Merge branch 'master' into legacy-mirror-mod-replays

osu.Game.Rulesets.Catch/Skinning/CatchLegacySkinTransformer.cs

@@ -6,6 +6,7 @@ using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Game.Skinning;
 using osuTK;
+using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Catch.Skinning
 {
@@ -61,7 +62,12 @@ namespace osu.Game.Rulesets.Catch.Skinning
             switch (lookup)
             {
                 case CatchSkinColour colour:
-                    return Source.GetConfig<SkinCustomColourLookup, TValue>(new SkinCustomColourLookup(colour));
+                    var result = (Bindable<Color4>)Source.GetConfig<SkinCustomColourLookup, TValue>(new SkinCustomColourLookup(colour));
+                    if (result == null)
+                        return null;
+
+                    result.Value = LegacyColourCompatibility.DisallowZeroAlpha(result.Value);
+                    return (IBindable<TValue>)result;
             }
 
             return Source.GetConfig<TLookup, TValue>(lookup);

osu.Game.Rulesets.Catch/Skinning/LegacyFruitPiece.cs

@@ -40,7 +40,6 @@ namespace osu.Game.Rulesets.Catch.Skinning
                 colouredSprite = new Sprite
                 {
                     Texture = skin.GetTexture(lookupName),
-                    Colour = drawableObject.AccentColour.Value,
                     Anchor = Anchor.Centre,
                     Origin = Anchor.Centre,
                 },
@@ -76,7 +75,7 @@ namespace osu.Game.Rulesets.Catch.Skinning
         {
             base.LoadComplete();
 
-            accentColour.BindValueChanged(colour => colouredSprite.Colour = colour.NewValue, true);
+            accentColour.BindValueChanged(colour => colouredSprite.Colour = LegacyColourCompatibility.DisallowZeroAlpha(colour.NewValue), true);
         }
     }
 }

osu.Game.Rulesets.Mania/Skinning/LegacyColumnBackground.cs

@@ -49,7 +49,7 @@ namespace osu.Game.Rulesets.Mania.Skinning
                     {
                         Anchor = Anchor.BottomCentre,
                         Origin = Anchor.BottomCentre,
-                        Colour = lightColour,
+                        Colour = LegacyColourCompatibility.DisallowZeroAlpha(lightColour),
                         Texture = skin.GetTexture(lightImage),
                         RelativeSizeAxes = Axes.X,
                         Width = 1,

osu.Game.Rulesets.Mania/Skinning/LegacyHitTarget.cs

@@ -51,7 +51,7 @@ namespace osu.Game.Rulesets.Mania.Skinning
                         Anchor = Anchor.CentreLeft,
                         RelativeSizeAxes = Axes.X,
                         Height = 1,
-                        Colour = lineColour,
+                        Colour = LegacyColourCompatibility.DisallowZeroAlpha(lineColour),
                         Alpha = showJudgementLine ? 0.9f : 0
                     }
                 }

osu.Game.Rulesets.Mania/Skinning/LegacyStageBackground.cs

@@ -106,37 +106,38 @@ namespace osu.Game.Rulesets.Mania.Skinning
 
                 InternalChildren = new Drawable[]
                 {
-                    new Container
+                    LegacyColourCompatibility.ApplyWithDoubledAlpha(new Box
                     {
-                        RelativeSizeAxes = Axes.Both,
-                        Child = new Box
-                        {
-                            RelativeSizeAxes = Axes.Both,
-                            Colour = backgroundColour
-                        },
-                    },
+                        RelativeSizeAxes = Axes.Both
+                    }, backgroundColour),
                     new HitTargetInsetContainer
                     {
                         RelativeSizeAxes = Axes.Both,
                         Children = new[]
                         {
-                            new Box
+                            new Container
                             {
                                 RelativeSizeAxes = Axes.Y,
                                 Width = leftLineWidth,
                                 Scale = new Vector2(0.740f, 1),
-                                Colour = lineColour,
-                                Alpha = hasLeftLine ? 1 : 0
+                                Alpha = hasLeftLine ? 1 : 0,
+                                Child = LegacyColourCompatibility.ApplyWithDoubledAlpha(new Box
+                                {
+                                    RelativeSizeAxes = Axes.Both
+                                }, lineColour)
                             },
-                            new Box
+                            new Container
                             {
                                 Anchor = Anchor.TopRight,
                                 Origin = Anchor.TopRight,
                                 RelativeSizeAxes = Axes.Y,
                                 Width = rightLineWidth,
                                 Scale = new Vector2(0.740f, 1),
-                                Colour = lineColour,
-                                Alpha = hasRightLine ? 1 : 0
+                                Alpha = hasRightLine ? 1 : 0,
+                                Child = LegacyColourCompatibility.ApplyWithDoubledAlpha(new Box
+                                {
+                                    RelativeSizeAxes = Axes.Both
+                                }, lineColour)
                             },
                         }
                     }

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

@@ -110,7 +110,7 @@ namespace osu.Game.Rulesets.Osu.Tests
                 this.hasColours = hasColours;
             }
 
-            protected override ISkin GetSkin() => new TestBeatmapSkin(BeatmapInfo, hasColours);
+            protected override IBeatmapSkin GetSkin() => new TestBeatmapSkin(BeatmapInfo, hasColours);
         }
 
         private class TestBeatmapSkin : LegacyBeatmapSkin

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

@@ -29,12 +29,12 @@ namespace osu.Game.Rulesets.Osu.Tests
     public class TestSceneSkinFallbacks : TestSceneOsuPlayer
     {
         private readonly TestSource testUserSkin;
-        private readonly TestSource testBeatmapSkin;
+        private readonly BeatmapTestSource testBeatmapSkin;
 
         public TestSceneSkinFallbacks()
         {
             testUserSkin = new TestSource("user");
-            testBeatmapSkin = new TestSource("beatmap");
+            testBeatmapSkin = new BeatmapTestSource();
         }
 
         [Test]
@@ -80,15 +80,15 @@ namespace osu.Game.Rulesets.Osu.Tests
 
         public class CustomSkinWorkingBeatmap : ClockBackedTestWorkingBeatmap
         {
-            private readonly ISkinSource skin;
+            private readonly IBeatmapSkin skin;
 
-            public CustomSkinWorkingBeatmap(IBeatmap beatmap, Storyboard storyboard, IFrameBasedClock frameBasedClock, AudioManager audio, ISkinSource skin)
+            public CustomSkinWorkingBeatmap(IBeatmap beatmap, Storyboard storyboard, IFrameBasedClock frameBasedClock, AudioManager audio, IBeatmapSkin skin)
                 : base(beatmap, storyboard, frameBasedClock, audio)
             {
                 this.skin = skin;
             }
 
-            protected override ISkin GetSkin() => skin;
+            protected override IBeatmapSkin GetSkin() => skin;
         }
 
         public class SkinProvidingPlayer : TestPlayer
@@ -112,6 +112,14 @@ namespace osu.Game.Rulesets.Osu.Tests
             }
         }
 
+        private class BeatmapTestSource : TestSource, IBeatmapSkin
+        {
+            public BeatmapTestSource()
+                : base("beatmap")
+            {
+            }
+        }
+
         public class TestSource : ISkinSource
         {
             private readonly string identifier;

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

@@ -9,6 +9,7 @@ using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.Osu.Objects;
 using osu.Game.Rulesets.Osu.Objects.Drawables;
+using osuTK;
 
 namespace osu.Game.Rulesets.Osu.Tests
 {
@@ -62,7 +63,8 @@ namespace osu.Game.Rulesets.Osu.Tests
             drawableSpinner = new TestDrawableSpinner(spinner, auto)
             {
                 Anchor = Anchor.Centre,
-                Depth = depthIndex++
+                Depth = depthIndex++,
+                Scale = new Vector2(0.75f)
             };
 
             foreach (var mod in SelectedMods.Value.OfType<IApplicableToDrawableHitObjects>())

osu.Game.Rulesets.Osu/Skinning/LegacyMainCirclePiece.cs

@@ -59,7 +59,6 @@ namespace osu.Game.Rulesets.Osu.Skinning
                         hitCircleSprite = new Sprite
                         {
                             Texture = getTextureWithFallback(string.Empty),
-                            Colour = drawableObject.AccentColour.Value,
                             Anchor = Anchor.Centre,
                             Origin = Anchor.Centre,
                         },
@@ -107,7 +106,7 @@ namespace osu.Game.Rulesets.Osu.Skinning
             base.LoadComplete();
 
             state.BindValueChanged(updateState, true);
-            accentColour.BindValueChanged(colour => hitCircleSprite.Colour = colour.NewValue, true);
+            accentColour.BindValueChanged(colour => hitCircleSprite.Colour = LegacyColourCompatibility.DisallowZeroAlpha(colour.NewValue), true);
             indexInCurrentCombo.BindValueChanged(index => hitCircleText.Text = (index.NewValue + 1).ToString(), true);
         }
 

osu.Game.Rulesets.Osu/Skinning/LegacyOldStyleSpinner.cs

@@ -22,11 +22,11 @@ namespace osu.Game.Rulesets.Osu.Skinning
     {
         private DrawableSpinner drawableSpinner;
         private Sprite disc;
+        private Sprite metreSprite;
         private Container metre;
 
-        private const float background_y_offset = 20;
-
         private const float sprite_scale = 1 / 1.6f;
+        private const float final_metre_height = 692 * sprite_scale;
 
         [BackgroundDependencyLoader]
         private void load(ISkinSource source, DrawableHitObject drawableObject)
@@ -35,50 +35,58 @@ namespace osu.Game.Rulesets.Osu.Skinning
 
             RelativeSizeAxes = Axes.Both;
 
-            InternalChildren = new Drawable[]
+            InternalChild = new Container
             {
-                new Sprite
+                // the old-style spinner relied heavily on absolute screen-space coordinate values.
+                // wrap everything in a container simulating absolute coords to preserve alignment
+                // as there are skins that depend on it.
+                Width = 640,
+                Height = 480,
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                Children = new Drawable[]
                 {
-                    Anchor = Anchor.BottomCentre,
-                    Origin = Anchor.BottomCentre,
-                    Texture = source.GetTexture("spinner-background"),
-                    Y = background_y_offset,
-                    Scale = new Vector2(sprite_scale)
-                },
-                disc = new Sprite
-                {
-                    Anchor = Anchor.Centre,
-                    Origin = Anchor.Centre,
-                    Texture = source.GetTexture("spinner-circle"),
-                    Scale = new Vector2(sprite_scale)
-                },
-                metre = new Container
-                {
-                    Anchor = Anchor.BottomCentre,
-                    Origin = Anchor.BottomCentre,
-                    Y = background_y_offset,
-                    Masking = true,
-                    Child = new Sprite
+                    new Sprite
                     {
-                        Texture = source.GetTexture("spinner-metre"),
-                        Anchor = Anchor.BottomCentre,
-                        Origin = Anchor.BottomCentre,
+                        Anchor = Anchor.Centre,
+                        Origin = Anchor.Centre,
+                        Texture = source.GetTexture("spinner-background"),
+                        Scale = new Vector2(sprite_scale)
                     },
-                    Scale = new Vector2(0.625f)
+                    disc = new Sprite
+                    {
+                        Anchor = Anchor.Centre,
+                        Origin = Anchor.Centre,
+                        Texture = source.GetTexture("spinner-circle"),
+                        Scale = new Vector2(sprite_scale)
+                    },
+                    metre = new Container
+                    {
+                        AutoSizeAxes = Axes.Both,
+                        // this anchor makes no sense, but that's what stable uses.
+                        Anchor = Anchor.TopLeft,
+                        Origin = Anchor.TopLeft,
+                        // adjustment for stable (metre has additional offset)
+                        Margin = new MarginPadding { Top = 20 },
+                        Masking = true,
+                        Child = metreSprite = new Sprite
+                        {
+                            Texture = source.GetTexture("spinner-metre"),
+                            Anchor = Anchor.TopLeft,
+                            Origin = Anchor.TopLeft,
+                            Scale = new Vector2(0.625f)
+                        }
+                    }
                 }
             };
         }
 
-        private Vector2 metreFinalSize;
-
         protected override void LoadComplete()
         {
             base.LoadComplete();
 
             this.FadeOut();
             drawableSpinner.State.BindValueChanged(updateStateTransforms, true);
-
-            metreFinalSize = metre.Size = metre.Child.Size;
         }
 
         private void updateStateTransforms(ValueChangedEvent<ArmedState> state)
@@ -93,7 +101,16 @@ namespace osu.Game.Rulesets.Osu.Skinning
         {
             base.Update();
             disc.Rotation = drawableSpinner.RotationTracker.Rotation;
-            metre.Height = getMetreHeight(drawableSpinner.Progress);
+
+            // careful: need to call this exactly once for all calculations in a frame
+            // as the function has a random factor in it
+            var metreHeight = getMetreHeight(drawableSpinner.Progress);
+
+            // hack to make the metre blink up from below than down from above.
+            // move down the container to be able to apply masking for the metre,
+            // and then move the sprite back up the same amount to keep its position absolute.
+            metre.Y = final_metre_height - metreHeight;
+            metreSprite.Y = -metre.Y;
         }
 
         private const int total_bars = 10;
@@ -108,7 +125,7 @@ namespace osu.Game.Rulesets.Osu.Skinning
             if (RNG.NextBool(((int)progress % 10) / 10f))
                 barCount++;
 
-            return (float)barCount / total_bars * metreFinalSize.Y;
+            return (float)barCount / total_bars * final_metre_height;
         }
     }
 }

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

@@ -28,7 +28,7 @@ namespace osu.Game.Rulesets.Osu.Skinning
         [BackgroundDependencyLoader]
         private void load(ISkinSource skin, DrawableHitObject drawableObject)
         {
-            animationContent.Colour = skin.GetConfig<OsuSkinColour, Color4>(OsuSkinColour.SliderBall)?.Value ?? Color4.White;
+            var ballColour = skin.GetConfig<OsuSkinColour, Color4>(OsuSkinColour.SliderBall)?.Value ?? Color4.White;
 
             InternalChildren = new[]
             {
@@ -39,11 +39,11 @@ namespace osu.Game.Rulesets.Osu.Skinning
                     Texture = skin.GetTexture("sliderb-nd"),
                     Colour = new Color4(5, 5, 5, 255),
                 },
-                animationContent.With(d =>
+                LegacyColourCompatibility.ApplyWithDoubledAlpha(animationContent.With(d =>
                 {
                     d.Anchor = Anchor.Centre;
                     d.Origin = Anchor.Centre;
-                }),
+                }), ballColour),
                 layerSpec = new Sprite
                 {
                     Anchor = Anchor.Centre,

osu.Game.Rulesets.Taiko/Skinning/LegacyCirclePiece.cs

@@ -90,7 +90,7 @@ namespace osu.Game.Rulesets.Taiko.Skinning
 
         private void updateAccentColour()
         {
-            backgroundLayer.Colour = accentColour;
+            backgroundLayer.Colour = LegacyColourCompatibility.DisallowZeroAlpha(accentColour);
         }
     }
 }

osu.Game.Rulesets.Taiko/Skinning/LegacyDrumRoll.cs

@@ -76,9 +76,11 @@ namespace osu.Game.Rulesets.Taiko.Skinning
 
         private void updateAccentColour()
         {
-            headCircle.AccentColour = accentColour;
-            body.Colour = accentColour;
-            end.Colour = accentColour;
+            var colour = LegacyColourCompatibility.DisallowZeroAlpha(accentColour);
+
+            headCircle.AccentColour = colour;
+            body.Colour = colour;
+            end.Colour = colour;
         }
     }
 }

osu.Game.Rulesets.Taiko/Skinning/LegacyHit.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Allocation;
+using osu.Game.Skinning;
 using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Taiko.Skinning
@@ -18,9 +19,10 @@ namespace osu.Game.Rulesets.Taiko.Skinning
         [BackgroundDependencyLoader]
         private void load()
         {
-            AccentColour = component == TaikoSkinComponents.CentreHit
-                ? new Color4(235, 69, 44, 255)
-                : new Color4(67, 142, 172, 255);
+            AccentColour = LegacyColourCompatibility.DisallowZeroAlpha(
+                component == TaikoSkinComponents.CentreHit
+                    ? new Color4(235, 69, 44, 255)
+                    : new Color4(67, 142, 172, 255));
         }
     }
 }

osu.Game.Tests/Gameplay/TestSceneStoryboardSamples.cs

@@ -116,7 +116,7 @@ namespace osu.Game.Tests.Gameplay
             AddAssert("sample playback rate matches mod rates", () => sample.Channel.AggregateFrequency.Value == expectedRate);
         }
 
-        private class TestSkin : LegacySkin
+        private class TestSkin : LegacySkin, IBeatmapSkin
         {
             public TestSkin(string resourceName, AudioManager audioManager)
                 : base(DefaultLegacySkin.Info, new TestResourceStore(resourceName), audioManager, "skin.ini")
@@ -156,7 +156,7 @@ namespace osu.Game.Tests.Gameplay
                 this.audio = audio;
             }
 
-            protected override ISkin GetSkin() => new TestSkin("test-sample", audio);
+            protected override IBeatmapSkin GetSkin() => new TestSkin("test-sample", audio);
         }
 
         private class TestDrawableStoryboardSample : DrawableStoryboardSample

osu.Game.Tests/Resources/skin-zero-alpha-colour.ini

@@ -1,5 +0,0 @@
-[General]
-Version: latest
-
-[Colours]
-Combo1: 255,255,255,0

osu.Game.Tests/Skins/LegacySkinDecoderTest.cs

@@ -108,15 +108,5 @@ namespace osu.Game.Tests.Skins
             using (var stream = new LineBufferedReader(resStream))
                 Assert.That(decoder.Decode(stream).LegacyVersion, Is.EqualTo(1.0m));
         }
-
-        [Test]
-        public void TestDecodeColourWithZeroAlpha()
-        {
-            var decoder = new LegacySkinDecoder();
-
-            using (var resStream = TestResources.OpenResource("skin-zero-alpha-colour.ini"))
-            using (var stream = new LineBufferedReader(resStream))
-                Assert.That(decoder.Decode(stream).ComboColours[0].A, Is.EqualTo(1.0f));
-        }
     }
 }

osu.Game/Beatmaps/BeatmapManager_WorkingBeatmap.cs

@@ -140,7 +140,7 @@ namespace osu.Game.Beatmaps
                 return storyboard;
             }
 
-            protected override ISkin GetSkin()
+            protected override IBeatmapSkin GetSkin()
             {
                 try
                 {

osu.Game/Beatmaps/Formats/LegacyDecoder.cs

@@ -104,10 +104,6 @@ namespace osu.Game.Beatmaps.Formats
             try
             {
                 byte alpha = split.Length == 4 ? byte.Parse(split[3]) : (byte)255;
-
-                if (alpha == 0)
-                    alpha = 255;
-
                 colour = new Color4(byte.Parse(split[0]), byte.Parse(split[1]), byte.Parse(split[2]), alpha);
             }
             catch

osu.Game/Beatmaps/IWorkingBeatmap.cs

@@ -42,9 +42,9 @@ namespace osu.Game.Beatmaps
         Storyboard Storyboard { get; }
 
         /// <summary>
-        /// Retrieves the <see cref="Skin"/> which this <see cref="WorkingBeatmap"/> provides.
+        /// Retrieves the <see cref="IBeatmapSkin"/> which this <see cref="WorkingBeatmap"/> provides.
         /// </summary>
-        ISkin Skin { get; }
+        IBeatmapSkin Skin { get; }
 
         /// <summary>
         /// Constructs a playable <see cref="IBeatmap"/> from <see cref="Beatmap"/> using the applicable converters for a specific <see cref="RulesetInfo"/>.

osu.Game/Beatmaps/WorkingBeatmap.cs

@@ -44,7 +44,7 @@ namespace osu.Game.Beatmaps
             background = new RecyclableLazy<Texture>(GetBackground, BackgroundStillValid);
             waveform = new RecyclableLazy<Waveform>(GetWaveform);
             storyboard = new RecyclableLazy<Storyboard>(GetStoryboard);
-            skin = new RecyclableLazy<ISkin>(GetSkin);
+            skin = new RecyclableLazy<IBeatmapSkin>(GetSkin);
 
             total_count.Value++;
         }
@@ -275,10 +275,10 @@ namespace osu.Game.Beatmaps
         private readonly RecyclableLazy<Storyboard> storyboard;
 
         public bool SkinLoaded => skin.IsResultAvailable;
-        public ISkin Skin => skin.Value;
+        public IBeatmapSkin Skin => skin.Value;
 
-        protected virtual ISkin GetSkin() => new DefaultSkin();
-        private readonly RecyclableLazy<ISkin> skin;
+        protected virtual IBeatmapSkin GetSkin() => new DefaultBeatmapSkin();
+        private readonly RecyclableLazy<IBeatmapSkin> skin;
 
         /// <summary>
         /// Transfer pieces of a beatmap to a new one, where possible, to save on loading.

osu.Game/Skinning/BeatmapSkinProvidingContainer.cs

@@ -11,7 +11,7 @@ namespace osu.Game.Skinning
     /// <summary>
     /// A container which overrides existing skin options with beatmap-local values.
     /// </summary>
-    public class BeatmapSkinProvidingContainer : SkinProvidingContainer
+    public class BeatmapSkinProvidingContainer : SkinProvidingContainer, IBeatmapSkin
     {
         private readonly Bindable<bool> beatmapSkins = new Bindable<bool>();
         private readonly Bindable<bool> beatmapHitsounds = new Bindable<bool>();
@@ -21,7 +21,7 @@ namespace osu.Game.Skinning
         protected override bool AllowTextureLookup(string componentName) => beatmapSkins.Value;
         protected override bool AllowSampleLookup(ISampleInfo componentName) => beatmapHitsounds.Value;
 
-        public BeatmapSkinProvidingContainer(ISkin skin)
+        public BeatmapSkinProvidingContainer(IBeatmapSkin skin)
             : base(skin)
         {
         }

osu.Game/Skinning/DefaultBeatmapSkin.cs

@@ -0,0 +1,9 @@
+// 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.Skinning
+{
+    public class DefaultBeatmapSkin : DefaultSkin, IBeatmapSkin
+    {
+    }
+}

osu.Game/Skinning/IBeatmapSkin.cs

@@ -0,0 +1,12 @@
+// 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.Skinning
+{
+    /// <summary>
+    /// Marker interface for skins that originate from beatmaps.
+    /// </summary>
+    public interface IBeatmapSkin : ISkin
+    {
+    }
+}

osu.Game/Skinning/LegacyBeatmapSkin.cs

@@ -11,7 +11,7 @@ using osu.Game.Rulesets.Objects.Legacy;
 
 namespace osu.Game.Skinning
 {
-    public class LegacyBeatmapSkin : LegacySkin
+    public class LegacyBeatmapSkin : LegacySkin, IBeatmapSkin
     {
         protected override bool AllowManiaSkin => false;
         protected override bool UseCustomSampleBanks => true;

osu.Game/Skinning/LegacyColourCompatibility.cs

@@ -0,0 +1,46 @@
+// 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 osu.Framework.Graphics;
+using osuTK.Graphics;
+
+namespace osu.Game.Skinning
+{
+    /// <summary>
+    /// Compatibility methods to convert osu!stable colours to osu!lazer-compatible ones. Should be used for legacy skins only.
+    /// </summary>
+    public static class LegacyColourCompatibility
+    {
+        /// <summary>
+        /// Forces an alpha of 1 if a given <see cref="Color4"/> is fully transparent.
+        /// </summary>
+        /// <remarks>
+        /// This is equivalent to setting colour post-constructor in osu!stable.
+        /// </remarks>
+        /// <param name="colour">The <see cref="Color4"/> to disallow zero alpha on.</param>
+        /// <returns>The resultant <see cref="Color4"/>.</returns>
+        public static Color4 DisallowZeroAlpha(Color4 colour)
+        {
+            if (colour.A == 0)
+                colour.A = 1;
+            return colour;
+        }
+
+        /// <summary>
+        /// Applies a <see cref="Color4"/> to a <see cref="Drawable"/>, doubling the alpha value into the <see cref="Drawable.Alpha"/> property.
+        /// </summary>
+        /// <remarks>
+        /// This is equivalent to setting colour in the constructor in osu!stable.
+        /// </remarks>
+        /// <param name="drawable">The <see cref="Drawable"/> to apply the colour to.</param>
+        /// <param name="colour">The <see cref="Color4"/> to apply.</param>
+        /// <returns>The given <paramref name="drawable"/>.</returns>
+        public static T ApplyWithDoubledAlpha<T>(T drawable, Color4 colour)
+            where T : Drawable
+        {
+            drawable.Alpha = colour.A;
+            drawable.Colour = DisallowZeroAlpha(colour);
+            return drawable;
+        }
+    }
+}

osu.Game/Tests/Beatmaps/HitObjectSampleTest.cs

@@ -188,7 +188,7 @@ namespace osu.Game.Tests.Beatmaps
                 this.resourceStore = resourceStore;
             }
 
-            protected override ISkin GetSkin() => new LegacyBeatmapSkin(skinBeatmapInfo, resourceStore, AudioManager);
+            protected override IBeatmapSkin GetSkin() => new LegacyBeatmapSkin(skinBeatmapInfo, resourceStore, AudioManager);
         }
     }
 }