Add skin source fallback chain

osu.Game/OsuGameBase.cs

@@ -105,6 +105,7 @@ namespace osu.Game
             runMigrations();
 
             dependencies.Cache(SkinManager = new SkinManager(Host.Storage, contextFactory, Host, Audio));
+            dependencies.CacheAs<ISkinSource>(SkinManager);
 
             var api = new APIAccess(LocalConfig);
 

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -6,7 +6,6 @@ using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Configuration;
-using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Primitives;
 using osu.Game.Audio;
 using osu.Game.Graphics;
@@ -19,7 +18,7 @@ using OpenTK.Graphics;
 
 namespace osu.Game.Rulesets.Objects.Drawables
 {
-    public abstract class DrawableHitObject : CompositeDrawable, IHasAccentColour
+    public abstract class DrawableHitObject : SkinReloadableDrawable, IHasAccentColour
     {
         public readonly HitObject HitObject;
 
@@ -103,6 +102,14 @@ namespace osu.Game.Rulesets.Objects.Drawables
             }
         }
 
+        protected override void SkinChanged(ISkinSource skin, bool allowFallback)
+        {
+            base.SkinChanged(skin, allowFallback);
+
+            if (HitObject is IHasComboIndex combo)
+                AccentColour = skin.GetComboColour(combo) ?? Color4.White;
+        }
+
         protected override void LoadComplete()
         {
             base.LoadComplete();

osu.Game/Screens/Play/Player.cs

@@ -26,6 +26,7 @@ using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Rulesets.UI;
 using osu.Game.Screens.Ranking;
+using osu.Game.Skinning;
 using osu.Game.Storyboards.Drawables;
 
 namespace osu.Game.Screens.Play
@@ -163,7 +164,11 @@ namespace osu.Game.Screens.Play
                             RelativeSizeAxes = Axes.Both,
                             Alpha = 0,
                         },
-                        RulesetContainer,
+                        new LocalSkinOverrideContainer(working.Skin)
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            Child = RulesetContainer
+                        },
                         new SkipOverlay(firstObjectTime)
                         {
                             Clock = Clock, // skip button doesn't want to use the audio clock directly

osu.Game/Skinning/DefaultSkin.cs

@@ -3,6 +3,7 @@
 
 using osu.Framework.Audio.Sample;
 using osu.Framework.Graphics;
+using OpenTK.Graphics;
 
 namespace osu.Game.Skinning
 {
@@ -11,17 +12,20 @@ namespace osu.Game.Skinning
         public DefaultSkin()
             : base(SkinInfo.Default)
         {
-            Configuration = new SkinConfiguration();
+            Configuration = new SkinConfiguration
+            {
+                ComboColours =
+                {
+                    new Color4(17, 136, 170, 255),
+                    new Color4(102, 136, 0, 255),
+                    new Color4(204, 102, 0, 255),
+                    new Color4(121, 9, 13, 255)
+                }
+            };
         }
 
-        public override Drawable GetDrawableComponent(string componentName)
+        public override Drawable GetDrawableComponent(string componentName) => null;
-        {
-            return null;
-        }
 
-        public override SampleChannel GetSample(string sampleName)
+        public override SampleChannel GetSample(string sampleName) => null;
-        {
-            return null;
-        }
     }
 }

osu.Game/Skinning/ISkinSource.cs

@@ -0,0 +1,25 @@
+// 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;
+using osu.Framework.Audio.Sample;
+using osu.Framework.Graphics;
+using osu.Game.Rulesets.Objects.Types;
+using OpenTK.Graphics;
+
+namespace osu.Game.Skinning
+{
+    /// <summary>
+    /// Provides access to skinnable elements.
+    /// </summary>
+    public interface ISkinSource
+    {
+        event Action SourceChanged;
+
+        Drawable GetDrawableComponent(string componentName);
+
+        SampleChannel GetSample(string sampleName);
+
+        Color4? GetComboColour(IHasComboIndex comboObject);
+    }
+}

osu.Game/Skinning/LocalSkinOverrideContainer.cs

@@ -0,0 +1,53 @@
+// 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;
+using osu.Framework.Allocation;
+using osu.Framework.Audio.Sample;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Objects.Types;
+using OpenTK.Graphics;
+
+namespace osu.Game.Skinning
+{
+    public class LocalSkinOverrideContainer : Container, ISkinSource
+    {
+        public event Action SourceChanged;
+
+        public Drawable GetDrawableComponent(string componentName) => source.GetDrawableComponent(componentName) ?? fallbackSource?.GetDrawableComponent(componentName);
+
+        public SampleChannel GetSample(string sampleName) => source.GetSample(sampleName) ?? fallbackSource?.GetSample(sampleName);
+
+        public Color4? GetComboColour(IHasComboIndex comboObject) => source.GetComboColour(comboObject) ?? fallbackSource?.GetComboColour(comboObject);
+
+        private readonly ISkinSource source;
+        private ISkinSource fallbackSource;
+
+        public LocalSkinOverrideContainer(ISkinSource source)
+        {
+            this.source = source;
+        }
+
+        protected override IReadOnlyDependencyContainer CreateLocalDependencies(IReadOnlyDependencyContainer parent)
+        {
+            var dependencies = new DependencyContainer(base.CreateLocalDependencies(parent));
+
+            fallbackSource = dependencies.Get<ISkinSource>();
+            if (fallbackSource != null)
+                fallbackSource.SourceChanged += () => SourceChanged?.Invoke();
+
+            dependencies.CacheAs<ISkinSource>(this);
+
+            return dependencies;
+        }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+
+            if (fallbackSource != null)
+                fallbackSource.SourceChanged -= SourceChanged;
+        }
+    }
+}

osu.Game/Skinning/Skin.cs

@@ -4,19 +4,26 @@
 using System;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Graphics;
+using osu.Game.Rulesets.Objects.Types;
+using OpenTK.Graphics;
 
 namespace osu.Game.Skinning
 {
-    public abstract class Skin : IDisposable
+    public abstract class Skin : IDisposable, ISkinSource
     {
         public readonly SkinInfo SkinInfo;
 
         public virtual SkinConfiguration Configuration { get; protected set; }
 
+        public event Action SourceChanged;
+
         public abstract Drawable GetDrawableComponent(string componentName);
 
         public abstract SampleChannel GetSample(string sampleName);
 
+        public virtual Color4? GetComboColour(IHasComboIndex comboObject) =>
+            Configuration.ComboColours.Count == 0 ? (Color4?)null : Configuration.ComboColours[comboObject.ComboIndex % Configuration.ComboColours.Count];
+
         protected Skin(SkinInfo skin)
         {
             SkinInfo = skin;

osu.Game/Skinning/SkinManager.cs

@@ -7,14 +7,18 @@ using System.Linq;
 using System.Linq.Expressions;
 using Microsoft.EntityFrameworkCore;
 using osu.Framework.Audio;
+using osu.Framework.Audio.Sample;
 using osu.Framework.Configuration;
+using osu.Framework.Graphics;
 using osu.Framework.Platform;
 using osu.Game.Database;
 using osu.Game.IO.Archives;
+using osu.Game.Rulesets.Objects.Types;
+using OpenTK.Graphics;
 
 namespace osu.Game.Skinning
 {
-    public class SkinManager : ArchiveModelManager<SkinInfo, SkinFileInfo>
+    public class SkinManager : ArchiveModelManager<SkinInfo, SkinFileInfo>, ISkinSource
     {
         private readonly AudioManager audio;
 
@@ -89,6 +93,8 @@ namespace osu.Game.Skinning
             {
                 if (skin.SkinInfo != CurrentSkinInfo.Value)
                     throw new InvalidOperationException($"Setting {nameof(CurrentSkin)}'s value directly is not supported. Use {nameof(CurrentSkinInfo)} instead.");
+
+                SourceChanged?.Invoke();
             };
 
             // migrate older imports which didn't have access to skin.ini
@@ -108,5 +114,13 @@ namespace osu.Game.Skinning
         /// <param name="query">The query.</param>
         /// <returns>The first result for the provided query, or null if no results were found.</returns>
         public SkinInfo Query(Expression<Func<SkinInfo, bool>> query) => ModelStore.ConsumableItems.AsNoTracking().FirstOrDefault(query);
+
+        public event Action SourceChanged;
+
+        public Drawable GetDrawableComponent(string componentName) => CurrentSkin.Value.GetDrawableComponent(componentName);
+
+        public SampleChannel GetSample(string sampleName) => CurrentSkin.Value.GetSample(sampleName);
+
+        public Color4? GetComboColour(IHasComboIndex comboObject) => CurrentSkin.Value.GetComboColour(comboObject);
     }
 }

osu.Game/Skinning/SkinReloadableDrawable.cs

@@ -2,7 +2,6 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using osu.Framework.Allocation;
-using osu.Framework.Configuration;
 using osu.Framework.Graphics.Containers;
 
 namespace osu.Game.Skinning
@@ -12,7 +11,7 @@ namespace osu.Game.Skinning
     /// </summary>
     public abstract class SkinReloadableDrawable : CompositeDrawable
     {
-        private Bindable<Skin> skin;
+        private ISkinSource skin;
 
         /// <summary>
         /// Whether fallback to default skin should be allowed if the custom skin is missing this resource.
@@ -29,16 +28,18 @@ namespace osu.Game.Skinning
         }
 
         [BackgroundDependencyLoader]
-        private void load(SkinManager skinManager)
+        private void load(ISkinSource source)
         {
-            skin = skinManager.CurrentSkin.GetBoundCopy();
+            skin = source;
-            skin.ValueChanged += skin => SkinChanged(skin, allowDefaultFallback || skin.SkinInfo == SkinInfo.Default);
+            skin.SourceChanged += onChange;
         }
 
+        private void onChange() => SkinChanged(skin, allowDefaultFallback);
+
         protected override void LoadAsyncComplete()
         {
             base.LoadAsyncComplete();
-            skin.TriggerChange();
+            onChange();
         }
 
         /// <summary>
@@ -46,7 +47,7 @@ namespace osu.Game.Skinning
         /// </summary>
         /// <param name="skin">The new skin.</param>
         /// <param name="allowFallback">Whether fallback to default skin should be allowed if the custom skin is missing this resource.</param>
-        protected virtual void SkinChanged(Skin skin, bool allowFallback)
+        protected virtual void SkinChanged(ISkinSource skin, bool allowFallback)
         {
         }
     }

osu.Game/Skinning/SkinnableDrawable.cs

@@ -40,7 +40,7 @@ namespace osu.Game.Skinning
             RelativeSizeAxes = Axes.Both;
         }
 
-        protected override void SkinChanged(Skin skin, bool allowFallback)
+        protected override void SkinChanged(ISkinSource skin, bool allowFallback)
         {
             var drawable = skin.GetDrawableComponent(componentName);
             if (drawable != null)

osu.Game/Skinning/SkinnableSound.cs

@@ -31,7 +31,7 @@ namespace osu.Game.Skinning
 
         public void Play() => channels?.ForEach(c => c.Play());
 
-        protected override void SkinChanged(Skin skin, bool allowFallback)
+        protected override void SkinChanged(ISkinSource skin, bool allowFallback)
         {
             channels = samples.Select(s =>
             {

osu.Game/osu.Game.csproj

@@ -874,8 +874,10 @@
     <Compile Include="Screens\Tournament\Teams\StorageBackedTeamList.cs" />
     <Compile Include="Skinning\BeatmapSkin.cs" />
     <Compile Include="Skinning\DefaultSkin.cs" />
+    <Compile Include="Skinning\ISkinSource.cs" />
     <Compile Include="Skinning\LegacySkin.cs" />
     <Compile Include="Skinning\LegacySkinDecoder.cs" />
+    <Compile Include="Skinning\LocalSkinOverrideContainer.cs" />
     <Compile Include="Skinning\Skin.cs" />
     <Compile Include="Skinning\SkinConfiguration.cs" />
     <Compile Include="Skinning\SkinFileInfo.cs" />