Fix slider ball tint not working

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

@@ -1,20 +1,30 @@
 // 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.Linq;
 using NUnit.Framework;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Testing;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Osu.Objects;
 using osu.Game.Rulesets.Osu.Objects.Drawables;
+using osu.Game.Rulesets.Osu.Objects.Drawables.Pieces;
+using osu.Game.Skinning;
 using osu.Game.Tests.Visual;
 using osuTK;
+using osuTK.Graphics;
 
 namespace osu.Game.Rulesets.Osu.Tests
 {
     public class TestSceneSliderApplication : OsuTestScene
     {
+        [Resolved]
+        private SkinManager skinManager { get; set; }
+
         [Test]
         public void TestApplyNewSlider()
         {
@@ -50,6 +60,41 @@ namespace osu.Game.Rulesets.Osu.Tests
             }), null));
         }
 
+        [Test]
+        public void TestBallTintChangedOnAccentChange()
+        {
+            DrawableSlider dho = null;
+
+            AddStep("create slider", () =>
+            {
+                var tintingSkin = skinManager.GetSkin(DefaultLegacySkin.Info);
+                tintingSkin.Configuration.ConfigDictionary["AllowSliderBallTint"] = "1";
+
+                Child = new SkinProvidingContainer(tintingSkin)
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Child = dho = new DrawableSlider(prepareObject(new Slider
+                    {
+                        Position = new Vector2(256, 192),
+                        IndexInCurrentCombo = 0,
+                        StartTime = Time.Current,
+                        Path = new SliderPath(PathType.Linear, new[]
+                        {
+                            Vector2.Zero,
+                            new Vector2(150, 100),
+                            new Vector2(300, 0),
+                        })
+                    }))
+                };
+            });
+
+            AddStep("set accent white", () => dho.AccentColour.Value = Color4.White);
+            AddAssert("ball is white", () => dho.ChildrenOfType<SliderBall>().Single().AccentColour == Color4.White);
+
+            AddStep("set accent red", () => dho.AccentColour.Value = Color4.Red);
+            AddAssert("ball is red", () => dho.ChildrenOfType<SliderBall>().Single().AccentColour == Color4.Red);
+        }
+
         private Slider prepareObject(Slider slider)
         {
             slider.ApplyDefaults(new ControlPointInfo(), new BeatmapDifficulty());

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -80,6 +80,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             {
                 foreach (var drawableHitObject in NestedHitObjects)
                     drawableHitObject.AccentColour.Value = colour.NewValue;
+                updateBallTint();
             }, true);
 
             Tracking.BindValueChanged(updateSlidingSample);
@@ -244,7 +245,15 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         {
             base.ApplySkin(skin, allowFallback);
 
-            bool allowBallTint = skin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.AllowSliderBallTint)?.Value ?? false;
+            updateBallTint();
+        }
+
+        private void updateBallTint()
+        {
+            if (CurrentSkin == null)
+                return;
+
+            bool allowBallTint = CurrentSkin.GetConfig<OsuSkinConfiguration, bool>(OsuSkinConfiguration.AllowSliderBallTint)?.Value ?? false;
             Ball.AccentColour = allowBallTint ? AccentColour.Value : Color4.White;
         }