Merge pull request #13264 from peppy/legacy-skin-default-fallback

Allow fallback to legacy defaults from legacy skins

osu.Game.Rulesets.Mania/Skinning/Legacy/ManiaLegacySkinTransformer.cs

@@ -69,10 +69,10 @@ namespace osu.Game.Rulesets.Mania.Skinning.Legacy
 
         private void sourceChanged()
         {
-            isLegacySkin = new Lazy<bool>(() => Source.GetConfig<LegacySkinConfiguration.LegacySetting, decimal>(LegacySkinConfiguration.LegacySetting.Version) != null);
-            hasKeyTexture = new Lazy<bool>(() => Source.GetAnimation(
+            isLegacySkin = new Lazy<bool>(() => FindProvider(s => s.GetConfig<LegacySkinConfiguration.LegacySetting, decimal>(LegacySkinConfiguration.LegacySetting.Version) != null) != null);
+            hasKeyTexture = new Lazy<bool>(() => FindProvider(s => s.GetAnimation(
                 this.GetManiaSkinConfig<string>(LegacyManiaSkinConfigurationLookups.KeyImage, 0)?.Value
-                ?? "mania-key1", true, true) != null);
+                ?? "mania-key1", true, true) != null) != null);
         }
 
         public override Drawable GetDrawableComponent(ISkinComponent component)

osu.Game.Rulesets.Osu.Tests/Resources/SampleLookups/osu-hitobject-beatmap-custom-sample-bank.osu

@@ -0,0 +1,10 @@
+osu file format v14
+
+[General]
+Mode: 0
+
+[TimingPoints]
+0,300,4,1,2,100,1,0
+
+[HitObjects]
+444,320,1000,5,0,0:0:0:0:

osu.Game.Rulesets.Osu.Tests/TestSceneCursorTrail.cs

@@ -39,18 +39,28 @@ namespace osu.Game.Rulesets.Osu.Tests
         [Test]
         public void TestLegacySmoothCursorTrail()
         {
-            createTest(() => new LegacySkinContainer(false)
+            createTest(() =>
             {
-                Child = new LegacyCursorTrail()
+                var skinContainer = new LegacySkinContainer(false);
+                var legacyCursorTrail = new LegacyCursorTrail(skinContainer);
+
+                skinContainer.Child = legacyCursorTrail;
+
+                return skinContainer;
             });
         }
 
         [Test]
         public void TestLegacyDisjointCursorTrail()
         {
-            createTest(() => new LegacySkinContainer(true)
+            createTest(() =>
             {
-                Child = new LegacyCursorTrail()
+                var skinContainer = new LegacySkinContainer(true);
+                var legacyCursorTrail = new LegacyCursorTrail(skinContainer);
+
+                skinContainer.Child = legacyCursorTrail;
+
+                return skinContainer;
             });
         }
 
@@ -102,6 +112,8 @@ namespace osu.Game.Rulesets.Osu.Tests
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => null;
 
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
+
             public event Action SourceChanged
             {
                 add { }

osu.Game.Rulesets.Osu.Tests/TestSceneGameplayCursor.cs

@@ -113,6 +113,7 @@ namespace osu.Game.Rulesets.Osu.Tests
             public Drawable GetDrawableComponent(ISkinComponent component) => null;
             public Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT) => null;
             public ISample GetSample(ISampleInfo sampleInfo) => null;
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
             {

osu.Game.Rulesets.Osu.Tests/TestSceneOsuHitObjectSamples.cs

@@ -0,0 +1,49 @@
+// 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.Reflection;
+using NUnit.Framework;
+using osu.Framework.IO.Stores;
+using osu.Game.Tests.Beatmaps;
+
+namespace osu.Game.Rulesets.Osu.Tests
+{
+    public class TestSceneOsuHitObjectSamples : HitObjectSampleTest
+    {
+        protected override Ruleset CreatePlayerRuleset() => new OsuRuleset();
+
+        protected override IResourceStore<byte[]> RulesetResources => new DllResourceStore(Assembly.GetAssembly(typeof(TestSceneOsuHitObjectSamples)));
+
+        [TestCase("normal-hitnormal")]
+        [TestCase("hitnormal")]
+        public void TestDefaultCustomSampleFromBeatmap(string expectedSample)
+        {
+            SetupSkins(expectedSample, expectedSample);
+
+            CreateTestWithBeatmap("osu-hitobject-beatmap-custom-sample-bank.osu");
+
+            AssertBeatmapLookup(expectedSample);
+        }
+
+        [TestCase("normal-hitnormal")]
+        [TestCase("hitnormal")]
+        public void TestDefaultCustomSampleFromUserSkinFallback(string expectedSample)
+        {
+            SetupSkins(string.Empty, expectedSample);
+
+            CreateTestWithBeatmap("osu-hitobject-beatmap-custom-sample-bank.osu");
+
+            AssertUserLookup(expectedSample);
+        }
+
+        [TestCase("normal-hitnormal2")]
+        public void TestUserSkinLookupIgnoresSampleBank(string unwantedSample)
+        {
+            SetupSkins(string.Empty, unwantedSample);
+
+            CreateTestWithBeatmap("osu-hitobject-beatmap-custom-sample-bank.osu");
+
+            AssertNoLookup(unwantedSample);
+        }
+    }
+}

osu.Game.Rulesets.Osu.Tests/TestSceneSkinFallbacks.cs

@@ -166,6 +166,7 @@ namespace osu.Game.Rulesets.Osu.Tests
 
             public TValue GetValue<TConfiguration, TValue>(Func<TConfiguration, TValue> query) where TConfiguration : SkinConfiguration => default;
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => null;
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
 
             public event Action SourceChanged;
 

osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursor.cs

@@ -11,10 +11,12 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
 {
     public class LegacyCursor : OsuCursorSprite
     {
+        private readonly ISkin skin;
         private bool spin;
 
-        public LegacyCursor()
+        public LegacyCursor(ISkin skin)
         {
+            this.skin = skin;
             Size = new Vector2(50);
 
             Anchor = Anchor.Centre;
@@ -22,7 +24,7 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
         }
 
         [BackgroundDependencyLoader]
-        private void load(ISkinSource skin)
+        private void load()
         {
             bool centre = skin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.CursorCentre)?.Value ?? true;
             spin = skin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.CursorRotate)?.Value ?? true;

osu.Game.Rulesets.Osu/Skinning/Legacy/LegacyCursorTrail.cs

@@ -14,14 +14,20 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
 {
     public class LegacyCursorTrail : CursorTrail
     {
+        private readonly ISkin skin;
         private const double disjoint_trail_time_separation = 1000 / 60.0;
 
         private bool disjointTrail;
         private double lastTrailTime;
         private IBindable<float> cursorSize;
 
+        public LegacyCursorTrail(ISkin skin)
+        {
+            this.skin = skin;
+        }
+
         [BackgroundDependencyLoader]
-        private void load(ISkinSource skin, OsuConfigManager config)
+        private void load(OsuConfigManager config)
         {
             Texture = skin.GetTexture("cursortrail");
             disjointTrail = skin.GetTexture("cursormiddle") == null;

osu.Game.Rulesets.Osu/Skinning/Legacy/LegacySliderBall.cs

@@ -14,18 +14,21 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
     {
         private readonly Drawable animationContent;
 
+        private readonly ISkin skin;
+
         private Sprite layerNd;
         private Sprite layerSpec;
 
-        public LegacySliderBall(Drawable animationContent)
+        public LegacySliderBall(Drawable animationContent, ISkin skin)
         {
             this.animationContent = animationContent;
+            this.skin = skin;
 
             AutoSizeAxes = Axes.Both;
         }
 
         [BackgroundDependencyLoader]
-        private void load(ISkinSource skin)
+        private void load()
         {
             var ballColour = skin.GetConfig<OsuSkinColour, Color4>(OsuSkinColour.SliderBall)?.Value ?? Color4.White;
 

osu.Game.Rulesets.Osu/Skinning/Legacy/OsuLegacySkinTransformer.cs

@@ -29,7 +29,7 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
 
         private void sourceChanged()
         {
-            hasHitCircle = new Lazy<bool>(() => Source.GetTexture("hitcircle") != null);
+            hasHitCircle = new Lazy<bool>(() => FindProvider(s => s.GetTexture("hitcircle") != null) != null);
         }
 
         public override Drawable GetDrawableComponent(ISkinComponent component)
@@ -49,13 +49,16 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
                         return followCircle;
 
                     case OsuSkinComponents.SliderBall:
-                        var sliderBallContent = this.GetAnimation("sliderb", true, true, animationSeparator: "");
+                        // specular and nd layers must come from the same source as the ball texure.
+                        var ballProvider = Source.FindProvider(s => s.GetTexture("sliderb") != null || s.GetTexture("sliderb0") != null);
+
+                        var sliderBallContent = ballProvider.GetAnimation("sliderb", true, true, animationSeparator: "");
 
                         // todo: slider ball has a custom frame delay based on velocity
                         // Math.Max((150 / Velocity) * GameBase.SIXTY_FRAME_TIME, GameBase.SIXTY_FRAME_TIME);
 
                         if (sliderBallContent != null)
-                            return new LegacySliderBall(sliderBallContent);
+                            return new LegacySliderBall(sliderBallContent, ballProvider);
 
                         return null;
 
@@ -84,14 +87,18 @@ namespace osu.Game.Rulesets.Osu.Skinning.Legacy
                         return null;
 
                     case OsuSkinComponents.Cursor:
-                        if (Source.GetTexture("cursor") != null)
-                            return new LegacyCursor();
+                        var cursorProvider = Source.FindProvider(s => s.GetTexture("cursor") != null);
+
+                        if (cursorProvider != null)
+                            return new LegacyCursor(cursorProvider);
 
                         return null;
 
                     case OsuSkinComponents.CursorTrail:
-                        if (Source.GetTexture("cursortrail") != null)
-                            return new LegacyCursorTrail();
+                        var trailProvider = Source.FindProvider(s => s.GetTexture("cursortrail") != null);
+
+                        if (trailProvider != null)
+                            return new LegacyCursorTrail(trailProvider);
 
                         return null;
 

osu.Game.Rulesets.Taiko/Skinning/Legacy/TaikoLegacySkinTransformer.cs

@@ -152,32 +152,35 @@ namespace osu.Game.Rulesets.Taiko.Skinning.Legacy
             throw new ArgumentOutOfRangeException(nameof(component), $"Invalid component type: {component}");
         }
 
-        public override ISample GetSample(ISampleInfo sampleInfo) => Source.GetSample(new LegacyTaikoSampleInfo(sampleInfo));
+        public override ISample GetSample(ISampleInfo sampleInfo)
+        {
+            if (sampleInfo is HitSampleInfo hitSampleInfo)
+                return Source.GetSample(new LegacyTaikoSampleInfo(hitSampleInfo));
+
+            return base.GetSample(sampleInfo);
+        }
 
         public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => Source.GetConfig<TLookup, TValue>(lookup);
 
-        private class LegacyTaikoSampleInfo : ISampleInfo
+        private class LegacyTaikoSampleInfo : HitSampleInfo
         {
-            private readonly ISampleInfo source;
+            public LegacyTaikoSampleInfo(HitSampleInfo sampleInfo)
+                : base(sampleInfo.Name, sampleInfo.Bank, sampleInfo.Suffix, sampleInfo.Volume)
 
-            public LegacyTaikoSampleInfo(ISampleInfo source)
             {
-                this.source = source;
             }
 
-            public IEnumerable<string> LookupNames
+            public override IEnumerable<string> LookupNames
             {
                 get
                 {
-                    foreach (var name in source.LookupNames)
+                    foreach (var name in base.LookupNames)
                         yield return name.Insert(name.LastIndexOf('/') + 1, "taiko-");
 
-                    foreach (var name in source.LookupNames)
+                    foreach (var name in base.LookupNames)
                         yield return name;
                 }
             }
-
-            public int Volume => source.Volume;
         }
     }
 }

osu.Game.Rulesets.Taiko/UI/TaikoMascotAnimation.cs

@@ -85,8 +85,12 @@ namespace osu.Game.Rulesets.Taiko.UI
             }
 
             [BackgroundDependencyLoader]
-            private void load(ISkinSource skin)
+            private void load(ISkinSource source)
             {
+                ISkin skin = source.FindProvider(s => getAnimationFrame(s, state, 0) != null);
+
+                if (skin == null) return;
+
                 for (int frameIndex = 0; true; frameIndex++)
                 {
                     var texture = getAnimationFrame(skin, state, frameIndex);
@@ -112,8 +116,12 @@ namespace osu.Game.Rulesets.Taiko.UI
             }
 
             [BackgroundDependencyLoader]
-            private void load(ISkinSource skin)
+            private void load(ISkinSource source)
             {
+                ISkin skin = source.FindProvider(s => getAnimationFrame(s, TaikoMascotAnimationState.Clear, 0) != null);
+
+                if (skin == null) return;
+
                 foreach (var frameIndex in clear_animation_sequence)
                 {
                     var texture = getAnimationFrame(skin, TaikoMascotAnimationState.Clear, frameIndex);

osu.Game.Tests/Gameplay/TestSceneHitObjectAccentColour.cs

@@ -123,6 +123,8 @@ namespace osu.Game.Tests.Gameplay
 
             public ISample GetSample(ISampleInfo sampleInfo) => throw new NotImplementedException();
 
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
+
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
             {
                 switch (lookup)

osu.Game.Tests/NonVisual/Skinning/LegacySkinAnimationTest.cs

@@ -61,6 +61,7 @@ namespace osu.Game.Tests.NonVisual.Skinning
             public Drawable GetDrawableComponent(ISkinComponent component) => throw new NotSupportedException();
             public ISample GetSample(ISampleInfo sampleInfo) => throw new NotSupportedException();
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => throw new NotSupportedException();
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
         }
 
         private class TestAnimationTimeReference : IAnimationTimeReference

osu.Game.Tests/Skins/TestSceneSkinConfigurationLookup.cs

@@ -1,6 +1,7 @@
 // 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;
 using System.Collections.Generic;
 using System.IO;
 using System.Linq;
@@ -222,6 +223,8 @@ namespace osu.Game.Tests.Skins
             public ISample GetSample(ISampleInfo sampleInfo) => skin.GetSample(sampleInfo);
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => skin.GetConfig<TLookup, TValue>(lookup);
+
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => skin.FindProvider(lookupFunction);
         }
     }
 }

osu.Game.Tests/Visual/Gameplay/TestSceneSkinnableDrawable.cs

@@ -301,6 +301,8 @@ namespace osu.Game.Tests.Visual.Gameplay
             public ISample GetSample(ISampleInfo sampleInfo) => throw new NotImplementedException();
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => throw new NotImplementedException();
+
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => throw new NotImplementedException();
         }
 
         private class SecondarySource : ISkin
@@ -312,6 +314,8 @@ namespace osu.Game.Tests.Visual.Gameplay
             public ISample GetSample(ISampleInfo sampleInfo) => throw new NotImplementedException();
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => throw new NotImplementedException();
+
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => throw new NotImplementedException();
         }
 
         [Cached(typeof(ISkinSource))]
@@ -325,6 +329,8 @@ namespace osu.Game.Tests.Visual.Gameplay
 
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => throw new NotImplementedException();
 
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => throw new NotImplementedException();
+
             public event Action SourceChanged
             {
                 add { }

osu.Game.Tests/Visual/Gameplay/TestSceneSkinnableSound.cs

@@ -147,6 +147,7 @@ namespace osu.Game.Tests.Visual.Gameplay
             public Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT) => source?.GetTexture(componentName, wrapModeS, wrapModeT);
             public ISample GetSample(ISampleInfo sampleInfo) => source?.GetSample(sampleInfo);
             public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => source?.GetConfig<TLookup, TValue>(lookup);
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => source?.FindProvider(lookupFunction);
 
             public void TriggerSourceChanged()
             {

osu.Game/Skinning/ISkinSource.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using JetBrains.Annotations;
 
 namespace osu.Game.Skinning
 {
@@ -11,5 +12,13 @@ namespace osu.Game.Skinning
     public interface ISkinSource : ISkin
     {
         event Action SourceChanged;
+
+        /// <summary>
+        /// Find the first (if any) skin that can fulfill the lookup.
+        /// This should be used for cases where subsequent lookups (for related components) need to occur on the same skin.
+        /// </summary>
+        /// <returns>The skin to be used for subsequent lookups, or <c>null</c> if none is available.</returns>
+        [CanBeNull]
+        ISkin FindProvider(Func<ISkin, bool> lookupFunction);
     }
 }

osu.Game/Skinning/LegacyHealthDisplay.cs

@@ -20,9 +20,6 @@ namespace osu.Game.Skinning
     {
         private const double epic_cutoff = 0.5;
 
-        [Resolved]
-        private ISkinSource skin { get; set; }
-
         private LegacyHealthPiece fill;
         private LegacyHealthPiece marker;
 
@@ -31,10 +28,13 @@ namespace osu.Game.Skinning
         private bool isNewStyle;
 
         [BackgroundDependencyLoader]
-        private void load()
+        private void load(ISkinSource source)
         {
             AutoSizeAxes = Axes.Both;
 
+            var skin = source.FindProvider(s => getTexture(s, "bg") != null);
+
+            // the marker lookup to decide which display style must be performed on the source of the bg, which is the most common element.
             isNewStyle = getTexture(skin, "marker") != null;
 
             // background implementation is the same for both versions.
@@ -76,7 +76,7 @@ namespace osu.Game.Skinning
 
         protected override void Flash(JudgementResult result) => marker.Flash(result);
 
-        private static Texture getTexture(ISkinSource skin, string name) => skin.GetTexture($"scorebar-{name}");
+        private static Texture getTexture(ISkin skin, string name) => skin?.GetTexture($"scorebar-{name}");
 
         private static Color4 getFillColour(double hp)
         {
@@ -95,7 +95,7 @@ namespace osu.Game.Skinning
             private readonly Texture dangerTexture;
             private readonly Texture superDangerTexture;
 
-            public LegacyOldStyleMarker(ISkinSource skin)
+            public LegacyOldStyleMarker(ISkin skin)
             {
                 normalTexture = getTexture(skin, "ki");
                 dangerTexture = getTexture(skin, "kidanger");
@@ -126,9 +126,9 @@ namespace osu.Game.Skinning
 
         public class LegacyNewStyleMarker : LegacyMarker
         {
-            private readonly ISkinSource skin;
+            private readonly ISkin skin;
 
-            public LegacyNewStyleMarker(ISkinSource skin)
+            public LegacyNewStyleMarker(ISkin skin)
             {
                 this.skin = skin;
             }
@@ -150,7 +150,7 @@ namespace osu.Game.Skinning
 
         internal class LegacyOldStyleFill : LegacyHealthPiece
         {
-            public LegacyOldStyleFill(ISkinSource skin)
+            public LegacyOldStyleFill(ISkin skin)
             {
                 // required for sizing correctly..
                 var firstFrame = getTexture(skin, "colour-0");
@@ -173,7 +173,7 @@ namespace osu.Game.Skinning
 
         internal class LegacyNewStyleFill : LegacyHealthPiece
         {
-            public LegacyNewStyleFill(ISkinSource skin)
+            public LegacyNewStyleFill(ISkin skin)
             {
                 InternalChild = new Sprite
                 {

osu.Game/Skinning/LegacySkin.cs

@@ -60,10 +60,17 @@ namespace osu.Game.Skinning
         {
         }
 
-        protected LegacySkin(SkinInfo skin, [CanBeNull] IResourceStore<byte[]> storage, [CanBeNull] IStorageResourceProvider resources, string filename)
+        /// <summary>
+        /// Construct a new legacy skin instance.
+        /// </summary>
+        /// <param name="skin">The model for this skin.</param>
+        /// <param name="storage">A storage for looking up files within this skin using user-facing filenames.</param>
+        /// <param name="resources">Access to raw game resources.</param>
+        /// <param name="configurationFilename">The user-facing filename of the configuration file to be parsed. Can accept an .osu or skin.ini file.</param>
+        protected LegacySkin(SkinInfo skin, [CanBeNull] IResourceStore<byte[]> storage, [CanBeNull] IStorageResourceProvider resources, string configurationFilename)
             : base(skin, resources)
         {
-            using (var stream = storage?.GetStream(filename))
+            using (var stream = storage?.GetStream(configurationFilename))
             {
                 if (stream != null)
                 {
@@ -127,7 +134,7 @@ namespace osu.Game.Skinning
 
                 case LegacyManiaSkinConfigurationLookup maniaLookup:
                     if (!AllowManiaSkin)
-                        return null;
+                        break;
 
                     var result = lookupForMania<TValue>(maniaLookup);
                     if (result != null)
@@ -390,6 +397,7 @@ namespace osu.Game.Skinning
                     return null;
 
                 case GameplaySkinComponent<HitResult> resultComponent:
+                    // TODO: this should be inside the judgement pieces.
                     Func<Drawable> createDrawable = () => getJudgementAnimation(resultComponent.Component);
 
                     // kind of wasteful that we throw this away, but should do for now.
@@ -485,8 +493,10 @@ namespace osu.Game.Skinning
                 var sample = Samples?.Get(lookup);
 
                 if (sample != null)
+                {
                     return sample;
                 }
+            }
 
             return null;
         }
@@ -518,8 +528,7 @@ namespace osu.Game.Skinning
             yield return componentName;
 
             // Fall back to using the last piece for components coming from lazer (e.g. "Gameplay/osu/approachcircle" -> "approachcircle").
-            string lastPiece = componentName.Split('/').Last();
-            yield return componentName.StartsWith("Gameplay/taiko/", StringComparison.Ordinal) ? "taiko-" + lastPiece : lastPiece;
+            yield return componentName.Split('/').Last();
         }
 
         protected override void Dispose(bool isDisposing)

osu.Game/Skinning/LegacySkinExtensions.cs

@@ -27,6 +27,18 @@ namespace osu.Game.Skinning
         {
             Texture texture;
 
+            // find the first source which provides either the animated or non-animated version.
+            ISkin skin = (source as ISkinSource)?.FindProvider(s =>
+            {
+                if (animatable && s.GetTexture(getFrameName(0)) != null)
+                    return true;
+
+                return s.GetTexture(componentName, wrapModeS, wrapModeT) != null;
+            }) ?? source;
+
+            if (skin == null)
+                return null;
+
             if (animatable)
             {
                 var textures = getTextures().ToArray();
@@ -35,7 +47,7 @@ namespace osu.Game.Skinning
                 {
                     var animation = new SkinnableTextureAnimation(startAtCurrentTime)
                     {
-                        DefaultFrameLength = frameLength ?? getFrameLength(source, applyConfigFrameRate, textures),
+                        DefaultFrameLength = frameLength ?? getFrameLength(skin, applyConfigFrameRate, textures),
                         Loop = looping,
                     };
 
@@ -47,7 +59,7 @@ namespace osu.Game.Skinning
             }
 
             // if an animation was not allowed or not found, fall back to a sprite retrieval.
-            if ((texture = source.GetTexture(componentName, wrapModeS, wrapModeT)) != null)
+            if ((texture = skin.GetTexture(componentName, wrapModeS, wrapModeT)) != null)
                 return new Sprite { Texture = texture };
 
             return null;
@@ -56,12 +68,14 @@ namespace osu.Game.Skinning
             {
                 for (int i = 0; true; i++)
                 {
-                    if ((texture = source.GetTexture($"{componentName}{animationSeparator}{i}", wrapModeS, wrapModeT)) == null)
+                    if ((texture = skin.GetTexture(getFrameName(i), wrapModeS, wrapModeT)) == null)
                         break;
 
                     yield return texture;
                 }
             }
+
+            string getFrameName(int frameIndex) => $"{componentName}{animationSeparator}{frameIndex}";
         }
 
         public static bool HasFont(this ISkin source, LegacyFont font)

osu.Game/Skinning/LegacySkinTransformer.cs

@@ -1,6 +1,7 @@
 // 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;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -15,7 +16,7 @@ namespace osu.Game.Skinning
     /// <summary>
     /// Transformer used to handle support of legacy features for individual rulesets.
     /// </summary>
-    public abstract class LegacySkinTransformer : ISkin
+    public abstract class LegacySkinTransformer : ISkinSource
     {
         /// <summary>
         /// Source of the <see cref="ISkin"/> which is being transformed.
@@ -47,5 +48,13 @@ namespace osu.Game.Skinning
         }
 
         public abstract IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup);
+
+        public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => Source.FindProvider(lookupFunction);
+
+        public event Action SourceChanged
+        {
+            add { throw new NotSupportedException(); }
+            remove { }
+        }
     }
 }

osu.Game/Skinning/SkinManager.cs

@@ -48,6 +48,8 @@ namespace osu.Game.Skinning
 
         protected override string ImportFromStablePath => "Skins";
 
+        private readonly Skin defaultLegacySkin;
+
         public SkinManager(Storage storage, DatabaseContextFactory contextFactory, GameHost host, IResourceStore<byte[]> resources, AudioManager audio)
             : base(storage, contextFactory, new SkinStore(contextFactory, storage), host)
         {
@@ -55,6 +57,8 @@ namespace osu.Game.Skinning
             this.host = host;
             this.resources = resources;
 
+            defaultLegacySkin = new DefaultLegacySkin(this);
+
             CurrentSkinInfo.ValueChanged += skin => CurrentSkin.Value = GetSkin(skin.NewValue);
             CurrentSkin.ValueChanged += skin =>
             {
@@ -204,13 +208,41 @@ namespace osu.Game.Skinning
 
         public event Action SourceChanged;
 
-        public Drawable GetDrawableComponent(ISkinComponent component) => CurrentSkin.Value.GetDrawableComponent(component);
+        public Drawable GetDrawableComponent(ISkinComponent component) => lookupWithFallback(s => s.GetDrawableComponent(component));
 
-        public Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT) => CurrentSkin.Value.GetTexture(componentName, wrapModeS, wrapModeT);
+        public Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT) => lookupWithFallback(s => s.GetTexture(componentName, wrapModeS, wrapModeT));
 
-        public ISample GetSample(ISampleInfo sampleInfo) => CurrentSkin.Value.GetSample(sampleInfo);
+        public ISample GetSample(ISampleInfo sampleInfo) => lookupWithFallback(s => s.GetSample(sampleInfo));
 
-        public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => CurrentSkin.Value.GetConfig<TLookup, TValue>(lookup);
+        public IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup) => lookupWithFallback(s => s.GetConfig<TLookup, TValue>(lookup));
+
+        public ISkin FindProvider(Func<ISkin, bool> lookupFunction)
+        {
+            if (lookupFunction(CurrentSkin.Value))
+                return CurrentSkin.Value;
+
+            if (CurrentSkin.Value is LegacySkin && lookupFunction(defaultLegacySkin))
+                return defaultLegacySkin;
+
+            return null;
+        }
+
+        private T lookupWithFallback<T>(Func<ISkin, T> func)
+            where T : class
+        {
+            var selectedSkin = func(CurrentSkin.Value);
+
+            if (selectedSkin != null)
+                return selectedSkin;
+
+            // TODO: we also want to return a DefaultLegacySkin here if the current *beatmap* is providing any skinned elements.
+            // When attempting to address this, we may want to move the full DefaultLegacySkin fallback logic to within Player itself (to better allow
+            // for beatmap skin visibility).
+            if (CurrentSkin.Value is LegacySkin)
+                return func(defaultLegacySkin);
+
+            return null;
+        }
 
         #region IResourceStorageProvider
 

osu.Game/Skinning/SkinProvidingContainer.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
@@ -20,8 +21,10 @@ namespace osu.Game.Skinning
     {
         public event Action SourceChanged;
 
+        [CanBeNull]
         private readonly ISkin skin;
 
+        [CanBeNull]
         private ISkinSource fallbackSource;
 
         protected virtual bool AllowDrawableLookup(ISkinComponent component) => true;
@@ -41,6 +44,22 @@ namespace osu.Game.Skinning
             RelativeSizeAxes = Axes.Both;
         }
 
+        public ISkin FindProvider(Func<ISkin, bool> lookupFunction)
+        {
+            if (skin is ISkinSource source)
+            {
+                if (source.FindProvider(lookupFunction) is ISkin found)
+                    return found;
+            }
+            else if (skin != null)
+            {
+                if (lookupFunction(skin))
+                    return skin;
+            }
+
+            return fallbackSource?.FindProvider(lookupFunction);
+        }
+
         public Drawable GetDrawableComponent(ISkinComponent component)
         {
             Drawable sourceDrawable;
@@ -85,7 +104,7 @@ namespace osu.Game.Skinning
         {
             if (canUseSkinLookup)
             {
-                var bindable = skin.GetConfig<TLookup, TValue>(lookup);
+                var bindable = skin?.GetConfig<TLookup, TValue>(lookup);
                 if (bindable != null)
                     return bindable;
             }

osu.Game/Tests/Beatmaps/LegacyBeatmapSkinColourTest.cs

@@ -158,6 +158,8 @@ namespace osu.Game.Tests.Beatmaps
                 add { }
                 remove { }
             }
+
+            public ISkin FindProvider(Func<ISkin, bool> lookupFunction) => null;
         }
     }
 }