Merge branch 'master' into countdown-button-icon

osu.Game.Tests/Visual/Multiplayer/TestSceneMultiplayerParticipantsList.cs

@@ -163,6 +163,25 @@ namespace osu.Game.Tests.Visual.Multiplayer
             AddUntilStep("second user crown visible", () => this.ChildrenOfType<ParticipantPanel>().ElementAt(1).ChildrenOfType<SpriteIcon>().First().Alpha == 1);
         }
 
+        [Test]
+        public void TestHostGetsPinnedToTop()
+        {
+            AddStep("add user", () => MultiplayerClient.AddUser(new APIUser
+            {
+                Id = 3,
+                Username = "Second",
+                CoverUrl = @"https://osu.ppy.sh/images/headers/profile-covers/c3.jpg",
+            }));
+
+            AddStep("make second user host", () => MultiplayerClient.TransferHost(3));
+            AddAssert("second user above first", () =>
+            {
+                var first = this.ChildrenOfType<ParticipantPanel>().ElementAt(0);
+                var second = this.ChildrenOfType<ParticipantPanel>().ElementAt(1);
+                return second.Y < first.Y;
+            });
+        }
+
         [Test]
         public void TestKickButtonOnlyPresentWhenHost()
         {
@@ -202,9 +221,11 @@ namespace osu.Game.Tests.Visual.Multiplayer
         [Test]
         public void TestManyUsers()
         {
+            const int users_count = 20;
+
             AddStep("add many users", () =>
             {
-                for (int i = 0; i < 20; i++)
+                for (int i = 0; i < users_count; i++)
                 {
                     MultiplayerClient.AddUser(new APIUser
                     {
@@ -243,6 +264,9 @@ namespace osu.Game.Tests.Visual.Multiplayer
                     }
                 }
             });
+
+            AddRepeatStep("switch hosts", () => MultiplayerClient.TransferHost(RNG.Next(0, users_count)), 10);
+            AddStep("give host back", () => MultiplayerClient.TransferHost(API.LocalUser.Value.Id));
         }
 
         [Test]

osu.Game.Tests/Visual/UserInterface/TestSceneModSettingsArea.cs

@@ -0,0 +1,40 @@
+// 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 NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Overlays;
+using osu.Game.Overlays.Mods;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.Osu.Mods;
+
+namespace osu.Game.Tests.Visual.UserInterface
+{
+    [TestFixture]
+    public class TestSceneModSettingsArea : OsuTestScene
+    {
+        [Cached]
+        private OverlayColourProvider colourProvider = new OverlayColourProvider(OverlayColourScheme.Green);
+
+        [Test]
+        public void TestModToggleArea()
+        {
+            ModSettingsArea modSettingsArea = null;
+
+            AddStep("create content", () => Child = new Container
+            {
+                RelativeSizeAxes = Axes.Both,
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                Child = modSettingsArea = new ModSettingsArea()
+            });
+            AddStep("set DT", () => modSettingsArea.SelectedMods.Value = new[] { new OsuModDoubleTime() });
+            AddStep("set DA", () => modSettingsArea.SelectedMods.Value = new Mod[] { new OsuModDifficultyAdjust() });
+            AddStep("set FL+WU+DA+AD", () => modSettingsArea.SelectedMods.Value = new Mod[] { new OsuModFlashlight(), new ModWindUp(), new OsuModDifficultyAdjust(), new OsuModApproachDifferent() });
+            AddStep("set empty", () => modSettingsArea.SelectedMods.Value = Array.Empty<Mod>());
+        }
+    }
+}

osu.Game/Overlays/Mods/ModSettingsArea.cs

@@ -0,0 +1,176 @@
+// 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.Collections.Generic;
+using System.Linq;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input.Events;
+using osu.Game.Configuration;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Containers;
+using osu.Game.Graphics.Sprites;
+using osu.Game.Rulesets.Mods;
+using osu.Game.Rulesets.UI;
+using osuTK;
+
+namespace osu.Game.Overlays.Mods
+{
+    public class ModSettingsArea : CompositeDrawable
+    {
+        public Bindable<IReadOnlyList<Mod>> SelectedMods { get; } = new Bindable<IReadOnlyList<Mod>>();
+
+        private readonly Box background;
+        private readonly FillFlowContainer modSettingsFlow;
+
+        [Resolved]
+        private OverlayColourProvider colourProvider { get; set; }
+
+        public ModSettingsArea()
+        {
+            RelativeSizeAxes = Axes.X;
+            Height = 250;
+
+            Anchor = Anchor.BottomRight;
+            Origin = Anchor.BottomRight;
+
+            InternalChild = new Container
+            {
+                RelativeSizeAxes = Axes.Both,
+                Masking = true,
+                BorderThickness = 2,
+                Children = new Drawable[]
+                {
+                    background = new Box
+                    {
+                        RelativeSizeAxes = Axes.Both
+                    },
+                    new OsuScrollContainer(Direction.Horizontal)
+                    {
+                        RelativeSizeAxes = Axes.Both,
+                        ScrollbarOverlapsContent = false,
+                        Child = modSettingsFlow = new FillFlowContainer
+                        {
+                            AutoSizeAxes = Axes.X,
+                            RelativeSizeAxes = Axes.Y,
+                            Padding = new MarginPadding { Vertical = 7, Horizontal = 70 },
+                            Spacing = new Vector2(7),
+                            Direction = FillDirection.Horizontal
+                        }
+                    }
+                }
+            };
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            background.Colour = colourProvider.Dark3;
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            SelectedMods.BindValueChanged(_ => updateMods());
+        }
+
+        private void updateMods()
+        {
+            modSettingsFlow.Clear();
+
+            foreach (var mod in SelectedMods.Value.OrderBy(mod => mod.Type).ThenBy(mod => mod.Acronym))
+            {
+                var settings = mod.CreateSettingsControls().ToList();
+
+                if (settings.Count > 0)
+                {
+                    if (modSettingsFlow.Any())
+                    {
+                        modSettingsFlow.Add(new Box
+                        {
+                            RelativeSizeAxes = Axes.Y,
+                            Width = 2,
+                            Colour = colourProvider.Dark4,
+                        });
+                    }
+
+                    modSettingsFlow.Add(new ModSettingsColumn(mod, settings));
+                }
+            }
+        }
+
+        protected override bool OnMouseDown(MouseDownEvent e) => true;
+        protected override bool OnHover(HoverEvent e) => true;
+
+        private class ModSettingsColumn : CompositeDrawable
+        {
+            public ModSettingsColumn(Mod mod, IEnumerable<Drawable> settingsControls)
+            {
+                Width = 250;
+                RelativeSizeAxes = Axes.Y;
+                Padding = new MarginPadding { Bottom = 7 };
+
+                InternalChild = new GridContainer
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    RowDimensions = new[]
+                    {
+                        new Dimension(GridSizeMode.AutoSize),
+                        new Dimension(GridSizeMode.Absolute, 10),
+                        new Dimension()
+                    },
+                    Content = new[]
+                    {
+                        new Drawable[]
+                        {
+                            new FillFlowContainer
+                            {
+                                RelativeSizeAxes = Axes.X,
+                                AutoSizeAxes = Axes.Y,
+                                Direction = FillDirection.Horizontal,
+                                Spacing = new Vector2(7),
+                                Children = new Drawable[]
+                                {
+                                    new ModSwitchTiny(mod)
+                                    {
+                                        Active = { Value = true },
+                                        Scale = new Vector2(0.6f),
+                                        Origin = Anchor.CentreLeft,
+                                        Anchor = Anchor.CentreLeft
+                                    },
+                                    new OsuSpriteText
+                                    {
+                                        Text = mod.Name,
+                                        Font = OsuFont.Default.With(size: 16, weight: FontWeight.SemiBold),
+                                        Origin = Anchor.CentreLeft,
+                                        Anchor = Anchor.CentreLeft,
+                                        Margin = new MarginPadding { Bottom = 2 }
+                                    }
+                                }
+                            }
+                        },
+                        new[] { Empty() },
+                        new Drawable[]
+                        {
+                            new OsuScrollContainer(Direction.Vertical)
+                            {
+                                RelativeSizeAxes = Axes.Both,
+                                Child = new FillFlowContainer
+                                {
+                                    RelativeSizeAxes = Axes.X,
+                                    AutoSizeAxes = Axes.Y,
+                                    Padding = new MarginPadding { Right = 7 },
+                                    ChildrenEnumerable = settingsControls,
+                                    Spacing = new Vector2(0, 7)
+                                }
+                            }
+                        }
+                    }
+                };
+            }
+        }
+    }
+}

osu.Game/Screens/OnlinePlay/Multiplayer/Match/MultiplayerReadyButton.cs

@@ -47,7 +47,7 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Match
             countdown = room?.Countdown;
 
             if (room?.Countdown != null)
-                countdownUpdateDelegate ??= Scheduler.AddDelayed(updateButtonText, 1000, true);
+                countdownUpdateDelegate ??= Scheduler.AddDelayed(updateButtonText, 100, true);
             else
             {
                 countdownUpdateDelegate?.Cancel();

osu.Game/Screens/OnlinePlay/Multiplayer/Participants/ParticipantPanel.cs

@@ -198,15 +198,8 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
             else
                 userModsDisplay.FadeOut(fade_time);
 
-            if (Client.IsHost && !User.Equals(Client.LocalUser))
+            kickButton.Alpha = Client.IsHost && !User.Equals(Client.LocalUser) ? 1 : 0;
-                kickButton.FadeIn(fade_time);
+            crown.Alpha = Room.Host?.Equals(User) == true ? 1 : 0;
-            else
-                kickButton.FadeOut(fade_time);
-
-            if (Room.Host?.Equals(User) == true)
-                crown.FadeIn(fade_time);
-            else
-                crown.FadeOut(fade_time);
 
             // If the mods are updated at the end of the frame, the flow container will skip a reflow cycle: https://github.com/ppy/osu-framework/issues/4187
             // This looks particularly jarring here, so re-schedule the update to that start of our frame as a fix.

osu.Game/Screens/OnlinePlay/Multiplayer/Participants/ParticipantsList.cs

@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System.Linq;
+using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -15,6 +16,9 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
     {
         private FillFlowContainer<ParticipantPanel> panels;
 
+        [CanBeNull]
+        private ParticipantPanel currentHostPanel;
+
         [BackgroundDependencyLoader]
         private void load()
         {
@@ -55,6 +59,24 @@ namespace osu.Game.Screens.OnlinePlay.Multiplayer.Participants
                 // Add panels for all users new to the room.
                 foreach (var user in Room.Users.Except(panels.Select(p => p.User)))
                     panels.Add(new ParticipantPanel(user));
+
+                if (currentHostPanel == null || !currentHostPanel.User.Equals(Room.Host))
+                {
+                    // Reset position of previous host back to normal, if one existing.
+                    if (currentHostPanel != null && panels.Contains(currentHostPanel))
+                        panels.SetLayoutPosition(currentHostPanel, 0);
+
+                    currentHostPanel = null;
+
+                    // Change position of new host to display above all participants.
+                    if (Room.Host != null)
+                    {
+                        currentHostPanel = panels.SingleOrDefault(u => u.User.Equals(Room.Host));
+
+                        if (currentHostPanel != null)
+                            panels.SetLayoutPosition(currentHostPanel, -1);
+                    }
+                }
             }
         }
     }

osu.Game/Skinning/ISkin.cs

@@ -1,7 +1,8 @@
 // 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 JetBrains.Annotations;
+#nullable enable
+
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -21,16 +22,14 @@ namespace osu.Game.Skinning
         /// </summary>
         /// <param name="component">The requested component.</param>
         /// <returns>A drawable representation for the requested component, or null if unavailable.</returns>
-        [CanBeNull]
+        Drawable? GetDrawableComponent(ISkinComponent component);
-        Drawable GetDrawableComponent(ISkinComponent component);
 
         /// <summary>
         /// Retrieve a <see cref="Texture"/>.
         /// </summary>
         /// <param name="componentName">The requested texture.</param>
         /// <returns>A matching texture, or null if unavailable.</returns>
-        [CanBeNull]
+        Texture? GetTexture(string componentName) => GetTexture(componentName, default, default);
-        Texture GetTexture(string componentName) => GetTexture(componentName, default, default);
 
         /// <summary>
         /// Retrieve a <see cref="Texture"/>.
@@ -39,23 +38,22 @@ namespace osu.Game.Skinning
         /// <param name="wrapModeS">The texture wrap mode in horizontal direction.</param>
         /// <param name="wrapModeT">The texture wrap mode in vertical direction.</param>
         /// <returns>A matching texture, or null if unavailable.</returns>
-        [CanBeNull]
+        Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
-        Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
 
         /// <summary>
         /// Retrieve a <see cref="SampleChannel"/>.
         /// </summary>
         /// <param name="sampleInfo">The requested sample.</param>
         /// <returns>A matching sample channel, or null if unavailable.</returns>
-        [CanBeNull]
+        ISample? GetSample(ISampleInfo sampleInfo);
-        ISample GetSample(ISampleInfo sampleInfo);
 
         /// <summary>
         /// Retrieve a configuration value.
         /// </summary>
         /// <param name="lookup">The requested configuration value.</param>
         /// <returns>A matching value boxed in an <see cref="IBindable{TValue}"/>, or null if unavailable.</returns>
-        [CanBeNull]
+        IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
-        IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup);
+            where TLookup : notnull
+            where TValue : notnull;
     }
 }

osu.Game/Skinning/LegacyBeatmapSkin.cs

@@ -1,9 +1,11 @@
 // 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 JetBrains.Annotations;
+#nullable enable
+
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
+using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.IO.Stores;
 using osu.Game.Audio;
@@ -26,14 +28,14 @@ namespace osu.Game.Skinning
         /// </summary>
         /// <param name="beatmapInfo">The model for this beatmap.</param>
         /// <param name="resources">Access to raw game resources.</param>
-        public LegacyBeatmapSkin(BeatmapInfo beatmapInfo, [CanBeNull] IStorageResourceProvider resources)
+        public LegacyBeatmapSkin(BeatmapInfo beatmapInfo, IStorageResourceProvider? resources)
-            : base(createSkinInfo(beatmapInfo), resources, createRealmBackedStore(beatmapInfo, resources), beatmapInfo.Path)
+            : base(createSkinInfo(beatmapInfo), resources, createRealmBackedStore(beatmapInfo, resources), beatmapInfo.Path.AsNonNull())
         {
             // Disallow default colours fallback on beatmap skins to allow using parent skin combo colours. (via SkinProvidingContainer)
             Configuration.AllowDefaultComboColoursFallback = false;
         }
 
-        private static IResourceStore<byte[]> createRealmBackedStore(BeatmapInfo beatmapInfo, [CanBeNull] IStorageResourceProvider resources)
+        private static IResourceStore<byte[]> createRealmBackedStore(BeatmapInfo beatmapInfo, IStorageResourceProvider? resources)
         {
             if (resources == null)
                 // should only ever be used in tests.
@@ -42,7 +44,7 @@ namespace osu.Game.Skinning
             return new RealmBackedResourceStore(beatmapInfo.BeatmapSet, resources.Files, new[] { @"ogg" });
         }
 
-        public override Drawable GetDrawableComponent(ISkinComponent component)
+        public override Drawable? GetDrawableComponent(ISkinComponent component)
         {
             if (component is SkinnableTargetComponent targetComponent)
             {
@@ -61,7 +63,7 @@ namespace osu.Game.Skinning
             return base.GetDrawableComponent(component);
         }
 
-        public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
+        public override IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
         {
             switch (lookup)
             {
@@ -77,10 +79,10 @@ namespace osu.Game.Skinning
             return base.GetConfig<TLookup, TValue>(lookup);
         }
 
-        protected override IBindable<Color4> GetComboColour(IHasComboColours source, int comboIndex, IHasComboInformation combo)
+        protected override IBindable<Color4>? GetComboColour(IHasComboColours source, int comboIndex, IHasComboInformation combo)
             => base.GetComboColour(source, combo.ComboIndexWithOffsets, combo);
 
-        public override ISample GetSample(ISampleInfo sampleInfo)
+        public override ISample? GetSample(ISampleInfo sampleInfo)
         {
             if (sampleInfo is ConvertHitObjectParser.LegacyHitSampleInfo legacy && legacy.CustomSampleBank == 0)
             {

osu.Game/Skinning/LegacySkin.cs

@@ -1,6 +1,8 @@
 // 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.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -57,7 +59,7 @@ namespace osu.Game.Skinning
         /// <param name="resources">Access to raw game resources.</param>
         /// <param name="storage">An optional store which will be used for looking up skin resources. If null, one will be created from realm <see cref="IHasRealmFiles"/> pattern.</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] IStorageResourceProvider resources, [CanBeNull] IResourceStore<byte[]> storage, string configurationFilename = @"skin.ini")
+        protected LegacySkin(SkinInfo skin, IStorageResourceProvider? resources, IResourceStore<byte[]>? storage, string configurationFilename = @"skin.ini")
             : base(skin, resources, storage, configurationFilename)
         {
             // todo: this shouldn't really be duplicated here (from ManiaLegacySkinTransformer). we need to come up with a better solution.
@@ -81,7 +83,7 @@ namespace osu.Game.Skinning
             }
         }
 
-        public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
+        public override IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
         {
             switch (lookup)
             {
@@ -127,7 +129,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        private IBindable<TValue> lookupForMania<TValue>(LegacyManiaSkinConfigurationLookup maniaLookup)
+        private IBindable<TValue>? lookupForMania<TValue>(LegacyManiaSkinConfigurationLookup maniaLookup)
         {
             if (!maniaConfigurations.TryGetValue(maniaLookup.Keys, out var existing))
                 maniaConfigurations[maniaLookup.Keys] = existing = new LegacyManiaSkinConfiguration(maniaLookup.Keys);
@@ -267,20 +269,20 @@ namespace osu.Game.Skinning
         /// <param name="source">The source to retrieve the combo colours from.</param>
         /// <param name="colourIndex">The preferred index for retrieving the combo colour with.</param>
         /// <param name="combo">Information on the combo whose using the returned colour.</param>
-        protected virtual IBindable<Color4> GetComboColour(IHasComboColours source, int colourIndex, IHasComboInformation combo)
+        protected virtual IBindable<Color4>? GetComboColour(IHasComboColours source, int colourIndex, IHasComboInformation combo)
         {
             var colour = source.ComboColours?[colourIndex % source.ComboColours.Count];
             return colour.HasValue ? new Bindable<Color4>(colour.Value) : null;
         }
 
-        private IBindable<Color4> getCustomColour(IHasCustomColours source, string lookup)
+        private IBindable<Color4>? getCustomColour(IHasCustomColours source, string lookup)
             => source.CustomColours.TryGetValue(lookup, out var col) ? new Bindable<Color4>(col) : null;
 
-        private IBindable<string> getManiaImage(LegacyManiaSkinConfiguration source, string lookup)
+        private IBindable<string>? getManiaImage(LegacyManiaSkinConfiguration source, string lookup)
             => source.ImageLookups.TryGetValue(lookup, out string image) ? new Bindable<string>(image) : null;
 
-        [CanBeNull]
+        private IBindable<TValue>? legacySettingLookup<TValue>(SkinConfiguration.LegacySetting legacySetting)
-        private IBindable<TValue> legacySettingLookup<TValue>(SkinConfiguration.LegacySetting legacySetting)
+            where TValue : notnull
         {
             switch (legacySetting)
             {
@@ -292,8 +294,9 @@ namespace osu.Game.Skinning
             }
         }
 
-        [CanBeNull]
+        private IBindable<TValue>? genericLookup<TLookup, TValue>(TLookup lookup)
-        private IBindable<TValue> genericLookup<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull
         {
             try
             {
@@ -316,7 +319,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override Drawable GetDrawableComponent(ISkinComponent component)
+        public override Drawable? GetDrawableComponent(ISkinComponent component)
         {
             if (base.GetDrawableComponent(component) is Drawable c)
                 return c;
@@ -374,7 +377,7 @@ namespace osu.Game.Skinning
 
                 case GameplaySkinComponent<HitResult> resultComponent:
                     // TODO: this should be inside the judgement pieces.
-                    Func<Drawable> createDrawable = () => getJudgementAnimation(resultComponent.Component);
+                    Func<Drawable?> createDrawable = () => getJudgementAnimation(resultComponent.Component);
 
                     // kind of wasteful that we throw this away, but should do for now.
                     if (createDrawable() != null)
@@ -393,7 +396,7 @@ namespace osu.Game.Skinning
             return this.GetAnimation(component.LookupName, false, false);
         }
 
-        private Texture getParticleTexture(HitResult result)
+        private Texture? getParticleTexture(HitResult result)
         {
             switch (result)
             {
@@ -410,7 +413,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        private Drawable getJudgementAnimation(HitResult result)
+        private Drawable? getJudgementAnimation(HitResult result)
         {
             switch (result)
             {
@@ -430,7 +433,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT)
+        public override Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT)
         {
             foreach (string name in getFallbackNames(componentName))
             {
@@ -458,7 +461,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override ISample GetSample(ISampleInfo sampleInfo)
+        public override ISample? GetSample(ISampleInfo sampleInfo)
         {
             IEnumerable<string> lookupNames;
 

osu.Game/Skinning/ResourceStoreBackedSkin.cs

@@ -46,7 +46,10 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup) => null;
+        public IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull
+            => null;
 
         public void Dispose()
         {

osu.Game/Skinning/Skin.cs

@@ -1,12 +1,14 @@
 // 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.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
-using JetBrains.Annotations;
 using Newtonsoft.Json;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
@@ -27,14 +29,12 @@ namespace osu.Game.Skinning
         /// <summary>
         /// A texture store which can be used to perform user file lookups for this skin.
         /// </summary>
-        [CanBeNull]
+        protected TextureStore? Textures { get; }
-        protected TextureStore Textures { get; }
 
         /// <summary>
         /// A sample store which can be used to perform user file lookups for this skin.
         /// </summary>
-        [CanBeNull]
+        protected ISampleStore? Samples { get; }
-        protected ISampleStore Samples { get; }
 
         public readonly Live<SkinInfo> SkinInfo;
 
@@ -44,13 +44,15 @@ namespace osu.Game.Skinning
 
         private readonly Dictionary<SkinnableTarget, SkinnableInfo[]> drawableComponentInfo = new Dictionary<SkinnableTarget, SkinnableInfo[]>();
 
-        public abstract ISample GetSample(ISampleInfo sampleInfo);
+        public abstract ISample? GetSample(ISampleInfo sampleInfo);
 
-        public Texture GetTexture(string componentName) => GetTexture(componentName, default, default);
+        public Texture? GetTexture(string componentName) => GetTexture(componentName, default, default);
 
-        public abstract Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
+        public abstract Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
 
-        public abstract IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup);
+        public abstract IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull;
 
         /// <summary>
         /// Construct a new skin.
@@ -59,13 +61,11 @@ namespace osu.Game.Skinning
         /// <param name="resources">Access to game-wide resources.</param>
         /// <param name="storage">An optional store which will *replace* all file lookups that are usually sourced from <paramref name="skin"/>.</param>
         /// <param name="configurationFilename">An optional filename to read the skin configuration from. If not provided, the configuration will be retrieved from the storage using "skin.ini".</param>
-        protected Skin(SkinInfo skin, [CanBeNull] IStorageResourceProvider resources, [CanBeNull] IResourceStore<byte[]> storage = null, [CanBeNull] string configurationFilename = @"skin.ini")
+        protected Skin(SkinInfo skin, IStorageResourceProvider? resources, IResourceStore<byte[]>? storage = null, string configurationFilename = @"skin.ini")
         {
             if (resources != null)
             {
-                SkinInfo = resources.RealmAccess != null
+                SkinInfo = skin.ToLive(resources.RealmAccess);
-                    ? skin.ToLive(resources.RealmAccess)
-                    : skin.ToLiveUnmanaged();
 
                 storage ??= new RealmBackedResourceStore(skin, resources.Files, new[] { @"ogg" });
 
@@ -76,12 +76,20 @@ namespace osu.Game.Skinning
                 Samples = samples;
                 Textures = new TextureStore(resources.CreateTextureLoaderStore(storage));
             }
+            else
+            {
+                // Generally only used for tests.
+                SkinInfo = skin.ToLiveUnmanaged();
+            }
 
             var configurationStream = storage?.GetStream(configurationFilename);
 
             if (configurationStream != null)
+            {
                 // stream will be closed after use by LineBufferedReader.
                 ParseConfigurationStream(configurationStream);
+                Debug.Assert(Configuration != null);
+            }
             else
                 Configuration = new SkinConfiguration();
 
@@ -90,7 +98,7 @@ namespace osu.Game.Skinning
             {
                 string filename = $"{skinnableTarget}.json";
 
-                byte[] bytes = storage?.Get(filename);
+                byte[]? bytes = storage?.Get(filename);
 
                 if (bytes == null)
                     continue;
@@ -136,7 +144,7 @@ namespace osu.Game.Skinning
             DrawableComponentInfo[targetContainer.Target] = targetContainer.CreateSkinnableInfo().ToArray();
         }
 
-        public virtual Drawable GetDrawableComponent(ISkinComponent component)
+        public virtual Drawable? GetDrawableComponent(ISkinComponent component)
         {
             switch (component)
             {

osu.Game/Tests/Visual/SkinnableTestScene.cs

@@ -96,7 +96,7 @@ namespace osu.Game.Tests.Visual
                     },
                     new OsuSpriteText
                     {
-                        Text = skin?.SkinInfo?.Value.Name ?? "none",
+                        Text = skin?.SkinInfo.Value.Name ?? "none",
                         Scale = new Vector2(1.5f),
                         Padding = new MarginPadding(5),
                     },