Add basic taiko scroller implementation

osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneTaikoPlayfield.cs

@@ -24,6 +24,7 @@ namespace osu.Game.Rulesets.Taiko.Tests.Skinning
             typeof(TaikoHitTarget),
             typeof(TaikoLegacyHitTarget),
             typeof(PlayfieldBackgroundRight),
+            typeof(LegacyTaikoScroller),
         }).ToList();
 
         [Cached(typeof(IScrollingInfo))]
@@ -51,6 +52,7 @@ namespace osu.Game.Rulesets.Taiko.Tests.Skinning
             {
                 Anchor = Anchor.CentreLeft,
                 Origin = Anchor.CentreLeft,
+                Height = 0.6f,
             }));
 
             AddRepeatStep("change height", () => this.ChildrenOfType<TaikoPlayfield>().ForEach(p => p.Height = Math.Max(0.2f, (p.Height + 0.2f) % 1f)), 50);

osu.Game.Rulesets.Taiko.Tests/Skinning/TestSceneTaikoScroller.cs

@@ -0,0 +1,16 @@
+// 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 osu.Game.Skinning;
+
+namespace osu.Game.Rulesets.Taiko.Tests.Skinning
+{
+    public class TestSceneTaikoScroller : TaikoSkinnableTestScene
+    {
+        public TestSceneTaikoScroller()
+        {
+            AddStep("Load scroller", () => SetContents(() => new SkinnableDrawable(new TaikoSkinComponent(TaikoSkinComponents.TaikoScroller), _ => Drawable.Empty())));
+        }
+    }
+}

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

@@ -0,0 +1,83 @@
+// 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 osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Skinning;
+
+namespace osu.Game.Rulesets.Taiko.Skinning
+{
+    public class LegacyTaikoScroller : CompositeDrawable
+    {
+        public LegacyTaikoScroller()
+        {
+            RelativeSizeAxes = Axes.Both;
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            foreach (var sprite in InternalChildren)
+            {
+                sprite.X -= (float)Time.Elapsed * 0.1f;
+
+                if (sprite.X + sprite.DrawWidth < 0)
+                    sprite.Expire();
+            }
+
+            var last = InternalChildren.LastOrDefault();
+
+            if (last == null || last.ScreenSpaceDrawQuad.TopRight.X < ScreenSpaceDrawQuad.TopRight.X)
+            {
+                AddInternal(new ScrollerSprite { X = last == null ? 0 : last.X + last.DrawWidth });
+            }
+        }
+
+        private class ScrollerSprite : CompositeDrawable
+        {
+            private Sprite passingSprite;
+            private Sprite failingSprite;
+
+            private bool passing = true;
+
+            public bool Passing
+            {
+                get => passing;
+                set
+                {
+                    if (value == passing)
+                        return;
+
+                    passing = value;
+
+                    if (passing)
+                    {
+                        passingSprite.Show();
+                        failingSprite.FadeOut(200);
+                    }
+                    else
+                    {
+                        failingSprite.FadeIn(200);
+                        passingSprite.Delay(200).FadeOut();
+                    }
+                }
+            }
+
+            [BackgroundDependencyLoader]
+            private void load(ISkinSource skin)
+            {
+                AutoSizeAxes = Axes.Both;
+
+                InternalChildren = new Drawable[]
+                {
+                    passingSprite = new Sprite { Texture = skin.GetTexture("taiko-slider") },
+                    failingSprite = new Sprite { Texture = skin.GetTexture("taiko-slider-fail"), Alpha = 0 },
+                };
+            }
+        }
+    }
+}

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

@@ -85,6 +85,12 @@ namespace osu.Game.Rulesets.Taiko.Skinning
                         return new LegacyHitExplosion(sprite);
 
                     return null;
+
+                case TaikoSkinComponents.TaikoScroller:
+                    if (GetTexture("taiko-slider") != null)
+                        return new LegacyTaikoScroller();
+
+                    return null;
             }
 
             return source.GetDrawableComponent(component);

osu.Game.Rulesets.Taiko/TaikoSkinComponents.cs

@@ -18,5 +18,6 @@ namespace osu.Game.Rulesets.Taiko
         TaikoExplosionMiss,
         TaikoExplosionGood,
         TaikoExplosionGreat,
+        TaikoScroller
     }
 }

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

@@ -50,6 +50,13 @@ namespace osu.Game.Rulesets.Taiko.UI
         {
             InternalChildren = new[]
             {
+                new SkinnableDrawable(new TaikoSkinComponent(TaikoSkinComponents.TaikoScroller), _ => Drawable.Empty())
+                {
+                    Origin = Anchor.BottomLeft,
+                    Anchor = Anchor.TopLeft,
+                    RelativeSizeAxes = Axes.X,
+                    Height = 100,
+                },
                 new SkinnableDrawable(new TaikoSkinComponent(TaikoSkinComponents.PlayfieldBackgroundRight), _ => new PlayfieldBackgroundRight()),
                 rightArea = new Container
                 {