Merge branch 'master' into editor-beat-snap-always

osu.Android.props

@@ -52,6 +52,6 @@
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1030.0" />
-    <PackageReference Include="ppy.osu.Framework.Android" Version="2020.1120.0" />
+    <PackageReference Include="ppy.osu.Framework.Android" Version="2020.1127.0" />
   </ItemGroup>
 </Project>

osu.Game.Rulesets.Catch.Tests/TestSceneFruitObjects.cs

@@ -1,9 +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;
 using NUnit.Framework;
 using osu.Framework.Graphics;
+using osu.Game.Beatmaps;
+using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Catch.Objects;
 using osu.Game.Rulesets.Catch.Objects.Drawables;
 using osuTK;
@@ -17,34 +18,49 @@ namespace osu.Game.Rulesets.Catch.Tests
         {
             base.LoadComplete();
 
-            foreach (FruitVisualRepresentation rep in Enum.GetValues(typeof(FruitVisualRepresentation)))
+            AddStep("show pear", () => SetContents(() => createDrawableFruit(0)));
-                AddStep($"show {rep}", () => SetContents(() => createDrawableFruit(rep)));
+            AddStep("show grape", () => SetContents(() => createDrawableFruit(1)));
+            AddStep("show pineapple / apple", () => SetContents(() => createDrawableFruit(2)));
+            AddStep("show raspberry / orange", () => SetContents(() => createDrawableFruit(3)));
+
+            AddStep("show banana", () => SetContents(createDrawableBanana));
 
             AddStep("show droplet", () => SetContents(() => createDrawableDroplet()));
             AddStep("show tiny droplet", () => SetContents(createDrawableTinyDroplet));
 
-            foreach (FruitVisualRepresentation rep in Enum.GetValues(typeof(FruitVisualRepresentation)))
+            AddStep("show hyperdash pear", () => SetContents(() => createDrawableFruit(0, true)));
-                AddStep($"show hyperdash {rep}", () => SetContents(() => createDrawableFruit(rep, true)));
+            AddStep("show hyperdash grape", () => SetContents(() => createDrawableFruit(1, true)));
+            AddStep("show hyperdash pineapple / apple", () => SetContents(() => createDrawableFruit(2, true)));
+            AddStep("show hyperdash raspberry / orange", () => SetContents(() => createDrawableFruit(3, true)));
 
             AddStep("show hyperdash droplet", () => SetContents(() => createDrawableDroplet(true)));
         }
 
-        private Drawable createDrawableFruit(FruitVisualRepresentation rep, bool hyperdash = false) =>
+        private Drawable createDrawableFruit(int indexInBeatmap, bool hyperdash = false) =>
-            setProperties(new DrawableFruit(new TestCatchFruit(rep)), hyperdash);
+            SetProperties(new DrawableFruit(new Fruit
+            {
+                IndexInBeatmap = indexInBeatmap,
+                HyperDashBindable = { Value = hyperdash }
+            }));
 
-        private Drawable createDrawableDroplet(bool hyperdash = false) => setProperties(new DrawableDroplet(new Droplet()), hyperdash);
+        private Drawable createDrawableBanana() =>
+            SetProperties(new DrawableBanana(new Banana()));
 
-        private Drawable createDrawableTinyDroplet() => setProperties(new DrawableTinyDroplet(new TinyDroplet()));
+        private Drawable createDrawableDroplet(bool hyperdash = false) =>
+            SetProperties(new DrawableDroplet(new Droplet
+            {
+                HyperDashBindable = { Value = hyperdash }
+            }));
 
-        private DrawableCatchHitObject setProperties(DrawableCatchHitObject d, bool hyperdash = false)
+        private Drawable createDrawableTinyDroplet() => SetProperties(new DrawableTinyDroplet(new TinyDroplet()));
+
+        protected virtual DrawableCatchHitObject SetProperties(DrawableCatchHitObject d)
         {
             var hitObject = d.HitObject;
+            hitObject.ApplyDefaults(new ControlPointInfo(), new BeatmapDifficulty { CircleSize = 0 });
             hitObject.StartTime = 1000000000000;
             hitObject.Scale = 1.5f;
 
-            if (hyperdash)
-                ((PalpableCatchHitObject)hitObject).HyperDashTarget = new Banana();
-
             d.Anchor = Anchor.Centre;
             d.RelativePositionAxes = Axes.None;
             d.Position = Vector2.Zero;
@@ -55,15 +71,5 @@ namespace osu.Game.Rulesets.Catch.Tests
             };
             return d;
         }
-
-        public class TestCatchFruit : Fruit
-        {
-            public TestCatchFruit(FruitVisualRepresentation rep)
-            {
-                VisualRepresentation = rep;
-            }
-
-            public override FruitVisualRepresentation VisualRepresentation { get; }
-        }
     }
 }

osu.Game.Rulesets.Catch.Tests/TestSceneFruitVisualChange.cs

@@ -0,0 +1,32 @@
+// 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.Bindables;
+using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.Objects.Drawables;
+
+namespace osu.Game.Rulesets.Catch.Tests
+{
+    public class TestSceneFruitVisualChange : TestSceneFruitObjects
+    {
+        private readonly Bindable<int> indexInBeatmap = new Bindable<int>();
+        private readonly Bindable<bool> hyperDash = new Bindable<bool>();
+
+        protected override void LoadComplete()
+        {
+            AddStep("fruit changes visual and hyper", () => SetContents(() => SetProperties(new DrawableFruit(new Fruit
+            {
+                IndexInBeatmapBindable = { BindTarget = indexInBeatmap },
+                HyperDashBindable = { BindTarget = hyperDash },
+            }))));
+
+            AddStep("droplet changes hyper", () => SetContents(() => SetProperties(new DrawableDroplet(new Droplet
+            {
+                HyperDashBindable = { BindTarget = hyperDash },
+            }))));
+
+            Scheduler.AddDelayed(() => indexInBeatmap.Value++, 250, true);
+            Scheduler.AddDelayed(() => hyperDash.Value = !hyperDash.Value, 1000, true);
+        }
+    }
+}

osu.Game.Rulesets.Catch/Objects/Banana.cs

@@ -2,21 +2,22 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
+using osu.Framework.Utils;
 using osu.Game.Audio;
 using osu.Game.Rulesets.Catch.Judgements;
 using osu.Game.Rulesets.Judgements;
+using osu.Game.Rulesets.Objects.Types;
+using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Catch.Objects
 {
-    public class Banana : Fruit
+    public class Banana : Fruit, IHasComboInformation
     {
         /// <summary>
         /// Index of banana in current shower.
         /// </summary>
         public int BananaIndex;
 
-        public override FruitVisualRepresentation VisualRepresentation => FruitVisualRepresentation.Banana;
-
         public override Judgement CreateJudgement() => new CatchBananaJudgement();
 
         private static readonly List<HitSampleInfo> samples = new List<HitSampleInfo> { new BananaHitSampleInfo() };
@@ -26,6 +27,29 @@ namespace osu.Game.Rulesets.Catch.Objects
             Samples = samples;
         }
 
+        private Color4? colour;
+
+        Color4 IHasComboInformation.GetComboColour(IReadOnlyList<Color4> comboColours)
+        {
+            // override any external colour changes with banananana
+            return colour ??= getBananaColour();
+        }
+
+        private Color4 getBananaColour()
+        {
+            switch (RNG.Next(0, 3))
+            {
+                default:
+                    return new Color4(255, 240, 0, 255);
+
+                case 1:
+                    return new Color4(255, 192, 0, 255);
+
+                case 2:
+                    return new Color4(214, 221, 28, 255);
+            }
+        }
+
         private class BananaHitSampleInfo : HitSampleInfo
         {
             private static string[] lookupNames { get; } = { "metronomelow", "catch-banana" };

osu.Game.Rulesets.Catch/Objects/BananaShower.cs

@@ -9,8 +9,6 @@ namespace osu.Game.Rulesets.Catch.Objects
 {
     public class BananaShower : CatchHitObject, IHasDuration
     {
-        public override FruitVisualRepresentation VisualRepresentation => FruitVisualRepresentation.Banana;
-
         public override bool LastInCombo => true;
 
         public override Judgement CreateJudgement() => new IgnoreJudgement();

osu.Game.Rulesets.Catch/Objects/CatchHitObject.cs

@@ -16,27 +16,47 @@ namespace osu.Game.Rulesets.Catch.Objects
     {
         public const float OBJECT_RADIUS = 64;
 
-        private float x;
+        // This value is after XOffset applied.
+        public readonly Bindable<float> XBindable = new Bindable<float>();
+
+        // This value is before XOffset applied.
+        private float originalX;
 
         /// <summary>
         /// The horizontal position of the fruit between 0 and <see cref="CatchPlayfield.WIDTH"/>.
         /// </summary>
         public float X
         {
-            get => x + XOffset;
+            // TODO: I don't like this asymmetry.
-            set => x = value;
+            get => XBindable.Value;
+            // originalX is set by `XBindable.BindValueChanged`
+            set => XBindable.Value = value + xOffset;
         }
 
+        private float xOffset;
+
         /// <summary>
         /// A random offset applied to <see cref="X"/>, set by the <see cref="CatchBeatmapProcessor"/>.
         /// </summary>
-        internal float XOffset { get; set; }
+        internal float XOffset
+        {
+            get => xOffset;
+            set
+            {
+                xOffset = value;
+                XBindable.Value = originalX + xOffset;
+            }
+        }
 
         public double TimePreempt = 1000;
 
-        public int IndexInBeatmap { get; set; }
+        public readonly Bindable<int> IndexInBeatmapBindable = new Bindable<int>();
 
-        public virtual FruitVisualRepresentation VisualRepresentation => (FruitVisualRepresentation)(IndexInBeatmap % 4);
+        public int IndexInBeatmap
+        {
+            get => IndexInBeatmapBindable.Value;
+            set => IndexInBeatmapBindable.Value = value;
+        }
 
         public virtual bool NewCombo { get; set; }
 
@@ -69,7 +89,13 @@ namespace osu.Game.Rulesets.Catch.Objects
             set => LastInComboBindable.Value = value;
         }
 
-        public float Scale { get; set; } = 1;
+        public readonly Bindable<float> ScaleBindable = new Bindable<float>(1);
+
+        public float Scale
+        {
+            get => ScaleBindable.Value;
+            set => ScaleBindable.Value = value;
+        }
 
         protected override void ApplyDefaultsToSelf(ControlPointInfo controlPointInfo, BeatmapDifficulty difficulty)
         {
@@ -81,14 +107,10 @@ namespace osu.Game.Rulesets.Catch.Objects
         }
 
         protected override HitWindows CreateHitWindows() => HitWindows.Empty;
-    }
 
-    public enum FruitVisualRepresentation
+        protected CatchHitObject()
-    {
+        {
-        Pear,
+            XBindable.BindValueChanged(x => originalX = x.NewValue - xOffset);
-        Grape,
+        }
-        Pineapple,
-        Raspberry,
-        Banana // banananananannaanana
     }
 }

osu.Game.Rulesets.Catch/Objects/Drawables/DrawableBanana.cs

@@ -1,28 +1,20 @@
 // 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 osu.Framework.Graphics;
 using osu.Framework.Utils;
-using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Catch.Objects.Drawables
 {
     public class DrawableBanana : DrawableFruit
     {
+        protected override FruitVisualRepresentation GetVisualRepresentation(int indexInBeatmap) => FruitVisualRepresentation.Banana;
+
         public DrawableBanana(Banana h)
             : base(h)
         {
         }
 
-        private Color4? colour;
-
-        protected override Color4 GetComboColour(IReadOnlyList<Color4> comboColours)
-        {
-            // override any external colour changes with banananana
-            return colour ??= getBananaColour();
-        }
-
         protected override void UpdateInitialTransforms()
         {
             base.UpdateInitialTransforms();
@@ -46,20 +38,5 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
             if (Samples != null)
                 Samples.Frequency.Value = 0.77f + ((Banana)HitObject).BananaIndex * 0.006f;
         }
-
-        private Color4 getBananaColour()
-        {
-            switch (RNG.Next(0, 3))
-            {
-                default:
-                    return new Color4(255, 240, 0, 255);
-
-                case 1:
-                    return new Color4(255, 192, 0, 255);
-
-                case 2:
-                    return new Color4(214, 221, 28, 255);
-            }
-        }
     }
 }

osu.Game.Rulesets.Catch/Objects/Drawables/DrawableCatchHitObject.cs

@@ -2,6 +2,8 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using JetBrains.Annotations;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -10,19 +12,34 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
 {
     public abstract class DrawableCatchHitObject : DrawableHitObject<CatchHitObject>
     {
+        public readonly Bindable<float> XBindable = new Bindable<float>();
+
         protected override double InitialLifetimeOffset => HitObject.TimePreempt;
 
         public float DisplayRadius => DrawSize.X / 2 * Scale.X * HitObject.Scale;
 
         protected override float SamplePlaybackPosition => HitObject.X / CatchPlayfield.WIDTH;
 
-        protected DrawableCatchHitObject(CatchHitObject hitObject)
+        protected DrawableCatchHitObject([CanBeNull] CatchHitObject hitObject)
             : base(hitObject)
         {
-            X = hitObject.X;
             Anchor = Anchor.BottomLeft;
         }
 
+        protected override void OnApply()
+        {
+            base.OnApply();
+
+            XBindable.BindTo(HitObject.XBindable);
+        }
+
+        protected override void OnFree()
+        {
+            base.OnFree();
+
+            XBindable.UnbindFrom(HitObject.XBindable);
+        }
+
         public Func<CatchHitObject, bool> CheckPosition;
 
         public bool IsOnPlate;

osu.Game.Rulesets.Catch/Objects/Drawables/DrawableDroplet.cs

@@ -21,7 +21,17 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
         [BackgroundDependencyLoader]
         private void load()
         {
-            ScaleContainer.Child = new SkinnableDrawable(new CatchSkinComponent(CatchSkinComponents.Droplet), _ => new DropletPiece());
+            HyperDash.BindValueChanged(_ => updatePiece(), true);
+        }
+
+        private void updatePiece()
+        {
+            ScaleContainer.Child = new SkinnableDrawable(
+                new CatchSkinComponent(CatchSkinComponents.Droplet),
+                _ => new DropletPiece
+                {
+                    HyperDash = { BindTarget = HyperDash }
+                });
         }
 
         protected override void UpdateInitialTransforms()

osu.Game.Rulesets.Catch/Objects/Drawables/DrawableFruit.cs

@@ -3,6 +3,7 @@
 
 using System;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Utils;
 using osu.Game.Rulesets.Catch.Objects.Drawables.Pieces;
 using osu.Game.Skinning;
@@ -11,6 +12,10 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
 {
     public class DrawableFruit : DrawablePalpableCatchHitObject
     {
+        public readonly Bindable<FruitVisualRepresentation> VisualRepresentation = new Bindable<FruitVisualRepresentation>();
+
+        protected virtual FruitVisualRepresentation GetVisualRepresentation(int indexInBeatmap) => (FruitVisualRepresentation)(indexInBeatmap % 4);
+
         public DrawableFruit(CatchHitObject h)
             : base(h)
         {
@@ -19,10 +24,26 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
         [BackgroundDependencyLoader]
         private void load()
         {
-            ScaleContainer.Child = new SkinnableDrawable(
-                new CatchSkinComponent(getComponent(HitObject.VisualRepresentation)), _ => new FruitPiece());
-
             ScaleContainer.Rotation = (float)(RNG.NextDouble() - 0.5f) * 40;
+
+            IndexInBeatmap.BindValueChanged(change =>
+            {
+                VisualRepresentation.Value = GetVisualRepresentation(change.NewValue);
+            }, true);
+
+            VisualRepresentation.BindValueChanged(_ => updatePiece());
+            HyperDash.BindValueChanged(_ => updatePiece(), true);
+        }
+
+        private void updatePiece()
+        {
+            ScaleContainer.Child = new SkinnableDrawable(
+                new CatchSkinComponent(getComponent(VisualRepresentation.Value)),
+                _ => new FruitPiece
+                {
+                    VisualRepresentation = { BindTarget = VisualRepresentation },
+                    HyperDash = { BindTarget = HyperDash },
+                });
         }
 
         private CatchSkinComponents getComponent(FruitVisualRepresentation hitObjectVisualRepresentation)
@@ -49,4 +70,13 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
             }
         }
     }
+
+    public enum FruitVisualRepresentation
+    {
+        Pear,
+        Grape,
+        Pineapple,
+        Raspberry,
+        Banana // banananananannaanana
+    }
 }

osu.Game.Rulesets.Catch/Objects/Drawables/DrawablePalpableCatchHitObject.cs

@@ -1,12 +1,12 @@
 // 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 JetBrains.Annotations;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osuTK;
-using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Catch.Objects.Drawables
 {
@@ -14,6 +14,17 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
     {
         public new PalpableCatchHitObject HitObject => (PalpableCatchHitObject)base.HitObject;
 
+        public readonly Bindable<bool> HyperDash = new Bindable<bool>();
+
+        public readonly Bindable<float> ScaleBindable = new Bindable<float>(1);
+
+        public readonly Bindable<int> IndexInBeatmap = new Bindable<int>();
+
+        /// <summary>
+        /// The multiplicative factor applied to <see cref="ScaleContainer"/> scale relative to <see cref="HitObject"/> scale.
+        /// </summary>
+        protected virtual float ScaleFactor => 1;
+
         /// <summary>
         /// Whether this hit object should stay on the catcher plate when the object is caught by the catcher.
         /// </summary>
@@ -21,7 +32,7 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
 
         protected readonly Container ScaleContainer;
 
-        protected DrawablePalpableCatchHitObject(CatchHitObject h)
+        protected DrawablePalpableCatchHitObject([CanBeNull] CatchHitObject h)
             : base(h)
         {
             Origin = Anchor.Centre;
@@ -38,10 +49,35 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables
         [BackgroundDependencyLoader]
         private void load()
         {
-            ScaleContainer.Scale = new Vector2(HitObject.Scale);
+            XBindable.BindValueChanged(x =>
+            {
+                if (!IsOnPlate) X = x.NewValue;
+            }, true);
+
+            ScaleBindable.BindValueChanged(scale =>
+            {
+                ScaleContainer.Scale = new Vector2(scale.NewValue * ScaleFactor);
+            }, true);
+
+            IndexInBeatmap.BindValueChanged(_ => UpdateComboColour());
         }
 
-        protected override Color4 GetComboColour(IReadOnlyList<Color4> comboColours) =>
+        protected override void OnApply()
-            comboColours[(HitObject.IndexInBeatmap + 1) % comboColours.Count];
+        {
+            base.OnApply();
+
+            HyperDash.BindTo(HitObject.HyperDashBindable);
+            ScaleBindable.BindTo(HitObject.ScaleBindable);
+            IndexInBeatmap.BindTo(HitObject.IndexInBeatmapBindable);
+        }
+
+        protected override void OnFree()
+        {
+            HyperDash.UnbindFrom(HitObject.HyperDashBindable);
+            ScaleBindable.UnbindFrom(HitObject.ScaleBindable);
+            IndexInBeatmap.UnbindFrom(HitObject.IndexInBeatmapBindable);
+
+            base.OnFree();
+        }
     }
 }

osu.Game.Rulesets.Catch/Objects/Drawables/DrawableTinyDroplet.cs

@@ -1,21 +1,15 @@
 // 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;
-
 namespace osu.Game.Rulesets.Catch.Objects.Drawables
 {
     public class DrawableTinyDroplet : DrawableDroplet
     {
+        protected override float ScaleFactor => base.ScaleFactor / 2;
+
         public DrawableTinyDroplet(TinyDroplet h)
             : base(h)
         {
         }
-
-        [BackgroundDependencyLoader]
-        private void load()
-        {
-            ScaleContainer.Scale /= 2;
-        }
     }
 }

osu.Game.Rulesets.Catch/Objects/Drawables/Pieces/DropletPiece.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -11,6 +12,8 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables.Pieces
 {
     public class DropletPiece : CompositeDrawable
     {
+        public readonly Bindable<bool> HyperDash = new Bindable<bool>();
+
         public DropletPiece()
         {
             Size = new Vector2(CatchHitObject.OBJECT_RADIUS / 2);
@@ -19,15 +22,13 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables.Pieces
         [BackgroundDependencyLoader]
         private void load(DrawableHitObject drawableObject)
         {
-            var drawableCatchObject = (DrawablePalpableCatchHitObject)drawableObject;
-
             InternalChild = new Pulp
             {
                 RelativeSizeAxes = Axes.Both,
                 AccentColour = { BindTarget = drawableObject.AccentColour }
             };
 
-            if (drawableCatchObject.HitObject.HyperDash)
+            if (HyperDash.Value)
             {
                 AddInternal(new HyperDropletBorderPiece());
             }

osu.Game.Rulesets.Catch/Objects/Drawables/Pieces/FruitPiece.cs

@@ -2,7 +2,9 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -16,36 +18,39 @@ namespace osu.Game.Rulesets.Catch.Objects.Drawables.Pieces
         /// </summary>
         public const float RADIUS_ADJUST = 1.1f;
 
-        private BorderPiece border;
+        public readonly Bindable<FruitVisualRepresentation> VisualRepresentation = new Bindable<FruitVisualRepresentation>();
-        private PalpableCatchHitObject hitObject;
+        public readonly Bindable<bool> HyperDash = new Bindable<bool>();
+
+        [CanBeNull]
+        private DrawableCatchHitObject drawableHitObject;
+
+        [CanBeNull]
+        private BorderPiece borderPiece;
 
         public FruitPiece()
         {
             RelativeSizeAxes = Axes.Both;
         }
 
-        [BackgroundDependencyLoader]
+        [BackgroundDependencyLoader(permitNulls: true)]
-        private void load(DrawableHitObject drawableObject)
+        private void load([CanBeNull] DrawableHitObject drawable)
         {
-            var drawableCatchObject = (DrawablePalpableCatchHitObject)drawableObject;
+            drawableHitObject = (DrawableCatchHitObject)drawable;
-            hitObject = drawableCatchObject.HitObject;
 
-            AddRangeInternal(new[]
+            AddInternal(getFruitFor(VisualRepresentation.Value));
-            {
-                getFruitFor(hitObject.VisualRepresentation),
-                border = new BorderPiece(),
-            });
 
-            if (hitObject.HyperDash)
+            // if it is not part of a DHO, the border is always invisible.
-            {
+            if (drawableHitObject != null)
+                AddInternal(borderPiece = new BorderPiece());
+
+            if (HyperDash.Value)
                 AddInternal(new HyperBorderPiece());
-            }
         }
 
         protected override void Update()
         {
-            base.Update();
+            if (borderPiece != null && drawableHitObject?.HitObject != null)
-            border.Alpha = (float)Math.Clamp((hitObject.StartTime - Time.Current) / 500, 0, 1);
+                borderPiece.Alpha = (float)Math.Clamp((drawableHitObject.HitObject.StartTime - Time.Current) / 500, 0, 1);
         }
 
         private Drawable getFruitFor(FruitVisualRepresentation representation)

osu.Game.Rulesets.Catch/Objects/PalpableCatchHitObject.cs

@@ -1,13 +1,18 @@
 // 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 osu.Framework.Bindables;
+using osu.Game.Rulesets.Objects.Types;
+using osuTK.Graphics;
+
 namespace osu.Game.Rulesets.Catch.Objects
 {
     /// <summary>
     /// Represents a single object that can be caught by the catcher.
     /// This includes normal fruits, droplets, and bananas but excludes objects that act only as a container of nested hit objects.
     /// </summary>
-    public abstract class PalpableCatchHitObject : CatchHitObject
+    public abstract class PalpableCatchHitObject : CatchHitObject, IHasComboInformation
     {
         /// <summary>
         /// Difference between the distance to the next object
@@ -16,14 +21,28 @@ namespace osu.Game.Rulesets.Catch.Objects
         /// </summary>
         public float DistanceToHyperDash { get; set; }
 
+        public readonly Bindable<bool> HyperDashBindable = new Bindable<bool>();
+
         /// <summary>
         /// Whether this fruit can initiate a hyperdash.
         /// </summary>
-        public bool HyperDash => HyperDashTarget != null;
+        public bool HyperDash => HyperDashBindable.Value;
+
+        private CatchHitObject hyperDashTarget;
 
         /// <summary>
         /// The target fruit if we are to initiate a hyperdash.
         /// </summary>
-        public CatchHitObject HyperDashTarget;
+        public CatchHitObject HyperDashTarget
+        {
+            get => hyperDashTarget;
+            set
+            {
+                hyperDashTarget = value;
+                HyperDashBindable.Value = value != null;
+            }
+        }
+
+        Color4 IHasComboInformation.GetComboColour(IReadOnlyList<Color4> comboColours) => comboColours[(IndexInBeatmap + 1) % comboColours.Count];
     }
 }

osu.Game.Rulesets.Catch/UI/CatchPlayfield.cs

@@ -55,7 +55,13 @@ namespace osu.Game.Rulesets.Catch.UI
                 HitObjectContainer,
                 CatcherArea,
             };
+        }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            // these subscriptions need to be done post constructor to ensure externally bound components have a chance to populate required fields (ScoreProcessor / ComboAtJudgement in this case).
             NewResult += onNewResult;
             RevertResult += onRevertResult;
         }

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

@@ -97,7 +97,7 @@ namespace osu.Game.Rulesets.Mania.UI
             DrawableManiaHitObject maniaObject = (DrawableManiaHitObject)hitObject;
             maniaObject.CheckHittable = hitPolicy.IsHittable;
 
-            HitObjectContainer.Add(hitObject);
+            base.Add(hitObject);
         }
 
         public override bool Remove(DrawableHitObject h)

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableOsuHitObject.cs

@@ -53,9 +53,9 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             });
         }
 
-        protected override void OnApply(HitObject hitObject)
+        protected override void OnApply()
         {
-            base.OnApply(hitObject);
+            base.OnApply();
 
             IndexInCurrentComboBindable.BindTo(HitObject.IndexInCurrentComboBindable);
             PositionBindable.BindTo(HitObject.PositionBindable);
@@ -70,9 +70,9 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             LifetimeEnd = HitObject.GetEndTime() + HitObject.HitWindows.WindowFor(HitResult.Miss) + 1000;
         }
 
-        protected override void OnFree(HitObject hitObject)
+        protected override void OnFree()
         {
-            base.OnFree(hitObject);
+            base.OnFree();
 
             IndexInCurrentComboBindable.UnbindFrom(HitObject.IndexInCurrentComboBindable);
             PositionBindable.UnbindFrom(HitObject.PositionBindable);

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -86,18 +86,18 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             Tracking.BindValueChanged(updateSlidingSample);
         }
 
-        protected override void OnApply(HitObject hitObject)
+        protected override void OnApply()
         {
-            base.OnApply(hitObject);
+            base.OnApply();
 
             // Ensure that the version will change after the upcoming BindTo().
             pathVersion.Value = int.MaxValue;
             PathVersion.BindTo(HitObject.Path.Version);
         }
 
-        protected override void OnFree(HitObject hitObject)
+        protected override void OnFree()
         {
-            base.OnFree(hitObject);
+            base.OnFree();
 
             PathVersion.UnbindFrom(HitObject.Path.Version);
         }

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderHead.cs

@@ -4,7 +4,6 @@
 using System;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
-using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Objects.Types;
 
@@ -36,9 +35,9 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             pathVersion.BindValueChanged(_ => updatePosition());
         }
 
-        protected override void OnFree(HitObject hitObject)
+        protected override void OnFree()
         {
-            base.OnFree(hitObject);
+            base.OnFree();
 
             pathVersion.UnbindFrom(drawableSlider.PathVersion);
         }

osu.Game.Rulesets.Osu/Objects/Drawables/Pieces/MainCirclePiece.cs

@@ -38,7 +38,6 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
             };
         }
 
-        private readonly IBindable<ArmedState> state = new Bindable<ArmedState>();
         private readonly IBindable<Color4> accentColour = new Bindable<Color4>();
         private readonly IBindable<int> indexInCurrentCombo = new Bindable<int>();
 
@@ -50,7 +49,6 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
         {
             var drawableOsuObject = (DrawableOsuHitObject)drawableObject;
 
-            state.BindTo(drawableObject.State);
             accentColour.BindTo(drawableObject.AccentColour);
             indexInCurrentCombo.BindTo(drawableOsuObject.IndexInCurrentComboBindable);
         }
@@ -59,7 +57,6 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
         {
             base.LoadComplete();
 
-            state.BindValueChanged(updateState, true);
             accentColour.BindValueChanged(colour =>
             {
                 explode.Colour = colour.NewValue;
@@ -68,15 +65,18 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
             }, true);
 
             indexInCurrentCombo.BindValueChanged(index => number.Text = (index.NewValue + 1).ToString(), true);
+
+            drawableObject.ApplyCustomUpdateState += updateState;
+            updateState(drawableObject, drawableObject.State.Value);
         }
 
-        private void updateState(ValueChangedEvent<ArmedState> state)
+        private void updateState(DrawableHitObject drawableObject, ArmedState state)
         {
             using (BeginAbsoluteSequence(drawableObject.HitStateUpdateTime, true))
             {
                 glow.FadeOut(400);
 
-                switch (state.NewValue)
+                switch (state)
                 {
                     case ArmedState.Hit:
                         const double flash_in = 40;

osu.Game.Rulesets.Osu/Objects/Drawables/Pieces/SliderBall.cs

@@ -248,7 +248,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
             }
 
             private void trackingChanged(ValueChangedEvent<bool> tracking) =>
-                box.FadeTo(tracking.NewValue ? 0.6f : 0.05f, 200, Easing.OutQuint);
+                box.FadeTo(tracking.NewValue ? 0.3f : 0.05f, 200, Easing.OutQuint);
         }
     }
 }

osu.Game.Rulesets.Osu/Skinning/LegacyMainCirclePiece.cs

@@ -38,7 +38,6 @@ namespace osu.Game.Rulesets.Osu.Skinning
 
         private SkinnableSpriteText hitCircleText;
 
-        private readonly IBindable<ArmedState> state = new Bindable<ArmedState>();
         private readonly Bindable<Color4> accentColour = new Bindable<Color4>();
         private readonly IBindable<int> indexInCurrentCombo = new Bindable<int>();
 
@@ -113,7 +112,6 @@ namespace osu.Game.Rulesets.Osu.Skinning
             if (overlayAboveNumber)
                 AddInternal(hitCircleOverlay.CreateProxy());
 
-            state.BindTo(drawableObject.State);
             accentColour.BindTo(drawableObject.AccentColour);
             indexInCurrentCombo.BindTo(drawableOsuObject.IndexInCurrentComboBindable);
 
@@ -137,19 +135,21 @@ namespace osu.Game.Rulesets.Osu.Skinning
         {
             base.LoadComplete();
 
-            state.BindValueChanged(updateState, true);
             accentColour.BindValueChanged(colour => hitCircleSprite.Colour = LegacyColourCompatibility.DisallowZeroAlpha(colour.NewValue), true);
             if (hasNumber)
                 indexInCurrentCombo.BindValueChanged(index => hitCircleText.Text = (index.NewValue + 1).ToString(), true);
+
+            drawableObject.ApplyCustomUpdateState += updateState;
+            updateState(drawableObject, drawableObject.State.Value);
         }
 
-        private void updateState(ValueChangedEvent<ArmedState> state)
+        private void updateState(DrawableHitObject drawableObject, ArmedState state)
         {
             const double legacy_fade_duration = 240;
 
             using (BeginAbsoluteSequence(drawableObject.HitStateUpdateTime, true))
             {
-                switch (state.NewValue)
+                switch (state)
                 {
                     case ArmedState.Hit:
                         circleSprites.FadeOut(legacy_fade_duration, Easing.Out);

osu.Game.Rulesets.Taiko/UI/TaikoPlayfield.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 osu.Framework.Allocation;
 using osu.Framework.Graphics;
@@ -37,7 +38,7 @@ namespace osu.Game.Rulesets.Taiko.UI
         private SkinnableDrawable mascot;
 
         private ProxyContainer topLevelHitContainer;
-        private ProxyContainer barlineContainer;
+        private ScrollingHitObjectContainer barlineContainer;
         private Container rightArea;
         private Container leftArea;
 
@@ -83,10 +84,7 @@ namespace osu.Game.Rulesets.Taiko.UI
                             RelativeSizeAxes = Axes.Both,
                             Children = new Drawable[]
                             {
-                                barlineContainer = new ProxyContainer
+                                barlineContainer = new ScrollingHitObjectContainer(),
-                                {
-                                    RelativeSizeAxes = Axes.Both,
-                                },
                                 new Container
                                 {
                                     Name = "Hit objects",
@@ -159,18 +157,37 @@ namespace osu.Game.Rulesets.Taiko.UI
 
         public override void Add(DrawableHitObject h)
         {
-            h.OnNewResult += OnNewResult;
-            base.Add(h);
-
             switch (h)
             {
                 case DrawableBarLine barline:
-                    barlineContainer.Add(barline.CreateProxy());
+                    barlineContainer.Add(barline);
                     break;
 
                 case DrawableTaikoHitObject taikoObject:
+                    h.OnNewResult += OnNewResult;
                     topLevelHitContainer.Add(taikoObject.CreateProxiedContent());
+                    base.Add(h);
                     break;
+
+                default:
+                    throw new ArgumentException($"Unsupported {nameof(DrawableHitObject)} type");
+            }
+        }
+
+        public override bool Remove(DrawableHitObject h)
+        {
+            switch (h)
+            {
+                case DrawableBarLine barline:
+                    return barlineContainer.Remove(barline);
+
+                case DrawableTaikoHitObject _:
+                    h.OnNewResult -= OnNewResult;
+                    // todo: consider tidying of proxied content if required.
+                    return base.Remove(h);
+
+                default:
+                    throw new ArgumentException($"Unsupported {nameof(DrawableHitObject)} type");
             }
         }
 

osu.Game.Tests/Editing/EditorChangeHandlerTest.cs

@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using NUnit.Framework;
-using osu.Framework.Utils;
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Osu.Objects;
 using osu.Game.Screens.Edit;
@@ -44,6 +43,36 @@ namespace osu.Game.Tests.Editing
             Assert.That(stateChangedFired, Is.EqualTo(2));
         }
 
+        [Test]
+        public void TestApplyThenUndoThenApplySameChange()
+        {
+            var (handler, beatmap) = createChangeHandler();
+
+            Assert.That(handler.CanUndo.Value, Is.False);
+            Assert.That(handler.CanRedo.Value, Is.False);
+
+            string originalHash = handler.CurrentStateHash;
+
+            addArbitraryChange(beatmap);
+            handler.SaveState();
+
+            Assert.That(handler.CanUndo.Value, Is.True);
+            Assert.That(handler.CanRedo.Value, Is.False);
+            Assert.That(stateChangedFired, Is.EqualTo(1));
+
+            string hash = handler.CurrentStateHash;
+
+            // undo a change without saving
+            handler.RestoreState(-1);
+
+            Assert.That(originalHash, Is.EqualTo(handler.CurrentStateHash));
+            Assert.That(stateChangedFired, Is.EqualTo(2));
+
+            addArbitraryChange(beatmap);
+            handler.SaveState();
+            Assert.That(hash, Is.EqualTo(handler.CurrentStateHash));
+        }
+
         [Test]
         public void TestSaveSameStateDoesNotSave()
         {
@@ -139,7 +168,7 @@ namespace osu.Game.Tests.Editing
 
         private void addArbitraryChange(EditorBeatmap beatmap)
         {
-            beatmap.Add(new HitCircle { StartTime = RNG.Next(0, 100000) });
+            beatmap.Add(new HitCircle { StartTime = 2760 });
         }
     }
 }

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

@@ -21,13 +21,13 @@ using osu.Game.Rulesets.Difficulty;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
-using osu.Game.Rulesets.Objects.Legacy;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Osu;
 using osu.Game.Rulesets.UI;
 using osu.Game.Rulesets.UI.Scrolling;
 using osuTK;
 using osuTK.Graphics;
+using JetBrains.Annotations;
 
 namespace osu.Game.Tests.Visual.Gameplay
 {
@@ -46,6 +46,50 @@ namespace osu.Game.Tests.Visual.Gameplay
         [SetUp]
         public void Setup() => Schedule(() => testClock.CurrentTime = 0);
 
+        [TestCase("pooled")]
+        [TestCase("non-pooled")]
+        public void TestHitObjectLifetime(string pooled)
+        {
+            var beatmap = createBeatmap(_ => pooled == "pooled" ? new TestPooledHitObject() : new TestHitObject());
+            beatmap.ControlPointInfo.Add(0, new TimingControlPoint { BeatLength = time_range });
+            createTest(beatmap);
+
+            assertPosition(0, 0f);
+            assertDead(3);
+
+            setTime(3 * time_range);
+            assertPosition(3, 0f);
+            assertDead(0);
+
+            setTime(0 * time_range);
+            assertPosition(0, 0f);
+            assertDead(3);
+        }
+
+        [TestCase("pooled")]
+        [TestCase("non-pooled")]
+        public void TestNestedHitObject(string pooled)
+        {
+            var beatmap = createBeatmap(i =>
+            {
+                var h = pooled == "pooled" ? new TestPooledParentHitObject() : new TestParentHitObject();
+                h.Duration = 300;
+                h.ChildTimeOffset = i % 3 * 100;
+                return h;
+            });
+            beatmap.ControlPointInfo.Add(0, new TimingControlPoint { BeatLength = time_range });
+            createTest(beatmap);
+
+            assertPosition(0, 0f);
+            assertHeight(0);
+            assertChildPosition(0);
+
+            setTime(5 * time_range);
+            assertPosition(5, 0f);
+            assertHeight(5);
+            assertChildPosition(5);
+        }
+
         [Test]
         public void TestRelativeBeatLengthScaleSingleTimingPoint()
         {
@@ -147,8 +191,37 @@ namespace osu.Game.Tests.Visual.Gameplay
             assertPosition(1, 1);
         }
 
+        /// <summary>
+        /// Get a <see cref="DrawableTestHitObject" /> corresponding to the <paramref name="index"/>'th <see cref="TestHitObject"/>.
+        /// When the hit object is not alive, `null` is returned.
+        /// </summary>
+        [CanBeNull]
+        private DrawableTestHitObject getDrawableHitObject(int index)
+        {
+            var hitObject = drawableRuleset.Beatmap.HitObjects.ElementAt(index);
+            return (DrawableTestHitObject)drawableRuleset.Playfield.HitObjectContainer.AliveObjects.FirstOrDefault(obj => obj.HitObject == hitObject);
+        }
+
+        private float yScale => drawableRuleset.Playfield.HitObjectContainer.DrawHeight;
+
+        private void assertDead(int index) => AddAssert($"hitobject {index} is dead", () => getDrawableHitObject(index) == null);
+
+        private void assertHeight(int index) => AddAssert($"hitobject {index} height", () =>
+        {
+            var d = getDrawableHitObject(index);
+            return d != null && Precision.AlmostEquals(d.DrawHeight, yScale * (float)(d.HitObject.Duration / time_range), 0.1f);
+        });
+
+        private void assertChildPosition(int index) => AddAssert($"hitobject {index} child position", () =>
+        {
+            var d = getDrawableHitObject(index);
+            return d is DrawableTestParentHitObject && Precision.AlmostEquals(
+                d.NestedHitObjects.First().DrawPosition.Y,
+                yScale * (float)((TestParentHitObject)d.HitObject).ChildTimeOffset / time_range, 0.1f);
+        });
+
         private void assertPosition(int index, float relativeY) => AddAssert($"hitobject {index} at {relativeY}",
-            () => Precision.AlmostEquals(drawableRuleset.Playfield.AllHitObjects.ElementAt(index).DrawPosition.Y, drawableRuleset.Playfield.HitObjectContainer.DrawHeight * relativeY));
+            () => Precision.AlmostEquals(getDrawableHitObject(index)?.DrawPosition.Y ?? -1, yScale * relativeY));
 
         private void setTime(double time)
         {
@@ -160,12 +233,16 @@ namespace osu.Game.Tests.Visual.Gameplay
         /// The hitobjects are spaced <see cref="time_range"/> milliseconds apart.
         /// </summary>
         /// <returns>The <see cref="IBeatmap"/>.</returns>
-        private IBeatmap createBeatmap()
+        private IBeatmap createBeatmap(Func<int, TestHitObject> createAction = null)
         {
-            var beatmap = new Beatmap<HitObject> { BeatmapInfo = { Ruleset = new OsuRuleset().RulesetInfo } };
+            var beatmap = new Beatmap<TestHitObject> { BeatmapInfo = { Ruleset = new OsuRuleset().RulesetInfo } };
 
             for (int i = 0; i < 10; i++)
-                beatmap.HitObjects.Add(new HitObject { StartTime = i * time_range });
+            {
+                var h = createAction?.Invoke(i) ?? new TestHitObject();
+                h.StartTime = i * time_range;
+                beatmap.HitObjects.Add(h);
+            }
 
             return beatmap;
         }
@@ -225,7 +302,21 @@ namespace osu.Game.Tests.Visual.Gameplay
                 TimeRange.Value = time_range;
             }
 
-            public override DrawableHitObject<TestHitObject> CreateDrawableRepresentation(TestHitObject h) => new DrawableTestHitObject(h);
+            public override DrawableHitObject<TestHitObject> CreateDrawableRepresentation(TestHitObject h)
+            {
+                switch (h)
+                {
+                    case TestPooledHitObject _:
+                    case TestPooledParentHitObject _:
+                        return null;
+
+                    case TestParentHitObject p:
+                        return new DrawableTestParentHitObject(p);
+
+                    default:
+                        return new DrawableTestHitObject(h);
+                }
+            }
 
             protected override PassThroughInputManager CreateInputManager() => new PassThroughInputManager();
 
@@ -265,6 +356,9 @@ namespace osu.Game.Tests.Visual.Gameplay
                         }
                     }
                 });
+
+                RegisterPool<TestPooledHitObject, DrawableTestPooledHitObject>(1);
+                RegisterPool<TestPooledParentHitObject, DrawableTestPooledParentHitObject>(1);
             }
         }
 
@@ -277,30 +371,46 @@ namespace osu.Game.Tests.Visual.Gameplay
 
             public override bool CanConvert() => true;
 
-            protected override IEnumerable<TestHitObject> ConvertHitObject(HitObject original, IBeatmap beatmap, CancellationToken cancellationToken)
+            protected override IEnumerable<TestHitObject> ConvertHitObject(HitObject original, IBeatmap beatmap, CancellationToken cancellationToken) =>
-            {
+                throw new NotImplementedException();
-                yield return new TestHitObject
-                {
-                    StartTime = original.StartTime,
-                    Duration = (original as IHasDuration)?.Duration ?? 100
-                };
-            }
         }
 
         #endregion
 
         #region HitObject
 
-        private class TestHitObject : ConvertHitObject, IHasDuration
+        private class TestHitObject : HitObject, IHasDuration
         {
             public double EndTime => StartTime + Duration;
 
-            public double Duration { get; set; }
+            public double Duration { get; set; } = 100;
+        }
+
+        private class TestPooledHitObject : TestHitObject
+        {
+        }
+
+        private class TestParentHitObject : TestHitObject
+        {
+            public double ChildTimeOffset;
+
+            protected override void CreateNestedHitObjects(CancellationToken cancellationToken)
+            {
+                AddNested(new TestHitObject { StartTime = StartTime + ChildTimeOffset });
+            }
+        }
+
+        private class TestPooledParentHitObject : TestParentHitObject
+        {
+            protected override void CreateNestedHitObjects(CancellationToken cancellationToken)
+            {
+                AddNested(new TestPooledHitObject { StartTime = StartTime + ChildTimeOffset });
+            }
         }
 
         private class DrawableTestHitObject : DrawableHitObject<TestHitObject>
         {
-            public DrawableTestHitObject(TestHitObject hitObject)
+            public DrawableTestHitObject([CanBeNull] TestHitObject hitObject)
                 : base(hitObject)
             {
                 Anchor = Anchor.TopCentre;
@@ -324,6 +434,52 @@ namespace osu.Game.Tests.Visual.Gameplay
                     }
                 });
             }
+
+            protected override void Update() => LifetimeEnd = HitObject.EndTime;
+        }
+
+        private class DrawableTestPooledHitObject : DrawableTestHitObject
+        {
+            public DrawableTestPooledHitObject()
+                : base(null)
+            {
+                InternalChildren[0].Colour = Color4.LightSkyBlue;
+                InternalChildren[1].Colour = Color4.Blue;
+            }
+        }
+
+        private class DrawableTestParentHitObject : DrawableTestHitObject
+        {
+            private readonly Container<DrawableHitObject> container;
+
+            public DrawableTestParentHitObject([CanBeNull] TestHitObject hitObject)
+                : base(hitObject)
+            {
+                InternalChildren[0].Colour = Color4.LightYellow;
+                InternalChildren[1].Colour = Color4.Yellow;
+
+                AddInternal(container = new Container<DrawableHitObject>
+                {
+                    RelativeSizeAxes = Axes.Both,
+                });
+            }
+
+            protected override DrawableHitObject CreateNestedHitObject(HitObject hitObject) =>
+                new DrawableTestHitObject((TestHitObject)hitObject);
+
+            protected override void AddNestedHitObject(DrawableHitObject hitObject) => container.Add(hitObject);
+
+            protected override void ClearNestedHitObjects() => container.Clear(false);
+        }
+
+        private class DrawableTestPooledParentHitObject : DrawableTestParentHitObject
+        {
+            public DrawableTestPooledParentHitObject()
+                : base(null)
+            {
+                InternalChildren[0].Colour = Color4.LightSeaGreen;
+                InternalChildren[1].Colour = Color4.Green;
+            }
         }
 
         #endregion

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

@@ -261,9 +261,9 @@ namespace osu.Game.Tests.Visual.Gameplay
                 });
             }
 
-            protected override void OnApply(HitObject hitObject)
+            protected override void OnApply()
             {
-                base.OnApply(hitObject);
+                base.OnApply();
                 Position = new Vector2(RNG.Next(-200, 200), RNG.Next(-200, 200));
             }
 

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

@@ -3,7 +3,6 @@
 
 using NUnit.Framework;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Sprites;
 using osu.Framework.Utils;
 using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
@@ -14,44 +13,41 @@ namespace osu.Game.Tests.Visual.Gameplay
     [TestFixture]
     public class TestSceneStarCounter : OsuTestScene
     {
+        private readonly StarCounter starCounter;
+        private readonly OsuSpriteText starsLabel;
+
         public TestSceneStarCounter()
         {
-            StarCounter stars = new StarCounter
+            starCounter = new StarCounter
             {
                 Origin = Anchor.Centre,
                 Anchor = Anchor.Centre,
-                Current = 5,
             };
 
-            Add(stars);
+            Add(starCounter);
 
-            SpriteText starsLabel = new OsuSpriteText
+            starsLabel = new OsuSpriteText
             {
                 Origin = Anchor.Centre,
                 Anchor = Anchor.Centre,
                 Scale = new Vector2(2),
                 Y = 50,
-                Text = stars.Current.ToString("0.00"),
             };
 
             Add(starsLabel);
 
-            AddRepeatStep(@"random value", delegate
+            setStars(5);
-            {
-                stars.Current = RNG.NextSingle() * (stars.StarCount + 1);
-                starsLabel.Text = stars.Current.ToString("0.00");
-            }, 10);
 
-            AddStep(@"Stop animation", delegate
+            AddRepeatStep("random value", () => setStars(RNG.NextSingle() * (starCounter.StarCount + 1)), 10);
-            {
+            AddSliderStep("exact value", 0f, 10f, 5f, setStars);
-                stars.StopAnimation();
+            AddStep("stop animation", () => starCounter.StopAnimation());
-            });
+            AddStep("reset", () => setStars(0));
+        }
 
-            AddStep(@"Reset", delegate
+        private void setStars(float stars)
-            {
+        {
-                stars.Current = 0;
+            starCounter.Current = stars;
-                starsLabel.Text = stars.Current.ToString("0.00");
+            starsLabel.Text = starCounter.Current.ToString("0.00");
-            });
         }
     }
 }

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs

@@ -917,7 +917,7 @@ namespace osu.Game.Tests.Visual.SongSelect
             {
                 get
                 {
-                    foreach (var item in ScrollableContent)
+                    foreach (var item in Scroll.Children)
                     {
                         yield return item;
 

osu.Game/Graphics/Containers/OsuScrollContainer.cs

@@ -12,7 +12,19 @@ using osuTK.Input;
 
 namespace osu.Game.Graphics.Containers
 {
-    public class OsuScrollContainer : ScrollContainer<Drawable>
+    public class OsuScrollContainer : OsuScrollContainer<Drawable>
+    {
+        public OsuScrollContainer()
+        {
+        }
+
+        public OsuScrollContainer(Direction direction)
+            : base(direction)
+        {
+        }
+    }
+
+    public class OsuScrollContainer<T> : ScrollContainer<T> where T : Drawable
     {
         public const float SCROLL_BAR_HEIGHT = 10;
         public const float SCROLL_BAR_PADDING = 3;

osu.Game/Graphics/UserInterface/StarCounter.cs

@@ -147,7 +147,7 @@ namespace osu.Game.Graphics.UserInterface
 
             public override void DisplayAt(float scale)
             {
-                scale = Math.Clamp(scale, min_star_scale, 1);
+                scale = (float)Interpolation.Lerp(min_star_scale, 1, Math.Clamp(scale, 0, 1));
 
                 this.FadeTo(scale, fading_duration);
                 Icon.ScaleTo(scale, scaling_duration, scaling_easing);

osu.Game/Input/Bindings/GlobalActionContainer.cs

@@ -69,6 +69,7 @@ namespace osu.Game.Input.Bindings
             new KeyBinding(new[] { InputKey.Control, InputKey.Plus }, GlobalAction.IncreaseScrollSpeed),
             new KeyBinding(new[] { InputKey.Control, InputKey.Minus }, GlobalAction.DecreaseScrollSpeed),
             new KeyBinding(InputKey.MouseMiddle, GlobalAction.PauseGameplay),
+            new KeyBinding(InputKey.Space, GlobalAction.TogglePauseReplay),
             new KeyBinding(InputKey.Control, GlobalAction.HoldForHUD),
         };
 
@@ -163,10 +164,10 @@ namespace osu.Game.Input.Bindings
         [Description("Toggle now playing overlay")]
         ToggleNowPlaying,
 
-        [Description("Previous Selection")]
+        [Description("Previous selection")]
         SelectPrevious,
 
-        [Description("Next Selection")]
+        [Description("Next selection")]
         SelectNext,
 
         [Description("Home")]
@@ -175,26 +176,29 @@ namespace osu.Game.Input.Bindings
         [Description("Toggle notifications")]
         ToggleNotifications,
 
-        [Description("Pause")]
+        [Description("Pause gameplay")]
         PauseGameplay,
 
         // Editor
-        [Description("Setup Mode")]
+        [Description("Setup mode")]
         EditorSetupMode,
 
-        [Description("Compose Mode")]
+        [Description("Compose mode")]
         EditorComposeMode,
 
-        [Description("Design Mode")]
+        [Description("Design mode")]
         EditorDesignMode,
 
-        [Description("Timing Mode")]
+        [Description("Timing mode")]
         EditorTimingMode,
 
         [Description("Hold for HUD")]
         HoldForHUD,
 
-        [Description("Random Skin")]
+        [Description("Random skin")]
         RandomSkin,
+
+        [Description("Pause / resume replay")]
+        TogglePauseReplay,
     }
 }

osu.Game/Overlays/Settings/Sections/AudioSection.cs

@@ -27,7 +27,6 @@ namespace osu.Game.Overlays.Settings.Sections
                 new AudioDevicesSettings(),
                 new VolumeSettings(),
                 new OffsetSettings(),
-                new MainMenuSettings()
             };
         }
     }

osu.Game/Overlays/Settings/Sections/GameplaySection.cs

@@ -26,7 +26,6 @@ namespace osu.Game.Overlays.Settings.Sections
             Children = new Drawable[]
             {
                 new GeneralSettings(),
-                new SongSelectSettings(),
                 new ModsSettings(),
             };
         }

osu.Game/Overlays/Settings/Sections/GraphicsSection.cs

@@ -23,7 +23,6 @@ namespace osu.Game.Overlays.Settings.Sections
                 new RendererSettings(),
                 new LayoutSettings(),
                 new DetailSettings(),
-                new UserInterfaceSettings(),
             };
         }
     }

osu.Game/Overlays/Settings/Sections/SizeSlider.cs

@@ -0,0 +1,15 @@
+// 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.Game.Graphics.UserInterface;
+
+namespace osu.Game.Overlays.Settings.Sections
+{
+    /// <summary>
+    /// A slider intended to show a "size" multiplier number, where 1x is 1.0.
+    /// </summary>
+    internal class SizeSlider : OsuSliderBar<float>
+    {
+        public override string TooltipText => Current.Value.ToString(@"0.##x");
+    }
+}

osu.Game/Overlays/Settings/Sections/SkinSection.cs

@@ -54,12 +54,6 @@ namespace osu.Game.Overlays.Settings.Sections
                 skinDropdown = new SkinSettingsDropdown(),
                 new ExportSkinButton(),
                 new SettingsSlider<float, SizeSlider>
-                {
-                    LabelText = "Menu cursor size",
-                    Current = config.GetBindable<float>(OsuSetting.MenuCursorSize),
-                    KeyboardStep = 0.01f
-                },
-                new SettingsSlider<float, SizeSlider>
                 {
                     LabelText = "Gameplay cursor size",
                     Current = config.GetBindable<float>(OsuSetting.GameplayCursorSize),
@@ -136,11 +130,6 @@ namespace osu.Game.Overlays.Settings.Sections
                 Schedule(() => skinDropdown.Items = skinDropdown.Items.Where(i => i.ID != item.ID).ToArray());
         }
 
-        private class SizeSlider : OsuSliderBar<float>
-        {
-            public override string TooltipText => Current.Value.ToString(@"0.##x");
-        }
-
         private class SkinSettingsDropdown : SettingsDropdown<SkinInfo>
         {
             protected override OsuDropdown<SkinInfo> CreateDropdown() => new SkinDropdownControl();

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

@@ -6,11 +6,11 @@ using osu.Framework.Graphics;
 using osu.Game.Configuration;
 using osu.Game.Graphics.UserInterface;
 
-namespace osu.Game.Overlays.Settings.Sections.Graphics
+namespace osu.Game.Overlays.Settings.Sections.UserInterface
 {
-    public class UserInterfaceSettings : SettingsSubsection
+    public class GeneralSettings : SettingsSubsection
     {
-        protected override string Header => "User Interface";
+        protected override string Header => "General";
 
         [BackgroundDependencyLoader]
         private void load(OsuConfigManager config)
@@ -22,6 +22,12 @@ namespace osu.Game.Overlays.Settings.Sections.Graphics
                     LabelText = "Rotate cursor when dragging",
                     Current = config.GetBindable<bool>(OsuSetting.CursorRotation)
                 },
+                new SettingsSlider<float, SizeSlider>
+                {
+                    LabelText = "Menu cursor size",
+                    Current = config.GetBindable<float>(OsuSetting.MenuCursorSize),
+                    KeyboardStep = 0.01f
+                },
                 new SettingsCheckbox
                 {
                     LabelText = "Parallax",

osu.Game/Overlays/Settings/Sections/UserInterface/MainMenuSettings.cs

@@ -7,7 +7,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Game.Configuration;
 
-namespace osu.Game.Overlays.Settings.Sections.Audio
+namespace osu.Game.Overlays.Settings.Sections.UserInterface
 {
     public class MainMenuSettings : SettingsSubsection
     {

osu.Game/Overlays/Settings/Sections/UserInterface/SongSelectSettings.cs

@@ -8,7 +8,7 @@ using osu.Framework.Graphics;
 using osu.Game.Configuration;
 using osu.Game.Graphics.UserInterface;
 
-namespace osu.Game.Overlays.Settings.Sections.Gameplay
+namespace osu.Game.Overlays.Settings.Sections.UserInterface
 {
     public class SongSelectSettings : SettingsSubsection
     {

osu.Game/Overlays/Settings/Sections/UserInterfaceSection.cs

@@ -0,0 +1,29 @@
+// 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.Framework.Graphics.Sprites;
+using osu.Game.Overlays.Settings.Sections.UserInterface;
+
+namespace osu.Game.Overlays.Settings.Sections
+{
+    public class UserInterfaceSection : SettingsSection
+    {
+        public override string Header => "User Interface";
+
+        public override Drawable CreateIcon() => new SpriteIcon
+        {
+            Icon = FontAwesome.Solid.LayerGroup
+        };
+
+        public UserInterfaceSection()
+        {
+            Children = new Drawable[]
+            {
+                new GeneralSettings(),
+                new MainMenuSettings(),
+                new SongSelectSettings()
+            };
+        }
+    }
+}

osu.Game/Overlays/SettingsOverlay.cs

@@ -23,10 +23,11 @@ namespace osu.Game.Overlays
         {
             new GeneralSection(),
             new GraphicsSection(),
-            new GameplaySection(),
             new AudioSection(),
-            new SkinSection(),
             new InputSection(createSubPanel(new KeyBindingPanel())),
+            new UserInterfaceSection(),
+            new GameplaySection(),
+            new SkinSection(),
             new OnlineSection(),
             new MaintenanceSection(),
             new DebugSection(),

osu.Game/Rulesets/Judgements/DrawableJudgement.cs

@@ -32,9 +32,6 @@ namespace osu.Game.Rulesets.Judgements
 
         private readonly Container aboveHitObjectsContent;
 
-        [Resolved]
-        private ISkinSource skinSource { get; set; }
-
         /// <summary>
         /// Duration of initial fade in.
         /// </summary>
@@ -78,29 +75,6 @@ namespace osu.Game.Rulesets.Judgements
 
         public Drawable GetProxyAboveHitObjectsContent() => aboveHitObjectsContent.CreateProxy();
 
-        protected override void LoadComplete()
-        {
-            base.LoadComplete();
-            skinSource.SourceChanged += onSkinChanged;
-        }
-
-        private void onSkinChanged()
-        {
-            // on a skin change, the child component will update but not get correctly triggered to play its animation.
-            // we need to trigger a reinitialisation to make things right.
-            currentDrawableType = null;
-
-            PrepareForUse();
-        }
-
-        protected override void Dispose(bool isDisposing)
-        {
-            base.Dispose(isDisposing);
-
-            if (skinSource != null)
-                skinSource.SourceChanged -= onSkinChanged;
-        }
-
         /// <summary>
         /// Apply top-level animations to the current judgement when successfully hit.
         /// If displaying components which require lifetime extensions, manually adjusting <see cref="Drawable.LifetimeEnd"/> is required.
@@ -142,13 +116,14 @@ namespace osu.Game.Rulesets.Judgements
 
             Debug.Assert(Result != null);
 
-            prepareDrawables();
-
             runAnimation();
         }
 
         private void runAnimation()
         {
+            // is a no-op if the drawables are already in a correct state.
+            prepareDrawables();
+
             // undo any transforms applies in ApplyMissAnimations/ApplyHitAnimations to get a sane initial state.
             ApplyTransformsAt(double.MinValue, true);
             ClearTransforms(true);
@@ -203,7 +178,6 @@ namespace osu.Game.Rulesets.Judgements
             if (JudgementBody != null)
                 RemoveInternal(JudgementBody);
 
-            aboveHitObjectsContent.Clear();
             AddInternal(JudgementBody = new SkinnableDrawable(new GameplaySkinComponent<HitResult>(type), _ =>
                 CreateDefaultJudgement(type), confineMode: ConfineMode.NoScaling)
             {
@@ -211,14 +185,29 @@ namespace osu.Game.Rulesets.Judgements
                 Origin = Anchor.Centre,
             });
 
-            if (JudgementBody.Drawable is IAnimatableJudgement animatable)
+            JudgementBody.OnSkinChanged += () =>
             {
-                var proxiedContent = animatable.GetAboveHitObjectsProxiedContent();
+                // on a skin change, the child component will update but not get correctly triggered to play its animation (or proxy the newly created content).
-                if (proxiedContent != null)
+                // we need to trigger a reinitialisation to make things right.
-                    aboveHitObjectsContent.Add(proxiedContent);
+                proxyContent();
-            }
+                runAnimation();
+            };
+
+            proxyContent();
 
             currentDrawableType = type;
+
+            void proxyContent()
+            {
+                aboveHitObjectsContent.Clear();
+
+                if (JudgementBody.Drawable is IAnimatableJudgement animatable)
+                {
+                    var proxiedContent = animatable.GetAboveHitObjectsProxiedContent();
+                    if (proxiedContent != null)
+                        aboveHitObjectsContent.Add(proxiedContent);
+                }
+            }
         }
 
         protected virtual Drawable CreateDefaultJudgement(HitResult result) => new DefaultJudgementPiece(result);

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -128,6 +128,12 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
         private readonly Bindable<ArmedState> state = new Bindable<ArmedState>();
 
+        /// <summary>
+        /// The state of this <see cref="DrawableHitObject"/>.
+        /// </summary>
+        /// <remarks>
+        /// For pooled hitobjects, <see cref="ApplyCustomUpdateState"/> is recommended to be used instead for better editor/rewinding support.
+        /// </remarks>
         public IBindable<ArmedState> State => state;
 
         /// <summary>
@@ -184,7 +190,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
         {
             base.LoadComplete();
 
-            comboIndexBindable.BindValueChanged(_ => updateComboColour(), true);
+            comboIndexBindable.BindValueChanged(_ => UpdateComboColour(), true);
 
             updateState(ArmedState.Idle, true);
         }
@@ -254,12 +260,19 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
             HitObject.DefaultsApplied += onDefaultsApplied;
 
-            OnApply(hitObject);
+            OnApply();
             HitObjectApplied?.Invoke(this);
 
-            // If not loaded, the state update happens in LoadComplete(). Otherwise, the update is scheduled to allow for lifetime updates.
+            // If not loaded, the state update happens in LoadComplete().
             if (IsLoaded)
-                Schedule(() => updateState(ArmedState.Idle, true));
+            {
+                if (Result.IsHit)
+                    updateState(ArmedState.Hit, true);
+                else if (Result.HasResult)
+                    updateState(ArmedState.Miss, true);
+                else
+                    updateState(ArmedState.Idle, true);
+            }
 
             hasHitObjectApplied = true;
         }
@@ -299,7 +312,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
 
             HitObject.DefaultsApplied -= onDefaultsApplied;
 
-            OnFree(HitObject);
+            OnFree();
 
             HitObject = null;
             Result = null;
@@ -324,16 +337,14 @@ namespace osu.Game.Rulesets.Objects.Drawables
         /// <summary>
         /// Invoked for this <see cref="DrawableHitObject"/> to take on any values from a newly-applied <see cref="HitObject"/>.
         /// </summary>
-        /// <param name="hitObject">The <see cref="HitObject"/> being applied.</param>
+        protected virtual void OnApply()
-        protected virtual void OnApply(HitObject hitObject)
         {
         }
 
         /// <summary>
         /// Invoked for this <see cref="DrawableHitObject"/> to revert any values previously taken on from the currently-applied <see cref="HitObject"/>.
         /// </summary>
-        /// <param name="hitObject">The currently-applied <see cref="HitObject"/>.</param>
+        protected virtual void OnFree()
-        protected virtual void OnFree(HitObject hitObject)
         {
         }
 
@@ -519,7 +530,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
         {
             base.SkinChanged(skin, allowFallback);
 
-            updateComboColour();
+            UpdateComboColour();
 
             ApplySkin(skin, allowFallback);
 
@@ -527,13 +538,12 @@ namespace osu.Game.Rulesets.Objects.Drawables
                 updateState(State.Value, true);
         }
 
-        private void updateComboColour()
+        protected void UpdateComboColour()
         {
-            if (!(HitObject is IHasComboInformation)) return;
+            if (!(HitObject is IHasComboInformation combo)) return;
 
-            var comboColours = CurrentSkin.GetConfig<GlobalSkinColours, IReadOnlyList<Color4>>(GlobalSkinColours.ComboColours)?.Value;
+            var comboColours = CurrentSkin.GetConfig<GlobalSkinColours, IReadOnlyList<Color4>>(GlobalSkinColours.ComboColours)?.Value ?? Array.Empty<Color4>();
-
+            AccentColour.Value = combo.GetComboColour(comboColours);
-            AccentColour.Value = GetComboColour(comboColours);
         }
 
         /// <summary>
@@ -544,6 +554,7 @@ namespace osu.Game.Rulesets.Objects.Drawables
         /// This will only be called if the <see cref="HitObject"/> implements <see cref="IHasComboInformation"/>.
         /// </remarks>
         /// <param name="comboColours">A list of combo colours provided by the beatmap or skin. Can be null if not available.</param>
+        [Obsolete("Unused. Implement IHasComboInformation and IHasComboInformation.GetComboColour() on the HitObject model instead.")] // Can be removed 20210527
         protected virtual Color4 GetComboColour(IReadOnlyList<Color4> comboColours)
         {
             if (!(HitObject is IHasComboInformation combo))

osu.Game/Rulesets/Objects/Types/IHasComboInformation.cs

@@ -1,7 +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.Collections.Generic;
+using JetBrains.Annotations;
 using osu.Framework.Bindables;
+using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Objects.Types
 {
@@ -35,5 +38,13 @@ namespace osu.Game.Rulesets.Objects.Types
         /// Whether this is the last object in the current combo.
         /// </summary>
         bool LastInCombo { get; set; }
+
+        /// <summary>
+        /// Retrieves the colour of the combo described by this <see cref="IHasComboInformation"/> object from a set of possible combo colours.
+        /// Defaults to using <see cref="ComboIndex"/> to decide the colour.
+        /// </summary>
+        /// <param name="comboColours">A list of possible combo colours provided by the beatmap or skin.</param>
+        /// <returns>The colour of the combo described by this <see cref="IHasComboInformation"/> object.</returns>
+        Color4 GetComboColour([NotNull] IReadOnlyList<Color4> comboColours) => comboColours.Count > 0 ? comboColours[ComboIndex % comboColours.Count] : Color4.White;
     }
 }

osu.Game/Rulesets/UI/HitObjectContainer.cs

@@ -114,6 +114,7 @@ namespace osu.Game.Rulesets.UI
 
             bindStartTime(drawable);
             AddInternal(drawableMap[entry] = drawable, false);
+            OnAdd(drawable);
 
             HitObjectUsageBegan?.Invoke(entry.HitObject);
         }
@@ -129,6 +130,7 @@ namespace osu.Game.Rulesets.UI
 
             drawableMap.Remove(entry);
 
+            OnRemove(drawable);
             unbindStartTime(drawable);
             RemoveInternal(drawable);
 
@@ -147,10 +149,12 @@ namespace osu.Game.Rulesets.UI
             hitObject.OnRevertResult += onRevertResult;
 
             AddInternal(hitObject);
+            OnAdd(hitObject);
         }
 
         public virtual bool Remove(DrawableHitObject hitObject)
         {
+            OnRemove(hitObject);
             if (!RemoveInternal(hitObject))
                 return false;
 
@@ -178,6 +182,26 @@ namespace osu.Game.Rulesets.UI
 
         #endregion
 
+        /// <summary>
+        /// Invoked when a <see cref="DrawableHitObject"/> is added to this container.
+        /// </summary>
+        /// <remarks>
+        /// This method is not invoked for nested <see cref="DrawableHitObject"/>s.
+        /// </remarks>
+        protected virtual void OnAdd(DrawableHitObject drawableHitObject)
+        {
+        }
+
+        /// <summary>
+        /// Invoked when a <see cref="DrawableHitObject"/> is removed from this container.
+        /// </summary>
+        /// <remarks>
+        /// This method is not invoked for nested <see cref="DrawableHitObject"/>s.
+        /// </remarks>
+        protected virtual void OnRemove(DrawableHitObject drawableHitObject)
+        {
+        }
+
         public virtual void Clear(bool disposeChildren = true)
         {
             lifetimeManager.ClearEntries();

osu.Game/Rulesets/UI/Playfield.cs

@@ -135,10 +135,8 @@ namespace osu.Game.Rulesets.UI
         /// <param name="h">The DrawableHitObject to add.</param>
         public virtual void Add(DrawableHitObject h)
         {
-            if (h.IsInitialized)
+            if (!h.IsInitialized)
-                throw new InvalidOperationException($"{nameof(Add)} doesn't support {nameof(DrawableHitObject)} reuse. Use pooling instead.");
+                onNewDrawableHitObject(h);
-
-            onNewDrawableHitObject(h);
 
             HitObjectContainer.Add(h);
             OnHitObjectAdded(h.HitObject);

osu.Game/Rulesets/UI/Scrolling/ScrollingHitObjectContainer.cs

@@ -2,13 +2,10 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Collections.Generic;
-using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
-using osu.Framework.Caching;
 using osu.Framework.Graphics;
 using osu.Framework.Layout;
-using osu.Framework.Threading;
 using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Objects.Types;
 using osuTK;
@@ -19,7 +16,16 @@ namespace osu.Game.Rulesets.UI.Scrolling
     {
         private readonly IBindable<double> timeRange = new BindableDouble();
         private readonly IBindable<ScrollingDirection> direction = new Bindable<ScrollingDirection>();
-        private readonly Dictionary<DrawableHitObject, InitialState> hitObjectInitialStateCache = new Dictionary<DrawableHitObject, InitialState>();
+
+        /// <summary>
+        /// Hit objects which require lifetime computation in the next update call.
+        /// </summary>
+        private readonly HashSet<DrawableHitObject> toComputeLifetime = new HashSet<DrawableHitObject>();
+
+        /// <summary>
+        /// A set containing all <see cref="HitObjectContainer.AliveObjects"/> which have an up-to-date layout.
+        /// </summary>
+        private readonly HashSet<DrawableHitObject> layoutComputed = new HashSet<DrawableHitObject>();
 
         [Resolved]
         private IScrollingInfo scrollingInfo { get; set; }
@@ -27,10 +33,6 @@ namespace osu.Game.Rulesets.UI.Scrolling
         // Responds to changes in the layout. When the layout changes, all hit object states must be recomputed.
         private readonly LayoutValue layoutCache = new LayoutValue(Invalidation.RequiredParentSizeToFit | Invalidation.DrawInfo);
 
-        // A combined cache across all hit object states to reduce per-update iterations.
-        // When invalidated, one or more (but not necessarily all) hitobject states must be re-validated.
-        private readonly Cached combinedObjCache = new Cached();
-
         public ScrollingHitObjectContainer()
         {
             RelativeSizeAxes = Axes.Both;
@@ -48,37 +50,12 @@ namespace osu.Game.Rulesets.UI.Scrolling
             timeRange.ValueChanged += _ => layoutCache.Invalidate();
         }
 
-        public override void Add(DrawableHitObject hitObject)
-        {
-            combinedObjCache.Invalidate();
-            hitObject.DefaultsApplied += onDefaultsApplied;
-            base.Add(hitObject);
-        }
-
-        public override bool Remove(DrawableHitObject hitObject)
-        {
-            var result = base.Remove(hitObject);
-
-            if (result)
-            {
-                combinedObjCache.Invalidate();
-                hitObjectInitialStateCache.Remove(hitObject);
-
-                hitObject.DefaultsApplied -= onDefaultsApplied;
-            }
-
-            return result;
-        }
-
         public override void Clear(bool disposeChildren = true)
         {
-            foreach (var h in Objects)
-                h.DefaultsApplied -= onDefaultsApplied;
-
             base.Clear(disposeChildren);
 
-            combinedObjCache.Invalidate();
+            toComputeLifetime.Clear();
-            hitObjectInitialStateCache.Clear();
+            layoutComputed.Clear();
         }
 
         /// <summary>
@@ -173,15 +150,40 @@ namespace osu.Game.Rulesets.UI.Scrolling
             }
         }
 
-        private void onDefaultsApplied(DrawableHitObject drawableObject)
+        protected override void OnAdd(DrawableHitObject drawableHitObject) => onAddRecursive(drawableHitObject);
+
+        protected override void OnRemove(DrawableHitObject drawableHitObject) => onRemoveRecursive(drawableHitObject);
+
+        private void onAddRecursive(DrawableHitObject hitObject)
         {
-            // The cache may not exist if the hitobject state hasn't been computed yet (e.g. if the hitobject was added + defaults applied in the same frame).
+            invalidateHitObject(hitObject);
-            // In such a case, combinedObjCache will take care of updating the hitobject.
+
-            if (hitObjectInitialStateCache.TryGetValue(drawableObject, out var state))
+            hitObject.DefaultsApplied += invalidateHitObject;
-            {
+
-                combinedObjCache.Invalidate();
+            foreach (var nested in hitObject.NestedHitObjects)
-                state.Cache.Invalidate();
+                onAddRecursive(nested);
-            }
+        }
+
+        private void onRemoveRecursive(DrawableHitObject hitObject)
+        {
+            toComputeLifetime.Remove(hitObject);
+            layoutComputed.Remove(hitObject);
+
+            hitObject.DefaultsApplied -= invalidateHitObject;
+
+            foreach (var nested in hitObject.NestedHitObjects)
+                onRemoveRecursive(nested);
+        }
+
+        /// <summary>
+        /// Make this <see cref="DrawableHitObject"/> lifetime and layout computed in next update.
+        /// </summary>
+        private void invalidateHitObject(DrawableHitObject hitObject)
+        {
+            // Lifetime computation is delayed until next update because
+            // when the hit object is not pooled this container is not loaded here and `scrollLength` cannot be computed.
+            toComputeLifetime.Add(hitObject);
+            layoutComputed.Remove(hitObject);
         }
 
         private float scrollLength;
@@ -192,17 +194,18 @@ namespace osu.Game.Rulesets.UI.Scrolling
 
             if (!layoutCache.IsValid)
             {
-                foreach (var state in hitObjectInitialStateCache.Values)
+                toComputeLifetime.Clear();
-                    state.Cache.Invalidate();
+
-                combinedObjCache.Invalidate();
+                foreach (var hitObject in Objects)
+                {
+                    if (hitObject.HitObject != null)
+                        toComputeLifetime.Add(hitObject);
+                }
+
+                layoutComputed.Clear();
 
                 scrollingInfo.Algorithm.Reset();
 
-                layoutCache.Validate();
-            }
-
-            if (!combinedObjCache.IsValid)
-            {
                 switch (direction.Value)
                 {
                     case ScrollingDirection.Up:
@@ -215,32 +218,24 @@ namespace osu.Game.Rulesets.UI.Scrolling
                         break;
                 }
 
-                foreach (var obj in Objects)
+                layoutCache.Validate();
-                {
-                    if (!hitObjectInitialStateCache.TryGetValue(obj, out var state))
-                        state = hitObjectInitialStateCache[obj] = new InitialState(new Cached());
-
-                    if (state.Cache.IsValid)
-                        continue;
-
-                    state.ScheduledComputation?.Cancel();
-                    state.ScheduledComputation = computeInitialStateRecursive(obj);
-
-                    computeLifetimeStartRecursive(obj);
-
-                    state.Cache.Validate();
-                }
-
-                combinedObjCache.Validate();
             }
-        }
 
-        private void computeLifetimeStartRecursive(DrawableHitObject hitObject)
+            foreach (var hitObject in toComputeLifetime)
-        {
+                hitObject.LifetimeStart = computeOriginAdjustedLifetimeStart(hitObject);
-            hitObject.LifetimeStart = computeOriginAdjustedLifetimeStart(hitObject);
 
-            foreach (var obj in hitObject.NestedHitObjects)
+            toComputeLifetime.Clear();
-                computeLifetimeStartRecursive(obj);
+
+            // only AliveObjects need to be considered for layout (reduces overhead in the case of scroll speed changes).
+            foreach (var obj in AliveObjects)
+            {
+                if (layoutComputed.Contains(obj))
+                    continue;
+
+                updateLayoutRecursive(obj);
+
+                layoutComputed.Add(obj);
+            }
         }
 
         private double computeOriginAdjustedLifetimeStart(DrawableHitObject hitObject)
@@ -271,7 +266,7 @@ namespace osu.Game.Rulesets.UI.Scrolling
             return scrollingInfo.Algorithm.GetDisplayStartTime(hitObject.HitObject.StartTime, originAdjustment, timeRange.Value, scrollLength);
         }
 
-        private ScheduledDelegate computeInitialStateRecursive(DrawableHitObject hitObject) => hitObject.Schedule(() =>
+        private void updateLayoutRecursive(DrawableHitObject hitObject)
         {
             if (hitObject.HitObject is IHasDuration e)
             {
@@ -291,12 +286,12 @@ namespace osu.Game.Rulesets.UI.Scrolling
 
             foreach (var obj in hitObject.NestedHitObjects)
             {
-                computeInitialStateRecursive(obj);
+                updateLayoutRecursive(obj);
 
                 // Nested hitobjects don't need to scroll, but they do need accurate positions
                 updatePosition(obj, hitObject.HitObject.StartTime);
             }
-        });
+        }
 
         protected override void UpdateAfterChildrenLife()
         {
@@ -328,19 +323,5 @@ namespace osu.Game.Rulesets.UI.Scrolling
                     break;
             }
         }
-
-        private class InitialState
-        {
-            [NotNull]
-            public readonly Cached Cache;
-
-            [CanBeNull]
-            public ScheduledDelegate ScheduledComputation;
-
-            public InitialState(Cached cache)
-            {
-                Cache = cache;
-            }
-        }
     }
 }

osu.Game/Rulesets/UI/Scrolling/ScrollingPlayfield.cs

@@ -15,6 +15,8 @@ namespace osu.Game.Rulesets.UI.Scrolling
     {
         protected readonly IBindable<ScrollingDirection> Direction = new Bindable<ScrollingDirection>();
 
+        public new ScrollingHitObjectContainer HitObjectContainer => (ScrollingHitObjectContainer)base.HitObjectContainer;
+
         [Resolved]
         protected IScrollingInfo ScrollingInfo { get; private set; }
 
@@ -27,14 +29,12 @@ namespace osu.Game.Rulesets.UI.Scrolling
         /// <summary>
         /// Given a position in screen space, return the time within this column.
         /// </summary>
-        public virtual double TimeAtScreenSpacePosition(Vector2 screenSpacePosition) =>
+        public virtual double TimeAtScreenSpacePosition(Vector2 screenSpacePosition) => HitObjectContainer.TimeAtScreenSpacePosition(screenSpacePosition);
-            ((ScrollingHitObjectContainer)HitObjectContainer).TimeAtScreenSpacePosition(screenSpacePosition);
 
         /// <summary>
         /// Given a time, return the screen space position within this column.
         /// </summary>
-        public virtual Vector2 ScreenSpacePositionAtTime(double time)
+        public virtual Vector2 ScreenSpacePositionAtTime(double time) => HitObjectContainer.ScreenSpacePositionAtTime(time);
-            => ((ScrollingHitObjectContainer)HitObjectContainer).ScreenSpacePositionAtTime(time);
 
         protected sealed override HitObjectContainer CreateHitObjectContainer() => new ScrollingHitObjectContainer();
     }

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

@@ -496,10 +496,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
                 double offset = result.Time.Value - movementBlueprints.First().HitObject.StartTime;
 
                 foreach (HitObject obj in Beatmap.SelectedHitObjects)
-                {
                     obj.StartTime += offset;
-                    Beatmap.Update(obj);
-                }
             }
 
             return true;

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs

@@ -3,7 +3,6 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
@@ -19,8 +18,8 @@ using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
-using osu.Game.Rulesets.Objects.Drawables;
 using osu.Game.Rulesets.Objects.Types;
+using osu.Game.Skinning;
 using osuTK;
 using osuTK.Graphics;
 
@@ -28,32 +27,26 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
     public class TimelineHitObjectBlueprint : SelectionBlueprint
     {
-        private readonly Circle circle;
+        private const float thickness = 5;
+        private const float shadow_radius = 5;
+        private const float circle_size = 24;
+
+        public Action<DragEvent> OnDragHandled;
 
         [UsedImplicitly]
         private readonly Bindable<double> startTime;
 
-        public Action<DragEvent> OnDragHandled;
+        private Bindable<int> indexInCurrentComboBindable;
+        private Bindable<int> comboIndexBindable;
 
+        private readonly Circle circle;
         private readonly DragBar dragBar;
-
         private readonly List<Container> shadowComponents = new List<Container>();
-
-        private DrawableHitObject drawableHitObject;
-
-        private Bindable<Color4> comboColour;
-
         private readonly Container mainComponents;
-
         private readonly OsuSpriteText comboIndexText;
 
-        private Bindable<int> comboIndex;
+        [Resolved]
-
+        private ISkinSource skin { get; set; }
-        private const float thickness = 5;
-
-        private const float shadow_radius = 5;
-
-        private const float circle_size = 24;
 
         public TimelineHitObjectBlueprint(HitObject hitObject)
             : base(hitObject)
@@ -152,46 +145,42 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             updateShadows();
         }
 
-        [BackgroundDependencyLoader(true)]
-        private void load(HitObjectComposer composer)
-        {
-            if (composer != null)
-            {
-                // best effort to get the drawable representation for grabbing colour and what not.
-                drawableHitObject = composer.HitObjects.FirstOrDefault(d => d.HitObject == HitObject);
-            }
-        }
-
         protected override void LoadComplete()
         {
             base.LoadComplete();
 
             if (HitObject is IHasComboInformation comboInfo)
             {
-                comboIndex = comboInfo.IndexInCurrentComboBindable.GetBoundCopy();
+                indexInCurrentComboBindable = comboInfo.IndexInCurrentComboBindable.GetBoundCopy();
-                comboIndex.BindValueChanged(combo =>
+                indexInCurrentComboBindable.BindValueChanged(_ => updateComboIndex(), true);
-                {
+
-                    comboIndexText.Text = (combo.NewValue + 1).ToString();
+                comboIndexBindable = comboInfo.ComboIndexBindable.GetBoundCopy();
-                }, true);
+                comboIndexBindable.BindValueChanged(_ => updateComboColour(), true);
+
+                skin.SourceChanged += updateComboColour;
             }
+        }
 
-            if (drawableHitObject != null)
+        private void updateComboIndex() => comboIndexText.Text = (indexInCurrentComboBindable.Value + 1).ToString();
-            {
-                comboColour = drawableHitObject.AccentColour.GetBoundCopy();
-                comboColour.BindValueChanged(colour =>
-                {
-                    if (HitObject is IHasDuration)
-                        mainComponents.Colour = ColourInfo.GradientHorizontal(drawableHitObject.AccentColour.Value, Color4.White);
-                    else
-                        mainComponents.Colour = drawableHitObject.AccentColour.Value;
 
-                    var col = mainComponents.Colour.TopLeft.Linear;
+        private void updateComboColour()
-                    float brightness = col.R + col.G + col.B;
+        {
+            if (!(HitObject is IHasComboInformation combo))
+                return;
 
-                    // decide the combo index colour based on brightness?
+            var comboColours = skin.GetConfig<GlobalSkinColours, IReadOnlyList<Color4>>(GlobalSkinColours.ComboColours)?.Value ?? Array.Empty<Color4>();
-                    comboIndexText.Colour = brightness > 0.5f ? Color4.Black : Color4.White;
+            var comboColour = combo.GetComboColour(comboColours);
-                }, true);
+
-            }
+            if (HitObject is IHasDuration)
+                mainComponents.Colour = ColourInfo.GradientHorizontal(comboColour, Color4.White);
+            else
+                mainComponents.Colour = comboColour;
+
+            var col = mainComponents.Colour.TopLeft.Linear;
+            float brightness = col.R + col.G + col.B;
+
+            // decide the combo index colour based on brightness?
+            comboIndexText.Colour = brightness > 0.5f ? Color4.Black : Color4.White;
         }
 
         protected override void Update()

osu.Game/Screens/Edit/Compose/ComposeScreen.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.Diagnostics;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -43,6 +44,21 @@ namespace osu.Game.Screens.Edit.Compose
             if (ruleset == null || composer == null)
                 return new ScreenWhiteBox.UnderConstructionMessage(ruleset == null ? "This beatmap" : $"{ruleset.Description}'s composer");
 
+            return wrapSkinnableContent(composer);
+        }
+
+        protected override Drawable CreateTimelineContent()
+        {
+            if (ruleset == null || composer == null)
+                return base.CreateTimelineContent();
+
+            return wrapSkinnableContent(new TimelineBlueprintContainer(composer));
+        }
+
+        private Drawable wrapSkinnableContent(Drawable content)
+        {
+            Debug.Assert(ruleset != null);
+
             var beatmapSkinProvider = new BeatmapSkinProvidingContainer(Beatmap.Value.Skin);
 
             // the beatmapSkinProvider is used as the fallback source here to allow the ruleset-specific skin implementation
@@ -51,9 +67,7 @@ namespace osu.Game.Screens.Edit.Compose
 
             // load the skinning hierarchy first.
             // this is intentionally done in two stages to ensure things are in a loaded state before exposing the ruleset to skin sources.
-            return beatmapSkinProvider.WithChild(rulesetSkinProvider.WithChild(composer));
+            return beatmapSkinProvider.WithChild(rulesetSkinProvider.WithChild(content));
         }
-
-        protected override Drawable CreateTimelineContent() => composer == null ? base.CreateTimelineContent() : new TimelineBlueprintContainer(composer);
     }
 }

osu.Game/Screens/Edit/EditorChangeHandler.cs

@@ -76,7 +76,7 @@ namespace osu.Game.Screens.Edit
                 var newState = stream.ToArray();
 
                 // if the previous state is binary equal we don't need to push a new one, unless this is the initial state.
-                if (savedStates.Count > 0 && newState.SequenceEqual(savedStates.Last())) return;
+                if (savedStates.Count > 0 && newState.SequenceEqual(savedStates[currentState])) return;
 
                 if (currentState < savedStates.Count - 1)
                     savedStates.RemoveRange(currentState + 1, savedStates.Count - currentState - 1);

osu.Game/Screens/Play/Player.cs

@@ -339,7 +339,11 @@ namespace osu.Game.Screens.Play
                         AlwaysVisible = { BindTarget = DrawableRuleset.HasReplayLoaded },
                         IsCounting = false
                     },
-                    RequestSeek = GameplayClockContainer.Seek,
+                    RequestSeek = time =>
+                    {
+                        GameplayClockContainer.Seek(time);
+                        GameplayClockContainer.Start();
+                    },
                     Anchor = Anchor.Centre,
                     Origin = Anchor.Centre
                 },

osu.Game/Screens/Play/ReplayPlayer.cs

@@ -1,12 +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 osu.Framework.Input.Bindings;
+using osu.Game.Input.Bindings;
 using osu.Game.Scoring;
 using osu.Game.Screens.Ranking;
 
 namespace osu.Game.Screens.Play
 {
-    public class ReplayPlayer : Player
+    public class ReplayPlayer : Player, IKeyBindingHandler<GlobalAction>
     {
         protected readonly Score Score;
 
@@ -35,5 +37,24 @@ namespace osu.Game.Screens.Play
 
             return Score.ScoreInfo;
         }
+
+        public bool OnPressed(GlobalAction action)
+        {
+            switch (action)
+            {
+                case GlobalAction.TogglePauseReplay:
+                    if (GameplayClockContainer.IsPaused.Value)
+                        GameplayClockContainer.Start();
+                    else
+                        GameplayClockContainer.Stop();
+                    return true;
+            }
+
+            return false;
+        }
+
+        public void OnReleased(GlobalAction action)
+        {
+        }
     }
 }

osu.Game/Screens/Play/SkipOverlay.cs

@@ -133,6 +133,9 @@ namespace osu.Game.Screens.Play
             switch (action)
             {
                 case GlobalAction.SkipCutscene:
+                    if (!button.Enabled.Value)
+                        return false;
+
                     button.Click();
                     return true;
             }

osu.Game/Screens/Select/BeatmapCarousel.cs

@@ -91,7 +91,7 @@ namespace osu.Game.Screens.Select
         /// </summary>
         public bool BeatmapSetsLoaded { get; private set; }
 
-        private readonly CarouselScrollContainer scroll;
+        protected readonly CarouselScrollContainer Scroll;
 
         private IEnumerable<CarouselBeatmapSet> beatmapSets => root.Children.OfType<CarouselBeatmapSet>();
 
@@ -112,9 +112,9 @@ namespace osu.Game.Screens.Select
             if (selectedBeatmapSet != null && !beatmapSets.Contains(selectedBeatmapSet.BeatmapSet))
                 selectedBeatmapSet = null;
 
-            ScrollableContent.Clear(false);
+            Scroll.Clear(false);
             itemsCache.Invalidate();
-            scrollPositionCache.Invalidate();
+            ScrollToSelected();
 
             // apply any pending filter operation that may have been delayed (see applyActiveCriteria's scheduling behaviour when BeatmapSetsLoaded is false).
             FlushPendingFilterOperations();
@@ -130,9 +130,7 @@ namespace osu.Game.Screens.Select
         private readonly List<CarouselItem> visibleItems = new List<CarouselItem>();
 
         private readonly Cached itemsCache = new Cached();
-        private readonly Cached scrollPositionCache = new Cached();
+        private PendingScrollOperation pendingScrollOperation = PendingScrollOperation.None;
-
-        protected readonly Container<DrawableCarouselItem> ScrollableContent;
 
         public Bindable<bool> RightClickScrollingEnabled = new Bindable<bool>();
 
@@ -155,17 +153,12 @@ namespace osu.Game.Screens.Select
             InternalChild = new OsuContextMenuContainer
             {
                 RelativeSizeAxes = Axes.Both,
-                Child = scroll = new CarouselScrollContainer
+                Children = new Drawable[]
                 {
-                    Masking = false,
+                    setPool,
-                    RelativeSizeAxes = Axes.Both,
+                    Scroll = new CarouselScrollContainer
-                    Children = new Drawable[]
                     {
-                        setPool,
+                        RelativeSizeAxes = Axes.Both,
-                        ScrollableContent = new Container<DrawableCarouselItem>
-                        {
-                            RelativeSizeAxes = Axes.X,
-                        }
                     }
                 }
             };
@@ -180,7 +173,7 @@ namespace osu.Game.Screens.Select
             config.BindWith(OsuSetting.RandomSelectAlgorithm, RandomAlgorithm);
             config.BindWith(OsuSetting.SongSelectRightMouseScroll, RightClickScrollingEnabled);
 
-            RightClickScrollingEnabled.ValueChanged += enabled => scroll.RightMouseScrollbar = enabled.NewValue;
+            RightClickScrollingEnabled.ValueChanged += enabled => Scroll.RightMouseScrollbar = enabled.NewValue;
             RightClickScrollingEnabled.TriggerChange();
 
             itemUpdated = beatmaps.ItemUpdated.GetBoundCopy();
@@ -421,12 +414,12 @@ namespace osu.Game.Screens.Select
         /// <summary>
         /// The position of the lower visible bound with respect to the current scroll position.
         /// </summary>
-        private float visibleBottomBound => scroll.Current + DrawHeight + BleedBottom;
+        private float visibleBottomBound => Scroll.Current + DrawHeight + BleedBottom;
 
         /// <summary>
         /// The position of the upper visible bound with respect to the current scroll position.
         /// </summary>
-        private float visibleUpperBound => scroll.Current - BleedTop;
+        private float visibleUpperBound => Scroll.Current - BleedTop;
 
         public void FlushPendingFilterOperations()
         {
@@ -468,8 +461,8 @@ namespace osu.Game.Screens.Select
                 root.Filter(activeCriteria);
                 itemsCache.Invalidate();
 
-                if (alwaysResetScrollPosition || !scroll.UserScrolling)
+                if (alwaysResetScrollPosition || !Scroll.UserScrolling)
-                    ScrollToSelected();
+                    ScrollToSelected(true);
             }
         }
 
@@ -478,7 +471,12 @@ namespace osu.Game.Screens.Select
         /// <summary>
         /// Scroll to the current <see cref="SelectedBeatmap"/>.
         /// </summary>
-        public void ScrollToSelected() => scrollPositionCache.Invalidate();
+        /// <param name="immediate">
+        /// Whether the scroll position should immediately be shifted to the target, delegating animation to visible panels.
+        /// This should be true for operations like filtering - where panels are changing visibility state - to avoid large jumps in animation.
+        /// </param>
+        public void ScrollToSelected(bool immediate = false) =>
+            pendingScrollOperation = immediate ? PendingScrollOperation.Immediate : PendingScrollOperation.Standard;
 
         #region Key / button selection logic
 
@@ -488,12 +486,12 @@ namespace osu.Game.Screens.Select
             {
                 case Key.Left:
                     if (!e.Repeat)
-                        beginRepeatSelection(() => SelectNext(-1, true), e.Key);
+                        beginRepeatSelection(() => SelectNext(-1), e.Key);
                     return true;
 
                 case Key.Right:
                     if (!e.Repeat)
-                        beginRepeatSelection(() => SelectNext(1, true), e.Key);
+                        beginRepeatSelection(() => SelectNext(), e.Key);
                     return true;
             }
 
@@ -580,6 +578,11 @@ namespace osu.Game.Screens.Select
             if (revalidateItems)
                 updateYPositions();
 
+            // if there is a pending scroll action we apply it without animation and transfer the difference in position to the panels.
+            // this is intentionally applied before updating the visible range below, to avoid animating new items (sourced from pool) from locations off-screen, as it looks bad.
+            if (pendingScrollOperation != PendingScrollOperation.None)
+                updateScrollPosition();
+
             // This data is consumed to find the currently displayable range.
             // This is the range we want to keep drawables for, and should exceed the visible range slightly to avoid drawable churn.
             var newDisplayRange = getDisplayRange();
@@ -594,7 +597,7 @@ namespace osu.Game.Screens.Select
                 {
                     var toDisplay = visibleItems.GetRange(displayedRange.first, displayedRange.last - displayedRange.first + 1);
 
-                    foreach (var panel in ScrollableContent.Children)
+                    foreach (var panel in Scroll.Children)
                     {
                         if (toDisplay.Remove(panel.Item))
                         {
@@ -620,24 +623,14 @@ namespace osu.Game.Screens.Select
                         panel.Depth = item.CarouselYPosition;
                         panel.Y = item.CarouselYPosition;
 
-                        ScrollableContent.Add(panel);
+                        Scroll.Add(panel);
                     }
                 }
             }
 
-            // Finally, if the filtered items have changed, animate drawables to their new locations.
-            // This is common if a selected/collapsed state has changed.
-            if (revalidateItems)
-            {
-                foreach (DrawableCarouselItem panel in ScrollableContent.Children)
-                {
-                    panel.MoveToY(panel.Item.CarouselYPosition, 800, Easing.OutQuint);
-                }
-            }
-
             // Update externally controlled state of currently visible items (e.g. x-offset and opacity).
             // This is a per-frame update on all drawable panels.
-            foreach (DrawableCarouselItem item in ScrollableContent.Children)
+            foreach (DrawableCarouselItem item in Scroll.Children)
             {
                 updateItem(item);
 
@@ -670,14 +663,6 @@ namespace osu.Game.Screens.Select
             return (firstIndex, lastIndex);
         }
 
-        protected override void UpdateAfterChildren()
-        {
-            base.UpdateAfterChildren();
-
-            if (!scrollPositionCache.IsValid)
-                updateScrollPosition();
-        }
-
         private void beatmapRemoved(ValueChangedEvent<WeakReference<BeatmapSetInfo>> weakItem)
         {
             if (weakItem.NewValue.TryGetTarget(out var item))
@@ -789,7 +774,8 @@ namespace osu.Game.Screens.Select
             }
 
             currentY += visibleHalfHeight;
-            ScrollableContent.Height = currentY;
+
+            Scroll.ScrollContent.Height = currentY;
 
             if (BeatmapSetsLoaded && (selectedBeatmapSet == null || selectedBeatmap == null || selectedBeatmapSet.State.Value != CarouselItemState.Selected))
             {
@@ -809,12 +795,31 @@ namespace osu.Game.Screens.Select
                 if (firstScroll)
                 {
                     // reduce movement when first displaying the carousel.
-                    scroll.ScrollTo(scrollTarget.Value - 200, false);
+                    Scroll.ScrollTo(scrollTarget.Value - 200, false);
                     firstScroll = false;
                 }
 
-                scroll.ScrollTo(scrollTarget.Value);
+                switch (pendingScrollOperation)
-                scrollPositionCache.Validate();
+                {
+                    case PendingScrollOperation.Standard:
+                        Scroll.ScrollTo(scrollTarget.Value);
+                        break;
+
+                    case PendingScrollOperation.Immediate:
+                        // in order to simplify animation logic, rather than using the animated version of ScrollTo,
+                        // we take the difference in scroll height and apply to all visible panels.
+                        // this avoids edge cases like when the visible panels is reduced suddenly, causing ScrollContainer
+                        // to enter clamp-special-case mode where it animates completely differently to normal.
+                        float scrollChange = scrollTarget.Value - Scroll.Current;
+
+                        Scroll.ScrollTo(scrollTarget.Value, false);
+
+                        foreach (var i in Scroll.Children)
+                            i.Y += scrollChange;
+                        break;
+                }
+
+                pendingScrollOperation = PendingScrollOperation.None;
             }
         }
 
@@ -844,7 +849,7 @@ namespace osu.Game.Screens.Select
         /// <param name="parent">For nested items, the parent of the item to be updated.</param>
         private void updateItem(DrawableCarouselItem item, DrawableCarouselItem parent = null)
         {
-            Vector2 posInScroll = ScrollableContent.ToLocalSpace(item.Header.ScreenSpaceDrawQuad.Centre);
+            Vector2 posInScroll = Scroll.ScrollContent.ToLocalSpace(item.Header.ScreenSpaceDrawQuad.Centre);
             float itemDrawY = posInScroll.Y - visibleUpperBound;
             float dist = Math.Abs(1f - itemDrawY / visibleHalfHeight);
 
@@ -858,6 +863,13 @@ namespace osu.Game.Screens.Select
             item.SetMultiplicativeAlpha(Math.Clamp(1.75f - 1.5f * dist, 0, 1));
         }
 
+        private enum PendingScrollOperation
+        {
+            None,
+            Standard,
+            Immediate,
+        }
+
         /// <summary>
         /// A carousel item strictly used for binary search purposes.
         /// </summary>
@@ -889,7 +901,7 @@ namespace osu.Game.Screens.Select
             }
         }
 
-        private class CarouselScrollContainer : OsuScrollContainer
+        protected class CarouselScrollContainer : OsuScrollContainer<DrawableCarouselItem>
         {
             private bool rightMouseScrollBlocked;
 
@@ -898,6 +910,12 @@ namespace osu.Game.Screens.Select
             /// </summary>
             public bool UserScrolling { get; private set; }
 
+            public CarouselScrollContainer()
+            {
+                // size is determined by the carousel itself, due to not all content necessarily being loaded.
+                ScrollContent.AutoSizeAxes = Axes.None;
+            }
+
             // ReSharper disable once OptionalParameterHierarchyMismatch 2020.3 EAP4 bug. (https://youtrack.jetbrains.com/issue/RSRP-481535?p=RIDER-51910)
             protected override void OnUserScroll(float value, bool animated = true, double? distanceDecay = default)
             {

osu.Game/Screens/Select/Carousel/DrawableCarouselBeatmapSet.cs

@@ -10,6 +10,7 @@ using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Cursor;
 using osu.Framework.Graphics.UserInterface;
+using osu.Framework.Utils;
 using osu.Game.Beatmaps;
 using osu.Game.Collections;
 using osu.Game.Graphics.UserInterface;
@@ -60,6 +61,25 @@ namespace osu.Game.Screens.Select.Carousel
                 viewDetails = beatmapOverlay.FetchAndShowBeatmapSet;
         }
 
+        protected override void Update()
+        {
+            base.Update();
+
+            // position updates should not occur if the item is filtered away.
+            // this avoids panels flying across the screen only to be eventually off-screen or faded out.
+            if (!Item.Visible)
+                return;
+
+            float targetY = Item.CarouselYPosition;
+
+            if (Precision.AlmostEquals(targetY, Y))
+                Y = targetY;
+            else
+                // algorithm for this is taken from ScrollContainer.
+                // while it doesn't necessarily need to match 1:1, as we are emulating scroll in some cases this feels most correct.
+                Y = (float)Interpolation.Lerp(targetY, Y, Math.Exp(-0.01 * Time.Elapsed));
+        }
+
         protected override void UpdateItem()
         {
             base.UpdateItem();

osu.Game/osu.Game.csproj

@@ -26,7 +26,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="ppy.osu.Framework" Version="2020.1120.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2020.1127.0" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1030.0" />
     <PackageReference Include="Sentry" Version="2.1.6" />
     <PackageReference Include="SharpCompress" Version="0.26.0" />

osu.iOS.props

@@ -70,7 +70,7 @@
     <Reference Include="System.Net.Http" />
   </ItemGroup>
   <ItemGroup Label="Package References">
-    <PackageReference Include="ppy.osu.Framework.iOS" Version="2020.1120.0" />
+    <PackageReference Include="ppy.osu.Framework.iOS" Version="2020.1127.0" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2020.1030.0" />
   </ItemGroup>
   <!-- See https://github.com/dotnet/runtime/issues/35988 (can be removed after Xamarin uses net5.0 / net6.0) -->
@@ -88,7 +88,7 @@
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite" Version="2.2.6" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Sqlite.Core" Version="2.2.6" />
     <PackageReference Include="Newtonsoft.Json" Version="12.0.3" />
-    <PackageReference Include="ppy.osu.Framework" Version="2020.1120.0" />
+    <PackageReference Include="ppy.osu.Framework" Version="2020.1127.0" />
     <PackageReference Include="SharpCompress" Version="0.26.0" />
     <PackageReference Include="NUnit" Version="3.12.0" />
     <PackageReference Include="SharpRaven" Version="2.4.0" />