Separate head/tail notes from hold note class

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

@@ -0,0 +1,74 @@
+// 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.Game.Rulesets.Scoring;
+
+namespace osu.Game.Rulesets.Mania.Objects.Drawables
+{
+    /// <summary>
+    /// The tail of a <see cref="DrawableHoldNote"/>.
+    /// </summary>
+    public class DrawableHoldNoteTail : DrawableNote
+    {
+        /// <summary>
+        /// Lenience of release hit windows. This is to make cases where the hold note release
+        /// is timed alongside presses of other hit objects less awkward.
+        /// Todo: This shouldn't exist for non-LegacyBeatmapDecoder beatmaps
+        /// </summary>
+        private const double release_window_lenience = 1.5;
+
+        private readonly DrawableHoldNote holdNote;
+
+        public DrawableHoldNoteTail(DrawableHoldNote holdNote)
+            : base(holdNote.HitObject.Tail)
+        {
+            this.holdNote = holdNote;
+        }
+
+        protected override void CheckForResult(bool userTriggered, double timeOffset)
+        {
+            Debug.Assert(HitObject.HitWindows != null);
+
+            // Factor in the release lenience
+            timeOffset /= release_window_lenience;
+
+            if (!userTriggered)
+            {
+                if (!HitObject.HitWindows.CanBeHit(timeOffset))
+                    ApplyResult(r => r.Type = HitResult.Miss);
+
+                return;
+            }
+
+            var result = HitObject.HitWindows.ResultFor(timeOffset);
+            if (result == HitResult.None)
+                return;
+
+            ApplyResult(r =>
+            {
+                if (holdNote.HasBroken && (result == HitResult.Perfect || result == HitResult.Perfect))
+                    result = HitResult.Good;
+
+                r.Type = result;
+            });
+        }
+
+        public override bool OnPressed(ManiaAction action) => false; // Tail doesn't handle key down
+
+        public override bool OnReleased(ManiaAction action)
+        {
+            // Make sure that the user started holding the key during the hold note
+            if (!holdNote.HoldStartTime.HasValue)
+                return false;
+
+            if (action != Action.Value)
+                return false;
+
+            UpdateResult(true);
+
+            // Handled by the hold note, which will set holding = false
+            return false;
+        }
+    }
+}