Move nested playfields to the base Playfield

osu.Game/Rulesets/UI/Playfield.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System;
+using System.Collections.Generic;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -23,6 +24,13 @@ namespace osu.Game.Rulesets.UI
         protected override Container<Drawable> Content => content;
         private readonly Container<Drawable> content;
 
+        private List<Playfield> nestedPlayfields;
+
+        /// <summary>
+        /// All the <see cref="Playfield"/>s nested inside this playfield.
+        /// </summary>
+        public IReadOnlyList<Playfield> NestedPlayfields => nestedPlayfields;
+
         /// <summary>
         /// A container for keeping track of DrawableHitObjects.
         /// </summary>
@@ -64,7 +72,7 @@ namespace osu.Game.Rulesets.UI
         /// <summary>
         /// Performs post-processing tasks (if any) after all DrawableHitObjects are loaded into this Playfield.
         /// </summary>
-        public virtual void PostProcess() { }
+        public virtual void PostProcess() => nestedPlayfields?.ForEach(p => p.PostProcess());
 
         /// <summary>
         /// Adds a DrawableHitObject to this Playfield.
@@ -85,6 +93,19 @@ namespace osu.Game.Rulesets.UI
         /// <param name="judgement">The <see cref="Judgement"/> that occurred.</param>
         public virtual void OnJudgement(DrawableHitObject judgedObject, Judgement judgement) { }
 
+        /// <summary>
+        /// Registers a <see cref="Playfield"/> as a nested <see cref="Playfield"/>.
+        /// This does not add the <see cref="Playfield"/> to the draw hierarchy.
+        /// </summary>
+        /// <param name="otherPlayfield">The <see cref="Playfield"/> to add.</param>
+        protected void AddNested(Playfield otherPlayfield)
+        {
+            if (nestedPlayfields == null)
+                nestedPlayfields = new List<Playfield>();
+
+            nestedPlayfields.Add(otherPlayfield);
+        }
+
         /// <summary>
         /// Creates the container that will be used to contain the <see cref="DrawableHitObject"/>s.
         /// </summary>

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

@@ -1,7 +1,6 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using System.Collections.Generic;
 using osu.Framework.Allocation;
 using osu.Framework.Configuration;
 using osu.Framework.Graphics;
@@ -76,25 +75,6 @@ namespace osu.Game.Rulesets.UI.Scrolling
             HitObjects.TimeRange.BindTo(VisibleTimeRange);
         }
 
-        private List<ScrollingPlayfield> nestedPlayfields;
-        /// <summary>
-        /// All the <see cref="ScrollingPlayfield"/>s nested inside this playfield.
-        /// </summary>
-        public IEnumerable<ScrollingPlayfield> NestedPlayfields => nestedPlayfields;
-
-        /// <summary>
-        /// Adds a <see cref="ScrollingPlayfield"/> to this playfield. The nested <see cref="ScrollingPlayfield"/>
-        /// will be given all of the same speed adjustments as this playfield.
-        /// </summary>
-        /// <param name="otherPlayfield">The <see cref="ScrollingPlayfield"/> to add.</param>
-        protected void AddNested(ScrollingPlayfield otherPlayfield)
-        {
-            if (nestedPlayfields == null)
-                nestedPlayfields = new List<ScrollingPlayfield>();
-
-            nestedPlayfields.Add(otherPlayfield);
-        }
-
         protected override bool OnKeyDown(InputState state, KeyDownEventArgs args)
         {
             if (!UserScrollSpeedAdjustment)

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

@@ -87,7 +87,7 @@ namespace osu.Game.Rulesets.UI.Scrolling
         private void applySpeedAdjustment(MultiplierControlPoint controlPoint, ScrollingPlayfield playfield)
         {
             playfield.HitObjects.AddControlPoint(controlPoint);
-            playfield.NestedPlayfields.ForEach(p => applySpeedAdjustment(controlPoint, p));
+            playfield.NestedPlayfields?.OfType<ScrollingPlayfield>().ForEach(p => applySpeedAdjustment(controlPoint, p));
         }
 
         /// <summary>