Initial rework of backgrounds

osu.Game/Screens/OnlinePlay/Components/PlaylistItemBackground.cs

@@ -0,0 +1,44 @@
+// 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.
+
+#nullable enable
+
+using osu.Framework.Allocation;
+using osu.Framework.Graphics.Textures;
+using osu.Game.Beatmaps;
+using osu.Game.Graphics.Backgrounds;
+using osu.Game.Online.Rooms;
+
+namespace osu.Game.Screens.OnlinePlay.Components
+{
+    public class PlaylistItemBackground : Background
+    {
+        public readonly BeatmapInfo? BeatmapInfo;
+
+        public PlaylistItemBackground(PlaylistItem? playlistItem)
+        {
+            BeatmapInfo = playlistItem?.Beatmap.Value;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(BeatmapManager beatmaps, LargeTextureStore textures)
+        {
+            Texture? texture = null;
+
+            // prefer online cover where available.
+            if (BeatmapInfo?.BeatmapSet?.OnlineInfo?.Covers.Cover != null)
+                texture = textures.Get(BeatmapInfo.BeatmapSet.OnlineInfo.Covers.Cover);
+
+            Sprite.Texture = texture ?? beatmaps.DefaultBeatmap.Background;
+        }
+
+        public override bool Equals(Background? other)
+        {
+            if (ReferenceEquals(null, other)) return false;
+            if (ReferenceEquals(this, other)) return true;
+
+            return other.GetType() == GetType()
+                   && ((PlaylistItemBackground)other).BeatmapInfo == BeatmapInfo;
+        }
+    }
+}

osu.Game/Screens/OnlinePlay/Components/RoomBackgroundScreen.cs

@@ -0,0 +1,82 @@
+// 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.
+
+#nullable enable
+
+using System.Linq;
+using System.Threading;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Game.Online.Rooms;
+using osuTK;
+
+namespace osu.Game.Screens.OnlinePlay.Components
+{
+    public class RoomBackgroundScreen : BackgroundScreen
+    {
+        private CancellationTokenSource? cancellationSource;
+        private PlaylistItemBackground? background;
+
+        private readonly BindableList<PlaylistItem> playlist = new BindableList<PlaylistItem>();
+
+        public RoomBackgroundScreen()
+        {
+            playlist.BindCollectionChanged((_, __) => updateBackground());
+        }
+
+        private Room? room;
+
+        public Room? Room
+        {
+            get => room;
+            set
+            {
+                if (room == value)
+                    return;
+
+                if (room != null)
+                    playlist.UnbindFrom(room.Playlist);
+
+                room = value;
+
+                if (room != null)
+                    playlist.BindTo(room.Playlist);
+                else
+                    playlist.Clear();
+            }
+        }
+
+        private void updateBackground()
+        {
+            Schedule(() =>
+            {
+                var playlistItem = playlist.FirstOrDefault();
+                var beatmap = playlistItem?.Beatmap.Value;
+
+                if (background?.BeatmapInfo?.BeatmapSet?.OnlineInfo?.Covers?.Cover == beatmap?.BeatmapSet?.OnlineInfo?.Covers?.Cover)
+                    return;
+
+                cancellationSource?.Cancel();
+                LoadComponentAsync(new PlaylistItemBackground(playlistItem), switchBackground, (cancellationSource = new CancellationTokenSource()).Token);
+            });
+        }
+
+        private void switchBackground(PlaylistItemBackground newBackground)
+        {
+            float newDepth = 0;
+
+            if (background != null)
+            {
+                newDepth = background.Depth + 1;
+                background.FinishTransforms();
+                background.FadeOut(250);
+                background.Expire();
+            }
+
+            newBackground.Depth = newDepth;
+            newBackground.BlurTo(new Vector2(10));
+
+            AddInternal(background = newBackground);
+        }
+    }
+}

osu.Game/Screens/OnlinePlay/Lounge/LoungeSubScreen.cs

@@ -23,7 +23,6 @@ using osu.Game.Input;
 using osu.Game.Online.Rooms;
 using osu.Game.Overlays;
 using osu.Game.Rulesets;
-using osu.Game.Screens.Backgrounds;
 using osu.Game.Screens.OnlinePlay.Components;
 using osu.Game.Screens.OnlinePlay.Lounge.Components;
 using osu.Game.Screens.OnlinePlay.Match;
@@ -37,7 +36,7 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
     {
         public override string Title => "Lounge";
 
-        protected override BackgroundScreen CreateBackground() => new BackgroundScreenDefault();
+        protected override BackgroundScreen CreateBackground() => new RoomBackgroundScreen();
 
         protected override UserActivity InitialActivity => new UserActivity.SearchingForLobby();
 
@@ -180,6 +179,8 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
                 var drawable = roomsContainer.Rooms.FirstOrDefault(r => r.Room == val.NewValue);
                 if (drawable != null)
                     scrollContainer.ScrollIntoView(drawable);
+
+                ApplyToBackground(b => ((RoomBackgroundScreen)b).Room = val.NewValue);
             });
         }
 
@@ -246,6 +247,7 @@ namespace osu.Game.Screens.OnlinePlay.Lounge
         public override void OnEntering(IScreen last)
         {
             base.OnEntering(last);
+
             onReturning();
         }
 

osu.Game/Screens/OnlinePlay/OnlinePlayScreen.cs

@@ -6,13 +6,9 @@ using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Colour;
 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.Online.API;
 using osu.Game.Online.Rooms;
@@ -21,8 +17,6 @@ using osu.Game.Screens.Menu;
 using osu.Game.Screens.OnlinePlay.Components;
 using osu.Game.Screens.OnlinePlay.Lounge;
 using osu.Game.Users;
-using osuTK;
-using osuTK.Graphics;
 
 namespace osu.Game.Screens.OnlinePlay
 {