Merge branch 'refactor-selection-rotate-logic' into fix-flip-logic-discrepancy

osu.Android.props

@@ -52,6 +52,6 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="ppy.osu.Game.Resources" Version="2021.422.0" />
-    <PackageReference Include="ppy.osu.Framework.Android" Version="2021.513.0" />
+    <PackageReference Include="ppy.osu.Framework.Android" Version="2021.521.0" />
   </ItemGroup>
 </Project>

osu.Game.Rulesets.Mania.Tests/Skinning/TestSceneColumnBackground.cs

@@ -28,7 +28,7 @@ namespace osu.Game.Rulesets.Mania.Tests.Skinning
                     {
                         RelativeSizeAxes = Axes.Both,
                         Width = 0.5f,
-                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground, 0), _ => new DefaultColumnBackground())
+                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground), _ => new DefaultColumnBackground())
                         {
                             RelativeSizeAxes = Axes.Both
                         }
@@ -37,7 +37,7 @@ namespace osu.Game.Rulesets.Mania.Tests.Skinning
                     {
                         RelativeSizeAxes = Axes.Both,
                         Width = 0.5f,
-                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground, 1), _ => new DefaultColumnBackground())
+                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground), _ => new DefaultColumnBackground())
                         {
                             RelativeSizeAxes = Axes.Both
                         }

osu.Game.Rulesets.Mania.Tests/Skinning/TestSceneKeyArea.cs

@@ -28,7 +28,7 @@ namespace osu.Game.Rulesets.Mania.Tests.Skinning
                     {
                         RelativeSizeAxes = Axes.Both,
                         Width = 0.5f,
-                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea, 0), _ => new DefaultKeyArea())
+                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea), _ => new DefaultKeyArea())
                         {
                             RelativeSizeAxes = Axes.Both
                         },
@@ -37,7 +37,7 @@ namespace osu.Game.Rulesets.Mania.Tests.Skinning
                     {
                         RelativeSizeAxes = Axes.Both,
                         Width = 0.5f,
-                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea, 1), _ => new DefaultKeyArea())
+                        Child = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea), _ => new DefaultKeyArea())
                         {
                             RelativeSizeAxes = Axes.Both
                         },

osu.Game.Rulesets.Mania.Tests/TestSceneHoldNoteInput.cs

@@ -4,6 +4,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using NUnit.Framework;
+using osu.Framework.Screens;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Replays;
@@ -408,6 +409,9 @@ namespace osu.Game.Rulesets.Mania.Tests
                 judgementResults = new List<JudgementResult>();
             });
 
+            AddUntilStep("Beatmap at 0", () => Beatmap.Value.Track.CurrentTime == 0);
+            AddUntilStep("Wait until player is loaded", () => currentPlayer.IsCurrentScreen());
+
             AddUntilStep("Wait for completion", () => currentPlayer.ScoreProcessor?.HasCompleted.Value == true);
         }
 

osu.Game.Rulesets.Mania/Edit/ManiaSelectionHandler.cs

@@ -58,8 +58,9 @@ namespace osu.Game.Rulesets.Mania.Edit
 
             EditorBeatmap.PerformOnSelection(h =>
             {
-                if (h is ManiaHitObject maniaObj)
-                    maniaObj.Column += columnDelta;
+                maniaPlayfield.Remove(h);
+                ((ManiaHitObject)h).Column += columnDelta;
+                maniaPlayfield.Add(h);
             });
         }
     }

osu.Game.Rulesets.Mania/ManiaSkinComponent.cs

@@ -9,12 +9,6 @@ namespace osu.Game.Rulesets.Mania
 {
     public class ManiaSkinComponent : GameplaySkinComponent<ManiaSkinComponents>
     {
-        /// <summary>
-        /// The intended <see cref="Column"/> index for this component.
-        /// May be null if the component does not exist in a <see cref="Column"/>.
-        /// </summary>
-        public readonly int? TargetColumn;
-
         /// <summary>
         /// The intended <see cref="StageDefinition"/> for this component.
         /// May be null if the component is not a direct member of a <see cref="Stage"/>.
@@ -25,12 +19,10 @@ namespace osu.Game.Rulesets.Mania
         /// Creates a new <see cref="ManiaSkinComponent"/>.
         /// </summary>
         /// <param name="component">The component.</param>
-        /// <param name="targetColumn">The intended <see cref="Column"/> index for this component. May be null if the component does not exist in a <see cref="Column"/>.</param>
         /// <param name="stageDefinition">The intended <see cref="StageDefinition"/> for this component. May be null if the component is not a direct member of a <see cref="Stage"/>.</param>
-        public ManiaSkinComponent(ManiaSkinComponents component, int? targetColumn = null, StageDefinition? stageDefinition = null)
+        public ManiaSkinComponent(ManiaSkinComponents component, StageDefinition? stageDefinition = null)
             : base(component)
         {
-            TargetColumn = targetColumn;
             StageDefinition = stageDefinition;
         }
 

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNote.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -12,6 +13,7 @@ using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.UI.Scrolling;
 using osu.Game.Skinning;
+using osuTK;
 
 namespace osu.Game.Rulesets.Mania.Objects.Drawables
 {
@@ -29,21 +31,21 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         public DrawableHoldNoteHead Head => headContainer.Child;
         public DrawableHoldNoteTail Tail => tailContainer.Child;
 
-        private readonly Container<DrawableHoldNoteHead> headContainer;
-        private readonly Container<DrawableHoldNoteTail> tailContainer;
-        private readonly Container<DrawableHoldNoteTick> tickContainer;
+        private Container<DrawableHoldNoteHead> headContainer;
+        private Container<DrawableHoldNoteTail> tailContainer;
+        private Container<DrawableHoldNoteTick> tickContainer;
 
         /// <summary>
         /// Contains the size of the hold note covering the whole head/tail bounds. The size of this container changes as the hold note is being pressed.
         /// </summary>
-        private readonly Container sizingContainer;
+        private Container sizingContainer;
 
         /// <summary>
         /// Contains the contents of the hold note that should be masked as the hold note is being pressed. Follows changes in the size of <see cref="sizingContainer"/>.
         /// </summary>
-        private readonly Container maskingContainer;
+        private Container maskingContainer;
 
-        private readonly SkinnableDrawable bodyPiece;
+        private SkinnableDrawable bodyPiece;
 
         /// <summary>
         /// Time at which the user started holding this hold note. Null if the user is not holding this hold note.
@@ -60,11 +62,19 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         /// </summary>
         private double? releaseTime;
 
+        public DrawableHoldNote()
+            : this(null)
+        {
+        }
+
         public DrawableHoldNote(HoldNote hitObject)
             : base(hitObject)
         {
-            RelativeSizeAxes = Axes.X;
+        }
 
+        [BackgroundDependencyLoader]
+        private void load()
+        {
             Container maskedContents;
 
             AddRangeInternal(new Drawable[]
@@ -86,7 +96,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                         headContainer = new Container<DrawableHoldNoteHead> { RelativeSizeAxes = Axes.Both }
                     }
                 },
-                bodyPiece = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HoldNoteBody, hitObject.Column), _ => new DefaultBodyPiece
+                bodyPiece = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HoldNoteBody), _ => new DefaultBodyPiece
                 {
                     RelativeSizeAxes = Axes.Both,
                 })
@@ -105,6 +115,16 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             });
         }
 
+        protected override void OnApply()
+        {
+            base.OnApply();
+
+            sizingContainer.Size = Vector2.One;
+            HoldStartTime = null;
+            HoldBrokenTime = null;
+            releaseTime = null;
+        }
+
         protected override void AddNestedHitObject(DrawableHitObject hitObject)
         {
             base.AddNestedHitObject(hitObject);
@@ -128,37 +148,23 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         protected override void ClearNestedHitObjects()
         {
             base.ClearNestedHitObjects();
-            headContainer.Clear();
-            tailContainer.Clear();
-            tickContainer.Clear();
+            headContainer.Clear(false);
+            tailContainer.Clear(false);
+            tickContainer.Clear(false);
         }
 
         protected override DrawableHitObject CreateNestedHitObject(HitObject hitObject)
         {
             switch (hitObject)
             {
-                case TailNote _:
-                    return new DrawableHoldNoteTail(this)
-                    {
-                        Anchor = Anchor.TopCentre,
-                        Origin = Anchor.TopCentre,
-                        AccentColour = { BindTarget = AccentColour }
-                    };
+                case TailNote tail:
+                    return new DrawableHoldNoteTail(tail);
 
-                case Note _:
-                    return new DrawableHoldNoteHead(this)
-                    {
-                        Anchor = Anchor.TopCentre,
-                        Origin = Anchor.TopCentre,
-                        AccentColour = { BindTarget = AccentColour }
-                    };
+                case HeadNote head:
+                    return new DrawableHoldNoteHead(head);
 
                 case HoldNoteTick tick:
-                    return new DrawableHoldNoteTick(tick)
-                    {
-                        HoldStartTime = () => HoldStartTime,
-                        AccentColour = { BindTarget = AccentColour }
-                    };
+                    return new DrawableHoldNoteTick(tick);
             }
 
             return base.CreateNestedHitObject(hitObject);

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNoteHead.cs

@@ -1,6 +1,7 @@
 // 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 osu.Framework.Graphics;
 using osu.Game.Rulesets.Objects.Drawables;
 
 namespace osu.Game.Rulesets.Mania.Objects.Drawables
@@ -12,11 +13,18 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
     {
         protected override ManiaSkinComponents Component => ManiaSkinComponents.HoldNoteHead;
 
-        public DrawableHoldNoteHead(DrawableHoldNote holdNote)
-            : base(holdNote.HitObject.Head)
+        public DrawableHoldNoteHead()
+            : this(null)
         {
         }
 
+        public DrawableHoldNoteHead(HeadNote headNote)
+            : base(headNote)
+        {
+            Anchor = Anchor.TopCentre;
+            Origin = Anchor.TopCentre;
+        }
+
         public void UpdateResult() => base.UpdateResult(true);
 
         protected override void UpdateInitialTransforms()

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNoteTail.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Diagnostics;
+using osu.Framework.Graphics;
 using osu.Game.Rulesets.Scoring;
 
 namespace osu.Game.Rulesets.Mania.Objects.Drawables
@@ -20,12 +21,18 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
 
         protected override ManiaSkinComponents Component => ManiaSkinComponents.HoldNoteTail;
 
-        private readonly DrawableHoldNote holdNote;
+        protected DrawableHoldNote HoldNote => (DrawableHoldNote)ParentHitObject;
 
-        public DrawableHoldNoteTail(DrawableHoldNote holdNote)
-            : base(holdNote.HitObject.Tail)
+        public DrawableHoldNoteTail()
+            : this(null)
         {
-            this.holdNote = holdNote;
+        }
+
+        public DrawableHoldNoteTail(TailNote tailNote)
+            : base(tailNote)
+        {
+            Anchor = Anchor.TopCentre;
+            Origin = Anchor.TopCentre;
         }
 
         public void UpdateResult() => base.UpdateResult(true);
@@ -54,7 +61,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             ApplyResult(r =>
             {
                 // If the head wasn't hit or the hold note was broken, cap the max score to Meh.
-                if (result > HitResult.Meh && (!holdNote.Head.IsHit || holdNote.HoldBrokenTime != null))
+                if (result > HitResult.Meh && (!HoldNote.Head.IsHit || HoldNote.HoldBrokenTime != null))
                     result = HitResult.Meh;
 
                 r.Type = result;

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableHoldNoteTick.cs

@@ -2,7 +2,8 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
-using osuTK;
+using System.Diagnostics;
+using osu.Framework.Allocation;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -19,38 +20,48 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         /// <summary>
         /// References the time at which the user started holding the hold note.
         /// </summary>
-        public Func<double?> HoldStartTime;
+        private Func<double?> holdStartTime;
+
+        private Container glowContainer;
+
+        public DrawableHoldNoteTick()
+            : this(null)
+        {
+        }
 
         public DrawableHoldNoteTick(HoldNoteTick hitObject)
             : base(hitObject)
         {
-            Container glowContainer;
-
             Anchor = Anchor.TopCentre;
             Origin = Anchor.TopCentre;
 
             RelativeSizeAxes = Axes.X;
-            Size = new Vector2(1);
+        }
 
-            AddRangeInternal(new[]
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            AddInternal(glowContainer = new CircularContainer
             {
-                glowContainer = new CircularContainer
+                Anchor = Anchor.TopCentre,
+                Origin = Anchor.TopCentre,
+                RelativeSizeAxes = Axes.Both,
+                Masking = true,
+                Children = new[]
                 {
-                    Anchor = Anchor.TopCentre,
-                    Origin = Anchor.TopCentre,
-                    RelativeSizeAxes = Axes.Both,
-                    Masking = true,
-                    Children = new[]
+                    new Box
                     {
-                        new Box
-                        {
-                            RelativeSizeAxes = Axes.Both,
-                            Alpha = 0,
-                            AlwaysPresent = true
-                        }
+                        RelativeSizeAxes = Axes.Both,
+                        Alpha = 0,
+                        AlwaysPresent = true
                     }
                 }
             });
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
 
             AccentColour.BindValueChanged(colour =>
             {
@@ -64,12 +75,29 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             }, true);
         }
 
+        protected override void OnApply()
+        {
+            base.OnApply();
+
+            Debug.Assert(ParentHitObject != null);
+
+            var holdNote = (DrawableHoldNote)ParentHitObject;
+            holdStartTime = () => holdNote.HoldStartTime;
+        }
+
+        protected override void OnFree()
+        {
+            base.OnFree();
+
+            holdStartTime = null;
+        }
+
         protected override void CheckForResult(bool userTriggered, double timeOffset)
         {
             if (Time.Current < HitObject.StartTime)
                 return;
 
-            var startTime = HoldStartTime?.Invoke();
+            var startTime = holdStartTime?.Invoke();
 
             if (startTime == null || startTime > HitObject.StartTime)
                 ApplyResult(r => r.Type = r.Judgement.MinResult);

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableManiaHitObject.cs

@@ -50,6 +50,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         protected DrawableManiaHitObject(ManiaHitObject hitObject)
             : base(hitObject)
         {
+            RelativeSizeAxes = Axes.X;
         }
 
         [BackgroundDependencyLoader(true)]
@@ -59,9 +60,31 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                 Action.BindTo(action);
 
             Direction.BindTo(scrollingInfo.Direction);
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
             Direction.BindValueChanged(OnDirectionChanged, true);
         }
 
+        protected override void OnApply()
+        {
+            base.OnApply();
+
+            if (ParentHitObject != null)
+                AccentColour.BindTo(ParentHitObject.AccentColour);
+        }
+
+        protected override void OnFree()
+        {
+            base.OnFree();
+
+            if (ParentHitObject != null)
+                AccentColour.UnbindFrom(ParentHitObject.AccentColour);
+        }
+
         private double computedLifetimeStart;
 
         public override double LifetimeStart
@@ -147,12 +170,11 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
     public abstract class DrawableManiaHitObject<TObject> : DrawableManiaHitObject
         where TObject : ManiaHitObject
     {
-        public new readonly TObject HitObject;
+        public new TObject HitObject => (TObject)base.HitObject;
 
         protected DrawableManiaHitObject(TObject hitObject)
             : base(hitObject)
         {
-            HitObject = hitObject;
         }
     }
 }

osu.Game.Rulesets.Mania/Objects/Drawables/DrawableNote.cs

@@ -33,31 +33,37 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
 
         protected virtual ManiaSkinComponents Component => ManiaSkinComponents.Note;
 
-        private readonly Drawable headPiece;
+        private Drawable headPiece;
+
+        public DrawableNote()
+            : this(null)
+        {
+        }
 
         public DrawableNote(Note hitObject)
             : base(hitObject)
         {
-            RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
-
-            AddInternal(headPiece = new SkinnableDrawable(new ManiaSkinComponent(Component, hitObject.Column), _ => new DefaultNotePiece())
-            {
-                RelativeSizeAxes = Axes.X,
-                AutoSizeAxes = Axes.Y
-            });
         }
 
         [BackgroundDependencyLoader(true)]
         private void load(ManiaRulesetConfigManager rulesetConfig)
         {
             rulesetConfig?.BindWith(ManiaRulesetSetting.TimingBasedNoteColouring, configTimingBasedNoteColouring);
+
+            AddInternal(headPiece = new SkinnableDrawable(new ManiaSkinComponent(Component), _ => new DefaultNotePiece())
+            {
+                RelativeSizeAxes = Axes.X,
+                AutoSizeAxes = Axes.Y
+            });
         }
 
         protected override void LoadComplete()
         {
-            HitObject.StartTimeBindable.BindValueChanged(_ => updateSnapColour());
-            configTimingBasedNoteColouring.BindValueChanged(_ => updateSnapColour(), true);
+            base.LoadComplete();
+
+            configTimingBasedNoteColouring.BindValueChanged(_ => updateSnapColour());
+            StartTimeBindable.BindValueChanged(_ => updateSnapColour(), true);
         }
 
         protected override void OnDirectionChanged(ValueChangedEvent<ScrollingDirection> e)
@@ -102,7 +108,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
 
         private void updateSnapColour()
         {
-            if (beatmap == null) return;
+            if (beatmap == null || HitObject == null) return;
 
             int snapDivisor = beatmap.ControlPointInfo.GetClosestBeatDivisor(HitObject.StartTime);
 

osu.Game.Rulesets.Mania/Objects/HeadNote.cs

@@ -0,0 +1,9 @@
+// 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.
+
+namespace osu.Game.Rulesets.Mania.Objects
+{
+    public class HeadNote : Note
+    {
+    }
+}

osu.Game.Rulesets.Mania/Objects/HoldNote.cs

@@ -72,7 +72,7 @@ namespace osu.Game.Rulesets.Mania.Objects
         /// <summary>
         /// The head note of the hold.
         /// </summary>
-        public Note Head { get; private set; }
+        public HeadNote Head { get; private set; }
 
         /// <summary>
         /// The tail note of the hold.
@@ -98,7 +98,7 @@ namespace osu.Game.Rulesets.Mania.Objects
 
             createTicks(cancellationToken);
 
-            AddNested(Head = new Note
+            AddNested(Head = new HeadNote
             {
                 StartTime = StartTime,
                 Column = Column,

osu.Game.Rulesets.Mania/UI/Column.cs

@@ -17,6 +17,7 @@ using osu.Game.Rulesets.UI.Scrolling;
 using osu.Game.Skinning;
 using osuTK;
 using osu.Game.Rulesets.Mania.Beatmaps;
+using osu.Game.Rulesets.Mania.Objects;
 using osu.Game.Rulesets.Mania.Objects.Drawables;
 
 namespace osu.Game.Rulesets.Mania.UI
@@ -55,7 +56,7 @@ namespace osu.Game.Rulesets.Mania.UI
             RelativeSizeAxes = Axes.Y;
             Width = COLUMN_WIDTH;
 
-            Drawable background = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground, Index), _ => new DefaultColumnBackground())
+            Drawable background = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.ColumnBackground), _ => new DefaultColumnBackground())
             {
                 RelativeSizeAxes = Axes.Both
             };
@@ -66,7 +67,7 @@ namespace osu.Game.Rulesets.Mania.UI
                 // For input purposes, the background is added at the highest depth, but is then proxied back below all other elements
                 background.CreateProxy(),
                 HitObjectArea = new ColumnHitObjectArea(Index, HitObjectContainer) { RelativeSizeAxes = Axes.Both },
-                new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea, Index), _ => new DefaultKeyArea())
+                new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.KeyArea), _ => new DefaultKeyArea())
                 {
                     RelativeSizeAxes = Axes.Both
                 },
@@ -83,6 +84,19 @@ namespace osu.Game.Rulesets.Mania.UI
             hitPolicy = new OrderedHitPolicy(HitObjectContainer);
 
             TopLevelContainer.Add(HitObjectArea.Explosions.CreateProxy());
+
+            RegisterPool<Note, DrawableNote>(10, 50);
+            RegisterPool<HoldNote, DrawableHoldNote>(10, 50);
+            RegisterPool<HeadNote, DrawableHoldNoteHead>(10, 50);
+            RegisterPool<TailNote, DrawableHoldNoteTail>(10, 50);
+            RegisterPool<HoldNoteTick, DrawableHoldNoteTick>(50, 250);
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            NewResult += OnNewResult;
         }
 
         public ColumnType ColumnType { get; set; }
@@ -98,28 +112,14 @@ namespace osu.Game.Rulesets.Mania.UI
             return dependencies;
         }
 
-        /// <summary>
-        /// Adds a DrawableHitObject to this Playfield.
-        /// </summary>
-        /// <param name="hitObject">The DrawableHitObject to add.</param>
-        public override void Add(DrawableHitObject hitObject)
+        protected override void OnNewDrawableHitObject(DrawableHitObject drawableHitObject)
         {
-            hitObject.AccentColour.Value = AccentColour;
-            hitObject.OnNewResult += OnNewResult;
+            base.OnNewDrawableHitObject(drawableHitObject);
 
-            DrawableManiaHitObject maniaObject = (DrawableManiaHitObject)hitObject;
+            DrawableManiaHitObject maniaObject = (DrawableManiaHitObject)drawableHitObject;
+
+            maniaObject.AccentColour.Value = AccentColour;
             maniaObject.CheckHittable = hitPolicy.IsHittable;
-
-            base.Add(hitObject);
-        }
-
-        public override bool Remove(DrawableHitObject h)
-        {
-            if (!base.Remove(h))
-                return false;
-
-            h.OnNewResult -= OnNewResult;
-            return true;
         }
 
         internal void OnNewResult(DrawableHitObject judgedObject, JudgementResult result)

osu.Game.Rulesets.Mania/UI/Components/ColumnHitObjectArea.cs

@@ -27,7 +27,7 @@ namespace osu.Game.Rulesets.Mania.UI.Components
                     RelativeSizeAxes = Axes.Both,
                     Depth = 2,
                 },
-                hitTarget = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HitTarget, columnIndex), _ => new DefaultHitTarget())
+                hitTarget = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HitTarget), _ => new DefaultHitTarget())
                 {
                     RelativeSizeAxes = Axes.X,
                     Depth = 1

osu.Game.Rulesets.Mania/UI/DrawableManiaRuleset.cs

@@ -18,7 +18,6 @@ using osu.Game.Replays;
 using osu.Game.Rulesets.Mania.Beatmaps;
 using osu.Game.Rulesets.Mania.Configuration;
 using osu.Game.Rulesets.Mania.Objects;
-using osu.Game.Rulesets.Mania.Objects.Drawables;
 using osu.Game.Rulesets.Mania.Replays;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Objects;
@@ -134,20 +133,7 @@ namespace osu.Game.Rulesets.Mania.UI
 
         protected override PassThroughInputManager CreateInputManager() => new ManiaInputManager(Ruleset.RulesetInfo, Variant);
 
-        public override DrawableHitObject<ManiaHitObject> CreateDrawableRepresentation(ManiaHitObject h)
-        {
-            switch (h)
-            {
-                case HoldNote holdNote:
-                    return new DrawableHoldNote(holdNote);
-
-                case Note note:
-                    return new DrawableNote(note);
-
-                default:
-                    return null;
-            }
-        }
+        public override DrawableHitObject<ManiaHitObject> CreateDrawableRepresentation(ManiaHitObject h) => null;
 
         protected override ReplayInputHandler CreateReplayInputHandler(Replay replay) => new ManiaFramedReplayInputHandler(replay);
 

osu.Game.Rulesets.Mania/UI/ManiaPlayfield.cs

@@ -9,6 +9,7 @@ using System.Linq;
 using osu.Framework.Allocation;
 using osu.Game.Rulesets.Mania.Beatmaps;
 using osu.Game.Rulesets.Mania.Objects;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.UI.Scrolling;
 using osuTK;
@@ -56,6 +57,10 @@ namespace osu.Game.Rulesets.Mania.UI
             }
         }
 
+        public override void Add(HitObject hitObject) => getStageByColumn(((ManiaHitObject)hitObject).Column).Add(hitObject);
+
+        public override bool Remove(HitObject hitObject) => getStageByColumn(((ManiaHitObject)hitObject).Column).Remove(hitObject);
+
         public override void Add(DrawableHitObject h) => getStageByColumn(((ManiaHitObject)h.HitObject).Column).Add(h);
 
         public override bool Remove(DrawableHitObject h) => getStageByColumn(((ManiaHitObject)h.HitObject).Column).Remove(h);

osu.Game.Rulesets.Mania/UI/PoolableHitExplosion.cs

@@ -28,7 +28,7 @@ namespace osu.Game.Rulesets.Mania.UI
         [BackgroundDependencyLoader]
         private void load()
         {
-            InternalChild = skinnableExplosion = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HitExplosion, column.Index), _ => new DefaultHitExplosion())
+            InternalChild = skinnableExplosion = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HitExplosion), _ => new DefaultHitExplosion())
             {
                 RelativeSizeAxes = Axes.Both
             };

osu.Game.Rulesets.Mania/UI/Stage.cs

@@ -11,6 +11,7 @@ using osu.Game.Rulesets.Mania.Beatmaps;
 using osu.Game.Rulesets.Mania.Objects;
 using osu.Game.Rulesets.Mania.Objects.Drawables;
 using osu.Game.Rulesets.Mania.UI.Components;
+using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.UI;
 using osu.Game.Rulesets.UI.Scrolling;
@@ -132,33 +133,19 @@ namespace osu.Game.Rulesets.Mania.UI
             }
         }
 
-        public override void Add(DrawableHitObject h)
+        protected override void LoadComplete()
         {
-            var maniaObject = (ManiaHitObject)h.HitObject;
-
-            int columnIndex = -1;
-
-            maniaObject.ColumnBindable.BindValueChanged(_ =>
-            {
-                if (columnIndex != -1)
-                    Columns.ElementAt(columnIndex).Remove(h);
-
-                columnIndex = maniaObject.Column - firstColumnIndex;
-                Columns.ElementAt(columnIndex).Add(h);
-            }, true);
-
-            h.OnNewResult += OnNewResult;
+            base.LoadComplete();
+            NewResult += OnNewResult;
         }
 
-        public override bool Remove(DrawableHitObject h)
-        {
-            var maniaObject = (ManiaHitObject)h.HitObject;
-            int columnIndex = maniaObject.Column - firstColumnIndex;
-            Columns.ElementAt(columnIndex).Remove(h);
+        public override void Add(HitObject hitObject) => Columns.ElementAt(((ManiaHitObject)hitObject).Column - firstColumnIndex).Add(hitObject);
 
-            h.OnNewResult -= OnNewResult;
-            return true;
-        }
+        public override bool Remove(HitObject hitObject) => Columns.ElementAt(((ManiaHitObject)hitObject).Column - firstColumnIndex).Remove(hitObject);
+
+        public override void Add(DrawableHitObject h) => Columns.ElementAt(((ManiaHitObject)h.HitObject).Column - firstColumnIndex).Add(h);
+
+        public override bool Remove(DrawableHitObject h) => Columns.ElementAt(((ManiaHitObject)h.HitObject).Column - firstColumnIndex).Remove(h);
 
         public void Add(BarLine barline) => base.Add(new DrawableBarLine(barline));
 

osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/Components/PathControlPointVisualiser.cs

@@ -243,7 +243,7 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
             int totalCount = Pieces.Count(p => p.IsSelected.Value);
             int countOfState = Pieces.Where(p => p.IsSelected.Value).Count(p => p.ControlPoint.Type.Value == type);
 
-            var item = new PathTypeMenuItem(type, () =>
+            var item = new TernaryStateRadioMenuItem(type == null ? "Inherit" : type.ToString().Humanize(), MenuItemType.Standard, _ =>
             {
                 foreach (var p in Pieces.Where(p => p.IsSelected.Value))
                     updatePathType(p, type);
@@ -258,15 +258,5 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
 
             return item;
         }
-
-        private class PathTypeMenuItem : TernaryStateMenuItem
-        {
-            public PathTypeMenuItem(PathType? type, Action action)
-                : base(type == null ? "Inherit" : type.ToString().Humanize(), changeState, MenuItemType.Standard, _ => action?.Invoke())
-            {
-            }
-
-            private static TernaryState changeState(TernaryState state) => TernaryState.True;
-        }
     }
 }

osu.Game.Rulesets.Taiko/Edit/Blueprints/HitPlacementBlueprint.cs

@@ -14,10 +14,10 @@ namespace osu.Game.Rulesets.Taiko.Edit.Blueprints
     {
         private readonly HitPiece piece;
 
-        private static Hit hit;
+        public new Hit HitObject => (Hit)base.HitObject;
 
         public HitPlacementBlueprint()
-            : base(hit = new Hit())
+            : base(new Hit())
         {
             InternalChild = piece = new HitPiece
             {
@@ -30,12 +30,12 @@ namespace osu.Game.Rulesets.Taiko.Edit.Blueprints
             switch (e.Button)
             {
                 case MouseButton.Left:
-                    hit.Type = HitType.Centre;
+                    HitObject.Type = HitType.Centre;
                     EndPlacement(true);
                     return true;
 
                 case MouseButton.Right:
-                    hit.Type = HitType.Rim;
+                    HitObject.Type = HitType.Rim;
                     EndPlacement(true);
                     return true;
             }

osu.Game.Rulesets.Taiko/Edit/TaikoSelectionHandler.cs

@@ -76,10 +76,10 @@ namespace osu.Game.Rulesets.Taiko.Edit
         protected override IEnumerable<MenuItem> GetContextMenuItemsForSelection(IEnumerable<SelectionBlueprint<HitObject>> selection)
         {
             if (selection.All(s => s.Item is Hit))
-                yield return new TernaryStateMenuItem("Rim") { State = { BindTarget = selectionRimState } };
+                yield return new TernaryStateToggleMenuItem("Rim") { State = { BindTarget = selectionRimState } };
 
             if (selection.All(s => s.Item is TaikoHitObject))
-                yield return new TernaryStateMenuItem("Strong") { State = { BindTarget = selectionStrongState } };
+                yield return new TernaryStateToggleMenuItem("Strong") { State = { BindTarget = selectionStrongState } };
 
             foreach (var item in base.GetContextMenuItemsForSelection(selection))
                 yield return item;

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableHit.cs

@@ -52,23 +52,18 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
         protected override void OnApply()
         {
             type.BindTo(HitObject.TypeBindable);
-            type.BindValueChanged(_ =>
-            {
-                updateActionsFromType();
-
-                // will overwrite samples, should only be called on subsequent changes
-                // after the initial application.
-                updateSamplesFromTypeChange();
-
-                RecreatePieces();
-            });
-
-            // action update also has to happen immediately on application.
-            updateActionsFromType();
+            // this doesn't need to be run inline as RecreatePieces is called by the base call below.
+            type.BindValueChanged(_ => Scheduler.AddOnce(RecreatePieces));
 
             base.OnApply();
         }
 
+        protected override void RecreatePieces()
+        {
+            updateActionsFromType();
+            base.RecreatePieces();
+        }
+
         protected override void OnFree()
         {
             base.OnFree();
@@ -83,33 +78,6 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
             validActionPressed = pressHandledThisFrame = false;
         }
 
-        private HitSampleInfo[] getRimSamples() => HitObject.Samples.Where(s => s.Name == HitSampleInfo.HIT_CLAP || s.Name == HitSampleInfo.HIT_WHISTLE).ToArray();
-
-        protected override void LoadSamples()
-        {
-            base.LoadSamples();
-
-            type.Value = getRimSamples().Any() ? HitType.Rim : HitType.Centre;
-        }
-
-        private void updateSamplesFromTypeChange()
-        {
-            var rimSamples = getRimSamples();
-
-            bool isRimType = HitObject.Type == HitType.Rim;
-
-            if (isRimType != rimSamples.Any())
-            {
-                if (isRimType)
-                    HitObject.Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_CLAP));
-                else
-                {
-                    foreach (var sample in rimSamples)
-                        HitObject.Samples.Remove(sample);
-                }
-            }
-        }
-
         private void updateActionsFromType()
         {
             HitActions =

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableTaikoHitObject.cs

@@ -137,7 +137,9 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
         {
             Size = BaseSize = new Vector2(TaikoHitObject.DEFAULT_SIZE);
 
-            MainPiece?.Expire();
+            if (MainPiece != null)
+                Content.Remove(MainPiece);
+
             Content.Add(MainPiece = CreateMainPiece());
         }
 

osu.Game.Rulesets.Taiko/Objects/Drawables/DrawableTaikoStrongableHitObject.cs

@@ -1,11 +1,9 @@
 // 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.Linq;
 using JetBrains.Annotations;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics.Containers;
-using osu.Game.Audio;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osuTK;
@@ -29,14 +27,8 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
         protected override void OnApply()
         {
             isStrong.BindTo(HitObject.IsStrongBindable);
-            isStrong.BindValueChanged(_ =>
-            {
-                // will overwrite samples, should only be called on subsequent changes
-                // after the initial application.
-                updateSamplesFromStrong();
-
-                RecreatePieces();
-            });
+            // this doesn't need to be run inline as RecreatePieces is called by the base call below.
+            isStrong.BindValueChanged(_ => Scheduler.AddOnce(RecreatePieces));
 
             base.OnApply();
         }
@@ -50,30 +42,6 @@ namespace osu.Game.Rulesets.Taiko.Objects.Drawables
             isStrong.UnbindEvents();
         }
 
-        private HitSampleInfo[] getStrongSamples() => HitObject.Samples.Where(s => s.Name == HitSampleInfo.HIT_FINISH).ToArray();
-
-        protected override void LoadSamples()
-        {
-            base.LoadSamples();
-            isStrong.Value = getStrongSamples().Any();
-        }
-
-        private void updateSamplesFromStrong()
-        {
-            var strongSamples = getStrongSamples();
-
-            if (isStrong.Value != strongSamples.Any())
-            {
-                if (isStrong.Value)
-                    HitObject.Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_FINISH));
-                else
-                {
-                    foreach (var sample in strongSamples)
-                        HitObject.Samples.Remove(sample);
-                }
-            }
-        }
-
         protected override void RecreatePieces()
         {
             base.RecreatePieces();

osu.Game.Rulesets.Taiko/Objects/Hit.cs

@@ -1,7 +1,9 @@
 // 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.Linq;
 using osu.Framework.Bindables;
+using osu.Game.Audio;
 
 namespace osu.Game.Rulesets.Taiko.Objects
 {
@@ -15,9 +17,36 @@ namespace osu.Game.Rulesets.Taiko.Objects
         public HitType Type
         {
             get => TypeBindable.Value;
-            set => TypeBindable.Value = value;
+            set
+            {
+                TypeBindable.Value = value;
+                updateSamplesFromType();
+            }
         }
 
+        private void updateSamplesFromType()
+        {
+            var rimSamples = getRimSamples();
+
+            bool isRimType = Type == HitType.Rim;
+
+            if (isRimType != rimSamples.Any())
+            {
+                if (isRimType)
+                    Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_CLAP));
+                else
+                {
+                    foreach (var sample in rimSamples)
+                        Samples.Remove(sample);
+                }
+            }
+        }
+
+        /// <summary>
+        /// Returns an array of any samples which would cause this object to be a "rim" type hit.
+        /// </summary>
+        private HitSampleInfo[] getRimSamples() => Samples.Where(s => s.Name == HitSampleInfo.HIT_CLAP || s.Name == HitSampleInfo.HIT_WHISTLE).ToArray();
+
         protected override StrongNestedHitObject CreateStrongNestedHit(double startTime) => new StrongNestedHit { StartTime = startTime };
 
         public class StrongNestedHit : StrongNestedHitObject

osu.Game.Rulesets.Taiko/Objects/TaikoStrongableHitObject.cs

@@ -1,8 +1,10 @@
 // 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.Linq;
 using System.Threading;
 using osu.Framework.Bindables;
+using osu.Game.Audio;
 using osu.Game.Rulesets.Objects;
 
 namespace osu.Game.Rulesets.Taiko.Objects
@@ -31,9 +33,31 @@ namespace osu.Game.Rulesets.Taiko.Objects
         public bool IsStrong
         {
             get => IsStrongBindable.Value;
-            set => IsStrongBindable.Value = value;
+            set
+            {
+                IsStrongBindable.Value = value;
+                updateSamplesFromStrong();
+            }
         }
 
+        private void updateSamplesFromStrong()
+        {
+            var strongSamples = getStrongSamples();
+
+            if (IsStrongBindable.Value != strongSamples.Any())
+            {
+                if (IsStrongBindable.Value)
+                    Samples.Add(new HitSampleInfo(HitSampleInfo.HIT_FINISH));
+                else
+                {
+                    foreach (var sample in strongSamples)
+                        Samples.Remove(sample);
+                }
+            }
+        }
+
+        private HitSampleInfo[] getStrongSamples() => Samples.Where(s => s.Name == HitSampleInfo.HIT_FINISH).ToArray();
+
         protected override void CreateNestedHitObjects(CancellationToken cancellationToken)
         {
             base.CreateNestedHitObjects(cancellationToken);

osu.Game.Tests/Gameplay/TestSceneProxyContainer.cs

@@ -0,0 +1,85 @@
+// 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.Collections.Generic;
+using NUnit.Framework;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Testing;
+using osu.Framework.Timing;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.UI;
+using osu.Game.Tests.Visual;
+
+namespace osu.Game.Tests.Gameplay
+{
+    [HeadlessTest]
+    public class TestSceneProxyContainer : OsuTestScene
+    {
+        private HitObjectContainer hitObjectContainer;
+        private ProxyContainer proxyContainer;
+        private readonly ManualClock clock = new ManualClock();
+
+        [SetUp]
+        public void SetUp() => Schedule(() =>
+        {
+            Child = new Container
+            {
+                Children = new Drawable[]
+                {
+                    hitObjectContainer = new HitObjectContainer(),
+                    proxyContainer = new ProxyContainer()
+                },
+                Clock = new FramedClock(clock)
+            };
+            clock.CurrentTime = 0;
+        });
+
+        [Test]
+        public void TestProxyLifetimeManagement()
+        {
+            AddStep("Add proxy drawables", () =>
+            {
+                addProxy(new TestDrawableHitObject(1000));
+                addProxy(new TestDrawableHitObject(3000));
+                addProxy(new TestDrawableHitObject(5000));
+            });
+
+            AddStep("time = 1000", () => clock.CurrentTime = 1000);
+            AddAssert("One proxy is alive", () => proxyContainer.AliveChildren.Count == 1);
+            AddStep("time = 5000", () => clock.CurrentTime = 5000);
+            AddAssert("One proxy is alive", () => proxyContainer.AliveChildren.Count == 1);
+            AddStep("time = 6000", () => clock.CurrentTime = 6000);
+            AddAssert("No proxy is alive", () => proxyContainer.AliveChildren.Count == 0);
+        }
+
+        private void addProxy(DrawableHitObject drawableHitObject)
+        {
+            hitObjectContainer.Add(drawableHitObject);
+            proxyContainer.AddProxy(drawableHitObject);
+        }
+
+        private class ProxyContainer : LifetimeManagementContainer
+        {
+            public IReadOnlyList<Drawable> AliveChildren => AliveInternalChildren;
+
+            public void AddProxy(Drawable d) => AddInternal(d.CreateProxy());
+        }
+
+        private class TestDrawableHitObject : DrawableHitObject
+        {
+            protected override double InitialLifetimeOffset => 100;
+
+            public TestDrawableHitObject(double startTime)
+                : base(new HitObject { StartTime = startTime })
+            {
+            }
+
+            protected override void UpdateInitialTransforms()
+            {
+                LifetimeEnd = LifetimeStart + 500;
+            }
+        }
+    }
+}

osu.Game.Tests/Visual/Gameplay/TestSceneHitErrorMeter.cs

@@ -1,6 +1,9 @@
 // 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.CodeAnalysis;
 using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
@@ -11,29 +14,35 @@ using osu.Game.Graphics.Sprites;
 using osu.Game.Rulesets.Catch.Scoring;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Mania.Scoring;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Objects;
+using osu.Game.Rulesets.Osu;
 using osu.Game.Rulesets.Osu.Objects;
 using osu.Game.Rulesets.Osu.Scoring;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.Taiko.Scoring;
+using osu.Game.Rulesets.UI;
+using osu.Game.Scoring;
 using osu.Game.Screens.Play.HUD.HitErrorMeters;
 
 namespace osu.Game.Tests.Visual.Gameplay
 {
     public class TestSceneHitErrorMeter : OsuTestScene
     {
-        private HitWindows hitWindows;
-
         [Cached]
         private ScoreProcessor scoreProcessor = new ScoreProcessor();
 
+        [Cached(typeof(DrawableRuleset))]
+        private TestDrawableRuleset drawableRuleset = new TestDrawableRuleset();
+
         public TestSceneHitErrorMeter()
         {
             recreateDisplay(new OsuHitWindows(), 5);
 
             AddRepeatStep("New random judgement", () => newJudgement(), 40);
 
-            AddRepeatStep("New max negative", () => newJudgement(-hitWindows.WindowFor(HitResult.Meh)), 20);
-            AddRepeatStep("New max positive", () => newJudgement(hitWindows.WindowFor(HitResult.Meh)), 20);
+            AddRepeatStep("New max negative", () => newJudgement(-drawableRuleset.HitWindows.WindowFor(HitResult.Meh)), 20);
+            AddRepeatStep("New max positive", () => newJudgement(drawableRuleset.HitWindows.WindowFor(HitResult.Meh)), 20);
             AddStep("New fixed judgement (50ms)", () => newJudgement(50));
 
             AddStep("Judgement barrage", () =>
@@ -83,10 +92,10 @@ namespace osu.Game.Tests.Visual.Gameplay
 
         private void recreateDisplay(HitWindows hitWindows, float overallDifficulty)
         {
-            this.hitWindows = hitWindows;
-
             hitWindows?.SetDifficulty(overallDifficulty);
 
+            drawableRuleset.HitWindows = hitWindows;
+
             Clear();
 
             Add(new FillFlowContainer
@@ -103,40 +112,40 @@ namespace osu.Game.Tests.Visual.Gameplay
                 }
             });
 
-            Add(new BarHitErrorMeter(hitWindows, true)
+            Add(new BarHitErrorMeter
             {
                 Anchor = Anchor.CentreRight,
                 Origin = Anchor.CentreRight,
             });
 
-            Add(new BarHitErrorMeter(hitWindows, false)
+            Add(new BarHitErrorMeter
             {
                 Anchor = Anchor.CentreLeft,
                 Origin = Anchor.CentreLeft,
             });
 
-            Add(new BarHitErrorMeter(hitWindows, true)
+            Add(new BarHitErrorMeter
             {
                 Anchor = Anchor.BottomCentre,
                 Origin = Anchor.CentreLeft,
                 Rotation = 270,
             });
 
-            Add(new ColourHitErrorMeter(hitWindows)
+            Add(new ColourHitErrorMeter
             {
                 Anchor = Anchor.CentreRight,
                 Origin = Anchor.CentreRight,
                 Margin = new MarginPadding { Right = 50 }
             });
 
-            Add(new ColourHitErrorMeter(hitWindows)
+            Add(new ColourHitErrorMeter
             {
                 Anchor = Anchor.CentreLeft,
                 Origin = Anchor.CentreLeft,
                 Margin = new MarginPadding { Left = 50 }
             });
 
-            Add(new ColourHitErrorMeter(hitWindows)
+            Add(new ColourHitErrorMeter
             {
                 Anchor = Anchor.BottomCentre,
                 Origin = Anchor.CentreLeft,
@@ -147,11 +156,47 @@ namespace osu.Game.Tests.Visual.Gameplay
 
         private void newJudgement(double offset = 0)
         {
-            scoreProcessor.ApplyResult(new JudgementResult(new HitCircle { HitWindows = hitWindows }, new Judgement())
+            scoreProcessor.ApplyResult(new JudgementResult(new HitCircle { HitWindows = drawableRuleset.HitWindows }, new Judgement())
             {
                 TimeOffset = offset == 0 ? RNG.Next(-150, 150) : offset,
                 Type = HitResult.Perfect,
             });
         }
+
+        [SuppressMessage("ReSharper", "UnassignedGetOnlyAutoProperty")]
+        private class TestDrawableRuleset : DrawableRuleset
+        {
+            public HitWindows HitWindows;
+
+            public override IEnumerable<HitObject> Objects => new[] { new HitCircle { HitWindows = HitWindows } };
+
+            public override event Action<JudgementResult> NewResult;
+            public override event Action<JudgementResult> RevertResult;
+
+            public override Playfield Playfield { get; }
+            public override Container Overlays { get; }
+            public override Container FrameStableComponents { get; }
+            public override IFrameStableClock FrameStableClock { get; }
+            public override IReadOnlyList<Mod> Mods { get; }
+
+            public override double GameplayStartTime { get; }
+            public override GameplayCursorContainer Cursor { get; }
+
+            public TestDrawableRuleset()
+                : base(new OsuRuleset())
+            {
+                // won't compile without this.
+                NewResult?.Invoke(null);
+                RevertResult?.Invoke(null);
+            }
+
+            public override void SetReplayScore(Score replayScore) => throw new NotImplementedException();
+
+            public override void SetRecordTarget(Score score) => throw new NotImplementedException();
+
+            public override void RequestResume(Action continueResume) => throw new NotImplementedException();
+
+            public override void CancelResume() => throw new NotImplementedException();
+        }
     }
 }

osu.Game.Tests/Visual/Gameplay/TestSceneSpectator.cs

@@ -27,8 +27,8 @@ namespace osu.Game.Tests.Visual.Gameplay
     {
         private readonly User streamingUser = new User { Id = MultiplayerTestScene.PLAYER_1_ID, Username = "Test user" };
 
-        [Cached(typeof(SpectatorStreamingClient))]
-        private TestSpectatorStreamingClient testSpectatorStreamingClient = new TestSpectatorStreamingClient();
+        [Cached(typeof(SpectatorClient))]
+        private TestSpectatorClient testSpectatorClient = new TestSpectatorClient();
 
         [Cached(typeof(UserLookupCache))]
         private UserLookupCache lookupCache = new TestUserLookupCache();
@@ -61,8 +61,8 @@ namespace osu.Game.Tests.Visual.Gameplay
 
             AddStep("add streaming client", () =>
             {
-                Remove(testSpectatorStreamingClient);
-                Add(testSpectatorStreamingClient);
+                Remove(testSpectatorClient);
+                Add(testSpectatorClient);
             });
 
             finish();
@@ -212,9 +212,9 @@ namespace osu.Game.Tests.Visual.Gameplay
 
         private void waitForPlayer() => AddUntilStep("wait for player", () => Stack.CurrentScreen is Player);
 
-        private void start(int? beatmapId = null) => AddStep("start play", () => testSpectatorStreamingClient.StartPlay(streamingUser.Id, beatmapId ?? importedBeatmapId));
+        private void start(int? beatmapId = null) => AddStep("start play", () => testSpectatorClient.StartPlay(streamingUser.Id, beatmapId ?? importedBeatmapId));
 
-        private void finish(int? beatmapId = null) => AddStep("end play", () => testSpectatorStreamingClient.EndPlay(streamingUser.Id, beatmapId ?? importedBeatmapId));
+        private void finish() => AddStep("end play", () => testSpectatorClient.EndPlay(streamingUser.Id));
 
         private void checkPaused(bool state) =>
             AddUntilStep($"game is {(state ? "paused" : "playing")}", () => player.ChildrenOfType<DrawableRuleset>().First().IsPaused.Value == state);
@@ -223,7 +223,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         {
             AddStep("send frames", () =>
             {
-                testSpectatorStreamingClient.SendFrames(streamingUser.Id, nextFrame, count);
+                testSpectatorClient.SendFrames(streamingUser.Id, nextFrame, count);
                 nextFrame += count;
             });
         }

osu.Game.Tests/Visual/Gameplay/TestSceneSpectatorPlayback.cs

@@ -59,7 +59,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         private IAPIProvider api { get; set; }
 
         [Resolved]
-        private SpectatorStreamingClient streamingClient { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [Cached]
         private GameplayBeatmap gameplayBeatmap = new GameplayBeatmap(new Beatmap());
@@ -69,7 +69,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         {
             replay = new Replay();
 
-            users.BindTo(streamingClient.PlayingUsers);
+            users.BindTo(spectatorClient.PlayingUsers);
             users.BindCollectionChanged((obj, args) =>
             {
                 switch (args.Action)
@@ -80,7 +80,7 @@ namespace osu.Game.Tests.Visual.Gameplay
                         foreach (int user in args.NewItems)
                         {
                             if (user == api.LocalUser.Value.Id)
-                                streamingClient.WatchUser(user);
+                                spectatorClient.WatchUser(user);
                         }
 
                         break;
@@ -91,14 +91,14 @@ namespace osu.Game.Tests.Visual.Gameplay
                         foreach (int user in args.OldItems)
                         {
                             if (user == api.LocalUser.Value.Id)
-                                streamingClient.StopWatchingUser(user);
+                                spectatorClient.StopWatchingUser(user);
                         }
 
                         break;
                 }
             }, true);
 
-            streamingClient.OnNewFrames += onNewFrames;
+            spectatorClient.OnNewFrames += onNewFrames;
 
             Add(new GridContainer
             {
@@ -189,7 +189,7 @@ namespace osu.Game.Tests.Visual.Gameplay
         {
         }
 
-        private double latency = SpectatorStreamingClient.TIME_BETWEEN_SENDS;
+        private double latency = SpectatorClient.TIME_BETWEEN_SENDS;
 
         protected override void Update()
         {
@@ -233,7 +233,7 @@ namespace osu.Game.Tests.Visual.Gameplay
             AddStep("stop recorder", () =>
             {
                 recorder.Expire();
-                streamingClient.OnNewFrames -= onNewFrames;
+                spectatorClient.OnNewFrames -= onNewFrames;
             });
         }
 

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiSpectatorLeaderboard.cs

@@ -23,8 +23,8 @@ namespace osu.Game.Tests.Visual.Multiplayer
 {
     public class TestSceneMultiSpectatorLeaderboard : MultiplayerTestScene
     {
-        [Cached(typeof(SpectatorStreamingClient))]
-        private TestSpectatorStreamingClient streamingClient = new TestSpectatorStreamingClient();
+        [Cached(typeof(SpectatorClient))]
+        private TestSpectatorClient spectatorClient = new TestSpectatorClient();
 
         [Cached(typeof(UserLookupCache))]
         private UserLookupCache lookupCache = new TestUserLookupCache();
@@ -42,7 +42,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
         {
             base.Content.AddRange(new Drawable[]
             {
-                streamingClient,
+                spectatorClient,
                 lookupCache,
                 content = new Container { RelativeSizeAxes = Axes.Both }
             });
@@ -59,7 +59,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
                 foreach (var (userId, clock) in clocks)
                 {
-                    streamingClient.EndPlay(userId, 0);
+                    spectatorClient.EndPlay(userId);
                     clock.CurrentTime = 0;
                 }
             });
@@ -67,7 +67,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddStep("create leaderboard", () =>
             {
                 foreach (var (userId, _) in clocks)
-                    streamingClient.StartPlay(userId, 0);
+                    spectatorClient.StartPlay(userId, 0);
 
                 Beatmap.Value = CreateWorkingBeatmap(Ruleset.Value);
 
@@ -96,10 +96,10 @@ namespace osu.Game.Tests.Visual.Multiplayer
                 // For player 2, send frames in sets of 10.
                 for (int i = 0; i < 100; i++)
                 {
-                    streamingClient.SendFrames(PLAYER_1_ID, i, 1);
+                    spectatorClient.SendFrames(PLAYER_1_ID, i, 1);
 
                     if (i % 10 == 0)
-                        streamingClient.SendFrames(PLAYER_2_ID, i, 10);
+                        spectatorClient.SendFrames(PLAYER_2_ID, i, 10);
                 }
             });
 

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiSpectatorScreen.cs

@@ -22,8 +22,8 @@ namespace osu.Game.Tests.Visual.Multiplayer
 {
     public class TestSceneMultiSpectatorScreen : MultiplayerTestScene
     {
-        [Cached(typeof(SpectatorStreamingClient))]
-        private TestSpectatorStreamingClient streamingClient = new TestSpectatorStreamingClient();
+        [Cached(typeof(SpectatorClient))]
+        private TestSpectatorClient spectatorClient = new TestSpectatorClient();
 
         [Cached(typeof(UserLookupCache))]
         private UserLookupCache lookupCache = new TestUserLookupCache();
@@ -59,14 +59,14 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
             AddStep("add streaming client", () =>
             {
-                Remove(streamingClient);
-                Add(streamingClient);
+                Remove(spectatorClient);
+                Add(spectatorClient);
             });
 
             AddStep("finish previous gameplay", () =>
             {
                 foreach (var id in playingUserIds)
-                    streamingClient.EndPlay(id, importedBeatmapId);
+                    spectatorClient.EndPlay(id);
                 playingUserIds.Clear();
             });
         }
@@ -87,11 +87,11 @@ namespace osu.Game.Tests.Visual.Multiplayer
             loadSpectateScreen(false);
 
             AddWaitStep("wait a bit", 10);
-            AddStep("load player first_player_id", () => streamingClient.StartPlay(PLAYER_1_ID, importedBeatmapId));
+            AddStep("load player first_player_id", () => spectatorClient.StartPlay(PLAYER_1_ID, importedBeatmapId));
             AddUntilStep("one player added", () => spectatorScreen.ChildrenOfType<Player>().Count() == 1);
 
             AddWaitStep("wait a bit", 10);
-            AddStep("load player second_player_id", () => streamingClient.StartPlay(PLAYER_2_ID, importedBeatmapId));
+            AddStep("load player second_player_id", () => spectatorClient.StartPlay(PLAYER_2_ID, importedBeatmapId));
             AddUntilStep("two players added", () => spectatorScreen.ChildrenOfType<Player>().Count() == 2);
         }
 
@@ -251,18 +251,18 @@ namespace osu.Game.Tests.Visual.Multiplayer
                 foreach (int id in userIds)
                 {
                     Client.CurrentMatchPlayingUserIds.Add(id);
-                    streamingClient.StartPlay(id, beatmapId ?? importedBeatmapId);
+                    spectatorClient.StartPlay(id, beatmapId ?? importedBeatmapId);
                     playingUserIds.Add(id);
                     nextFrame[id] = 0;
                 }
             });
         }
 
-        private void finish(int userId, int? beatmapId = null)
+        private void finish(int userId)
         {
             AddStep("end play", () =>
             {
-                streamingClient.EndPlay(userId, beatmapId ?? importedBeatmapId);
+                spectatorClient.EndPlay(userId);
                 playingUserIds.Remove(userId);
                 nextFrame.Remove(userId);
             });
@@ -276,7 +276,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
             {
                 foreach (int id in userIds)
                 {
-                    streamingClient.SendFrames(id, nextFrame[id], count);
+                    spectatorClient.SendFrames(id, nextFrame[id], count);
                     nextFrame[id] += count;
                 }
             });

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiplayer.cs

@@ -195,7 +195,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
         private class TestMultiplayer : Screens.OnlinePlay.Multiplayer.Multiplayer
         {
-            [Cached(typeof(StatefulMultiplayerClient))]
+            [Cached(typeof(MultiplayerClient))]
             public readonly TestMultiplayerClient Client;
 
             public TestMultiplayer()

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiplayerGameplayLeaderboard.cs

@@ -28,8 +28,8 @@ namespace osu.Game.Tests.Visual.Multiplayer
     {
         private const int users = 16;
 
-        [Cached(typeof(SpectatorStreamingClient))]
-        private TestMultiplayerStreaming streamingClient = new TestMultiplayerStreaming();
+        [Cached(typeof(SpectatorClient))]
+        private TestMultiplayerSpectatorClient spectatorClient = new TestMultiplayerSpectatorClient();
 
         [Cached(typeof(UserLookupCache))]
         private UserLookupCache lookupCache = new TestSceneCurrentlyPlayingDisplay.TestUserLookupCache();
@@ -44,7 +44,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
         {
             base.Content.Children = new Drawable[]
             {
-                streamingClient,
+                spectatorClient,
                 lookupCache,
                 Content
             };
@@ -71,10 +71,10 @@ namespace osu.Game.Tests.Visual.Multiplayer
                 var playable = Beatmap.Value.GetPlayableBeatmap(Ruleset.Value);
 
                 for (int i = 0; i < users; i++)
-                    streamingClient.StartPlay(i, Beatmap.Value.BeatmapInfo.OnlineBeatmapID ?? 0);
+                    spectatorClient.StartPlay(i, Beatmap.Value.BeatmapInfo.OnlineBeatmapID ?? 0);
 
                 Client.CurrentMatchPlayingUserIds.Clear();
-                Client.CurrentMatchPlayingUserIds.AddRange(streamingClient.PlayingUsers);
+                Client.CurrentMatchPlayingUserIds.AddRange(spectatorClient.PlayingUsers);
 
                 Children = new Drawable[]
                 {
@@ -83,7 +83,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
 
                 scoreProcessor.ApplyBeatmap(playable);
 
-                LoadComponentAsync(leaderboard = new MultiplayerGameplayLeaderboard(scoreProcessor, streamingClient.PlayingUsers.ToArray())
+                LoadComponentAsync(leaderboard = new MultiplayerGameplayLeaderboard(scoreProcessor, spectatorClient.PlayingUsers.ToArray())
                 {
                     Anchor = Anchor.Centre,
                     Origin = Anchor.Centre,
@@ -96,7 +96,7 @@ namespace osu.Game.Tests.Visual.Multiplayer
         [Test]
         public void TestScoreUpdates()
         {
-            AddRepeatStep("update state", () => streamingClient.RandomlyUpdateState(), 100);
+            AddRepeatStep("update state", () => spectatorClient.RandomlyUpdateState(), 100);
             AddToggleStep("switch compact mode", expanded => leaderboard.Expanded.Value = expanded);
         }
 
@@ -109,12 +109,12 @@ namespace osu.Game.Tests.Visual.Multiplayer
         [Test]
         public void TestChangeScoringMode()
         {
-            AddRepeatStep("update state", () => streamingClient.RandomlyUpdateState(), 5);
+            AddRepeatStep("update state", () => spectatorClient.RandomlyUpdateState(), 5);
             AddStep("change to classic", () => config.SetValue(OsuSetting.ScoreDisplayMode, ScoringMode.Classic));
             AddStep("change to standardised", () => config.SetValue(OsuSetting.ScoreDisplayMode, ScoringMode.Standardised));
         }
 
-        public class TestMultiplayerStreaming : TestSpectatorStreamingClient
+        public class TestMultiplayerSpectatorClient : TestSpectatorClient
         {
             private readonly Dictionary<int, FrameHeader> lastHeaders = new Dictionary<int, FrameHeader>();
 

osu.Game.Tests/Visual/Navigation/TestScenePerformFromScreen.cs

@@ -11,8 +11,8 @@ using osu.Game.Overlays;
 using osu.Game.Screens;
 using osu.Game.Screens.Menu;
 using osu.Game.Screens.Play;
-using osu.Game.Screens.Select;
 using osuTK.Input;
+using static osu.Game.Tests.Visual.Navigation.TestSceneScreenNavigation;
 
 namespace osu.Game.Tests.Visual.Navigation
 {
@@ -37,17 +37,17 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestPerformAtSongSelect()
         {
-            PushAndConfirm(() => new PlaySongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
 
-            AddStep("perform immediately", () => Game.PerformFromScreen(_ => actionPerformed = true, new[] { typeof(PlaySongSelect) }));
+            AddStep("perform immediately", () => Game.PerformFromScreen(_ => actionPerformed = true, new[] { typeof(TestPlaySongSelect) }));
             AddAssert("did perform", () => actionPerformed);
-            AddAssert("screen didn't change", () => Game.ScreenStack.CurrentScreen is PlaySongSelect);
+            AddAssert("screen didn't change", () => Game.ScreenStack.CurrentScreen is TestPlaySongSelect);
         }
 
         [Test]
         public void TestPerformAtMenuFromSongSelect()
         {
-            PushAndConfirm(() => new PlaySongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
 
             AddStep("try to perform", () => Game.PerformFromScreen(_ => actionPerformed = true));
             AddUntilStep("returned to menu", () => Game.ScreenStack.CurrentScreen is MainMenu);
@@ -57,18 +57,18 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestPerformAtSongSelectFromPlayerLoader()
         {
-            PushAndConfirm(() => new PlaySongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
             PushAndConfirm(() => new PlayerLoader(() => new SoloPlayer()));
 
-            AddStep("try to perform", () => Game.PerformFromScreen(_ => actionPerformed = true, new[] { typeof(PlaySongSelect) }));
-            AddUntilStep("returned to song select", () => Game.ScreenStack.CurrentScreen is PlaySongSelect);
+            AddStep("try to perform", () => Game.PerformFromScreen(_ => actionPerformed = true, new[] { typeof(TestPlaySongSelect) }));
+            AddUntilStep("returned to song select", () => Game.ScreenStack.CurrentScreen is TestPlaySongSelect);
             AddAssert("did perform", () => actionPerformed);
         }
 
         [Test]
         public void TestPerformAtMenuFromPlayerLoader()
         {
-            PushAndConfirm(() => new PlaySongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
             PushAndConfirm(() => new PlayerLoader(() => new SoloPlayer()));
 
             AddStep("try to perform", () => Game.PerformFromScreen(_ => actionPerformed = true));

osu.Game.Tests/Visual/Navigation/TestSceneScreenNavigation.cs

@@ -34,9 +34,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestExitSongSelectWithEscape()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
             AddStep("Show mods overlay", () => songSelect.ModSelectOverlay.Show());
             AddAssert("Overlay was shown", () => songSelect.ModSelectOverlay.State.Value == Visibility.Visible);
             pushEscape();
@@ -51,9 +51,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestOpenModSelectOverlayUsingAction()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
             AddStep("Show mods overlay", () => InputManager.Key(Key.F1));
             AddAssert("Overlay was shown", () => songSelect.ModSelectOverlay.State.Value == Visibility.Visible);
         }
@@ -63,7 +63,7 @@ namespace osu.Game.Tests.Visual.Navigation
         {
             Player player = null;
 
-            PushAndConfirm(() => new TestSongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
 
             AddStep("import beatmap", () => ImportBeatmapTest.LoadQuickOszIntoOsu(Game).Wait());
 
@@ -89,7 +89,7 @@ namespace osu.Game.Tests.Visual.Navigation
 
             WorkingBeatmap beatmap() => Game.Beatmap.Value;
 
-            PushAndConfirm(() => new TestSongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
 
             AddStep("import beatmap", () => ImportBeatmapTest.LoadQuickOszIntoOsu(Game).Wait());
 
@@ -113,7 +113,7 @@ namespace osu.Game.Tests.Visual.Navigation
 
             WorkingBeatmap beatmap() => Game.Beatmap.Value;
 
-            PushAndConfirm(() => new TestSongSelect());
+            PushAndConfirm(() => new TestPlaySongSelect());
 
             AddStep("import beatmap", () => ImportBeatmapTest.LoadOszIntoOsu(Game, virtualTrack: true).Wait());
 
@@ -139,9 +139,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestMenuMakesMusic()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
 
             AddUntilStep("wait for no track", () => Game.MusicController.CurrentTrack.IsDummyDevice);
 
@@ -153,9 +153,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestExitSongSelectWithClick()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
             AddStep("Show mods overlay", () => songSelect.ModSelectOverlay.Show());
             AddAssert("Overlay was shown", () => songSelect.ModSelectOverlay.State.Value == Visibility.Visible);
             AddStep("Move mouse to backButton", () => InputManager.MoveMouseTo(backButtonPosition));
@@ -213,9 +213,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestModSelectInput()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
 
             AddStep("Show mods overlay", () => songSelect.ModSelectOverlay.Show());
 
@@ -234,9 +234,9 @@ namespace osu.Game.Tests.Visual.Navigation
         [Test]
         public void TestBeatmapOptionsInput()
         {
-            TestSongSelect songSelect = null;
+            TestPlaySongSelect songSelect = null;
 
-            PushAndConfirm(() => songSelect = new TestSongSelect());
+            PushAndConfirm(() => songSelect = new TestPlaySongSelect());
 
             AddStep("Show options overlay", () => songSelect.BeatmapOptionsOverlay.Show());
 
@@ -312,11 +312,13 @@ namespace osu.Game.Tests.Visual.Navigation
             ConfirmAtMainMenu();
         }
 
-        private class TestSongSelect : PlaySongSelect
+        public class TestPlaySongSelect : PlaySongSelect
         {
             public ModSelectOverlay ModSelectOverlay => ModSelect;
 
             public BeatmapOptionsOverlay BeatmapOptionsOverlay => BeatmapOptions;
+
+            protected override bool DisplayStableImportPrompt => false;
         }
     }
 }

osu.Game.Tests/Visual/Online/TestSceneAccountCreationOverlay.cs

@@ -1,12 +1,16 @@
 // 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.Linq;
 using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Testing;
 using osu.Game.Overlays;
+using osu.Game.Overlays.AccountCreation;
+using osu.Game.Overlays.Settings;
 using osu.Game.Users;
 
 namespace osu.Game.Tests.Visual.Online
@@ -36,8 +40,6 @@ namespace osu.Game.Tests.Visual.Online
         [BackgroundDependencyLoader]
         private void load()
         {
-            API.Logout();
-
             localUser = API.LocalUser.GetBoundCopy();
             localUser.BindValueChanged(user => { userPanelArea.Child = new UserGridPanel(user.NewValue) { Width = 200 }; }, true);
         }
@@ -46,11 +48,14 @@ namespace osu.Game.Tests.Visual.Online
         public void TestOverlayVisibility()
         {
             AddStep("start hidden", () => accountCreation.Hide());
-            AddStep("log out", API.Logout);
+            AddStep("log out", () => API.Logout());
 
             AddStep("show manually", () => accountCreation.Show());
             AddUntilStep("overlay is visible", () => accountCreation.State.Value == Visibility.Visible);
 
+            AddStep("click button", () => accountCreation.ChildrenOfType<SettingsButton>().Single().Click());
+            AddUntilStep("warning screen is present", () => accountCreation.ChildrenOfType<ScreenWarning>().SingleOrDefault()?.IsPresent == true);
+
             AddStep("log back in", () => API.Login("dummy", "password"));
             AddUntilStep("overlay is hidden", () => accountCreation.State.Value == Visibility.Hidden);
         }

osu.Game.Tests/Visual/Online/TestSceneCurrentlyPlayingDisplay.cs

@@ -19,8 +19,10 @@ namespace osu.Game.Tests.Visual.Online
 {
     public class TestSceneCurrentlyPlayingDisplay : OsuTestScene
     {
-        [Cached(typeof(SpectatorStreamingClient))]
-        private TestSpectatorStreamingClient testSpectatorStreamingClient = new TestSpectatorStreamingClient();
+        private readonly User streamingUser = new User { Id = 2, Username = "Test user" };
+
+        [Cached(typeof(SpectatorClient))]
+        private TestSpectatorClient testSpectatorClient = new TestSpectatorClient();
 
         private CurrentlyPlayingDisplay currentlyPlaying;
 
@@ -34,7 +36,7 @@ namespace osu.Game.Tests.Visual.Online
         {
             AddStep("add streaming client", () =>
             {
-                nestedContainer?.Remove(testSpectatorStreamingClient);
+                nestedContainer?.Remove(testSpectatorClient);
                 Remove(lookupCache);
 
                 Children = new Drawable[]
@@ -45,7 +47,7 @@ namespace osu.Game.Tests.Visual.Online
                         RelativeSizeAxes = Axes.Both,
                         Children = new Drawable[]
                         {
-                            testSpectatorStreamingClient,
+                            testSpectatorClient,
                             currentlyPlaying = new CurrentlyPlayingDisplay
                             {
                                 RelativeSizeAxes = Axes.Both,
@@ -55,15 +57,15 @@ namespace osu.Game.Tests.Visual.Online
                 };
             });
 
-            AddStep("Reset players", () => testSpectatorStreamingClient.PlayingUsers.Clear());
+            AddStep("Reset players", () => testSpectatorClient.EndPlay(streamingUser.Id));
         }
 
         [Test]
         public void TestBasicDisplay()
         {
-            AddStep("Add playing user", () => testSpectatorStreamingClient.PlayingUsers.Add(2));
+            AddStep("Add playing user", () => testSpectatorClient.StartPlay(streamingUser.Id, 0));
             AddUntilStep("Panel loaded", () => currentlyPlaying.ChildrenOfType<UserGridPanel>()?.FirstOrDefault()?.User.Id == 2);
-            AddStep("Remove playing user", () => testSpectatorStreamingClient.PlayingUsers.Remove(2));
+            AddStep("Remove playing user", () => testSpectatorClient.EndPlay(streamingUser.Id));
             AddUntilStep("Panel no longer present", () => !currentlyPlaying.ChildrenOfType<UserGridPanel>().Any());
         }
 

osu.Game.Tests/Visual/Ranking/TestSceneAccuracyCircle.cs

@@ -22,82 +22,17 @@ namespace osu.Game.Tests.Visual.Ranking
 {
     public class TestSceneAccuracyCircle : OsuTestScene
     {
-        [Test]
-        public void TestLowDRank()
+        [TestCase(0.2, ScoreRank.D)]
+        [TestCase(0.5, ScoreRank.D)]
+        [TestCase(0.75, ScoreRank.C)]
+        [TestCase(0.85, ScoreRank.B)]
+        [TestCase(0.925, ScoreRank.A)]
+        [TestCase(0.975, ScoreRank.S)]
+        [TestCase(0.9999, ScoreRank.S)]
+        [TestCase(1, ScoreRank.X)]
+        public void TestRank(double accuracy, ScoreRank rank)
         {
-            var score = createScore();
-            score.Accuracy = 0.2;
-            score.Rank = ScoreRank.D;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestDRank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.5;
-            score.Rank = ScoreRank.D;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestCRank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.75;
-            score.Rank = ScoreRank.C;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestBRank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.85;
-            score.Rank = ScoreRank.B;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestARank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.925;
-            score.Rank = ScoreRank.A;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestSRank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.975;
-            score.Rank = ScoreRank.S;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestAlmostSSRank()
-        {
-            var score = createScore();
-            score.Accuracy = 0.9999;
-            score.Rank = ScoreRank.S;
-
-            addCircleStep(score);
-        }
-
-        [Test]
-        public void TestSSRank()
-        {
-            var score = createScore();
-            score.Accuracy = 1;
-            score.Rank = ScoreRank.X;
+            var score = createScore(accuracy, rank);
 
             addCircleStep(score);
         }
@@ -120,7 +55,7 @@ namespace osu.Game.Tests.Visual.Ranking
                         }
                     }
                 },
-                new AccuracyCircle(score, true)
+                new AccuracyCircle(score)
                 {
                     Anchor = Anchor.Centre,
                     Origin = Anchor.Centre,
@@ -129,7 +64,7 @@ namespace osu.Game.Tests.Visual.Ranking
             };
         });
 
-        private ScoreInfo createScore() => new ScoreInfo
+        private ScoreInfo createScore(double accuracy, ScoreRank rank) => new ScoreInfo
         {
             User = new User
             {
@@ -139,9 +74,9 @@ namespace osu.Game.Tests.Visual.Ranking
             Beatmap = new TestBeatmap(new OsuRuleset().RulesetInfo).BeatmapInfo,
             Mods = new Mod[] { new OsuModHardRock(), new OsuModDoubleTime() },
             TotalScore = 2845370,
-            Accuracy = 0.95,
+            Accuracy = accuracy,
             MaxCombo = 999,
-            Rank = ScoreRank.S,
+            Rank = rank,
             Date = DateTimeOffset.Now,
             Statistics =
             {

osu.Game.Tests/Visual/Ranking/TestSceneResultsScreen.cs

@@ -29,13 +29,8 @@ namespace osu.Game.Tests.Visual.Ranking
     [TestFixture]
     public class TestSceneResultsScreen : OsuManualInputManagerTestScene
     {
-        private BeatmapManager beatmaps;
-
-        [BackgroundDependencyLoader]
-        private void load(BeatmapManager beatmaps)
-        {
-            this.beatmaps = beatmaps;
-        }
+        [Resolved]
+        private BeatmapManager beatmaps { get; set; }
 
         protected override void LoadComplete()
         {
@@ -46,10 +41,6 @@ namespace osu.Game.Tests.Visual.Ranking
                 Beatmap.Value = beatmaps.GetWorkingBeatmap(beatmapInfo);
         }
 
-        private TestResultsScreen createResultsScreen() => new TestResultsScreen(new TestScoreInfo(new OsuRuleset().RulesetInfo));
-
-        private UnrankedSoloResultsScreen createUnrankedSoloResultsScreen() => new UnrankedSoloResultsScreen(new TestScoreInfo(new OsuRuleset().RulesetInfo));
-
         [Test]
         public void TestResultsWithoutPlayer()
         {
@@ -69,12 +60,25 @@ namespace osu.Game.Tests.Visual.Ranking
             AddAssert("retry overlay not present", () => screen.RetryOverlay == null);
         }
 
-        [Test]
-        public void TestResultsWithPlayer()
+        [TestCase(0.2, ScoreRank.D)]
+        [TestCase(0.5, ScoreRank.D)]
+        [TestCase(0.75, ScoreRank.C)]
+        [TestCase(0.85, ScoreRank.B)]
+        [TestCase(0.925, ScoreRank.A)]
+        [TestCase(0.975, ScoreRank.S)]
+        [TestCase(0.9999, ScoreRank.S)]
+        [TestCase(1, ScoreRank.X)]
+        public void TestResultsWithPlayer(double accuracy, ScoreRank rank)
         {
             TestResultsScreen screen = null;
 
-            AddStep("load results", () => Child = new TestResultsContainer(screen = createResultsScreen()));
+            var score = new TestScoreInfo(new OsuRuleset().RulesetInfo)
+            {
+                Accuracy = accuracy,
+                Rank = rank
+            };
+
+            AddStep("load results", () => Child = new TestResultsContainer(screen = createResultsScreen(score)));
             AddUntilStep("wait for loaded", () => screen.IsLoaded);
             AddAssert("retry overlay present", () => screen.RetryOverlay != null);
         }
@@ -232,6 +236,10 @@ namespace osu.Game.Tests.Visual.Ranking
             AddAssert("download button is enabled", () => screen.ChildrenOfType<DownloadButton>().Last().Enabled.Value);
         }
 
+        private TestResultsScreen createResultsScreen(ScoreInfo score = null) => new TestResultsScreen(score ?? new TestScoreInfo(new OsuRuleset().RulesetInfo));
+
+        private UnrankedSoloResultsScreen createUnrankedSoloResultsScreen() => new UnrankedSoloResultsScreen(new TestScoreInfo(new OsuRuleset().RulesetInfo));
+
         private class TestResultsContainer : Container
         {
             [Cached(typeof(Player))]

osu.Game.Tests/Visual/UserInterface/TestSceneBreadcrumbControlHeader.cs

@@ -0,0 +1,86 @@
+// 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.Linq;
+using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Game.Overlays;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    public class TestSceneBreadcrumbControlHeader : OsuTestScene
+    {
+        private static readonly string[] items = { "first", "second", "third", "fourth", "fifth" };
+
+        [Cached]
+        private readonly OverlayColourProvider colourProvider = new OverlayColourProvider(OverlayColourScheme.Red);
+
+        private TestHeader header;
+
+        [SetUp]
+        public void SetUp() => Schedule(() =>
+        {
+            Child = header = new TestHeader
+            {
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+            };
+        });
+
+        [Test]
+        public void TestAddAndRemoveItem()
+        {
+            foreach (var item in items.Skip(1))
+                AddStep($"Add {item} item", () => header.AddItem(item));
+
+            foreach (var item in items.Reverse().SkipLast(3))
+                AddStep($"Remove {item} item", () => header.RemoveItem(item));
+
+            AddStep("Clear items", () => header.ClearItems());
+
+            foreach (var item in items)
+                AddStep($"Add {item} item", () => header.AddItem(item));
+
+            foreach (var item in items)
+                AddStep($"Remove {item} item", () => header.RemoveItem(item));
+        }
+
+        private class TestHeader : BreadcrumbControlOverlayHeader
+        {
+            public TestHeader()
+            {
+                TabControl.AddItem(items[0]);
+                Current.Value = items[0];
+            }
+
+            public void AddItem(string value)
+            {
+                TabControl.AddItem(value);
+                Current.Value = TabControl.Items.LastOrDefault();
+            }
+
+            public void RemoveItem(string value)
+            {
+                TabControl.RemoveItem(value);
+                Current.Value = TabControl.Items.LastOrDefault();
+            }
+
+            public void ClearItems()
+            {
+                TabControl.Clear();
+                Current.Value = null;
+            }
+
+            protected override OverlayTitle CreateTitle() => new TestTitle();
+        }
+
+        private class TestTitle : OverlayTitle
+        {
+            public TestTitle()
+            {
+                Title = "Test Title";
+            }
+        }
+    }
+}

osu.Game.Tests/Visual/UserInterface/TestSceneStatefulMenuItem.cs

@@ -14,7 +14,7 @@ namespace osu.Game.Tests.Visual.UserInterface
     public class TestSceneStatefulMenuItem : OsuManualInputManagerTestScene
     {
         [Test]
-        public void TestTernaryMenuItem()
+        public void TestTernaryRadioMenuItem()
         {
             OsuMenu menu = null;
 
@@ -30,9 +30,57 @@ namespace osu.Game.Tests.Visual.UserInterface
                     Origin = Anchor.Centre,
                     Items = new[]
                     {
-                        new TernaryStateMenuItem("First"),
-                        new TernaryStateMenuItem("Second") { State = { BindTarget = state } },
-                        new TernaryStateMenuItem("Third") { State = { Value = TernaryState.True } },
+                        new TernaryStateRadioMenuItem("First"),
+                        new TernaryStateRadioMenuItem("Second") { State = { BindTarget = state } },
+                        new TernaryStateRadioMenuItem("Third") { State = { Value = TernaryState.True } },
+                    }
+                };
+            });
+
+            checkState(TernaryState.Indeterminate);
+
+            click();
+            checkState(TernaryState.True);
+
+            click();
+            checkState(TernaryState.True);
+
+            click();
+            checkState(TernaryState.True);
+
+            AddStep("change state via bindable", () => state.Value = TernaryState.True);
+
+            void click() =>
+                AddStep("click", () =>
+                {
+                    InputManager.MoveMouseTo(menu.ScreenSpaceDrawQuad.Centre);
+                    InputManager.Click(MouseButton.Left);
+                });
+
+            void checkState(TernaryState expected)
+                => AddAssert($"state is {expected}", () => state.Value == expected);
+        }
+
+        [Test]
+        public void TestTernaryToggleMenuItem()
+        {
+            OsuMenu menu = null;
+
+            Bindable<TernaryState> state = new Bindable<TernaryState>(TernaryState.Indeterminate);
+
+            AddStep("create menu", () =>
+            {
+                state.Value = TernaryState.Indeterminate;
+
+                Child = menu = new OsuMenu(Direction.Vertical, true)
+                {
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.Centre,
+                    Items = new[]
+                    {
+                        new TernaryStateToggleMenuItem("First"),
+                        new TernaryStateToggleMenuItem("Second") { State = { BindTarget = state } },
+                        new TernaryStateToggleMenuItem("Third") { State = { Value = TernaryState.True } },
                     }
                 };
             });

osu.Game/Collections/CollectionManager.cs

@@ -8,13 +8,13 @@ using System.IO;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using osu.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Logging;
 using osu.Framework.Platform;
 using osu.Game.Beatmaps;
+using osu.Game.IO;
 using osu.Game.IO.Legacy;
 using osu.Game.Overlays.Notifications;
 
@@ -38,8 +38,6 @@ namespace osu.Game.Collections
 
         public readonly BindableList<BeatmapCollection> Collections = new BindableList<BeatmapCollection>();
 
-        public bool SupportsImportFromStable => RuntimeInfo.IsDesktop;
-
         [Resolved]
         private GameHost host { get; set; }
 
@@ -96,25 +94,12 @@ namespace osu.Game.Collections
         /// </summary>
         public Action<Notification> PostNotification { protected get; set; }
 
-        /// <summary>
-        /// Set a storage with access to an osu-stable install for import purposes.
-        /// </summary>
-        public Func<Storage> GetStableStorage { private get; set; }
-
         /// <summary>
         /// This is a temporary method and will likely be replaced by a full-fledged (and more correctly placed) migration process in the future.
         /// </summary>
-        public Task ImportFromStableAsync()
+        public Task ImportFromStableAsync(StableStorage stableStorage)
         {
-            var stable = GetStableStorage?.Invoke();
-
-            if (stable == null)
-            {
-                Logger.Log("No osu!stable installation available!", LoggingTarget.Information, LogLevel.Error);
-                return Task.CompletedTask;
-            }
-
-            if (!stable.Exists(database_name))
+            if (!stableStorage.Exists(database_name))
             {
                 // This handles situations like when the user does not have a collections.db file
                 Logger.Log($"No {database_name} available in osu!stable installation", LoggingTarget.Information, LogLevel.Error);
@@ -123,7 +108,7 @@ namespace osu.Game.Collections
 
             return Task.Run(async () =>
             {
-                using (var stream = stable.GetStream(database_name))
+                using (var stream = stableStorage.GetStream(database_name))
                     await Import(stream).ConfigureAwait(false);
             });
         }

osu.Game/Configuration/OsuConfigManager.cs

@@ -104,7 +104,6 @@ namespace osu.Game.Configuration
             SetDefault(OsuSetting.KeyOverlay, false);
             SetDefault(OsuSetting.PositionalHitSounds, true);
             SetDefault(OsuSetting.AlwaysPlayFirstComboBreak, true);
-            SetDefault(OsuSetting.ScoreMeter, ScoreMeterType.HitErrorBoth);
 
             SetDefault(OsuSetting.FloatingComments, false);
 
@@ -213,7 +212,6 @@ namespace osu.Game.Configuration
         KeyOverlay,
         PositionalHitSounds,
         AlwaysPlayFirstComboBreak,
-        ScoreMeter,
         FloatingComments,
         HUDVisibilityMode,
         ShowProgressGraph,

osu.Game/Configuration/ScoreMeterType.cs

@@ -1,37 +0,0 @@
-// 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.ComponentModel;
-
-namespace osu.Game.Configuration
-{
-    public enum ScoreMeterType
-    {
-        [Description("None")]
-        None,
-
-        [Description("Hit Error (left)")]
-        HitErrorLeft,
-
-        [Description("Hit Error (right)")]
-        HitErrorRight,
-
-        [Description("Hit Error (left+right)")]
-        HitErrorBoth,
-
-        [Description("Hit Error (bottom)")]
-        HitErrorBottom,
-
-        [Description("Colour (left)")]
-        ColourLeft,
-
-        [Description("Colour (right)")]
-        ColourRight,
-
-        [Description("Colour (left+right)")]
-        ColourBoth,
-
-        [Description("Colour (bottom)")]
-        ColourBottom,
-    }
-}

osu.Game/Database/ArchiveModelManager.cs

@@ -10,7 +10,6 @@ using System.Threading.Tasks;
 using Humanizer;
 using JetBrains.Annotations;
 using Microsoft.EntityFrameworkCore;
-using osu.Framework;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions;
 using osu.Framework.Extensions.IEnumerableExtensions;
@@ -81,8 +80,6 @@ namespace osu.Game.Database
 
         public virtual IEnumerable<string> HandledExtensions => new[] { ".zip" };
 
-        public virtual bool SupportsImportFromStable => RuntimeInfo.IsDesktop;
-
         protected readonly FileStore Files;
 
         protected readonly IDatabaseContextFactory ContextFactory;
@@ -669,16 +666,6 @@ namespace osu.Game.Database
 
         #region osu-stable import
 
-        /// <summary>
-        /// Set a storage with access to an osu-stable install for import purposes.
-        /// </summary>
-        public Func<StableStorage> GetStableStorage { private get; set; }
-
-        /// <summary>
-        /// Denotes whether an osu-stable installation is present to perform automated imports from.
-        /// </summary>
-        public bool StableInstallationAvailable => GetStableStorage?.Invoke() != null;
-
         /// <summary>
         /// The relative path from osu-stable's data directory to import items from.
         /// </summary>
@@ -700,22 +687,16 @@ namespace osu.Game.Database
         /// <summary>
         /// This is a temporary method and will likely be replaced by a full-fledged (and more correctly placed) migration process in the future.
         /// </summary>
-        public Task ImportFromStableAsync()
+        public Task ImportFromStableAsync(StableStorage stableStorage)
         {
-            var stableStorage = GetStableStorage?.Invoke();
-
-            if (stableStorage == null)
-            {
-                Logger.Log("No osu!stable installation available!", LoggingTarget.Information, LogLevel.Error);
-                return Task.CompletedTask;
-            }
-
             var storage = PrepareStableStorage(stableStorage);
 
+            // Handle situations like when the user does not have a Skins folder.
             if (!storage.ExistsDirectory(ImportFromStablePath))
             {
-                // This handles situations like when the user does not have a Skins folder
-                Logger.Log($"No {ImportFromStablePath} folder available in osu!stable installation", LoggingTarget.Information, LogLevel.Error);
+                string fullPath = storage.GetFullPath(ImportFromStablePath);
+
+                Logger.Log($"Folder \"{fullPath}\" not available in the target osu!stable installation to import {HumanisedModelName}s.", LoggingTarget.Information, LogLevel.Error);
                 return Task.CompletedTask;
             }
 

osu.Game/Database/StableImportManager.cs

@@ -0,0 +1,96 @@
+// 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.Threading.Tasks;
+using osu.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Extensions.EnumExtensions;
+using osu.Framework.Graphics;
+using osu.Framework.Platform;
+using osu.Game.Beatmaps;
+using osu.Game.Collections;
+using osu.Game.IO;
+using osu.Game.Overlays;
+using osu.Game.Overlays.Settings.Sections.Maintenance;
+using osu.Game.Scoring;
+using osu.Game.Skinning;
+
+namespace osu.Game.Database
+{
+    public class StableImportManager : Component
+    {
+        [Resolved]
+        private SkinManager skins { get; set; }
+
+        [Resolved]
+        private BeatmapManager beatmaps { get; set; }
+
+        [Resolved]
+        private ScoreManager scores { get; set; }
+
+        [Resolved]
+        private CollectionManager collections { get; set; }
+
+        [Resolved]
+        private OsuGame game { get; set; }
+
+        [Resolved]
+        private DialogOverlay dialogOverlay { get; set; }
+
+        [Resolved(CanBeNull = true)]
+        private DesktopGameHost desktopGameHost { get; set; }
+
+        private StableStorage cachedStorage;
+
+        public bool SupportsImportFromStable => RuntimeInfo.IsDesktop;
+
+        public async Task ImportFromStableAsync(StableContent content)
+        {
+            var stableStorage = await getStableStorage().ConfigureAwait(false);
+            var importTasks = new List<Task>();
+
+            Task beatmapImportTask = Task.CompletedTask;
+            if (content.HasFlagFast(StableContent.Beatmaps))
+                importTasks.Add(beatmapImportTask = beatmaps.ImportFromStableAsync(stableStorage));
+
+            if (content.HasFlagFast(StableContent.Skins))
+                importTasks.Add(skins.ImportFromStableAsync(stableStorage));
+
+            if (content.HasFlagFast(StableContent.Collections))
+                importTasks.Add(beatmapImportTask.ContinueWith(_ => collections.ImportFromStableAsync(stableStorage), TaskContinuationOptions.OnlyOnRanToCompletion));
+
+            if (content.HasFlagFast(StableContent.Scores))
+                importTasks.Add(beatmapImportTask.ContinueWith(_ => scores.ImportFromStableAsync(stableStorage), TaskContinuationOptions.OnlyOnRanToCompletion));
+
+            await Task.WhenAll(importTasks.ToArray()).ConfigureAwait(false);
+        }
+
+        private async Task<StableStorage> getStableStorage()
+        {
+            if (cachedStorage != null)
+                return cachedStorage;
+
+            var stableStorage = game.GetStorageForStableInstall();
+            if (stableStorage != null)
+                return cachedStorage = stableStorage;
+
+            var taskCompletionSource = new TaskCompletionSource<string>(TaskCreationOptions.RunContinuationsAsynchronously);
+            Schedule(() => dialogOverlay.Push(new StableDirectoryLocationDialog(taskCompletionSource)));
+            var stablePath = await taskCompletionSource.Task.ConfigureAwait(false);
+
+            return cachedStorage = new StableStorage(stablePath, desktopGameHost);
+        }
+    }
+
+    [Flags]
+    public enum StableContent
+    {
+        Beatmaps = 1 << 0,
+        Scores = 1 << 1,
+        Skins = 1 << 2,
+        Collections = 1 << 3,
+        All = Beatmaps | Scores | Skins | Collections
+    }
+}

osu.Game/Graphics/UserInterface/TernaryStateMenuItem.cs

@@ -9,28 +9,17 @@ namespace osu.Game.Graphics.UserInterface
     /// <summary>
     /// An <see cref="OsuMenuItem"/> with three possible states.
     /// </summary>
-    public class TernaryStateMenuItem : StatefulMenuItem<TernaryState>
+    public abstract class TernaryStateMenuItem : StatefulMenuItem<TernaryState>
     {
         /// <summary>
         /// Creates a new <see cref="TernaryStateMenuItem"/>.
         /// </summary>
         /// <param name="text">The text to display.</param>
+        /// <param name="nextStateFunction">A function to inform what the next state should be when this item is clicked.</param>
         /// <param name="type">The type of action which this <see cref="TernaryStateMenuItem"/> performs.</param>
         /// <param name="action">A delegate to be invoked when this <see cref="TernaryStateMenuItem"/> is pressed.</param>
-        public TernaryStateMenuItem(string text, MenuItemType type = MenuItemType.Standard, Action<TernaryState> action = null)
-            : this(text, getNextState, type, action)
-        {
-        }
-
-        /// <summary>
-        /// Creates a new <see cref="TernaryStateMenuItem"/>.
-        /// </summary>
-        /// <param name="text">The text to display.</param>
-        /// <param name="changeStateFunc">A function that mutates a state to another state after this <see cref="TernaryStateMenuItem"/> is pressed.</param>
-        /// <param name="type">The type of action which this <see cref="TernaryStateMenuItem"/> performs.</param>
-        /// <param name="action">A delegate to be invoked when this <see cref="TernaryStateMenuItem"/> is pressed.</param>
-        protected TernaryStateMenuItem(string text, Func<TernaryState, TernaryState> changeStateFunc, MenuItemType type, Action<TernaryState> action)
-            : base(text, changeStateFunc, type, action)
+        protected TernaryStateMenuItem(string text, Func<TernaryState, TernaryState> nextStateFunction, MenuItemType type = MenuItemType.Standard, Action<TernaryState> action = null)
+            : base(text, nextStateFunction, type, action)
         {
         }
 
@@ -47,23 +36,5 @@ namespace osu.Game.Graphics.UserInterface
 
             return null;
         }
-
-        private static TernaryState getNextState(TernaryState state)
-        {
-            switch (state)
-            {
-                case TernaryState.False:
-                    return TernaryState.True;
-
-                case TernaryState.Indeterminate:
-                    return TernaryState.True;
-
-                case TernaryState.True:
-                    return TernaryState.False;
-
-                default:
-                    throw new ArgumentOutOfRangeException(nameof(state), state, null);
-            }
-        }
     }
 }

osu.Game/Graphics/UserInterface/TernaryStateRadioMenuItem.cs

@@ -0,0 +1,26 @@
+// 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;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    /// <summary>
+    /// A ternary state menu item which will always set the item to <c>true</c> on click, even if already <c>true</c>.
+    /// </summary>
+    public class TernaryStateRadioMenuItem : TernaryStateMenuItem
+    {
+        /// <summary>
+        /// Creates a new <see cref="TernaryStateMenuItem"/>.
+        /// </summary>
+        /// <param name="text">The text to display.</param>
+        /// <param name="type">The type of action which this <see cref="TernaryStateMenuItem"/> performs.</param>
+        /// <param name="action">A delegate to be invoked when this <see cref="TernaryStateMenuItem"/> is pressed.</param>
+        public TernaryStateRadioMenuItem(string text, MenuItemType type = MenuItemType.Standard, Action<TernaryState> action = null)
+            : base(text, getNextState, type, action)
+        {
+        }
+
+        private static TernaryState getNextState(TernaryState state) => TernaryState.True;
+    }
+}

osu.Game/Graphics/UserInterface/TernaryStateToggleMenuItem.cs

@@ -0,0 +1,42 @@
+// 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;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    /// <summary>
+    /// A ternary state menu item which toggles the state of this item <c>false</c> if clicked when <c>true</c>.
+    /// </summary>
+    public class TernaryStateToggleMenuItem : TernaryStateMenuItem
+    {
+        /// <summary>
+        /// Creates a new <see cref="TernaryStateToggleMenuItem"/>.
+        /// </summary>
+        /// <param name="text">The text to display.</param>
+        /// <param name="type">The type of action which this <see cref="TernaryStateMenuItem"/> performs.</param>
+        /// <param name="action">A delegate to be invoked when this <see cref="TernaryStateMenuItem"/> is pressed.</param>
+        public TernaryStateToggleMenuItem(string text, MenuItemType type = MenuItemType.Standard, Action<TernaryState> action = null)
+            : base(text, getNextState, type, action)
+        {
+        }
+
+        private static TernaryState getNextState(TernaryState state)
+        {
+            switch (state)
+            {
+                case TernaryState.False:
+                    return TernaryState.True;
+
+                case TernaryState.Indeterminate:
+                    return TernaryState.True;
+
+                case TernaryState.True:
+                    return TernaryState.False;
+
+                default:
+                    throw new ArgumentOutOfRangeException(nameof(state), state, null);
+            }
+        }
+    }
+}

osu.Game/Online/API/Requests/GetNewsRequest.cs

@@ -8,10 +8,12 @@ namespace osu.Game.Online.API.Requests
 {
     public class GetNewsRequest : APIRequest<GetNewsResponse>
     {
+        private readonly int? year;
         private readonly Cursor cursor;
 
-        public GetNewsRequest(Cursor cursor = null)
+        public GetNewsRequest(int? year = null, Cursor cursor = null)
         {
+            this.year = year;
             this.cursor = cursor;
         }
 
@@ -19,6 +21,10 @@ namespace osu.Game.Online.API.Requests
         {
             var req = base.CreateWebRequest();
             req.AddCursor(cursor);
+
+            if (year.HasValue)
+                req.AddParameter("year", year.Value.ToString());
+
             return req;
         }
 

osu.Game/Online/Multiplayer/MultiplayerClient.cs

@@ -3,132 +3,621 @@
 
 #nullable enable
 
+using System;
 using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
-using Microsoft.AspNetCore.SignalR.Client;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
+using osu.Framework.Extensions.ObjectExtensions;
+using osu.Framework.Graphics;
+using osu.Framework.Logging;
 using osu.Game.Beatmaps;
+using osu.Game.Database;
 using osu.Game.Online.API;
-using osu.Game.Online.API.Requests;
 using osu.Game.Online.Rooms;
+using osu.Game.Online.Rooms.RoomStatuses;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Users;
+using osu.Game.Utils;
 
 namespace osu.Game.Online.Multiplayer
 {
-    public class MultiplayerClient : StatefulMultiplayerClient
+    public abstract class MultiplayerClient : Component, IMultiplayerClient, IMultiplayerRoomServer
     {
-        private readonly string endpoint;
+        /// <summary>
+        /// Invoked when any change occurs to the multiplayer room.
+        /// </summary>
+        public event Action? RoomUpdated;
 
-        private IHubClientConnector? connector;
+        /// <summary>
+        /// Invoked when the multiplayer server requests the current beatmap to be loaded into play.
+        /// </summary>
+        public event Action? LoadRequested;
 
-        public override IBindable<bool> IsConnected { get; } = new BindableBool();
+        /// <summary>
+        /// Invoked when the multiplayer server requests gameplay to be started.
+        /// </summary>
+        public event Action? MatchStarted;
 
-        private HubConnection? connection => connector?.CurrentConnection;
+        /// <summary>
+        /// Invoked when the multiplayer server has finished collating results.
+        /// </summary>
+        public event Action? ResultsReady;
 
-        public MultiplayerClient(EndpointConfiguration endpoints)
+        /// <summary>
+        /// Whether the <see cref="MultiplayerClient"/> is currently connected.
+        /// This is NOT thread safe and usage should be scheduled.
+        /// </summary>
+        public abstract IBindable<bool> IsConnected { get; }
+
+        /// <summary>
+        /// The joined <see cref="MultiplayerRoom"/>.
+        /// </summary>
+        public MultiplayerRoom? Room { get; private set; }
+
+        /// <summary>
+        /// The users in the joined <see cref="Room"/> which are participating in the current gameplay loop.
+        /// </summary>
+        public readonly BindableList<int> CurrentMatchPlayingUserIds = new BindableList<int>();
+
+        public readonly Bindable<PlaylistItem?> CurrentMatchPlayingItem = new Bindable<PlaylistItem?>();
+
+        /// <summary>
+        /// The <see cref="MultiplayerRoomUser"/> corresponding to the local player, if available.
+        /// </summary>
+        public MultiplayerRoomUser? LocalUser => Room?.Users.SingleOrDefault(u => u.User?.Id == API.LocalUser.Value.Id);
+
+        /// <summary>
+        /// Whether the <see cref="LocalUser"/> is the host in <see cref="Room"/>.
+        /// </summary>
+        public bool IsHost
         {
-            endpoint = endpoints.MultiplayerEndpointUrl;
-        }
-
-        [BackgroundDependencyLoader]
-        private void load(IAPIProvider api)
-        {
-            connector = api.GetHubConnector(nameof(MultiplayerClient), endpoint);
-
-            if (connector != null)
+            get
             {
-                connector.ConfigureConnection = connection =>
-                {
-                    // this is kind of SILLY
-                    // https://github.com/dotnet/aspnetcore/issues/15198
-                    connection.On<MultiplayerRoomState>(nameof(IMultiplayerClient.RoomStateChanged), ((IMultiplayerClient)this).RoomStateChanged);
-                    connection.On<MultiplayerRoomUser>(nameof(IMultiplayerClient.UserJoined), ((IMultiplayerClient)this).UserJoined);
-                    connection.On<MultiplayerRoomUser>(nameof(IMultiplayerClient.UserLeft), ((IMultiplayerClient)this).UserLeft);
-                    connection.On<int>(nameof(IMultiplayerClient.HostChanged), ((IMultiplayerClient)this).HostChanged);
-                    connection.On<MultiplayerRoomSettings>(nameof(IMultiplayerClient.SettingsChanged), ((IMultiplayerClient)this).SettingsChanged);
-                    connection.On<int, MultiplayerUserState>(nameof(IMultiplayerClient.UserStateChanged), ((IMultiplayerClient)this).UserStateChanged);
-                    connection.On(nameof(IMultiplayerClient.LoadRequested), ((IMultiplayerClient)this).LoadRequested);
-                    connection.On(nameof(IMultiplayerClient.MatchStarted), ((IMultiplayerClient)this).MatchStarted);
-                    connection.On(nameof(IMultiplayerClient.ResultsReady), ((IMultiplayerClient)this).ResultsReady);
-                    connection.On<int, IEnumerable<APIMod>>(nameof(IMultiplayerClient.UserModsChanged), ((IMultiplayerClient)this).UserModsChanged);
-                    connection.On<int, BeatmapAvailability>(nameof(IMultiplayerClient.UserBeatmapAvailabilityChanged), ((IMultiplayerClient)this).UserBeatmapAvailabilityChanged);
-                };
-
-                IsConnected.BindTo(connector.IsConnected);
+                var localUser = LocalUser;
+                return localUser != null && Room?.Host != null && localUser.Equals(Room.Host);
             }
         }
 
-        protected override Task<MultiplayerRoom> JoinRoom(long roomId)
-        {
-            if (!IsConnected.Value)
-                return Task.FromCanceled<MultiplayerRoom>(new CancellationToken(true));
+        [Resolved]
+        protected IAPIProvider API { get; private set; } = null!;
 
-            return connection.InvokeAsync<MultiplayerRoom>(nameof(IMultiplayerServer.JoinRoom), roomId);
+        [Resolved]
+        protected RulesetStore Rulesets { get; private set; } = null!;
+
+        [Resolved]
+        private UserLookupCache userLookupCache { get; set; } = null!;
+
+        private Room? apiRoom;
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            IsConnected.BindValueChanged(connected =>
+            {
+                // clean up local room state on server disconnect.
+                if (!connected.NewValue && Room != null)
+                {
+                    Logger.Log("Connection to multiplayer server was lost.", LoggingTarget.Runtime, LogLevel.Important);
+                    LeaveRoom();
+                }
+            });
         }
 
-        protected override Task LeaveRoomInternal()
-        {
-            if (!IsConnected.Value)
-                return Task.FromCanceled(new CancellationToken(true));
+        private readonly TaskChain joinOrLeaveTaskChain = new TaskChain();
+        private CancellationTokenSource? joinCancellationSource;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.LeaveRoom));
+        /// <summary>
+        /// Joins the <see cref="MultiplayerRoom"/> for a given API <see cref="Room"/>.
+        /// </summary>
+        /// <param name="room">The API <see cref="Room"/>.</param>
+        public async Task JoinRoom(Room room)
+        {
+            var cancellationSource = joinCancellationSource = new CancellationTokenSource();
+
+            await joinOrLeaveTaskChain.Add(async () =>
+            {
+                if (Room != null)
+                    throw new InvalidOperationException("Cannot join a multiplayer room while already in one.");
+
+                Debug.Assert(room.RoomID.Value != null);
+
+                // Join the server-side room.
+                var joinedRoom = await JoinRoom(room.RoomID.Value.Value).ConfigureAwait(false);
+                Debug.Assert(joinedRoom != null);
+
+                // Populate users.
+                Debug.Assert(joinedRoom.Users != null);
+                await Task.WhenAll(joinedRoom.Users.Select(PopulateUser)).ConfigureAwait(false);
+
+                // Update the stored room (must be done on update thread for thread-safety).
+                await scheduleAsync(() =>
+                {
+                    Room = joinedRoom;
+                    apiRoom = room;
+                    foreach (var user in joinedRoom.Users)
+                        updateUserPlayingState(user.UserID, user.State);
+                }, cancellationSource.Token).ConfigureAwait(false);
+
+                // Update room settings.
+                await updateLocalRoomSettings(joinedRoom.Settings, cancellationSource.Token).ConfigureAwait(false);
+            }, cancellationSource.Token).ConfigureAwait(false);
         }
 
-        public override Task TransferHost(int userId)
+        /// <summary>
+        /// Joins the <see cref="MultiplayerRoom"/> with a given ID.
+        /// </summary>
+        /// <param name="roomId">The room ID.</param>
+        /// <returns>The joined <see cref="MultiplayerRoom"/>.</returns>
+        protected abstract Task<MultiplayerRoom> JoinRoom(long roomId);
+
+        public Task LeaveRoom()
         {
-            if (!IsConnected.Value)
+            // The join may have not completed yet, so certain tasks that either update the room or reference the room should be cancelled.
+            // This includes the setting of Room itself along with the initial update of the room settings on join.
+            joinCancellationSource?.Cancel();
+
+            // Leaving rooms is expected to occur instantaneously whilst the operation is finalised in the background.
+            // However a few members need to be reset immediately to prevent other components from entering invalid states whilst the operation hasn't yet completed.
+            // For example, if a room was left and the user immediately pressed the "create room" button, then the user could be taken into the lobby if the value of Room is not reset in time.
+            var scheduledReset = scheduleAsync(() =>
+            {
+                apiRoom = null;
+                Room = null;
+                CurrentMatchPlayingUserIds.Clear();
+
+                RoomUpdated?.Invoke();
+            });
+
+            return joinOrLeaveTaskChain.Add(async () =>
+            {
+                await scheduledReset.ConfigureAwait(false);
+                await LeaveRoomInternal().ConfigureAwait(false);
+            });
+        }
+
+        protected abstract Task LeaveRoomInternal();
+
+        /// <summary>
+        /// Change the current <see cref="MultiplayerRoom"/> settings.
+        /// </summary>
+        /// <remarks>
+        /// A room must be joined for this to have any effect.
+        /// </remarks>
+        /// <param name="name">The new room name, if any.</param>
+        /// <param name="item">The new room playlist item, if any.</param>
+        public Task ChangeSettings(Optional<string> name = default, Optional<PlaylistItem> item = default)
+        {
+            if (Room == null)
+                throw new InvalidOperationException("Must be joined to a match to change settings.");
+
+            // A dummy playlist item filled with the current room settings (except mods).
+            var existingPlaylistItem = new PlaylistItem
+            {
+                Beatmap =
+                {
+                    Value = new BeatmapInfo
+                    {
+                        OnlineBeatmapID = Room.Settings.BeatmapID,
+                        MD5Hash = Room.Settings.BeatmapChecksum
+                    }
+                },
+                RulesetID = Room.Settings.RulesetID
+            };
+
+            return ChangeSettings(new MultiplayerRoomSettings
+            {
+                Name = name.GetOr(Room.Settings.Name),
+                BeatmapID = item.GetOr(existingPlaylistItem).BeatmapID,
+                BeatmapChecksum = item.GetOr(existingPlaylistItem).Beatmap.Value.MD5Hash,
+                RulesetID = item.GetOr(existingPlaylistItem).RulesetID,
+                RequiredMods = item.HasValue ? item.Value.AsNonNull().RequiredMods.Select(m => new APIMod(m)).ToList() : Room.Settings.RequiredMods,
+                AllowedMods = item.HasValue ? item.Value.AsNonNull().AllowedMods.Select(m => new APIMod(m)).ToList() : Room.Settings.AllowedMods,
+            });
+        }
+
+        /// <summary>
+        /// Toggles the <see cref="LocalUser"/>'s ready state.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">If a toggle of ready state is not valid at this time.</exception>
+        public async Task ToggleReady()
+        {
+            var localUser = LocalUser;
+
+            if (localUser == null)
+                return;
+
+            switch (localUser.State)
+            {
+                case MultiplayerUserState.Idle:
+                    await ChangeState(MultiplayerUserState.Ready).ConfigureAwait(false);
+                    return;
+
+                case MultiplayerUserState.Ready:
+                    await ChangeState(MultiplayerUserState.Idle).ConfigureAwait(false);
+                    return;
+
+                default:
+                    throw new InvalidOperationException($"Cannot toggle ready when in {localUser.State}");
+            }
+        }
+
+        /// <summary>
+        /// Toggles the <see cref="LocalUser"/>'s spectating state.
+        /// </summary>
+        /// <exception cref="InvalidOperationException">If a toggle of the spectating state is not valid at this time.</exception>
+        public async Task ToggleSpectate()
+        {
+            var localUser = LocalUser;
+
+            if (localUser == null)
+                return;
+
+            switch (localUser.State)
+            {
+                case MultiplayerUserState.Idle:
+                case MultiplayerUserState.Ready:
+                    await ChangeState(MultiplayerUserState.Spectating).ConfigureAwait(false);
+                    return;
+
+                case MultiplayerUserState.Spectating:
+                    await ChangeState(MultiplayerUserState.Idle).ConfigureAwait(false);
+                    return;
+
+                default:
+                    throw new InvalidOperationException($"Cannot toggle spectate when in {localUser.State}");
+            }
+        }
+
+        public abstract Task TransferHost(int userId);
+
+        public abstract Task ChangeSettings(MultiplayerRoomSettings settings);
+
+        public abstract Task ChangeState(MultiplayerUserState newState);
+
+        public abstract Task ChangeBeatmapAvailability(BeatmapAvailability newBeatmapAvailability);
+
+        /// <summary>
+        /// Change the local user's mods in the currently joined room.
+        /// </summary>
+        /// <param name="newMods">The proposed new mods, excluding any required by the room itself.</param>
+        public Task ChangeUserMods(IEnumerable<Mod> newMods) => ChangeUserMods(newMods.Select(m => new APIMod(m)).ToList());
+
+        public abstract Task ChangeUserMods(IEnumerable<APIMod> newMods);
+
+        public abstract Task StartMatch();
+
+        Task IMultiplayerClient.RoomStateChanged(MultiplayerRoomState state)
+        {
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.TransferHost), userId);
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                Debug.Assert(apiRoom != null);
+
+                Room.State = state;
+
+                switch (state)
+                {
+                    case MultiplayerRoomState.Open:
+                        apiRoom.Status.Value = new RoomStatusOpen();
+                        break;
+
+                    case MultiplayerRoomState.Playing:
+                        apiRoom.Status.Value = new RoomStatusPlaying();
+                        break;
+
+                    case MultiplayerRoomState.Closed:
+                        apiRoom.Status.Value = new RoomStatusEnded();
+                        break;
+                }
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        public override Task ChangeSettings(MultiplayerRoomSettings settings)
+        async Task IMultiplayerClient.UserJoined(MultiplayerRoomUser user)
         {
-            if (!IsConnected.Value)
+            if (Room == null)
+                return;
+
+            await PopulateUser(user).ConfigureAwait(false);
+
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                // for sanity, ensure that there can be no duplicate users in the room user list.
+                if (Room.Users.Any(existing => existing.UserID == user.UserID))
+                    return;
+
+                Room.Users.Add(user);
+
+                RoomUpdated?.Invoke();
+            }, false);
+        }
+
+        Task IMultiplayerClient.UserLeft(MultiplayerRoomUser user)
+        {
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeSettings), settings);
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                Room.Users.Remove(user);
+                CurrentMatchPlayingUserIds.Remove(user.UserID);
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        public override Task ChangeState(MultiplayerUserState newState)
+        Task IMultiplayerClient.HostChanged(int userId)
         {
-            if (!IsConnected.Value)
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeState), newState);
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                Debug.Assert(apiRoom != null);
+
+                var user = Room.Users.FirstOrDefault(u => u.UserID == userId);
+
+                Room.Host = user;
+                apiRoom.Host.Value = user?.User;
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        public override Task ChangeBeatmapAvailability(BeatmapAvailability newBeatmapAvailability)
+        Task IMultiplayerClient.SettingsChanged(MultiplayerRoomSettings newSettings)
         {
-            if (!IsConnected.Value)
+            updateLocalRoomSettings(newSettings);
+            return Task.CompletedTask;
+        }
+
+        Task IMultiplayerClient.UserStateChanged(int userId, MultiplayerUserState state)
+        {
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeBeatmapAvailability), newBeatmapAvailability);
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                Room.Users.Single(u => u.UserID == userId).State = state;
+
+                updateUserPlayingState(userId, state);
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        public override Task ChangeUserMods(IEnumerable<APIMod> newMods)
+        Task IMultiplayerClient.UserBeatmapAvailabilityChanged(int userId, BeatmapAvailability beatmapAvailability)
         {
-            if (!IsConnected.Value)
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeUserMods), newMods);
+            Scheduler.Add(() =>
+            {
+                var user = Room?.Users.SingleOrDefault(u => u.UserID == userId);
+
+                // errors here are not critical - beatmap availability state is mostly for display.
+                if (user == null)
+                    return;
+
+                user.BeatmapAvailability = beatmapAvailability;
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        public override Task StartMatch()
+        public Task UserModsChanged(int userId, IEnumerable<APIMod> mods)
         {
-            if (!IsConnected.Value)
+            if (Room == null)
                 return Task.CompletedTask;
 
-            return connection.InvokeAsync(nameof(IMultiplayerServer.StartMatch));
+            Scheduler.Add(() =>
+            {
+                var user = Room?.Users.SingleOrDefault(u => u.UserID == userId);
+
+                // errors here are not critical - user mods are mostly for display.
+                if (user == null)
+                    return;
+
+                user.Mods = mods;
+
+                RoomUpdated?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
         }
 
-        protected override Task<BeatmapSetInfo> GetOnlineBeatmapSet(int beatmapId, CancellationToken cancellationToken = default)
+        Task IMultiplayerClient.LoadRequested()
         {
-            var tcs = new TaskCompletionSource<BeatmapSetInfo>();
-            var req = new GetBeatmapSetRequest(beatmapId, BeatmapSetLookupType.BeatmapId);
+            if (Room == null)
+                return Task.CompletedTask;
 
-            req.Success += res =>
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                LoadRequested?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
+        }
+
+        Task IMultiplayerClient.MatchStarted()
+        {
+            if (Room == null)
+                return Task.CompletedTask;
+
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                MatchStarted?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
+        }
+
+        Task IMultiplayerClient.ResultsReady()
+        {
+            if (Room == null)
+                return Task.CompletedTask;
+
+            Scheduler.Add(() =>
+            {
+                if (Room == null)
+                    return;
+
+                ResultsReady?.Invoke();
+            }, false);
+
+            return Task.CompletedTask;
+        }
+
+        /// <summary>
+        /// Populates the <see cref="User"/> for a given <see cref="MultiplayerRoomUser"/>.
+        /// </summary>
+        /// <param name="multiplayerUser">The <see cref="MultiplayerRoomUser"/> to populate.</param>
+        protected async Task PopulateUser(MultiplayerRoomUser multiplayerUser) => multiplayerUser.User ??= await userLookupCache.GetUserAsync(multiplayerUser.UserID).ConfigureAwait(false);
+
+        /// <summary>
+        /// Updates the local room settings with the given <see cref="MultiplayerRoomSettings"/>.
+        /// </summary>
+        /// <remarks>
+        /// This updates both the joined <see cref="MultiplayerRoom"/> and the respective API <see cref="Room"/>.
+        /// </remarks>
+        /// <param name="settings">The new <see cref="MultiplayerRoomSettings"/> to update from.</param>
+        /// <param name="cancellationToken">The <see cref="CancellationToken"/> to cancel the update.</param>
+        private Task updateLocalRoomSettings(MultiplayerRoomSettings settings, CancellationToken cancellationToken = default) => scheduleAsync(() =>
+        {
+            if (Room == null)
+                return;
+
+            Debug.Assert(apiRoom != null);
+
+            // Update a few properties of the room instantaneously.
+            Room.Settings = settings;
+            apiRoom.Name.Value = Room.Settings.Name;
+
+            // The current item update is delayed until an online beatmap lookup (below) succeeds.
+            // In-order for the client to not display an outdated beatmap, the current item is forcefully cleared here.
+            CurrentMatchPlayingItem.Value = null;
+
+            RoomUpdated?.Invoke();
+
+            GetOnlineBeatmapSet(settings.BeatmapID, cancellationToken).ContinueWith(set => Schedule(() =>
+            {
+                if (cancellationToken.IsCancellationRequested)
+                    return;
+
+                updatePlaylist(settings, set.Result);
+            }), TaskContinuationOptions.OnlyOnRanToCompletion);
+        }, cancellationToken);
+
+        private void updatePlaylist(MultiplayerRoomSettings settings, BeatmapSetInfo beatmapSet)
+        {
+            if (Room == null || !Room.Settings.Equals(settings))
+                return;
+
+            Debug.Assert(apiRoom != null);
+
+            var beatmap = beatmapSet.Beatmaps.Single(b => b.OnlineBeatmapID == settings.BeatmapID);
+            beatmap.MD5Hash = settings.BeatmapChecksum;
+
+            var ruleset = Rulesets.GetRuleset(settings.RulesetID).CreateInstance();
+            var mods = settings.RequiredMods.Select(m => m.ToMod(ruleset));
+            var allowedMods = settings.AllowedMods.Select(m => m.ToMod(ruleset));
+
+            // Try to retrieve the existing playlist item from the API room.
+            var playlistItem = apiRoom.Playlist.FirstOrDefault(i => i.ID == settings.PlaylistItemId);
+
+            if (playlistItem != null)
+                updateItem(playlistItem);
+            else
+            {
+                // An existing playlist item does not exist, so append a new one.
+                updateItem(playlistItem = new PlaylistItem());
+                apiRoom.Playlist.Add(playlistItem);
+            }
+
+            CurrentMatchPlayingItem.Value = playlistItem;
+
+            void updateItem(PlaylistItem item)
+            {
+                item.ID = settings.PlaylistItemId;
+                item.Beatmap.Value = beatmap;
+                item.Ruleset.Value = ruleset.RulesetInfo;
+                item.RequiredMods.Clear();
+                item.RequiredMods.AddRange(mods);
+                item.AllowedMods.Clear();
+                item.AllowedMods.AddRange(allowedMods);
+            }
+        }
+
+        /// <summary>
+        /// Retrieves a <see cref="BeatmapSetInfo"/> from an online source.
+        /// </summary>
+        /// <param name="beatmapId">The beatmap set ID.</param>
+        /// <param name="cancellationToken">A token to cancel the request.</param>
+        /// <returns>The <see cref="BeatmapSetInfo"/> retrieval task.</returns>
+        protected abstract Task<BeatmapSetInfo> GetOnlineBeatmapSet(int beatmapId, CancellationToken cancellationToken = default);
+
+        /// <summary>
+        /// For the provided user ID, update whether the user is included in <see cref="CurrentMatchPlayingUserIds"/>.
+        /// </summary>
+        /// <param name="userId">The user's ID.</param>
+        /// <param name="state">The new state of the user.</param>
+        private void updateUserPlayingState(int userId, MultiplayerUserState state)
+        {
+            bool wasPlaying = CurrentMatchPlayingUserIds.Contains(userId);
+            bool isPlaying = state >= MultiplayerUserState.WaitingForLoad && state <= MultiplayerUserState.FinishedPlay;
+
+            if (isPlaying == wasPlaying)
+                return;
+
+            if (isPlaying)
+                CurrentMatchPlayingUserIds.Add(userId);
+            else
+                CurrentMatchPlayingUserIds.Remove(userId);
+        }
+
+        private Task scheduleAsync(Action action, CancellationToken cancellationToken = default)
+        {
+            var tcs = new TaskCompletionSource<bool>();
+
+            Scheduler.Add(() =>
             {
                 if (cancellationToken.IsCancellationRequested)
                 {
@@ -136,20 +625,18 @@ namespace osu.Game.Online.Multiplayer
                     return;
                 }
 
-                tcs.SetResult(res.ToBeatmapSet(Rulesets));
-            };
-
-            req.Failure += e => tcs.SetException(e);
-
-            API.Queue(req);
+                try
+                {
+                    action();
+                    tcs.SetResult(true);
+                }
+                catch (Exception ex)
+                {
+                    tcs.SetException(ex);
+                }
+            });
 
             return tcs.Task;
         }
-
-        protected override void Dispose(bool isDisposing)
-        {
-            base.Dispose(isDisposing);
-            connector?.Dispose();
-        }
     }
 }

osu.Game/Online/Multiplayer/OnlineMultiplayerClient.cs

@@ -0,0 +1,158 @@
+// 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.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.SignalR.Client;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Game.Beatmaps;
+using osu.Game.Online.API;
+using osu.Game.Online.API.Requests;
+using osu.Game.Online.Rooms;
+
+namespace osu.Game.Online.Multiplayer
+{
+    /// <summary>
+    /// A <see cref="MultiplayerClient"/> with online connectivity.
+    /// </summary>
+    public class OnlineMultiplayerClient : MultiplayerClient
+    {
+        private readonly string endpoint;
+
+        private IHubClientConnector? connector;
+
+        public override IBindable<bool> IsConnected { get; } = new BindableBool();
+
+        private HubConnection? connection => connector?.CurrentConnection;
+
+        public OnlineMultiplayerClient(EndpointConfiguration endpoints)
+        {
+            endpoint = endpoints.MultiplayerEndpointUrl;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(IAPIProvider api)
+        {
+            connector = api.GetHubConnector(nameof(OnlineMultiplayerClient), endpoint);
+
+            if (connector != null)
+            {
+                connector.ConfigureConnection = connection =>
+                {
+                    // this is kind of SILLY
+                    // https://github.com/dotnet/aspnetcore/issues/15198
+                    connection.On<MultiplayerRoomState>(nameof(IMultiplayerClient.RoomStateChanged), ((IMultiplayerClient)this).RoomStateChanged);
+                    connection.On<MultiplayerRoomUser>(nameof(IMultiplayerClient.UserJoined), ((IMultiplayerClient)this).UserJoined);
+                    connection.On<MultiplayerRoomUser>(nameof(IMultiplayerClient.UserLeft), ((IMultiplayerClient)this).UserLeft);
+                    connection.On<int>(nameof(IMultiplayerClient.HostChanged), ((IMultiplayerClient)this).HostChanged);
+                    connection.On<MultiplayerRoomSettings>(nameof(IMultiplayerClient.SettingsChanged), ((IMultiplayerClient)this).SettingsChanged);
+                    connection.On<int, MultiplayerUserState>(nameof(IMultiplayerClient.UserStateChanged), ((IMultiplayerClient)this).UserStateChanged);
+                    connection.On(nameof(IMultiplayerClient.LoadRequested), ((IMultiplayerClient)this).LoadRequested);
+                    connection.On(nameof(IMultiplayerClient.MatchStarted), ((IMultiplayerClient)this).MatchStarted);
+                    connection.On(nameof(IMultiplayerClient.ResultsReady), ((IMultiplayerClient)this).ResultsReady);
+                    connection.On<int, IEnumerable<APIMod>>(nameof(IMultiplayerClient.UserModsChanged), ((IMultiplayerClient)this).UserModsChanged);
+                    connection.On<int, BeatmapAvailability>(nameof(IMultiplayerClient.UserBeatmapAvailabilityChanged), ((IMultiplayerClient)this).UserBeatmapAvailabilityChanged);
+                };
+
+                IsConnected.BindTo(connector.IsConnected);
+            }
+        }
+
+        protected override Task<MultiplayerRoom> JoinRoom(long roomId)
+        {
+            if (!IsConnected.Value)
+                return Task.FromCanceled<MultiplayerRoom>(new CancellationToken(true));
+
+            return connection.InvokeAsync<MultiplayerRoom>(nameof(IMultiplayerServer.JoinRoom), roomId);
+        }
+
+        protected override Task LeaveRoomInternal()
+        {
+            if (!IsConnected.Value)
+                return Task.FromCanceled(new CancellationToken(true));
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.LeaveRoom));
+        }
+
+        public override Task TransferHost(int userId)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.TransferHost), userId);
+        }
+
+        public override Task ChangeSettings(MultiplayerRoomSettings settings)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeSettings), settings);
+        }
+
+        public override Task ChangeState(MultiplayerUserState newState)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeState), newState);
+        }
+
+        public override Task ChangeBeatmapAvailability(BeatmapAvailability newBeatmapAvailability)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeBeatmapAvailability), newBeatmapAvailability);
+        }
+
+        public override Task ChangeUserMods(IEnumerable<APIMod> newMods)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.ChangeUserMods), newMods);
+        }
+
+        public override Task StartMatch()
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.InvokeAsync(nameof(IMultiplayerServer.StartMatch));
+        }
+
+        protected override Task<BeatmapSetInfo> GetOnlineBeatmapSet(int beatmapId, CancellationToken cancellationToken = default)
+        {
+            var tcs = new TaskCompletionSource<BeatmapSetInfo>();
+            var req = new GetBeatmapSetRequest(beatmapId, BeatmapSetLookupType.BeatmapId);
+
+            req.Success += res =>
+            {
+                if (cancellationToken.IsCancellationRequested)
+                {
+                    tcs.SetCanceled();
+                    return;
+                }
+
+                tcs.SetResult(res.ToBeatmapSet(Rulesets));
+            };
+
+            req.Failure += e => tcs.SetException(e);
+
+            API.Queue(req);
+
+            return tcs.Task;
+        }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+            connector?.Dispose();
+        }
+    }
+}

osu.Game/Online/Multiplayer/StatefulMultiplayerClient.cs

@@ -1,642 +0,0 @@
-// 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;
-using System.Collections.Generic;
-using System.Diagnostics;
-using System.Linq;
-using System.Threading;
-using System.Threading.Tasks;
-using osu.Framework.Allocation;
-using osu.Framework.Bindables;
-using osu.Framework.Extensions.ObjectExtensions;
-using osu.Framework.Graphics;
-using osu.Framework.Logging;
-using osu.Game.Beatmaps;
-using osu.Game.Database;
-using osu.Game.Online.API;
-using osu.Game.Online.Rooms;
-using osu.Game.Online.Rooms.RoomStatuses;
-using osu.Game.Rulesets;
-using osu.Game.Rulesets.Mods;
-using osu.Game.Users;
-using osu.Game.Utils;
-
-namespace osu.Game.Online.Multiplayer
-{
-    public abstract class StatefulMultiplayerClient : Component, IMultiplayerClient, IMultiplayerRoomServer
-    {
-        /// <summary>
-        /// Invoked when any change occurs to the multiplayer room.
-        /// </summary>
-        public event Action? RoomUpdated;
-
-        /// <summary>
-        /// Invoked when the multiplayer server requests the current beatmap to be loaded into play.
-        /// </summary>
-        public event Action? LoadRequested;
-
-        /// <summary>
-        /// Invoked when the multiplayer server requests gameplay to be started.
-        /// </summary>
-        public event Action? MatchStarted;
-
-        /// <summary>
-        /// Invoked when the multiplayer server has finished collating results.
-        /// </summary>
-        public event Action? ResultsReady;
-
-        /// <summary>
-        /// Whether the <see cref="StatefulMultiplayerClient"/> is currently connected.
-        /// This is NOT thread safe and usage should be scheduled.
-        /// </summary>
-        public abstract IBindable<bool> IsConnected { get; }
-
-        /// <summary>
-        /// The joined <see cref="MultiplayerRoom"/>.
-        /// </summary>
-        public MultiplayerRoom? Room { get; private set; }
-
-        /// <summary>
-        /// The users in the joined <see cref="Room"/> which are participating in the current gameplay loop.
-        /// </summary>
-        public readonly BindableList<int> CurrentMatchPlayingUserIds = new BindableList<int>();
-
-        public readonly Bindable<PlaylistItem?> CurrentMatchPlayingItem = new Bindable<PlaylistItem?>();
-
-        /// <summary>
-        /// The <see cref="MultiplayerRoomUser"/> corresponding to the local player, if available.
-        /// </summary>
-        public MultiplayerRoomUser? LocalUser => Room?.Users.SingleOrDefault(u => u.User?.Id == API.LocalUser.Value.Id);
-
-        /// <summary>
-        /// Whether the <see cref="LocalUser"/> is the host in <see cref="Room"/>.
-        /// </summary>
-        public bool IsHost
-        {
-            get
-            {
-                var localUser = LocalUser;
-                return localUser != null && Room?.Host != null && localUser.Equals(Room.Host);
-            }
-        }
-
-        [Resolved]
-        protected IAPIProvider API { get; private set; } = null!;
-
-        [Resolved]
-        protected RulesetStore Rulesets { get; private set; } = null!;
-
-        [Resolved]
-        private UserLookupCache userLookupCache { get; set; } = null!;
-
-        private Room? apiRoom;
-
-        [BackgroundDependencyLoader]
-        private void load()
-        {
-            IsConnected.BindValueChanged(connected =>
-            {
-                // clean up local room state on server disconnect.
-                if (!connected.NewValue && Room != null)
-                {
-                    Logger.Log("Connection to multiplayer server was lost.", LoggingTarget.Runtime, LogLevel.Important);
-                    LeaveRoom();
-                }
-            });
-        }
-
-        private readonly TaskChain joinOrLeaveTaskChain = new TaskChain();
-        private CancellationTokenSource? joinCancellationSource;
-
-        /// <summary>
-        /// Joins the <see cref="MultiplayerRoom"/> for a given API <see cref="Room"/>.
-        /// </summary>
-        /// <param name="room">The API <see cref="Room"/>.</param>
-        public async Task JoinRoom(Room room)
-        {
-            var cancellationSource = joinCancellationSource = new CancellationTokenSource();
-
-            await joinOrLeaveTaskChain.Add(async () =>
-            {
-                if (Room != null)
-                    throw new InvalidOperationException("Cannot join a multiplayer room while already in one.");
-
-                Debug.Assert(room.RoomID.Value != null);
-
-                // Join the server-side room.
-                var joinedRoom = await JoinRoom(room.RoomID.Value.Value).ConfigureAwait(false);
-                Debug.Assert(joinedRoom != null);
-
-                // Populate users.
-                Debug.Assert(joinedRoom.Users != null);
-                await Task.WhenAll(joinedRoom.Users.Select(PopulateUser)).ConfigureAwait(false);
-
-                // Update the stored room (must be done on update thread for thread-safety).
-                await scheduleAsync(() =>
-                {
-                    Room = joinedRoom;
-                    apiRoom = room;
-                    foreach (var user in joinedRoom.Users)
-                        updateUserPlayingState(user.UserID, user.State);
-                }, cancellationSource.Token).ConfigureAwait(false);
-
-                // Update room settings.
-                await updateLocalRoomSettings(joinedRoom.Settings, cancellationSource.Token).ConfigureAwait(false);
-            }, cancellationSource.Token).ConfigureAwait(false);
-        }
-
-        /// <summary>
-        /// Joins the <see cref="MultiplayerRoom"/> with a given ID.
-        /// </summary>
-        /// <param name="roomId">The room ID.</param>
-        /// <returns>The joined <see cref="MultiplayerRoom"/>.</returns>
-        protected abstract Task<MultiplayerRoom> JoinRoom(long roomId);
-
-        public Task LeaveRoom()
-        {
-            // The join may have not completed yet, so certain tasks that either update the room or reference the room should be cancelled.
-            // This includes the setting of Room itself along with the initial update of the room settings on join.
-            joinCancellationSource?.Cancel();
-
-            // Leaving rooms is expected to occur instantaneously whilst the operation is finalised in the background.
-            // However a few members need to be reset immediately to prevent other components from entering invalid states whilst the operation hasn't yet completed.
-            // For example, if a room was left and the user immediately pressed the "create room" button, then the user could be taken into the lobby if the value of Room is not reset in time.
-            var scheduledReset = scheduleAsync(() =>
-            {
-                apiRoom = null;
-                Room = null;
-                CurrentMatchPlayingUserIds.Clear();
-
-                RoomUpdated?.Invoke();
-            });
-
-            return joinOrLeaveTaskChain.Add(async () =>
-            {
-                await scheduledReset.ConfigureAwait(false);
-                await LeaveRoomInternal().ConfigureAwait(false);
-            });
-        }
-
-        protected abstract Task LeaveRoomInternal();
-
-        /// <summary>
-        /// Change the current <see cref="MultiplayerRoom"/> settings.
-        /// </summary>
-        /// <remarks>
-        /// A room must be joined for this to have any effect.
-        /// </remarks>
-        /// <param name="name">The new room name, if any.</param>
-        /// <param name="item">The new room playlist item, if any.</param>
-        public Task ChangeSettings(Optional<string> name = default, Optional<PlaylistItem> item = default)
-        {
-            if (Room == null)
-                throw new InvalidOperationException("Must be joined to a match to change settings.");
-
-            // A dummy playlist item filled with the current room settings (except mods).
-            var existingPlaylistItem = new PlaylistItem
-            {
-                Beatmap =
-                {
-                    Value = new BeatmapInfo
-                    {
-                        OnlineBeatmapID = Room.Settings.BeatmapID,
-                        MD5Hash = Room.Settings.BeatmapChecksum
-                    }
-                },
-                RulesetID = Room.Settings.RulesetID
-            };
-
-            return ChangeSettings(new MultiplayerRoomSettings
-            {
-                Name = name.GetOr(Room.Settings.Name),
-                BeatmapID = item.GetOr(existingPlaylistItem).BeatmapID,
-                BeatmapChecksum = item.GetOr(existingPlaylistItem).Beatmap.Value.MD5Hash,
-                RulesetID = item.GetOr(existingPlaylistItem).RulesetID,
-                RequiredMods = item.HasValue ? item.Value.AsNonNull().RequiredMods.Select(m => new APIMod(m)).ToList() : Room.Settings.RequiredMods,
-                AllowedMods = item.HasValue ? item.Value.AsNonNull().AllowedMods.Select(m => new APIMod(m)).ToList() : Room.Settings.AllowedMods,
-            });
-        }
-
-        /// <summary>
-        /// Toggles the <see cref="LocalUser"/>'s ready state.
-        /// </summary>
-        /// <exception cref="InvalidOperationException">If a toggle of ready state is not valid at this time.</exception>
-        public async Task ToggleReady()
-        {
-            var localUser = LocalUser;
-
-            if (localUser == null)
-                return;
-
-            switch (localUser.State)
-            {
-                case MultiplayerUserState.Idle:
-                    await ChangeState(MultiplayerUserState.Ready).ConfigureAwait(false);
-                    return;
-
-                case MultiplayerUserState.Ready:
-                    await ChangeState(MultiplayerUserState.Idle).ConfigureAwait(false);
-                    return;
-
-                default:
-                    throw new InvalidOperationException($"Cannot toggle ready when in {localUser.State}");
-            }
-        }
-
-        /// <summary>
-        /// Toggles the <see cref="LocalUser"/>'s spectating state.
-        /// </summary>
-        /// <exception cref="InvalidOperationException">If a toggle of the spectating state is not valid at this time.</exception>
-        public async Task ToggleSpectate()
-        {
-            var localUser = LocalUser;
-
-            if (localUser == null)
-                return;
-
-            switch (localUser.State)
-            {
-                case MultiplayerUserState.Idle:
-                case MultiplayerUserState.Ready:
-                    await ChangeState(MultiplayerUserState.Spectating).ConfigureAwait(false);
-                    return;
-
-                case MultiplayerUserState.Spectating:
-                    await ChangeState(MultiplayerUserState.Idle).ConfigureAwait(false);
-                    return;
-
-                default:
-                    throw new InvalidOperationException($"Cannot toggle spectate when in {localUser.State}");
-            }
-        }
-
-        public abstract Task TransferHost(int userId);
-
-        public abstract Task ChangeSettings(MultiplayerRoomSettings settings);
-
-        public abstract Task ChangeState(MultiplayerUserState newState);
-
-        public abstract Task ChangeBeatmapAvailability(BeatmapAvailability newBeatmapAvailability);
-
-        /// <summary>
-        /// Change the local user's mods in the currently joined room.
-        /// </summary>
-        /// <param name="newMods">The proposed new mods, excluding any required by the room itself.</param>
-        public Task ChangeUserMods(IEnumerable<Mod> newMods) => ChangeUserMods(newMods.Select(m => new APIMod(m)).ToList());
-
-        public abstract Task ChangeUserMods(IEnumerable<APIMod> newMods);
-
-        public abstract Task StartMatch();
-
-        Task IMultiplayerClient.RoomStateChanged(MultiplayerRoomState state)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                Debug.Assert(apiRoom != null);
-
-                Room.State = state;
-
-                switch (state)
-                {
-                    case MultiplayerRoomState.Open:
-                        apiRoom.Status.Value = new RoomStatusOpen();
-                        break;
-
-                    case MultiplayerRoomState.Playing:
-                        apiRoom.Status.Value = new RoomStatusPlaying();
-                        break;
-
-                    case MultiplayerRoomState.Closed:
-                        apiRoom.Status.Value = new RoomStatusEnded();
-                        break;
-                }
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        async Task IMultiplayerClient.UserJoined(MultiplayerRoomUser user)
-        {
-            if (Room == null)
-                return;
-
-            await PopulateUser(user).ConfigureAwait(false);
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                // for sanity, ensure that there can be no duplicate users in the room user list.
-                if (Room.Users.Any(existing => existing.UserID == user.UserID))
-                    return;
-
-                Room.Users.Add(user);
-
-                RoomUpdated?.Invoke();
-            }, false);
-        }
-
-        Task IMultiplayerClient.UserLeft(MultiplayerRoomUser user)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                Room.Users.Remove(user);
-                CurrentMatchPlayingUserIds.Remove(user.UserID);
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.HostChanged(int userId)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                Debug.Assert(apiRoom != null);
-
-                var user = Room.Users.FirstOrDefault(u => u.UserID == userId);
-
-                Room.Host = user;
-                apiRoom.Host.Value = user?.User;
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.SettingsChanged(MultiplayerRoomSettings newSettings)
-        {
-            updateLocalRoomSettings(newSettings);
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.UserStateChanged(int userId, MultiplayerUserState state)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                Room.Users.Single(u => u.UserID == userId).State = state;
-
-                updateUserPlayingState(userId, state);
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.UserBeatmapAvailabilityChanged(int userId, BeatmapAvailability beatmapAvailability)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                var user = Room?.Users.SingleOrDefault(u => u.UserID == userId);
-
-                // errors here are not critical - beatmap availability state is mostly for display.
-                if (user == null)
-                    return;
-
-                user.BeatmapAvailability = beatmapAvailability;
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        public Task UserModsChanged(int userId, IEnumerable<APIMod> mods)
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                var user = Room?.Users.SingleOrDefault(u => u.UserID == userId);
-
-                // errors here are not critical - user mods are mostly for display.
-                if (user == null)
-                    return;
-
-                user.Mods = mods;
-
-                RoomUpdated?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.LoadRequested()
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                LoadRequested?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.MatchStarted()
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                MatchStarted?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        Task IMultiplayerClient.ResultsReady()
-        {
-            if (Room == null)
-                return Task.CompletedTask;
-
-            Scheduler.Add(() =>
-            {
-                if (Room == null)
-                    return;
-
-                ResultsReady?.Invoke();
-            }, false);
-
-            return Task.CompletedTask;
-        }
-
-        /// <summary>
-        /// Populates the <see cref="User"/> for a given <see cref="MultiplayerRoomUser"/>.
-        /// </summary>
-        /// <param name="multiplayerUser">The <see cref="MultiplayerRoomUser"/> to populate.</param>
-        protected async Task PopulateUser(MultiplayerRoomUser multiplayerUser) => multiplayerUser.User ??= await userLookupCache.GetUserAsync(multiplayerUser.UserID).ConfigureAwait(false);
-
-        /// <summary>
-        /// Updates the local room settings with the given <see cref="MultiplayerRoomSettings"/>.
-        /// </summary>
-        /// <remarks>
-        /// This updates both the joined <see cref="MultiplayerRoom"/> and the respective API <see cref="Room"/>.
-        /// </remarks>
-        /// <param name="settings">The new <see cref="MultiplayerRoomSettings"/> to update from.</param>
-        /// <param name="cancellationToken">The <see cref="CancellationToken"/> to cancel the update.</param>
-        private Task updateLocalRoomSettings(MultiplayerRoomSettings settings, CancellationToken cancellationToken = default) => scheduleAsync(() =>
-        {
-            if (Room == null)
-                return;
-
-            Debug.Assert(apiRoom != null);
-
-            // Update a few properties of the room instantaneously.
-            Room.Settings = settings;
-            apiRoom.Name.Value = Room.Settings.Name;
-
-            // The current item update is delayed until an online beatmap lookup (below) succeeds.
-            // In-order for the client to not display an outdated beatmap, the current item is forcefully cleared here.
-            CurrentMatchPlayingItem.Value = null;
-
-            RoomUpdated?.Invoke();
-
-            GetOnlineBeatmapSet(settings.BeatmapID, cancellationToken).ContinueWith(set => Schedule(() =>
-            {
-                if (cancellationToken.IsCancellationRequested)
-                    return;
-
-                updatePlaylist(settings, set.Result);
-            }), TaskContinuationOptions.OnlyOnRanToCompletion);
-        }, cancellationToken);
-
-        private void updatePlaylist(MultiplayerRoomSettings settings, BeatmapSetInfo beatmapSet)
-        {
-            if (Room == null || !Room.Settings.Equals(settings))
-                return;
-
-            Debug.Assert(apiRoom != null);
-
-            var beatmap = beatmapSet.Beatmaps.Single(b => b.OnlineBeatmapID == settings.BeatmapID);
-            beatmap.MD5Hash = settings.BeatmapChecksum;
-
-            var ruleset = Rulesets.GetRuleset(settings.RulesetID).CreateInstance();
-            var mods = settings.RequiredMods.Select(m => m.ToMod(ruleset));
-            var allowedMods = settings.AllowedMods.Select(m => m.ToMod(ruleset));
-
-            // Try to retrieve the existing playlist item from the API room.
-            var playlistItem = apiRoom.Playlist.FirstOrDefault(i => i.ID == settings.PlaylistItemId);
-
-            if (playlistItem != null)
-                updateItem(playlistItem);
-            else
-            {
-                // An existing playlist item does not exist, so append a new one.
-                updateItem(playlistItem = new PlaylistItem());
-                apiRoom.Playlist.Add(playlistItem);
-            }
-
-            CurrentMatchPlayingItem.Value = playlistItem;
-
-            void updateItem(PlaylistItem item)
-            {
-                item.ID = settings.PlaylistItemId;
-                item.Beatmap.Value = beatmap;
-                item.Ruleset.Value = ruleset.RulesetInfo;
-                item.RequiredMods.Clear();
-                item.RequiredMods.AddRange(mods);
-                item.AllowedMods.Clear();
-                item.AllowedMods.AddRange(allowedMods);
-            }
-        }
-
-        /// <summary>
-        /// Retrieves a <see cref="BeatmapSetInfo"/> from an online source.
-        /// </summary>
-        /// <param name="beatmapId">The beatmap set ID.</param>
-        /// <param name="cancellationToken">A token to cancel the request.</param>
-        /// <returns>The <see cref="BeatmapSetInfo"/> retrieval task.</returns>
-        protected abstract Task<BeatmapSetInfo> GetOnlineBeatmapSet(int beatmapId, CancellationToken cancellationToken = default);
-
-        /// <summary>
-        /// For the provided user ID, update whether the user is included in <see cref="CurrentMatchPlayingUserIds"/>.
-        /// </summary>
-        /// <param name="userId">The user's ID.</param>
-        /// <param name="state">The new state of the user.</param>
-        private void updateUserPlayingState(int userId, MultiplayerUserState state)
-        {
-            bool wasPlaying = CurrentMatchPlayingUserIds.Contains(userId);
-            bool isPlaying = state >= MultiplayerUserState.WaitingForLoad && state <= MultiplayerUserState.FinishedPlay;
-
-            if (isPlaying == wasPlaying)
-                return;
-
-            if (isPlaying)
-                CurrentMatchPlayingUserIds.Add(userId);
-            else
-                CurrentMatchPlayingUserIds.Remove(userId);
-        }
-
-        private Task scheduleAsync(Action action, CancellationToken cancellationToken = default)
-        {
-            var tcs = new TaskCompletionSource<bool>();
-
-            Scheduler.Add(() =>
-            {
-                if (cancellationToken.IsCancellationRequested)
-                {
-                    tcs.SetCanceled();
-                    return;
-                }
-
-                try
-                {
-                    action();
-                    tcs.SetResult(true);
-                }
-                catch (Exception ex)
-                {
-                    tcs.SetException(ex);
-                }
-            });
-
-            return tcs.Task;
-        }
-    }
-}

osu.Game/Online/Spectator/OnlineSpectatorClient.cs

@@ -0,0 +1,89 @@
+// 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.Threading.Tasks;
+using Microsoft.AspNetCore.SignalR.Client;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Game.Online.API;
+
+namespace osu.Game.Online.Spectator
+{
+    public class OnlineSpectatorClient : SpectatorClient
+    {
+        private readonly string endpoint;
+
+        private IHubClientConnector? connector;
+
+        public override IBindable<bool> IsConnected { get; } = new BindableBool();
+
+        private HubConnection? connection => connector?.CurrentConnection;
+
+        public OnlineSpectatorClient(EndpointConfiguration endpoints)
+        {
+            endpoint = endpoints.SpectatorEndpointUrl;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(IAPIProvider api)
+        {
+            connector = api.GetHubConnector(nameof(SpectatorClient), endpoint);
+
+            if (connector != null)
+            {
+                connector.ConfigureConnection = connection =>
+                {
+                    // until strong typed client support is added, each method must be manually bound
+                    // (see https://github.com/dotnet/aspnetcore/issues/15198)
+                    connection.On<int, SpectatorState>(nameof(ISpectatorClient.UserBeganPlaying), ((ISpectatorClient)this).UserBeganPlaying);
+                    connection.On<int, FrameDataBundle>(nameof(ISpectatorClient.UserSentFrames), ((ISpectatorClient)this).UserSentFrames);
+                    connection.On<int, SpectatorState>(nameof(ISpectatorClient.UserFinishedPlaying), ((ISpectatorClient)this).UserFinishedPlaying);
+                };
+
+                IsConnected.BindTo(connector.IsConnected);
+            }
+        }
+
+        protected override Task BeginPlayingInternal(SpectatorState state)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.SendAsync(nameof(ISpectatorServer.BeginPlaySession), state);
+        }
+
+        protected override Task SendFramesInternal(FrameDataBundle data)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.SendAsync(nameof(ISpectatorServer.SendFrameData), data);
+        }
+
+        protected override Task EndPlayingInternal(SpectatorState state)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.SendAsync(nameof(ISpectatorServer.EndPlaySession), state);
+        }
+
+        protected override Task WatchUserInternal(int userId)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.SendAsync(nameof(ISpectatorServer.StartWatchingUser), userId);
+        }
+
+        protected override Task StopWatchingUserInternal(int userId)
+        {
+            if (!IsConnected.Value)
+                return Task.CompletedTask;
+
+            return connection.SendAsync(nameof(ISpectatorServer.EndWatchingUser), userId);
+        }
+    }
+}

osu.Game/Online/Spectator/SpectatorClient.cs

@@ -0,0 +1,261 @@
+// 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;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Threading.Tasks;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Development;
+using osu.Framework.Graphics;
+using osu.Game.Beatmaps;
+using osu.Game.Online.API;
+using osu.Game.Replays.Legacy;
+using osu.Game.Rulesets;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Replays;
+using osu.Game.Rulesets.Replays.Types;
+using osu.Game.Scoring;
+using osu.Game.Screens.Play;
+
+namespace osu.Game.Online.Spectator
+{
+    public abstract class SpectatorClient : Component, ISpectatorClient
+    {
+        /// <summary>
+        /// The maximum milliseconds between frame bundle sends.
+        /// </summary>
+        public const double TIME_BETWEEN_SENDS = 200;
+
+        /// <summary>
+        /// Whether the <see cref="SpectatorClient"/> is currently connected.
+        /// This is NOT thread safe and usage should be scheduled.
+        /// </summary>
+        public abstract IBindable<bool> IsConnected { get; }
+
+        private readonly List<int> watchingUsers = new List<int>();
+
+        public IBindableList<int> PlayingUsers => playingUsers;
+        private readonly BindableList<int> playingUsers = new BindableList<int>();
+
+        public IBindableDictionary<int, SpectatorState> PlayingUserStates => playingUserStates;
+        private readonly BindableDictionary<int, SpectatorState> playingUserStates = new BindableDictionary<int, SpectatorState>();
+
+        private IBeatmap? currentBeatmap;
+
+        private Score? currentScore;
+
+        [Resolved]
+        private IBindable<RulesetInfo> currentRuleset { get; set; } = null!;
+
+        [Resolved]
+        private IBindable<IReadOnlyList<Mod>> currentMods { get; set; } = null!;
+
+        private readonly SpectatorState currentState = new SpectatorState();
+
+        /// <summary>
+        /// Whether the local user is playing.
+        /// </summary>
+        protected bool IsPlaying { get; private set; }
+
+        /// <summary>
+        /// Called whenever new frames arrive from the server.
+        /// </summary>
+        public event Action<int, FrameDataBundle>? OnNewFrames;
+
+        /// <summary>
+        /// Called whenever a user starts a play session, or immediately if the user is being watched and currently in a play session.
+        /// </summary>
+        public event Action<int, SpectatorState>? OnUserBeganPlaying;
+
+        /// <summary>
+        /// Called whenever a user finishes a play session.
+        /// </summary>
+        public event Action<int, SpectatorState>? OnUserFinishedPlaying;
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            IsConnected.BindValueChanged(connected => Schedule(() =>
+            {
+                if (connected.NewValue)
+                {
+                    // get all the users that were previously being watched
+                    int[] users = watchingUsers.ToArray();
+                    watchingUsers.Clear();
+
+                    // resubscribe to watched users.
+                    foreach (var userId in users)
+                        WatchUser(userId);
+
+                    // re-send state in case it wasn't received
+                    if (IsPlaying)
+                        BeginPlayingInternal(currentState);
+                }
+                else
+                {
+                    playingUsers.Clear();
+                    playingUserStates.Clear();
+                }
+            }), true);
+        }
+
+        Task ISpectatorClient.UserBeganPlaying(int userId, SpectatorState state)
+        {
+            Schedule(() =>
+            {
+                if (!playingUsers.Contains(userId))
+                    playingUsers.Add(userId);
+
+                // UserBeganPlaying() is called by the server regardless of whether the local user is watching the remote user, and is called a further time when the remote user is watched.
+                // This may be a temporary thing (see: https://github.com/ppy/osu-server-spectator/blob/2273778e02cfdb4a9c6a934f2a46a8459cb5d29c/osu.Server.Spectator/Hubs/SpectatorHub.cs#L28-L29).
+                // We don't want the user states to update unless the player is being watched, otherwise calling BindUserBeganPlaying() can lead to double invocations.
+                if (watchingUsers.Contains(userId))
+                    playingUserStates[userId] = state;
+
+                OnUserBeganPlaying?.Invoke(userId, state);
+            });
+
+            return Task.CompletedTask;
+        }
+
+        Task ISpectatorClient.UserFinishedPlaying(int userId, SpectatorState state)
+        {
+            Schedule(() =>
+            {
+                playingUsers.Remove(userId);
+                playingUserStates.Remove(userId);
+
+                OnUserFinishedPlaying?.Invoke(userId, state);
+            });
+
+            return Task.CompletedTask;
+        }
+
+        Task ISpectatorClient.UserSentFrames(int userId, FrameDataBundle data)
+        {
+            Schedule(() => OnNewFrames?.Invoke(userId, data));
+
+            return Task.CompletedTask;
+        }
+
+        public void BeginPlaying(GameplayBeatmap beatmap, Score score)
+        {
+            Debug.Assert(ThreadSafety.IsUpdateThread);
+
+            if (IsPlaying)
+                throw new InvalidOperationException($"Cannot invoke {nameof(BeginPlaying)} when already playing");
+
+            IsPlaying = true;
+
+            // transfer state at point of beginning play
+            currentState.BeatmapID = beatmap.BeatmapInfo.OnlineBeatmapID;
+            currentState.RulesetID = currentRuleset.Value.ID;
+            currentState.Mods = currentMods.Value.Select(m => new APIMod(m));
+
+            currentBeatmap = beatmap.PlayableBeatmap;
+            currentScore = score;
+
+            BeginPlayingInternal(currentState);
+        }
+
+        public void SendFrames(FrameDataBundle data) => lastSend = SendFramesInternal(data);
+
+        public void EndPlaying()
+        {
+            // This method is most commonly called via Dispose(), which is asynchronous.
+            // Todo: This should not be a thing, but requires framework changes.
+            Schedule(() =>
+            {
+                if (!IsPlaying)
+                    return;
+
+                IsPlaying = false;
+                currentBeatmap = null;
+
+                EndPlayingInternal(currentState);
+            });
+        }
+
+        public void WatchUser(int userId)
+        {
+            Debug.Assert(ThreadSafety.IsUpdateThread);
+
+            if (watchingUsers.Contains(userId))
+                return;
+
+            watchingUsers.Add(userId);
+
+            WatchUserInternal(userId);
+        }
+
+        public void StopWatchingUser(int userId)
+        {
+            // This method is most commonly called via Dispose(), which is asynchronous.
+            // Todo: This should not be a thing, but requires framework changes.
+            Schedule(() =>
+            {
+                watchingUsers.Remove(userId);
+                playingUserStates.Remove(userId);
+                StopWatchingUserInternal(userId);
+            });
+        }
+
+        protected abstract Task BeginPlayingInternal(SpectatorState state);
+
+        protected abstract Task SendFramesInternal(FrameDataBundle data);
+
+        protected abstract Task EndPlayingInternal(SpectatorState state);
+
+        protected abstract Task WatchUserInternal(int userId);
+
+        protected abstract Task StopWatchingUserInternal(int userId);
+
+        private readonly Queue<LegacyReplayFrame> pendingFrames = new Queue<LegacyReplayFrame>();
+
+        private double lastSendTime;
+
+        private Task? lastSend;
+
+        private const int max_pending_frames = 30;
+
+        protected override void Update()
+        {
+            base.Update();
+
+            if (pendingFrames.Count > 0 && Time.Current - lastSendTime > TIME_BETWEEN_SENDS)
+                purgePendingFrames();
+        }
+
+        public void HandleFrame(ReplayFrame frame)
+        {
+            Debug.Assert(ThreadSafety.IsUpdateThread);
+
+            if (frame is IConvertibleReplayFrame convertible)
+                pendingFrames.Enqueue(convertible.ToLegacy(currentBeatmap));
+
+            if (pendingFrames.Count > max_pending_frames)
+                purgePendingFrames();
+        }
+
+        private void purgePendingFrames()
+        {
+            if (lastSend?.IsCompleted == false)
+                return;
+
+            var frames = pendingFrames.ToArray();
+
+            pendingFrames.Clear();
+
+            Debug.Assert(currentScore != null);
+
+            SendFrames(new FrameDataBundle(currentScore.ScoreInfo, frames));
+
+            lastSendTime = Time.Current;
+        }
+    }
+}

osu.Game/Online/Spectator/SpectatorStreamingClient.cs

@@ -1,323 +0,0 @@
-// 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.Linq;
-using System.Threading.Tasks;
-using JetBrains.Annotations;
-using Microsoft.AspNetCore.SignalR.Client;
-using osu.Framework.Allocation;
-using osu.Framework.Bindables;
-using osu.Framework.Graphics;
-using osu.Game.Beatmaps;
-using osu.Game.Online.API;
-using osu.Game.Replays.Legacy;
-using osu.Game.Rulesets;
-using osu.Game.Rulesets.Mods;
-using osu.Game.Rulesets.Replays;
-using osu.Game.Rulesets.Replays.Types;
-using osu.Game.Scoring;
-using osu.Game.Screens.Play;
-
-namespace osu.Game.Online.Spectator
-{
-    public class SpectatorStreamingClient : Component, ISpectatorClient
-    {
-        /// <summary>
-        /// The maximum milliseconds between frame bundle sends.
-        /// </summary>
-        public const double TIME_BETWEEN_SENDS = 200;
-
-        private readonly string endpoint;
-
-        [CanBeNull]
-        private IHubClientConnector connector;
-
-        private readonly IBindable<bool> isConnected = new BindableBool();
-
-        private HubConnection connection => connector?.CurrentConnection;
-
-        private readonly List<int> watchingUsers = new List<int>();
-
-        private readonly object userLock = new object();
-
-        public IBindableList<int> PlayingUsers => playingUsers;
-
-        private readonly BindableList<int> playingUsers = new BindableList<int>();
-
-        private readonly Dictionary<int, SpectatorState> playingUserStates = new Dictionary<int, SpectatorState>();
-
-        [CanBeNull]
-        private IBeatmap currentBeatmap;
-
-        [CanBeNull]
-        private Score currentScore;
-
-        [Resolved]
-        private IBindable<RulesetInfo> currentRuleset { get; set; }
-
-        [Resolved]
-        private IBindable<IReadOnlyList<Mod>> currentMods { get; set; }
-
-        private readonly SpectatorState currentState = new SpectatorState();
-
-        private bool isPlaying;
-
-        /// <summary>
-        /// Called whenever new frames arrive from the server.
-        /// </summary>
-        public event Action<int, FrameDataBundle> OnNewFrames;
-
-        /// <summary>
-        /// Called whenever a user starts a play session, or immediately if the user is being watched and currently in a play session.
-        /// </summary>
-        public event Action<int, SpectatorState> OnUserBeganPlaying;
-
-        /// <summary>
-        /// Called whenever a user finishes a play session.
-        /// </summary>
-        public event Action<int, SpectatorState> OnUserFinishedPlaying;
-
-        public SpectatorStreamingClient(EndpointConfiguration endpoints)
-        {
-            endpoint = endpoints.SpectatorEndpointUrl;
-        }
-
-        [BackgroundDependencyLoader]
-        private void load(IAPIProvider api)
-        {
-            connector = api.GetHubConnector(nameof(SpectatorStreamingClient), endpoint);
-
-            if (connector != null)
-            {
-                connector.ConfigureConnection = connection =>
-                {
-                    // until strong typed client support is added, each method must be manually bound
-                    // (see https://github.com/dotnet/aspnetcore/issues/15198)
-                    connection.On<int, SpectatorState>(nameof(ISpectatorClient.UserBeganPlaying), ((ISpectatorClient)this).UserBeganPlaying);
-                    connection.On<int, FrameDataBundle>(nameof(ISpectatorClient.UserSentFrames), ((ISpectatorClient)this).UserSentFrames);
-                    connection.On<int, SpectatorState>(nameof(ISpectatorClient.UserFinishedPlaying), ((ISpectatorClient)this).UserFinishedPlaying);
-                };
-
-                isConnected.BindTo(connector.IsConnected);
-                isConnected.BindValueChanged(connected =>
-                {
-                    if (connected.NewValue)
-                    {
-                        // get all the users that were previously being watched
-                        int[] users;
-
-                        lock (userLock)
-                        {
-                            users = watchingUsers.ToArray();
-                            watchingUsers.Clear();
-                        }
-
-                        // resubscribe to watched users.
-                        foreach (var userId in users)
-                            WatchUser(userId);
-
-                        // re-send state in case it wasn't received
-                        if (isPlaying)
-                            beginPlaying();
-                    }
-                    else
-                    {
-                        lock (userLock)
-                        {
-                            playingUsers.Clear();
-                            playingUserStates.Clear();
-                        }
-                    }
-                }, true);
-            }
-        }
-
-        Task ISpectatorClient.UserBeganPlaying(int userId, SpectatorState state)
-        {
-            lock (userLock)
-            {
-                if (!playingUsers.Contains(userId))
-                    playingUsers.Add(userId);
-
-                // UserBeganPlaying() is called by the server regardless of whether the local user is watching the remote user, and is called a further time when the remote user is watched.
-                // This may be a temporary thing (see: https://github.com/ppy/osu-server-spectator/blob/2273778e02cfdb4a9c6a934f2a46a8459cb5d29c/osu.Server.Spectator/Hubs/SpectatorHub.cs#L28-L29).
-                // We don't want the user states to update unless the player is being watched, otherwise calling BindUserBeganPlaying() can lead to double invocations.
-                if (watchingUsers.Contains(userId))
-                    playingUserStates[userId] = state;
-            }
-
-            OnUserBeganPlaying?.Invoke(userId, state);
-
-            return Task.CompletedTask;
-        }
-
-        Task ISpectatorClient.UserFinishedPlaying(int userId, SpectatorState state)
-        {
-            lock (userLock)
-            {
-                playingUsers.Remove(userId);
-                playingUserStates.Remove(userId);
-            }
-
-            OnUserFinishedPlaying?.Invoke(userId, state);
-
-            return Task.CompletedTask;
-        }
-
-        Task ISpectatorClient.UserSentFrames(int userId, FrameDataBundle data)
-        {
-            OnNewFrames?.Invoke(userId, data);
-
-            return Task.CompletedTask;
-        }
-
-        public void BeginPlaying(GameplayBeatmap beatmap, Score score)
-        {
-            if (isPlaying)
-                throw new InvalidOperationException($"Cannot invoke {nameof(BeginPlaying)} when already playing");
-
-            isPlaying = true;
-
-            // transfer state at point of beginning play
-            currentState.BeatmapID = beatmap.BeatmapInfo.OnlineBeatmapID;
-            currentState.RulesetID = currentRuleset.Value.ID;
-            currentState.Mods = currentMods.Value.Select(m => new APIMod(m));
-
-            currentBeatmap = beatmap.PlayableBeatmap;
-            currentScore = score;
-
-            beginPlaying();
-        }
-
-        private void beginPlaying()
-        {
-            Debug.Assert(isPlaying);
-
-            if (!isConnected.Value) return;
-
-            connection.SendAsync(nameof(ISpectatorServer.BeginPlaySession), currentState);
-        }
-
-        public void SendFrames(FrameDataBundle data)
-        {
-            if (!isConnected.Value) return;
-
-            lastSend = connection.SendAsync(nameof(ISpectatorServer.SendFrameData), data);
-        }
-
-        public void EndPlaying()
-        {
-            isPlaying = false;
-            currentBeatmap = null;
-
-            if (!isConnected.Value) return;
-
-            connection.SendAsync(nameof(ISpectatorServer.EndPlaySession), currentState);
-        }
-
-        public virtual void WatchUser(int userId)
-        {
-            lock (userLock)
-            {
-                if (watchingUsers.Contains(userId))
-                    return;
-
-                watchingUsers.Add(userId);
-
-                if (!isConnected.Value)
-                    return;
-            }
-
-            connection.SendAsync(nameof(ISpectatorServer.StartWatchingUser), userId);
-        }
-
-        public virtual void StopWatchingUser(int userId)
-        {
-            lock (userLock)
-            {
-                watchingUsers.Remove(userId);
-
-                if (!isConnected.Value)
-                    return;
-            }
-
-            connection.SendAsync(nameof(ISpectatorServer.EndWatchingUser), userId);
-        }
-
-        private readonly Queue<LegacyReplayFrame> pendingFrames = new Queue<LegacyReplayFrame>();
-
-        private double lastSendTime;
-
-        private Task lastSend;
-
-        private const int max_pending_frames = 30;
-
-        protected override void Update()
-        {
-            base.Update();
-
-            if (pendingFrames.Count > 0 && Time.Current - lastSendTime > TIME_BETWEEN_SENDS)
-                purgePendingFrames();
-        }
-
-        public void HandleFrame(ReplayFrame frame)
-        {
-            if (frame is IConvertibleReplayFrame convertible)
-                pendingFrames.Enqueue(convertible.ToLegacy(currentBeatmap));
-
-            if (pendingFrames.Count > max_pending_frames)
-                purgePendingFrames();
-        }
-
-        private void purgePendingFrames()
-        {
-            if (lastSend?.IsCompleted == false)
-                return;
-
-            var frames = pendingFrames.ToArray();
-
-            pendingFrames.Clear();
-
-            Debug.Assert(currentScore != null);
-
-            SendFrames(new FrameDataBundle(currentScore.ScoreInfo, frames));
-
-            lastSendTime = Time.Current;
-        }
-
-        /// <summary>
-        /// Attempts to retrieve the <see cref="SpectatorState"/> for a currently-playing user.
-        /// </summary>
-        /// <param name="userId">The user.</param>
-        /// <param name="state">The current <see cref="SpectatorState"/> for the user, if they're playing. <c>null</c> if the user is not playing.</param>
-        /// <returns><c>true</c> if successful (the user is playing), <c>false</c> otherwise.</returns>
-        public bool TryGetPlayingUserState(int userId, out SpectatorState state)
-        {
-            lock (userLock)
-                return playingUserStates.TryGetValue(userId, out state);
-        }
-
-        /// <summary>
-        /// Bind an action to <see cref="OnUserBeganPlaying"/> with the option of running the bound action once immediately.
-        /// </summary>
-        /// <param name="callback">The action to perform when a user begins playing.</param>
-        /// <param name="runOnceImmediately">Whether the action provided in <paramref name="callback"/> should be run once immediately for all users currently playing.</param>
-        public void BindUserBeganPlaying(Action<int, SpectatorState> callback, bool runOnceImmediately = false)
-        {
-            // The lock is taken before the event is subscribed to to prevent doubling of events.
-            lock (userLock)
-            {
-                OnUserBeganPlaying += callback;
-
-                if (!runOnceImmediately)
-                    return;
-
-                foreach (var (userId, state) in playingUserStates)
-                    callback(userId, state);
-            }
-        }
-    }
-}

osu.Game/OsuGame.cs

@@ -100,6 +100,9 @@ namespace osu.Game
         [Cached]
         private readonly DifficultyRecommender difficultyRecommender = new DifficultyRecommender();
 
+        [Cached]
+        private readonly StableImportManager stableImportManager = new StableImportManager();
+
         [Cached]
         private readonly ScreenshotManager screenshotManager = new ScreenshotManager();
 
@@ -566,14 +569,11 @@ namespace osu.Game
 
             // todo: all archive managers should be able to be looped here.
             SkinManager.PostNotification = n => notifications.Post(n);
-            SkinManager.GetStableStorage = GetStorageForStableInstall;
 
             BeatmapManager.PostNotification = n => notifications.Post(n);
-            BeatmapManager.GetStableStorage = GetStorageForStableInstall;
             BeatmapManager.PresentImport = items => PresentBeatmap(items.First());
 
             ScoreManager.PostNotification = n => notifications.Post(n);
-            ScoreManager.GetStableStorage = GetStorageForStableInstall;
             ScoreManager.PresentImport = items => PresentScore(items.First());
 
             // make config aware of how to lookup skins for on-screen display purposes.
@@ -690,10 +690,10 @@ namespace osu.Game
             loadComponentSingleFile(new CollectionManager(Storage)
             {
                 PostNotification = n => notifications.Post(n),
-                GetStableStorage = GetStorageForStableInstall
             }, Add, true);
 
             loadComponentSingleFile(difficultyRecommender, Add);
+            loadComponentSingleFile(stableImportManager, Add);
 
             loadComponentSingleFile(screenshotManager, Add);
 

osu.Game/OsuGameBase.cs

@@ -85,8 +85,8 @@ namespace osu.Game
 
         protected IAPIProvider API;
 
-        private SpectatorStreamingClient spectatorStreaming;
-        private StatefulMultiplayerClient multiplayerClient;
+        private SpectatorClient spectatorClient;
+        private MultiplayerClient multiplayerClient;
 
         protected MenuCursorContainer MenuCursorContainer;
 
@@ -240,8 +240,8 @@ namespace osu.Game
 
             dependencies.CacheAs(API ??= new APIAccess(LocalConfig, endpoints, VersionHash));
 
-            dependencies.CacheAs(spectatorStreaming = new SpectatorStreamingClient(endpoints));
-            dependencies.CacheAs(multiplayerClient = new MultiplayerClient(endpoints));
+            dependencies.CacheAs(spectatorClient = new OnlineSpectatorClient(endpoints));
+            dependencies.CacheAs(multiplayerClient = new OnlineMultiplayerClient(endpoints));
 
             var defaultBeatmap = new DummyWorkingBeatmap(Audio, Textures);
 
@@ -313,7 +313,7 @@ namespace osu.Game
             // add api components to hierarchy.
             if (API is APIAccess apiAccess)
                 AddInternal(apiAccess);
-            AddInternal(spectatorStreaming);
+            AddInternal(spectatorClient);
             AddInternal(multiplayerClient);
 
             AddInternal(RulesetConfigCache);

osu.Game/Overlays/AccountCreation/ScreenWarning.cs

@@ -23,14 +23,17 @@ namespace osu.Game.Overlays.AccountCreation
         private OsuTextFlowContainer multiAccountExplanationText;
         private LinkFlowContainer furtherAssistance;
 
-        [Resolved(CanBeNull = true)]
+        [Resolved(canBeNull: true)]
         private IAPIProvider api { get; set; }
 
+        [Resolved(canBeNull: true)]
+        private OsuGame game { get; set; }
+
         private const string help_centre_url = "/help/wiki/Help_Centre#login";
 
         public override void OnEntering(IScreen last)
         {
-            if (string.IsNullOrEmpty(api?.ProvidedUsername))
+            if (string.IsNullOrEmpty(api?.ProvidedUsername) || game?.UseDevelopmentServer == true)
             {
                 this.FadeOut();
                 this.Push(new ScreenEntry());
@@ -41,7 +44,7 @@ namespace osu.Game.Overlays.AccountCreation
         }
 
         [BackgroundDependencyLoader(true)]
-        private void load(OsuColour colours, OsuGame game, TextureStore textures)
+        private void load(OsuColour colours, TextureStore textures)
         {
             if (string.IsNullOrEmpty(api?.ProvidedUsername))
                 return;

osu.Game/Overlays/BreadcrumbControlOverlayHeader.cs

@@ -26,7 +26,10 @@ namespace osu.Game.Overlays
                 AccentColour = colourProvider.Light2;
             }
 
-            protected override TabItem<string> CreateTabItem(string value) => new ControlTabItem(value);
+            protected override TabItem<string> CreateTabItem(string value) => new ControlTabItem(value)
+            {
+                AccentColour = AccentColour,
+            };
 
             private class ControlTabItem : BreadcrumbTabItem
             {

osu.Game/Overlays/Dashboard/CurrentlyPlayingDisplay.cs

@@ -25,7 +25,7 @@ namespace osu.Game.Overlays.Dashboard
         private FillFlowContainer<PlayingUserPanel> userFlow;
 
         [Resolved]
-        private SpectatorStreamingClient spectatorStreaming { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [BackgroundDependencyLoader]
         private void load()
@@ -52,7 +52,7 @@ namespace osu.Game.Overlays.Dashboard
         {
             base.LoadComplete();
 
-            playingUsers.BindTo(spectatorStreaming.PlayingUsers);
+            playingUsers.BindTo(spectatorClient.PlayingUsers);
             playingUsers.BindCollectionChanged(onUsersChanged, true);
         }
 

osu.Game/Overlays/Mods/ModSelectOverlay.cs

@@ -96,7 +96,8 @@ namespace osu.Game.Overlays.Mods
             Waves.ThirdWaveColour = Color4Extensions.FromHex(@"005774");
             Waves.FourthWaveColour = Color4Extensions.FromHex(@"003a4e");
 
-            RelativeSizeAxes = Axes.Both;
+            RelativeSizeAxes = Axes.X;
+            Height = HEIGHT;
 
             Padding = new MarginPadding { Horizontal = -OsuScreen.HORIZONTAL_OVERFLOW_PADDING };
 

osu.Game/Overlays/News/Displays/ArticleListing.cs

@@ -1,6 +1,7 @@
 // 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.Linq;
 using System.Threading;
 using osu.Framework.Allocation;
@@ -9,12 +10,18 @@ using osu.Framework.Graphics.Containers;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Online.API;
 using osu.Game.Online.API.Requests;
+using osu.Game.Online.API.Requests.Responses;
 using osuTK;
 
 namespace osu.Game.Overlays.News.Displays
 {
-    public class FrontPageDisplay : CompositeDrawable
+    /// <summary>
+    /// Lists articles in a vertical flow for a specified year.
+    /// </summary>
+    public class ArticleListing : CompositeDrawable
     {
+        public Action<APINewsSidebar> SidebarMetadataUpdated;
+
         [Resolved]
         private IAPIProvider api { get; set; }
 
@@ -24,6 +31,17 @@ namespace osu.Game.Overlays.News.Displays
         private GetNewsRequest request;
         private Cursor lastCursor;
 
+        private readonly int? year;
+
+        /// <summary>
+        /// Instantiate a listing for the specified year.
+        /// </summary>
+        /// <param name="year">The year to load articles from. If null, will show the most recent articles.</param>
+        public ArticleListing(int? year = null)
+        {
+            this.year = year;
+        }
+
         [BackgroundDependencyLoader]
         private void load()
         {
@@ -74,7 +92,7 @@ namespace osu.Game.Overlays.News.Displays
         {
             request?.Cancel();
 
-            request = new GetNewsRequest(lastCursor);
+            request = new GetNewsRequest(year, lastCursor);
             request.Success += response => Schedule(() => onSuccess(response));
             api.PerformAsync(request);
         }
@@ -85,22 +103,19 @@ namespace osu.Game.Overlays.News.Displays
         {
             cancellationToken?.Cancel();
 
+            // only needs to be updated on the initial load, as the content won't change during pagination.
+            if (lastCursor == null)
+                SidebarMetadataUpdated?.Invoke(response.SidebarMetadata);
+
+            // store cursor for next pagination request.
             lastCursor = response.Cursor;
 
-            var flow = new FillFlowContainer<NewsCard>
+            LoadComponentsAsync(response.NewsPosts.Select(p => new NewsCard(p)).ToList(), loaded =>
             {
-                RelativeSizeAxes = Axes.X,
-                AutoSizeAxes = Axes.Y,
-                Direction = FillDirection.Vertical,
-                Spacing = new Vector2(0, 10),
-                Children = response.NewsPosts.Select(p => new NewsCard(p)).ToList()
-            };
+                content.AddRange(loaded);
 
-            LoadComponentAsync(flow, loaded =>
-            {
-                content.Add(loaded);
                 showMore.IsLoading = false;
-                showMore.Alpha = lastCursor == null ? 0 : 1;
+                showMore.Alpha = response.Cursor != null ? 1 : 0;
             }, (cancellationToken = new CancellationTokenSource()).Token);
         }
 

osu.Game/Overlays/News/NewsHeader.cs

@@ -19,13 +19,18 @@ namespace osu.Game.Overlays.News
         {
             TabControl.AddItem(front_page_string);
 
+            article.BindValueChanged(onArticleChanged, true);
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
             Current.BindValueChanged(e =>
             {
                 if (e.NewValue == front_page_string)
                     ShowFrontPage?.Invoke();
             });
-
-            article.BindValueChanged(onArticleChanged, true);
         }
 
         public void SetFrontPage() => article.Value = null;

osu.Game/Overlays/News/Sidebar/NewsSidebar.cs

@@ -9,6 +9,7 @@ using osu.Game.Online.API.Requests.Responses;
 using osu.Framework.Graphics.Shapes;
 using osuTK;
 using System.Linq;
+using osu.Game.Graphics.Containers;
 
 namespace osu.Game.Overlays.News.Sidebar
 {
@@ -31,30 +32,55 @@ namespace osu.Game.Overlays.News.Sidebar
                     RelativeSizeAxes = Axes.Both,
                     Colour = colourProvider.Background4
                 },
+                new Box
+                {
+                    RelativeSizeAxes = Axes.Y,
+                    Width = OsuScrollContainer.SCROLL_BAR_HEIGHT,
+                    Anchor = Anchor.TopRight,
+                    Origin = Anchor.TopRight,
+                    Colour = colourProvider.Background3,
+                    Alpha = 0.5f
+                },
                 new Container
                 {
                     RelativeSizeAxes = Axes.Both,
-                    Padding = new MarginPadding
+                    Padding = new MarginPadding { Right = -3 }, // Compensate for scrollbar margin
+                    Child = new OsuScrollContainer
                     {
-                        Vertical = 20,
-                        Left = 50,
-                        Right = 30
-                    },
-                    Child = new FillFlowContainer
-                    {
-                        Direction = FillDirection.Vertical,
-                        RelativeSizeAxes = Axes.X,
-                        AutoSizeAxes = Axes.Y,
-                        Spacing = new Vector2(0, 20),
-                        Children = new Drawable[]
+                        RelativeSizeAxes = Axes.Both,
+                        Child = new Container
                         {
-                            new YearsPanel(),
-                            monthsFlow = new FillFlowContainer<MonthSection>
+                            RelativeSizeAxes = Axes.X,
+                            AutoSizeAxes = Axes.Y,
+                            Padding = new MarginPadding { Right = 3 }, // Addeded 3px back
+                            Child = new Container
                             {
-                                AutoSizeAxes = Axes.Y,
                                 RelativeSizeAxes = Axes.X,
-                                Direction = FillDirection.Vertical,
-                                Spacing = new Vector2(0, 10)
+                                AutoSizeAxes = Axes.Y,
+                                Padding = new MarginPadding
+                                {
+                                    Vertical = 20,
+                                    Left = 50,
+                                    Right = 30
+                                },
+                                Child = new FillFlowContainer
+                                {
+                                    Direction = FillDirection.Vertical,
+                                    RelativeSizeAxes = Axes.X,
+                                    AutoSizeAxes = Axes.Y,
+                                    Spacing = new Vector2(0, 20),
+                                    Children = new Drawable[]
+                                    {
+                                        new YearsPanel(),
+                                        monthsFlow = new FillFlowContainer<MonthSection>
+                                        {
+                                            AutoSizeAxes = Axes.Y,
+                                            RelativeSizeAxes = Axes.X,
+                                            Direction = FillDirection.Vertical,
+                                            Spacing = new Vector2(0, 10)
+                                        }
+                                    }
+                                }
                             }
                         }
                     }

osu.Game/Overlays/News/Sidebar/YearsPanel.cs

@@ -81,6 +81,9 @@ namespace osu.Game.Overlays.News.Sidebar
         {
             public int Year { get; }
 
+            [Resolved(canBeNull: true)]
+            private NewsOverlay overlay { get; set; }
+
             private readonly bool isCurrent;
 
             public YearButton(int year, bool isCurrent)
@@ -106,7 +109,11 @@ namespace osu.Game.Overlays.News.Sidebar
             {
                 IdleColour = isCurrent ? Color4.White : colourProvider.Light2;
                 HoverColour = isCurrent ? Color4.White : colourProvider.Light1;
-                Action = () => { }; // Avoid button being disabled since there's no proper action assigned.
+                Action = () =>
+                {
+                    if (!isCurrent)
+                        overlay?.ShowYear(Year);
+                };
             }
         }
     }

osu.Game/Overlays/NewsOverlay.cs

@@ -1,11 +1,14 @@
 // 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.Threading;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
 using osu.Game.Overlays.News;
 using osu.Game.Overlays.News.Displays;
+using osu.Game.Overlays.News.Sidebar;
 
 namespace osu.Game.Overlays
 {
@@ -13,9 +16,48 @@ namespace osu.Game.Overlays
     {
         private readonly Bindable<string> article = new Bindable<string>(null);
 
+        private readonly Container sidebarContainer;
+        private readonly NewsSidebar sidebar;
+
+        private readonly Container content;
+
+        private CancellationTokenSource cancellationToken;
+
+        private bool displayUpdateRequired = true;
+
         public NewsOverlay()
             : base(OverlayColourScheme.Purple, false)
         {
+            Child = new GridContainer
+            {
+                RelativeSizeAxes = Axes.X,
+                AutoSizeAxes = Axes.Y,
+                RowDimensions = new[]
+                {
+                    new Dimension(GridSizeMode.AutoSize)
+                },
+                ColumnDimensions = new[]
+                {
+                    new Dimension(GridSizeMode.AutoSize),
+                    new Dimension()
+                },
+                Content = new[]
+                {
+                    new Drawable[]
+                    {
+                        sidebarContainer = new Container
+                        {
+                            AutoSizeAxes = Axes.X,
+                            Child = sidebar = new NewsSidebar()
+                        },
+                        content = new Container
+                        {
+                            RelativeSizeAxes = Axes.X,
+                            AutoSizeAxes = Axes.Y
+                        }
+                    }
+                }
+            };
         }
 
         protected override void LoadComplete()
@@ -26,12 +68,7 @@ namespace osu.Game.Overlays
             article.BindValueChanged(onArticleChanged);
         }
 
-        protected override NewsHeader CreateHeader() => new NewsHeader
-        {
-            ShowFrontPage = ShowFrontPage
-        };
-
-        private bool displayUpdateRequired = true;
+        protected override NewsHeader CreateHeader() => new NewsHeader { ShowFrontPage = ShowFrontPage };
 
         protected override void PopIn()
         {
@@ -56,38 +93,69 @@ namespace osu.Game.Overlays
             Show();
         }
 
+        public void ShowYear(int year)
+        {
+            loadFrontPage(year);
+            Show();
+        }
+
         public void ShowArticle(string slug)
         {
             article.Value = slug;
             Show();
         }
 
-        private CancellationTokenSource cancellationToken;
-
-        private void onArticleChanged(ValueChangedEvent<string> e)
-        {
-            cancellationToken?.Cancel();
-            Loading.Show();
-
-            if (e.NewValue == null)
-            {
-                Header.SetFrontPage();
-                LoadDisplay(new FrontPageDisplay());
-                return;
-            }
-
-            Header.SetArticle(e.NewValue);
-            LoadDisplay(Empty());
-        }
-
         protected void LoadDisplay(Drawable display)
         {
             ScrollFlow.ScrollToStart();
-            LoadComponentAsync(display, loaded =>
+            LoadComponentAsync(display, loaded => content.Child = loaded, (cancellationToken = new CancellationTokenSource()).Token);
+        }
+
+        protected override void UpdateAfterChildren()
+        {
+            base.UpdateAfterChildren();
+            sidebarContainer.Height = DrawHeight;
+            sidebarContainer.Y = Math.Clamp(ScrollFlow.Current - Header.DrawHeight, 0, Math.Max(ScrollFlow.ScrollContent.DrawHeight - DrawHeight - Header.DrawHeight, 0));
+        }
+
+        private void onArticleChanged(ValueChangedEvent<string> article)
+        {
+            if (article.NewValue == null)
+                loadFrontPage();
+            else
+                loadArticle(article.NewValue);
+        }
+
+        private void loadFrontPage(int? year = null)
+        {
+            beginLoading();
+
+            Header.SetFrontPage();
+
+            var page = new ArticleListing(year);
+            page.SidebarMetadataUpdated += metadata => Schedule(() =>
             {
-                Child = loaded;
+                sidebar.Metadata.Value = metadata;
                 Loading.Hide();
-            }, (cancellationToken = new CancellationTokenSource()).Token);
+            });
+            LoadDisplay(page);
+        }
+
+        private void loadArticle(string article)
+        {
+            beginLoading();
+
+            Header.SetArticle(article);
+
+            // Temporary, should be handled by ArticleDisplay later
+            LoadDisplay(Empty());
+            Loading.Hide();
+        }
+
+        private void beginLoading()
+        {
+            cancellationToken?.Cancel();
+            Loading.Show();
         }
 
         protected override void Dispose(bool isDisposing)

osu.Game/Overlays/Settings/Sections/Gameplay/GeneralSettings.cs

@@ -73,11 +73,6 @@ namespace osu.Game.Overlays.Settings.Sections.Gameplay
                     LabelText = "Always play first combo break sound",
                     Current = config.GetBindable<bool>(OsuSetting.AlwaysPlayFirstComboBreak)
                 },
-                new SettingsEnumDropdown<ScoreMeterType>
-                {
-                    LabelText = "Score meter type",
-                    Current = config.GetBindable<ScoreMeterType>(OsuSetting.ScoreMeter)
-                },
                 new SettingsEnumDropdown<ScoringMode>
                 {
                     LabelText = "Score display mode",

osu.Game/Overlays/Settings/Sections/Maintenance/DirectorySelectScreen.cs

@@ -11,9 +11,9 @@ using osuTK;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Localisation;
-using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
 using osu.Framework.Screens;
+using osu.Game.Graphics.Containers;
 
 namespace osu.Game.Overlays.Settings.Sections.Maintenance
 {
@@ -69,20 +69,24 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                         RelativeSizeAxes = Axes.Both,
                         RowDimensions = new[]
                         {
+                            new Dimension(GridSizeMode.AutoSize),
                             new Dimension(),
-                            new Dimension(GridSizeMode.Relative, 0.8f),
-                            new Dimension(),
+                            new Dimension(GridSizeMode.AutoSize),
                         },
                         Content = new[]
                         {
                             new Drawable[]
                             {
-                                new OsuSpriteText
+                                new OsuTextFlowContainer(cp =>
                                 {
-                                    Text = HeaderText,
-                                    Font = OsuFont.Default.With(size: 40),
-                                    Origin = Anchor.Centre,
-                                    Anchor = Anchor.Centre,
+                                    cp.Font = OsuFont.Default.With(size: 24);
+                                })
+                                {
+                                    Text = HeaderText.ToString(),
+                                    TextAnchor = Anchor.TopCentre,
+                                    Margin = new MarginPadding(10),
+                                    RelativeSizeAxes = Axes.X,
+                                    AutoSizeAxes = Axes.Y,
                                 }
                             },
                             new Drawable[]
@@ -99,6 +103,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                                     Anchor = Anchor.Centre,
                                     Origin = Anchor.Centre,
                                     Width = 300,
+                                    Margin = new MarginPadding(10),
                                     Text = "Select directory",
                                     Action = () => OnSelection(directorySelector.CurrentPath.Value)
                                 },

osu.Game/Overlays/Settings/Sections/Maintenance/GeneralSettings.cs

@@ -8,6 +8,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Game.Beatmaps;
 using osu.Game.Collections;
+using osu.Game.Database;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Scoring;
 using osu.Game.Skinning;
@@ -29,9 +30,9 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
         private TriangleButton undeleteButton;
 
         [BackgroundDependencyLoader(permitNulls: true)]
-        private void load(BeatmapManager beatmaps, ScoreManager scores, SkinManager skins, [CanBeNull] CollectionManager collectionManager, DialogOverlay dialogOverlay)
+        private void load(BeatmapManager beatmaps, ScoreManager scores, SkinManager skins, [CanBeNull] CollectionManager collectionManager, [CanBeNull] StableImportManager stableImportManager, DialogOverlay dialogOverlay)
         {
-            if (beatmaps.SupportsImportFromStable)
+            if (stableImportManager?.SupportsImportFromStable == true)
             {
                 Add(importBeatmapsButton = new SettingsButton
                 {
@@ -39,7 +40,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                     Action = () =>
                     {
                         importBeatmapsButton.Enabled.Value = false;
-                        beatmaps.ImportFromStableAsync().ContinueWith(t => Schedule(() => importBeatmapsButton.Enabled.Value = true));
+                        stableImportManager.ImportFromStableAsync(StableContent.Beatmaps).ContinueWith(t => Schedule(() => importBeatmapsButton.Enabled.Value = true));
                     }
                 });
             }
@@ -57,7 +58,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                 }
             });
 
-            if (scores.SupportsImportFromStable)
+            if (stableImportManager?.SupportsImportFromStable == true)
             {
                 Add(importScoresButton = new SettingsButton
                 {
@@ -65,7 +66,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                     Action = () =>
                     {
                         importScoresButton.Enabled.Value = false;
-                        scores.ImportFromStableAsync().ContinueWith(t => Schedule(() => importScoresButton.Enabled.Value = true));
+                        stableImportManager.ImportFromStableAsync(StableContent.Scores).ContinueWith(t => Schedule(() => importScoresButton.Enabled.Value = true));
                     }
                 });
             }
@@ -83,7 +84,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                 }
             });
 
-            if (skins.SupportsImportFromStable)
+            if (stableImportManager?.SupportsImportFromStable == true)
             {
                 Add(importSkinsButton = new SettingsButton
                 {
@@ -91,7 +92,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                     Action = () =>
                     {
                         importSkinsButton.Enabled.Value = false;
-                        skins.ImportFromStableAsync().ContinueWith(t => Schedule(() => importSkinsButton.Enabled.Value = true));
+                        stableImportManager.ImportFromStableAsync(StableContent.Skins).ContinueWith(t => Schedule(() => importSkinsButton.Enabled.Value = true));
                     }
                 });
             }
@@ -111,7 +112,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
 
             if (collectionManager != null)
             {
-                if (collectionManager.SupportsImportFromStable)
+                if (stableImportManager?.SupportsImportFromStable == true)
                 {
                     Add(importCollectionsButton = new SettingsButton
                     {
@@ -119,7 +120,7 @@ namespace osu.Game.Overlays.Settings.Sections.Maintenance
                         Action = () =>
                         {
                             importCollectionsButton.Enabled.Value = false;
-                            collectionManager.ImportFromStableAsync().ContinueWith(t => Schedule(() => importCollectionsButton.Enabled.Value = true));
+                            stableImportManager.ImportFromStableAsync(StableContent.Collections).ContinueWith(t => Schedule(() => importCollectionsButton.Enabled.Value = true));
                         }
                     });
                 }

osu.Game/Overlays/Settings/Sections/Maintenance/StableDirectoryLocationDialog.cs

@@ -0,0 +1,38 @@
+// 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.Threading.Tasks;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Screens;
+using osu.Game.Overlays.Dialog;
+
+namespace osu.Game.Overlays.Settings.Sections.Maintenance
+{
+    public class StableDirectoryLocationDialog : PopupDialog
+    {
+        [Resolved]
+        private OsuGame game { get; set; }
+
+        public StableDirectoryLocationDialog(TaskCompletionSource<string> taskCompletionSource)
+        {
+            HeaderText = "Failed to automatically locate an osu!stable installation.";
+            BodyText = "An existing install could not be located. If you know where it is, you can help locate it.";
+            Icon = FontAwesome.Solid.QuestionCircle;
+
+            Buttons = new PopupDialogButton[]
+            {
+                new PopupDialogOkButton
+                {
+                    Text = "Sure! I know where it is located!",
+                    Action = () => Schedule(() => game.PerformFromScreen(screen => screen.Push(new StableDirectorySelectScreen(taskCompletionSource))))
+                },
+                new PopupDialogCancelButton
+                {
+                    Text = "Actually I don't have osu!stable installed.",
+                    Action = () => taskCompletionSource.TrySetCanceled()
+                }
+            };
+        }
+    }
+}

osu.Game/Overlays/Settings/Sections/Maintenance/StableDirectorySelectScreen.cs

@@ -0,0 +1,39 @@
+// 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.IO;
+using System.Linq;
+using System.Threading.Tasks;
+using osu.Framework.Localisation;
+using osu.Framework.Screens;
+
+namespace osu.Game.Overlays.Settings.Sections.Maintenance
+{
+    public class StableDirectorySelectScreen : DirectorySelectScreen
+    {
+        private readonly TaskCompletionSource<string> taskCompletionSource;
+
+        protected override OverlayActivation InitialOverlayActivationMode => OverlayActivation.Disabled;
+
+        protected override bool IsValidDirectory(DirectoryInfo info) => info?.GetFiles("osu!.*.cfg").Any() ?? false;
+
+        public override LocalisableString HeaderText => "Please select your osu!stable install location";
+
+        public StableDirectorySelectScreen(TaskCompletionSource<string> taskCompletionSource)
+        {
+            this.taskCompletionSource = taskCompletionSource;
+        }
+
+        protected override void OnSelection(DirectoryInfo directory)
+        {
+            taskCompletionSource.TrySetResult(directory.FullName);
+            this.Exit();
+        }
+
+        public override bool OnExiting(IScreen next)
+        {
+            taskCompletionSource.TrySetCanceled();
+            return base.OnExiting(next);
+        }
+    }
+}

osu.Game/Rulesets/Edit/PlacementBlueprint.cs

@@ -36,7 +36,8 @@ namespace osu.Game.Rulesets.Edit
         [Resolved(canBeNull: true)]
         protected EditorClock EditorClock { get; private set; }
 
-        private readonly IBindable<WorkingBeatmap> beatmap = new Bindable<WorkingBeatmap>();
+        [Resolved]
+        private EditorBeatmap beatmap { get; set; }
 
         private Bindable<double> startTimeBindable;
 
@@ -58,10 +59,8 @@ namespace osu.Game.Rulesets.Edit
         }
 
         [BackgroundDependencyLoader]
-        private void load(IBindable<WorkingBeatmap> beatmap)
+        private void load()
         {
-            this.beatmap.BindTo(beatmap);
-
             startTimeBindable = HitObject.StartTimeBindable.GetBoundCopy();
             startTimeBindable.BindValueChanged(_ => ApplyDefaultsToHitObject(), true);
         }
@@ -113,7 +112,7 @@ namespace osu.Game.Rulesets.Edit
         /// Invokes <see cref="Objects.HitObject.ApplyDefaults(ControlPointInfo,BeatmapDifficulty, CancellationToken)"/>,
         /// refreshing <see cref="Objects.HitObject.NestedHitObjects"/> and parameters for the <see cref="HitObject"/>.
         /// </summary>
-        protected void ApplyDefaultsToHitObject() => HitObject.ApplyDefaults(beatmap.Value.Beatmap.ControlPointInfo, beatmap.Value.Beatmap.BeatmapInfo.BaseDifficulty);
+        protected void ApplyDefaultsToHitObject() => HitObject.ApplyDefaults(beatmap.ControlPointInfo, beatmap.BeatmapInfo.BaseDifficulty);
 
         public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => Parent?.ReceivePositionalInputAt(screenSpacePos) ?? false;
 

osu.Game/Rulesets/Objects/Pooling/PoolableDrawableWithLifetime.cs

@@ -3,7 +3,6 @@
 
 #nullable enable
 
-using System;
 using System.Diagnostics;
 using osu.Framework.Graphics.Performance;
 using osu.Framework.Graphics.Pooling;
@@ -27,13 +26,14 @@ namespace osu.Game.Rulesets.Objects.Pooling
         /// </summary>
         protected bool HasEntryApplied { get; private set; }
 
+        // Drawable's lifetime gets out of sync with entry's lifetime if entry's lifetime is modified.
+        // We cannot delegate getter to `Entry.LifetimeStart` because it is incompatible with `LifetimeManagementContainer` due to how lifetime change is detected.
         public override double LifetimeStart
         {
-            get => Entry?.LifetimeStart ?? double.MinValue;
+            get => base.LifetimeStart;
             set
             {
-                if (Entry == null && LifetimeStart != value)
-                    throw new InvalidOperationException($"Cannot modify lifetime of {nameof(PoolableDrawableWithLifetime<TEntry>)} when entry is not set");
+                base.LifetimeStart = value;
 
                 if (Entry != null)
                     Entry.LifetimeStart = value;
@@ -42,11 +42,10 @@ namespace osu.Game.Rulesets.Objects.Pooling
 
         public override double LifetimeEnd
         {
-            get => Entry?.LifetimeEnd ?? double.MaxValue;
+            get => base.LifetimeEnd;
             set
             {
-                if (Entry == null && LifetimeEnd != value)
-                    throw new InvalidOperationException($"Cannot modify lifetime of {nameof(PoolableDrawableWithLifetime<TEntry>)} when entry is not set");
+                base.LifetimeEnd = value;
 
                 if (Entry != null)
                     Entry.LifetimeEnd = value;
@@ -80,7 +79,12 @@ namespace osu.Game.Rulesets.Objects.Pooling
                 free();
 
             Entry = entry;
+
+            base.LifetimeStart = entry.LifetimeStart;
+            base.LifetimeEnd = entry.LifetimeEnd;
+
             OnApply(entry);
+
             HasEntryApplied = true;
         }
 
@@ -112,7 +116,11 @@ namespace osu.Game.Rulesets.Objects.Pooling
             Debug.Assert(Entry != null && HasEntryApplied);
 
             OnFree(Entry);
+
             Entry = null;
+            base.LifetimeStart = double.MinValue;
+            base.LifetimeEnd = double.MaxValue;
+
             HasEntryApplied = false;
         }
     }

osu.Game/Rulesets/UI/ReplayRecorder.cs

@@ -29,7 +29,7 @@ namespace osu.Game.Rulesets.UI
         public int RecordFrameRate = 60;
 
         [Resolved(canBeNull: true)]
-        private SpectatorStreamingClient spectatorStreaming { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [Resolved]
         private GameplayBeatmap gameplayBeatmap { get; set; }
@@ -49,13 +49,13 @@ namespace osu.Game.Rulesets.UI
 
             inputManager = GetContainingInputManager();
 
-            spectatorStreaming?.BeginPlaying(gameplayBeatmap, target);
+            spectatorClient?.BeginPlaying(gameplayBeatmap, target);
         }
 
         protected override void Dispose(bool isDisposing)
         {
             base.Dispose(isDisposing);
-            spectatorStreaming?.EndPlaying();
+            spectatorClient?.EndPlaying();
         }
 
         protected override void Update()
@@ -98,7 +98,7 @@ namespace osu.Game.Rulesets.UI
             {
                 target.Replay.Frames.Add(frame);
 
-                spectatorStreaming?.HandleFrame(frame);
+                spectatorClient?.HandleFrame(frame);
             }
         }
 

osu.Game/Screens/Edit/Compose/Components/EditorSelectionHandler.cs

@@ -168,13 +168,13 @@ namespace osu.Game.Screens.Edit.Compose.Components
         {
             if (SelectedBlueprints.All(b => b.Item is IHasComboInformation))
             {
-                yield return new TernaryStateMenuItem("New combo") { State = { BindTarget = SelectionNewComboState } };
+                yield return new TernaryStateToggleMenuItem("New combo") { State = { BindTarget = SelectionNewComboState } };
             }
 
             yield return new OsuMenuItem("Sound")
             {
                 Items = SelectionSampleStates.Select(kvp =>
-                    new TernaryStateMenuItem(kvp.Value.Description) { State = { BindTarget = kvp.Value } }).ToArray()
+                    new TernaryStateToggleMenuItem(kvp.Value.Description) { State = { BindTarget = kvp.Value } }).ToArray()
             };
         }
 

osu.Game/Screens/OnlinePlay/Match/RoomSubScreen.cs

@@ -72,8 +72,8 @@ namespace osu.Game.Screens.OnlinePlay.Match
                     Anchor = Anchor.BottomLeft,
                     Origin = Anchor.BottomLeft,
                     Depth = float.MinValue,
-                    RelativeSizeAxes = Axes.Both,
-                    Height = 0.5f,
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
                     Padding = new MarginPadding { Horizontal = HORIZONTAL_OVERFLOW_PADDING },
                     Child = userModsSelectOverlay = new UserModSelectOverlay
                     {

osu.Game/Screens/OnlinePlay/Multiplayer/CreateMultiplayerMatchButton.cs

@@ -14,7 +14,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         private IBindable<bool> operationInProgress;
 
         [Resolved]
-        private StatefulMultiplayerClient multiplayerClient { get; set; }
+        private MultiplayerClient multiplayerClient { get; set; }
 
         [Resolved]
         private OngoingOperationTracker ongoingOperationTracker { get; set; }

osu.Game/Screens/OnlinePlay/Multiplayer/Match/MultiplayerMatchSettingsOverlay.cs

@@ -59,7 +59,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Match
             private IRoomManager manager { get; set; }
 
             [Resolved]
-            private StatefulMultiplayerClient client { get; set; }
+            private MultiplayerClient client { get; set; }
 
             [Resolved]
             private Bindable<Room> currentRoom { get; set; }

osu.Game/Screens/OnlinePlay/Multiplayer/Multiplayer.cs

@@ -15,7 +15,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
     public class Multiplayer : OnlinePlayScreen
     {
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         public override void OnResuming(IScreen last)
         {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerLoungeSubScreen.cs

@@ -18,7 +18,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         protected override RoomSubScreen CreateRoomSubScreen(Room room) => new MultiplayerMatchSubScreen(room);
 
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         public override void Open(Room room)
         {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSongSelect.cs

@@ -17,7 +17,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
     public class MultiplayerMatchSongSelect : OnlinePlaySongSelect
     {
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         private LoadingLayer loadingLayer;
 

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerMatchSubScreen.cs

@@ -43,7 +43,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         public override string ShortTitle => "room";
 
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         [Resolved]
         private OngoingOperationTracker ongoingOperationTracker { get; set; }

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerPlayer.cs

@@ -26,7 +26,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         protected override bool CheckModsAllowFailure() => false;
 
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         private IBindable<bool> isConnected;
 

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerRoomComposite.cs

@@ -13,7 +13,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
         protected MultiplayerRoom Room => Client.Room;
 
         [Resolved]
-        protected StatefulMultiplayerClient Client { get; private set; }
+        protected MultiplayerClient Client { get; private set; }
 
         protected override void LoadComplete()
         {

osu.Game/Screens/OnlinePlay/Multiplayer/MultiplayerRoomManager.cs

@@ -19,7 +19,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer
     public class MultiplayerRoomManager : RoomManager
     {
         [Resolved]
-        private StatefulMultiplayerClient multiplayerClient { get; set; }
+        private MultiplayerClient multiplayerClient { get; set; }
 
         public readonly Bindable<double> TimeBetweenListingPolls = new Bindable<double>();
         public readonly Bindable<double> TimeBetweenSelectionPolls = new Bindable<double>();

osu.Game/Screens/OnlinePlay/Multiplayer/Participants/ParticipantsListHeader.cs

@@ -10,7 +10,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
     public class ParticipantsListHeader : OverlinedHeader
     {
         [Resolved]
-        private StatefulMultiplayerClient client { get; set; }
+        private MultiplayerClient client { get; set; }
 
         public ParticipantsListHeader()
             : base("Participants")

osu.Game/Screens/OnlinePlay/Multiplayer/Spectate/MultiSpectatorScreen.cs

@@ -28,10 +28,10 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Spectate
         public bool AllPlayersLoaded => instances.All(p => p?.PlayerLoaded == true);
 
         [Resolved]
-        private SpectatorStreamingClient spectatorClient { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [Resolved]
-        private StatefulMultiplayerClient multiplayerClient { get; set; }
+        private MultiplayerClient multiplayerClient { get; set; }
 
         private readonly PlayerArea[] instances;
         private MasterGameplayClockContainer masterClockContainer;

osu.Game/Screens/Play/HUD/HitErrorDisplay.cs

@@ -1,127 +0,0 @@
-// 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 osu.Framework.Allocation;
-using osu.Framework.Bindables;
-using osu.Framework.Extensions.IEnumerableExtensions;
-using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
-using osu.Game.Configuration;
-using osu.Game.Rulesets.Scoring;
-using osu.Game.Screens.Play.HUD.HitErrorMeters;
-
-namespace osu.Game.Screens.Play.HUD
-{
-    public class HitErrorDisplay : Container<HitErrorMeter>
-    {
-        private const int fade_duration = 200;
-        private const int margin = 10;
-
-        private readonly Bindable<ScoreMeterType> type = new Bindable<ScoreMeterType>();
-
-        private readonly HitWindows hitWindows;
-
-        public HitErrorDisplay(HitWindows hitWindows)
-        {
-            this.hitWindows = hitWindows;
-
-            RelativeSizeAxes = Axes.Both;
-        }
-
-        [BackgroundDependencyLoader]
-        private void load(OsuConfigManager config)
-        {
-            config.BindWith(OsuSetting.ScoreMeter, type);
-        }
-
-        protected override void LoadComplete()
-        {
-            base.LoadComplete();
-            type.BindValueChanged(typeChanged, true);
-        }
-
-        private void typeChanged(ValueChangedEvent<ScoreMeterType> type)
-        {
-            Children.ForEach(c => c.FadeOut(fade_duration, Easing.OutQuint));
-
-            if (hitWindows == null)
-                return;
-
-            switch (type.NewValue)
-            {
-                case ScoreMeterType.HitErrorBoth:
-                    createBar(Anchor.CentreLeft);
-                    createBar(Anchor.CentreRight);
-                    break;
-
-                case ScoreMeterType.HitErrorLeft:
-                    createBar(Anchor.CentreLeft);
-                    break;
-
-                case ScoreMeterType.HitErrorRight:
-                    createBar(Anchor.CentreRight);
-                    break;
-
-                case ScoreMeterType.HitErrorBottom:
-                    createBar(Anchor.BottomCentre);
-                    break;
-
-                case ScoreMeterType.ColourBoth:
-                    createColour(Anchor.CentreLeft);
-                    createColour(Anchor.CentreRight);
-                    break;
-
-                case ScoreMeterType.ColourLeft:
-                    createColour(Anchor.CentreLeft);
-                    break;
-
-                case ScoreMeterType.ColourRight:
-                    createColour(Anchor.CentreRight);
-                    break;
-
-                case ScoreMeterType.ColourBottom:
-                    createColour(Anchor.BottomCentre);
-                    break;
-            }
-        }
-
-        private void createBar(Anchor anchor)
-        {
-            bool rightAligned = (anchor & Anchor.x2) > 0;
-            bool bottomAligned = (anchor & Anchor.y2) > 0;
-
-            var display = new BarHitErrorMeter(hitWindows, rightAligned)
-            {
-                Margin = new MarginPadding(margin),
-                Anchor = anchor,
-                Origin = bottomAligned ? Anchor.CentreLeft : anchor,
-                Alpha = 0,
-                Rotation = bottomAligned ? 270 : 0
-            };
-
-            completeDisplayLoading(display);
-        }
-
-        private void createColour(Anchor anchor)
-        {
-            bool bottomAligned = (anchor & Anchor.y2) > 0;
-
-            var display = new ColourHitErrorMeter(hitWindows)
-            {
-                Margin = new MarginPadding(margin),
-                Anchor = anchor,
-                Origin = bottomAligned ? Anchor.CentreLeft : anchor,
-                Alpha = 0,
-                Rotation = bottomAligned ? 270 : 0
-            };
-
-            completeDisplayLoading(display);
-        }
-
-        private void completeDisplayLoading(HitErrorMeter display)
-        {
-            Add(display);
-            display.FadeInFromZero(fade_duration, Easing.OutQuint);
-        }
-    }
-}

osu.Game/Screens/Play/HUD/HitErrorMeters/BarHitErrorMeter.cs

@@ -20,8 +20,6 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
 {
     public class BarHitErrorMeter : HitErrorMeter
     {
-        private readonly Anchor alignment;
-
         private const int arrow_move_duration = 400;
 
         private const int judgement_line_width = 6;
@@ -43,11 +41,8 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
 
         private double maxHitWindow;
 
-        public BarHitErrorMeter(HitWindows hitWindows, bool rightAligned = false)
-            : base(hitWindows)
+        public BarHitErrorMeter()
         {
-            alignment = rightAligned ? Anchor.x0 : Anchor.x2;
-
             AutoSizeAxes = Axes.Both;
         }
 
@@ -63,33 +58,42 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
                 Margin = new MarginPadding(2),
                 Children = new Drawable[]
                 {
-                    judgementsContainer = new Container
+                    new Container
                     {
-                        Anchor = Anchor.y1 | alignment,
-                        Origin = Anchor.y1 | alignment,
-                        Width = judgement_line_width,
+                        Anchor = Anchor.CentreLeft,
+                        Origin = Anchor.CentreLeft,
+                        Width = chevron_size,
                         RelativeSizeAxes = Axes.Y,
+                        Child = arrow = new SpriteIcon
+                        {
+                            Anchor = Anchor.TopCentre,
+                            Origin = Anchor.Centre,
+                            RelativePositionAxes = Axes.Y,
+                            Y = 0.5f,
+                            Icon = FontAwesome.Solid.ChevronRight,
+                            Size = new Vector2(chevron_size),
+                        }
                     },
                     colourBars = new Container
                     {
                         Width = bar_width,
                         RelativeSizeAxes = Axes.Y,
-                        Anchor = Anchor.y1 | alignment,
-                        Origin = Anchor.y1 | alignment,
+                        Anchor = Anchor.CentreLeft,
+                        Origin = Anchor.CentreLeft,
                         Children = new Drawable[]
                         {
                             colourBarsEarly = new Container
                             {
-                                Anchor = Anchor.y1 | alignment,
-                                Origin = alignment,
+                                Anchor = Anchor.CentreLeft,
+                                Origin = Anchor.TopRight,
                                 RelativeSizeAxes = Axes.Both,
                                 Height = 0.5f,
                                 Scale = new Vector2(1, -1),
                             },
                             colourBarsLate = new Container
                             {
-                                Anchor = Anchor.y1 | alignment,
-                                Origin = alignment,
+                                Anchor = Anchor.CentreLeft,
+                                Origin = Anchor.TopRight,
                                 RelativeSizeAxes = Axes.Both,
                                 Height = 0.5f,
                             },
@@ -115,21 +119,12 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
                             }
                         }
                     },
-                    new Container
+                    judgementsContainer = new Container
                     {
-                        Anchor = Anchor.y1 | alignment,
-                        Origin = Anchor.y1 | alignment,
-                        Width = chevron_size,
+                        Anchor = Anchor.CentreLeft,
+                        Origin = Anchor.CentreLeft,
+                        Width = judgement_line_width,
                         RelativeSizeAxes = Axes.Y,
-                        Child = arrow = new SpriteIcon
-                        {
-                            Anchor = Anchor.TopCentre,
-                            Origin = Anchor.Centre,
-                            RelativePositionAxes = Axes.Y,
-                            Y = 0.5f,
-                            Icon = alignment == Anchor.x2 ? FontAwesome.Solid.ChevronRight : FontAwesome.Solid.ChevronLeft,
-                            Size = new Vector2(chevron_size),
-                        }
                     },
                 }
             };
@@ -152,19 +147,22 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
         {
             var windows = HitWindows.GetAllAvailableWindows().ToArray();
 
-            maxHitWindow = windows.First().length;
+            // max to avoid div-by-zero.
+            maxHitWindow = Math.Max(1, windows.First().length);
 
             for (var i = 0; i < windows.Length; i++)
             {
                 var (result, length) = windows[i];
 
-                colourBarsEarly.Add(createColourBar(result, (float)(length / maxHitWindow), i == 0));
-                colourBarsLate.Add(createColourBar(result, (float)(length / maxHitWindow), i == 0));
+                var hitWindow = (float)(length / maxHitWindow);
+
+                colourBarsEarly.Add(createColourBar(result, hitWindow, i == 0));
+                colourBarsLate.Add(createColourBar(result, hitWindow, i == 0));
             }
 
             // a little nub to mark the centre point.
             var centre = createColourBar(windows.Last().result, 0.01f);
-            centre.Anchor = centre.Origin = Anchor.y1 | (alignment == Anchor.x2 ? Anchor.x0 : Anchor.x2);
+            centre.Anchor = centre.Origin = Anchor.CentreLeft;
             centre.Width = 2.5f;
             colourBars.Add(centre);
 
@@ -236,8 +234,7 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
             judgementsContainer.Add(new JudgementLine
             {
                 Y = getRelativeJudgementPosition(judgement.TimeOffset),
-                Anchor = alignment == Anchor.x2 ? Anchor.x0 : Anchor.x2,
-                Origin = Anchor.y1 | (alignment == Anchor.x2 ? Anchor.x0 : Anchor.x2),
+                Origin = Anchor.CentreLeft,
             });
 
             arrow.MoveToY(

osu.Game/Screens/Play/HUD/HitErrorMeters/ColourHitErrorMeter.cs

@@ -7,7 +7,6 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
 using osu.Game.Rulesets.Judgements;
-using osu.Game.Rulesets.Scoring;
 using osuTK;
 using osuTK.Graphics;
 
@@ -19,8 +18,7 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
 
         private readonly JudgementFlow judgementsFlow;
 
-        public ColourHitErrorMeter(HitWindows hitWindows)
-            : base(hitWindows)
+        public ColourHitErrorMeter()
         {
             AutoSizeAxes = Axes.Both;
             InternalChild = judgementsFlow = new JudgementFlow();

osu.Game/Screens/Play/HUD/HitErrorMeters/HitErrorMeter.cs

@@ -6,13 +6,15 @@ using osu.Framework.Graphics.Containers;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Scoring;
+using osu.Game.Rulesets.UI;
+using osu.Game.Skinning;
 using osuTK.Graphics;
 
 namespace osu.Game.Screens.Play.HUD.HitErrorMeters
 {
-    public abstract class HitErrorMeter : CompositeDrawable
+    public abstract class HitErrorMeter : CompositeDrawable, ISkinnableDrawable
     {
-        protected readonly HitWindows HitWindows;
+        protected HitWindows HitWindows { get; private set; }
 
         [Resolved]
         private ScoreProcessor processor { get; set; }
@@ -20,9 +22,10 @@ namespace osu.Game.Screens.Play.HUD.HitErrorMeters
         [Resolved]
         private OsuColour colours { get; set; }
 
-        protected HitErrorMeter(HitWindows hitWindows)
+        [BackgroundDependencyLoader(true)]
+        private void load(DrawableRuleset drawableRuleset)
         {
-            HitWindows = hitWindows;
+            HitWindows = drawableRuleset?.FirstAvailableHitWindows ?? HitWindows.Empty;
         }
 
         protected override void LoadComplete()

osu.Game/Screens/Play/HUD/MultiplayerGameplayLeaderboard.cs

@@ -22,10 +22,10 @@ namespace osu.Game.Screens.Play.HUD
         protected readonly Dictionary<int, TrackedUserData> UserScores = new Dictionary<int, TrackedUserData>();
 
         [Resolved]
-        private SpectatorStreamingClient streamingClient { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [Resolved]
-        private StatefulMultiplayerClient multiplayerClient { get; set; }
+        private MultiplayerClient multiplayerClient { get; set; }
 
         [Resolved]
         private UserLookupCache userLookupCache { get; set; }
@@ -55,8 +55,6 @@ namespace osu.Game.Screens.Play.HUD
 
             foreach (var userId in playingUsers)
             {
-                streamingClient.WatchUser(userId);
-
                 // probably won't be required in the final implementation.
                 var resolvedUser = userLookupCache.GetUserAsync(userId).Result;
 
@@ -80,6 +78,8 @@ namespace osu.Game.Screens.Play.HUD
             // BindableList handles binding in a really bad way (Clear then AddRange) so we need to do this manually..
             foreach (int userId in playingUsers)
             {
+                spectatorClient.WatchUser(userId);
+
                 if (!multiplayerClient.CurrentMatchPlayingUserIds.Contains(userId))
                     usersChanged(this, new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, new[] { userId }));
             }
@@ -88,7 +88,7 @@ namespace osu.Game.Screens.Play.HUD
             playingUsers.BindCollectionChanged(usersChanged);
 
             // this leaderboard should be guaranteed to be completely loaded before the gameplay starts (is a prerequisite in MultiplayerPlayer).
-            streamingClient.OnNewFrames += handleIncomingFrames;
+            spectatorClient.OnNewFrames += handleIncomingFrames;
         }
 
         private void usersChanged(object sender, NotifyCollectionChangedEventArgs e)
@@ -98,7 +98,7 @@ namespace osu.Game.Screens.Play.HUD
                 case NotifyCollectionChangedAction.Remove:
                     foreach (var userId in e.OldItems.OfType<int>())
                     {
-                        streamingClient.StopWatchingUser(userId);
+                        spectatorClient.StopWatchingUser(userId);
 
                         if (UserScores.TryGetValue(userId, out var trackedData))
                             trackedData.MarkUserQuit();
@@ -123,14 +123,14 @@ namespace osu.Game.Screens.Play.HUD
         {
             base.Dispose(isDisposing);
 
-            if (streamingClient != null)
+            if (spectatorClient != null)
             {
                 foreach (var user in playingUsers)
                 {
-                    streamingClient.StopWatchingUser(user);
+                    spectatorClient.StopWatchingUser(user);
                 }
 
-                streamingClient.OnNewFrames -= handleIncomingFrames;
+                spectatorClient.OnNewFrames -= handleIncomingFrames;
             }
         }
 

osu.Game/Screens/Play/HUDOverlay.cs

@@ -87,22 +87,10 @@ namespace osu.Game.Screens.Play
                 visibilityContainer = new Container
                 {
                     RelativeSizeAxes = Axes.Both,
-                    Children = new Drawable[]
+                    Child = mainComponents = new SkinnableTargetContainer(SkinnableTarget.MainHUDComponents)
                     {
-                        mainComponents = new SkinnableTargetContainer(SkinnableTarget.MainHUDComponents)
-                        {
-                            RelativeSizeAxes = Axes.Both,
-                        },
-                        new Container
-                        {
-                            RelativeSizeAxes = Axes.Both,
-                            Children = new Drawable[]
-                            {
-                                // still need to be migrated; a bit more involved.
-                                new HitErrorDisplay(this.drawableRuleset?.FirstAvailableHitWindows),
-                            }
-                        },
-                    }
+                        RelativeSizeAxes = Axes.Both,
+                    },
                 },
                 topRightElements = new FillFlowContainer
                 {

osu.Game/Screens/Play/Player.cs

@@ -22,6 +22,7 @@ using osu.Game.Configuration;
 using osu.Game.Graphics.Containers;
 using osu.Game.IO.Archives;
 using osu.Game.Online.API;
+using osu.Game.Online.Spectator;
 using osu.Game.Overlays;
 using osu.Game.Replays;
 using osu.Game.Rulesets;
@@ -93,6 +94,9 @@ namespace osu.Game.Screens.Play
         [Resolved]
         private MusicController musicController { get; set; }
 
+        [Resolved]
+        private SpectatorClient spectatorClient { get; set; }
+
         private Sample sampleRestart;
 
         public BreakOverlay BreakOverlay;
@@ -882,6 +886,11 @@ namespace osu.Game.Screens.Play
                 return true;
             }
 
+            // EndPlaying() is typically called from ReplayRecorder.Dispose(). Disposal is currently asynchronous.
+            // To resolve test failures, forcefully end playing synchronously when this screen exits.
+            // Todo: Replace this with a more permanent solution once osu-framework has a synchronous cleanup method.
+            spectatorClient.EndPlaying();
+
             // GameplayClockContainer performs seeks / start / stop operations on the beatmap's track.
             // as we are no longer the current screen, we cannot guarantee the track is still usable.
             (GameplayClockContainer as MasterGameplayClockContainer)?.StopUsingBeatmapClock();

osu.Game/Screens/Play/SongProgress.cs

@@ -20,10 +20,14 @@ namespace osu.Game.Screens.Play
 {
     public class SongProgress : OverlayContainer, ISkinnableDrawable
     {
-        private const int info_height = 20;
-        private const int bottom_bar_height = 5;
+        public const float MAX_HEIGHT = info_height + bottom_bar_height + graph_height + handle_height;
+
+        private const float info_height = 20;
+        private const float bottom_bar_height = 5;
         private const float graph_height = SquareGraph.Column.WIDTH * 6;
-        private static readonly Vector2 handle_size = new Vector2(10, 18);
+        private const float handle_height = 18;
+
+        private static readonly Vector2 handle_size = new Vector2(10, handle_height);
 
         private const float transition_duration = 200;
 

osu.Game/Screens/Play/SpectatorPlayer.cs

@@ -31,12 +31,12 @@ namespace osu.Game.Screens.Play
         }
 
         [Resolved]
-        private SpectatorStreamingClient spectatorStreaming { get; set; }
+        private SpectatorClient spectatorClient { get; set; }
 
         [BackgroundDependencyLoader]
         private void load()
         {
-            spectatorStreaming.OnUserBeganPlaying += userBeganPlaying;
+            spectatorClient.OnUserBeganPlaying += userBeganPlaying;
 
             AddInternal(new OsuSpriteText
             {
@@ -66,7 +66,7 @@ namespace osu.Game.Screens.Play
 
         public override bool OnExiting(IScreen next)
         {
-            spectatorStreaming.OnUserBeganPlaying -= userBeganPlaying;
+            spectatorClient.OnUserBeganPlaying -= userBeganPlaying;
             return base.OnExiting(next);
         }
 
@@ -84,8 +84,8 @@ namespace osu.Game.Screens.Play
         {
             base.Dispose(isDisposing);
 
-            if (spectatorStreaming != null)
-                spectatorStreaming.OnUserBeganPlaying -= userBeganPlaying;
+            if (spectatorClient != null)
+                spectatorClient.OnUserBeganPlaying -= userBeganPlaying;
         }
     }
 }