Implement hold "sliding" samples in osu!mania

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

@@ -4,12 +4,14 @@
 #nullable disable
 
 using System;
+using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
+using osu.Game.Audio;
 using osu.Game.Rulesets.Mania.Skinning.Default;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -38,6 +40,8 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         private Container<DrawableHoldNoteTail> tailContainer;
         private Container<DrawableHoldNoteTick> tickContainer;
 
+        private PausableSkinnableSound slidingSample;
+
         /// <summary>
         /// Contains the size of the hold note covering the whole head/tail bounds. The size of this container changes as the hold note is being pressed.
         /// </summary>
@@ -108,6 +112,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                 },
                 tickContainer = new Container<DrawableHoldNoteTick> { RelativeSizeAxes = Axes.Both },
                 tailContainer = new Container<DrawableHoldNoteTail> { RelativeSizeAxes = Axes.Both },
+                slidingSample = new PausableSkinnableSound { Looping = true }
             });
 
             maskedContents.AddRange(new[]
@@ -118,6 +123,13 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             });
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            isHitting.BindValueChanged(updateSlidingSample, true);
+        }
+
         protected override void OnApply()
         {
             base.OnApply();
@@ -322,5 +334,38 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             HoldStartTime = null;
             isHitting.Value = false;
         }
+
+        protected override void LoadSamples()
+        {
+            // Note: base.LoadSamples() isn't called since the slider plays the tail's hitsounds for the time being.
+
+            if (HitObject.SampleControlPoint == null)
+            {
+                throw new InvalidOperationException($"{nameof(HitObject)}s must always have an attached {nameof(HitObject.SampleControlPoint)}."
+                                                    + $" This is an indication that {nameof(HitObject.ApplyDefaults)} has not been invoked on {this}.");
+            }
+
+            slidingSample.Samples = HitObject.CreateSlidingSamples().Select(s => HitObject.SampleControlPoint.ApplyTo(s)).Cast<ISampleInfo>().ToArray();
+        }
+
+        public override void StopAllSamples()
+        {
+            base.StopAllSamples();
+            slidingSample?.Stop();
+        }
+
+        private void updateSlidingSample(ValueChangedEvent<bool> tracking)
+        {
+            if (tracking.NewValue)
+                slidingSample?.Play();
+            else
+                slidingSample?.Stop();
+        }
+
+        protected override void OnFree()
+        {
+            slidingSample.Samples = null;
+            base.OnFree();
+        }
     }
 }

osu.Game.Rulesets.Osu/Objects/Slider.cs

@@ -34,21 +34,6 @@ namespace osu.Game.Rulesets.Osu.Objects
 
         public override IList<HitSampleInfo> AuxiliarySamples => CreateSlidingSamples().Concat(TailSamples).ToArray();
 
-        public IList<HitSampleInfo> CreateSlidingSamples()
-        {
-            var slidingSamples = new List<HitSampleInfo>();
-
-            var normalSample = Samples.FirstOrDefault(s => s.Name == HitSampleInfo.HIT_NORMAL);
-            if (normalSample != null)
-                slidingSamples.Add(normalSample.With("sliderslide"));
-
-            var whistleSample = Samples.FirstOrDefault(s => s.Name == HitSampleInfo.HIT_WHISTLE);
-            if (whistleSample != null)
-                slidingSamples.Add(whistleSample.With("sliderwhistle"));
-
-            return slidingSamples;
-        }
-
         private readonly Cached<Vector2> endPositionCache = new Cached<Vector2>();
 
         public override Vector2 EndPosition => endPositionCache.IsValid ? endPositionCache.Value : endPositionCache.Value = Position + this.CurvePositionAt(1);

osu.Game/Rulesets/Objects/HitObject.cs

@@ -6,6 +6,7 @@
 using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Linq;
 using System.Threading;
 using JetBrains.Annotations;
 using Newtonsoft.Json;
@@ -198,6 +199,21 @@ namespace osu.Game.Rulesets.Objects
         /// </summary>
         [NotNull]
         protected virtual HitWindows CreateHitWindows() => new HitWindows();
+
+        public IList<HitSampleInfo> CreateSlidingSamples()
+        {
+            var slidingSamples = new List<HitSampleInfo>();
+
+            var normalSample = Samples.FirstOrDefault(s => s.Name == HitSampleInfo.HIT_NORMAL);
+            if (normalSample != null)
+                slidingSamples.Add(normalSample.With("sliderslide"));
+
+            var whistleSample = Samples.FirstOrDefault(s => s.Name == HitSampleInfo.HIT_WHISTLE);
+            if (whistleSample != null)
+                slidingSamples.Add(whistleSample.With("sliderwhistle"));
+
+            return slidingSamples;
+        }
     }
 
     public static class HitObjectExtensions