatmapSetCoverType) { RelativeSizeAxes = Axes.Both };
 
-            private class BackgroundSprite : UpdateableBeatmapBackgroundSprite
+            public class BlurredBackgroundSprite : UpdateableBeatmapBackgroundSprite
             {
+                public BlurredBackgroundSprite(BeatmapSetCoverType type)
+                    : base(type)
+                {
+                }
+
                 protected override double LoadDelay => 200;
+
+                protected override Drawable CreateDrawable(BeatmapInfo model) =>
+                    new BufferedLoader(base.CreateDrawable(model));
+            }
+
+            // This class is an unfortunate requirement due to `LongRunningLoad` requiring direct async loading.
+            // It means that if the web request fetching the beatmap background takes too long, it will suddenly appear.
+            internal class BufferedLoader : BufferedContainer
+            {
+                private readonly Drawable drawable;
+
+                public BufferedLoader(Drawable drawable)
+                {
+                    this.drawable = drawable;
+
+                    RelativeSizeAxes = Axes.Both;
+                    BlurSigma = new Vector2(10);
+                    CacheDrawnFrameBuffer = true;
+                }
+
+                [BackgroundDependencyLoader]
+                private void load()
+                {
+                    LoadComponentAsync(drawable, d =>
+                    {
+                        Add(d);
+                        ForceRedraw();
+                    });
+                }
             }
         }