Update body styling of hold notes

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

@@ -49,6 +49,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
                 {
                     Anchor = Anchor.TopCentre,
                     Origin = Anchor.TopCentre,
+                    RelativeSizeAxes = Axes.X,
                 },
                 tickContainer = new Container<DrawableHoldNoteTick>
                 {
@@ -104,6 +105,14 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
         {
         }
 
+        protected override void Update()
+        {
+            base.Update();
+
+            bodyPiece.Y = head.Height;
+            bodyPiece.Height = DrawHeight - head.Height;
+        }
+
         public bool OnPressed(ManiaAction action)
         {
             // Make sure the action happened within the body of the hold note

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

@@ -22,7 +22,7 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables
             : base(hitObject, action)
         {
             RelativeSizeAxes = Axes.X;
-            Height = 100;
+            AutoSizeAxes = Axes.Y;
 
             Add(headPiece = new NotePiece
             {

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

@@ -1,7 +1,10 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using System;
+using osu.Framework.Caching;
 using OpenTK.Graphics;
+using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Shapes;
@@ -14,22 +17,61 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
     /// </summary>
     internal class BodyPiece : Container, IHasAccentColour
     {
-        private readonly Box box;
+        private readonly Container subtractionLayer;
+
+        private readonly Drawable background;
+        private readonly BufferedContainer foreground;
+        private readonly BufferedContainer subtractionContainer;
 
         public BodyPiece()
         {
-            RelativeSizeAxes = Axes.Both;
+            Blending = BlendingMode.Additive;
 
             Children = new[]
             {
-                box = new Box
+                background = new Box { RelativeSizeAxes = Axes.Both },
+                foreground = new BufferedContainer
                 {
                     RelativeSizeAxes = Axes.Both,
-                    Alpha = 0.3f
+                    CacheDrawnFrameBuffer = true,
+                    Children = new Drawable[]
+                    {
+                        new Box { RelativeSizeAxes = Axes.Both },
+                        subtractionContainer = new BufferedContainer
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            // This is needed because we're blending with another object
+                            BackgroundColour = Color4.White.Opacity(0),
+                            CacheDrawnFrameBuffer = true,
+                            // The 'hole' is achieved by subtracting the result of this container with the parent
+                            Blending = new BlendingModeParameters { AlphaEquation = BlendingEquation.ReverseSubtract },
+                            Child = subtractionLayer = new CircularContainer
+                            {
+                                Anchor = Anchor.Centre,
+                                Origin = Anchor.Centre,
+                                // Height computed in Update
+                                Width = 1,
+                                Masking = true,
+                                Child = new Box
+                                {
+                                    RelativeSizeAxes = Axes.Both,
+                                    Alpha = 0,
+                                    AlwaysPresent = true
+                                }
+                            }
+                        }
+                    }
                 }
             };
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            updateAccentColour();
+        }
+
         private Color4 accentColour;
         public Color4 AccentColour
         {
@@ -40,8 +82,51 @@ namespace osu.Game.Rulesets.Mania.Objects.Drawables.Pieces
                     return;
                 accentColour = value;
 
-                box.Colour = accentColour;
+                updateAccentColour();
             }
         }
+
+        private Cached subtractionCache = new Cached();
+
+        public override bool Invalidate(Invalidation invalidation = Invalidation.All, Drawable source = null, bool shallPropagate = true)
+        {
+            if ((invalidation & Invalidation.DrawSize) > 0)
+                subtractionCache.Invalidate();
+
+            return base.Invalidate(invalidation, source, shallPropagate);
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            if (!subtractionCache.IsValid)
+            {
+                subtractionLayer.Width = 5;
+                subtractionLayer.Height = Math.Max(0, DrawHeight - DrawWidth);
+                subtractionLayer.EdgeEffect = new EdgeEffectParameters
+                {
+                    Colour = Color4.White,
+                    Type = EdgeEffectType.Glow,
+                    Radius = DrawWidth
+                };
+
+                foreground.ForceRedraw();
+                subtractionContainer.ForceRedraw();
+
+                subtractionCache.Validate();
+            }
+        }
+
+        private void updateAccentColour()
+        {
+            if (!IsLoaded)
+                return;
+
+            foreground.Colour = AccentColour.Opacity(0.4f);
+            background.Colour = AccentColour.Opacity(0.2f);
+
+            subtractionCache.Invalidate();
+        }
     }
 }