Implement mania hold note body recycling

osu.Game.Rulesets.Mania/Edit/Blueprints/Components/EditBodyPiece.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Allocation;
+using osu.Framework.Graphics;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Mania.Objects.Drawables.Pieces;
 
@@ -15,7 +16,8 @@ namespace osu.Game.Rulesets.Mania.Edit.Blueprints.Components
             AccentColour.Value = colours.Yellow;
 
             Background.Alpha = 0.5f;
-            Foreground.Alpha = 0;
         }
+
+        protected override Drawable CreateForeground() => base.CreateForeground().With(d => d.Alpha = 0);
     }
 }

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

@@ -32,7 +32,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         private readonly Container<DrawableHoldNoteTail> tailContainer;
         private readonly Container<DrawableHoldNoteTick> tickContainer;
 
-        private readonly Drawable bodyPiece;
+        private readonly SkinnableDrawable bodyPiece;
 
         /// <summary>
         /// Time at which the user started holding this hold note. Null if the user is not holding this hold note.
@@ -49,7 +49,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         {
             RelativeSizeAxes = Axes.X;
 
-            AddRangeInternal(new[]
+            AddRangeInternal(new Drawable[]
             {
                 bodyPiece = new SkinnableDrawable(new ManiaSkinComponent(ManiaSkinComponents.HoldNoteBody, hitObject.Column), _ => new DefaultBodyPiece
                 {
@@ -135,6 +135,12 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             // Samples are played by the head/tail notes.
         }
 
+        public override void OnKilled()
+        {
+            base.OnKilled();
+            (bodyPiece.Drawable as IHoldNoteBody)?.Recycle();
+        }
+
         protected override void Update()
         {
             base.Update();

osu.Game.Rulesets.Mania/Objects/Drawables/Pieces/DefaultBodyPiece.cs

@@ -19,24 +19,17 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
     /// <summary>
     /// Represents length-wise portion of a hold note.
     /// </summary>
-    public class DefaultBodyPiece : CompositeDrawable
+    public class DefaultBodyPiece : CompositeDrawable, IHoldNoteBody
     {
         protected readonly Bindable<Color4> AccentColour = new Bindable<Color4>();
-
+        protected readonly IBindable<bool> IsHitting = new Bindable<bool>();
-        private readonly LayoutValue subtractionCache = new LayoutValue(Invalidation.DrawSize);
-        private readonly IBindable<bool> isHitting = new Bindable<bool>();
 
         protected Drawable Background { get; private set; }
-        protected BufferedContainer Foreground { get; private set; }
+        private Container foregroundContainer;
-
-        private BufferedContainer subtractionContainer;
-        private Container subtractionLayer;
 
         public DefaultBodyPiece()
         {
             Blending = BlendingParameters.Additive;
-
-            AddLayout(subtractionCache);
         }
 
         [BackgroundDependencyLoader(true)]
@@ -45,7 +38,54 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
             InternalChildren = new[]
             {
                 Background = new Box { RelativeSizeAxes = Axes.Both },
-                Foreground = new BufferedContainer
+                foregroundContainer = new Container { RelativeSizeAxes = Axes.Both }
+            };
+
+            if (drawableObject != null)
+            {
+                var holdNote = (DrawableHoldNote)drawableObject;
+
+                AccentColour.BindTo(drawableObject.AccentColour);
+                IsHitting.BindTo(holdNote.IsHitting);
+            }
+
+            AccentColour.BindValueChanged(onAccentChanged, true);
+
+            Recycle();
+        }
+
+        public void Recycle() => foregroundContainer.Child = CreateForeground();
+
+        protected virtual Drawable CreateForeground() => new ForegroundPiece
+        {
+            AccentColour = { BindTarget = AccentColour },
+            IsHitting = { BindTarget = IsHitting }
+        };
+
+        private void onAccentChanged(ValueChangedEvent<Color4> accent) => Background.Colour = accent.NewValue.Opacity(0.7f);
+
+        private class ForegroundPiece : CompositeDrawable
+        {
+            public readonly Bindable<Color4> AccentColour = new Bindable<Color4>();
+            public readonly IBindable<bool> IsHitting = new Bindable<bool>();
+
+            private readonly LayoutValue subtractionCache = new LayoutValue(Invalidation.DrawSize);
+
+            private BufferedContainer foregroundBuffer;
+            private BufferedContainer subtractionBuffer;
+            private Container subtractionLayer;
+
+            public ForegroundPiece()
+            {
+                RelativeSizeAxes = Axes.Both;
+
+                AddLayout(subtractionCache);
+            }
+
+            [BackgroundDependencyLoader]
+            private void load()
+            {
+                InternalChild = foregroundBuffer = new BufferedContainer
                 {
                     Blending = BlendingParameters.Additive,
                     RelativeSizeAxes = Axes.Both,
@@ -53,7 +93,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
                     Children = new Drawable[]
                     {
                         new Box { RelativeSizeAxes = Axes.Both },
-                        subtractionContainer = new BufferedContainer
+                        subtractionBuffer = new BufferedContainer
                         {
                             RelativeSizeAxes = Axes.Both,
                             // This is needed because we're blending with another object
@@ -77,36 +117,26 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
                             }
                         }
                     }
-                }
                 };
 
-            if (drawableObject != null)
-            {
-                var holdNote = (DrawableHoldNote)drawableObject;
-
-                AccentColour.BindTo(drawableObject.AccentColour);
-                isHitting.BindTo(holdNote.IsHitting);
-            }
-
                 AccentColour.BindValueChanged(onAccentChanged, true);
-            isHitting.BindValueChanged(_ => onAccentChanged(new ValueChangedEvent<Color4>(AccentColour.Value, AccentColour.Value)), true);
+                IsHitting.BindValueChanged(_ => onAccentChanged(new ValueChangedEvent<Color4>(AccentColour.Value, AccentColour.Value)), true);
             }
 
             private void onAccentChanged(ValueChangedEvent<Color4> accent)
             {
-            Foreground.Colour = accent.NewValue.Opacity(0.5f);
+                foregroundBuffer.Colour = accent.NewValue.Opacity(0.5f);
-            Background.Colour = accent.NewValue.Opacity(0.7f);
 
                 const float animation_length = 50;
 
-            Foreground.ClearTransforms(false, nameof(Foreground.Colour));
+                foregroundBuffer.ClearTransforms(false, nameof(foregroundBuffer.Colour));
 
-            if (isHitting.Value)
+                if (IsHitting.Value)
                 {
                     // wait for the next sync point
                     double synchronisedOffset = animation_length * 2 - Time.Current % (animation_length * 2);
-                using (Foreground.BeginDelayedSequence(synchronisedOffset))
+                    using (foregroundBuffer.BeginDelayedSequence(synchronisedOffset))
-                    Foreground.FadeColour(accent.NewValue.Lighten(0.2f), animation_length).Then().FadeColour(Foreground.Colour, animation_length).Loop();
+                        foregroundBuffer.FadeColour(accent.NewValue.Lighten(0.2f), animation_length).Then().FadeColour(foregroundBuffer.Colour, animation_length).Loop();
                 }
 
                 subtractionCache.Invalidate();
@@ -127,11 +157,12 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
                         Radius = DrawWidth
                     };
 
-                Foreground.ForceRedraw();
+                    foregroundBuffer.ForceRedraw();
-                subtractionContainer.ForceRedraw();
+                    subtractionBuffer.ForceRedraw();
 
                     subtractionCache.Validate();
                 }
             }
         }
+    }
 }

osu.Game.Rulesets.Mania/Objects/Drawables/Pieces/IHoldNoteBody.cs

@@ -0,0 +1,16 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
+{
+    /// <summary>
+    /// Interface for mania hold note bodies.
+    /// </summary>
+    public interface IHoldNoteBody
+    {
+        /// <summary>
+        /// Recycles the contents of this <see cref="IHoldNoteBody"/> to free used resources.
+        /// </summary>
+        void Recycle();
+    }
+}