Move catcher trail generation logic to Catcher

It resolves mutual dependency of `Catcher` and `CatcherTrailDisplay`.
Trail generation logic is moved to `Catcher`.
The generation logic no longer uses delayed scheduling because the hidden state is hard to manage.
Instead, the last time a trail is generated is calculated and used.
The new logic has a different behavior when the dash key is pressed in succession under 50ms, but it is not noticeable for normal plays.

osu.Game.Rulesets.Catch.Tests/TestSceneCatchSkinConfiguration.cs

@@ -41,7 +41,7 @@ namespace osu.Game.Rulesets.Catch.Tests
                 var skin = new TestSkin { FlipCatcherPlate = flip };
                 container.Child = new SkinProvidingContainer(skin)
                 {
-                    Child = catcher = new Catcher(new Container(), new DroppedObjectContainer())
+                    Child = catcher = new Catcher(new CatcherTrailDisplay(), new DroppedObjectContainer())
                     {
                         Anchor = Anchor.Centre
                     }

osu.Game.Rulesets.Catch.Tests/TestSceneCatcher.cs

@@ -31,7 +31,7 @@ namespace osu.Game.Rulesets.Catch.Tests
         [Resolved]
         private OsuConfigManager config { get; set; }
 
-        private Container trailContainer;
+        private CatcherTrailDisplay trailDisplay;
 
         private DroppedObjectContainer droppedObjectContainer;
 
@@ -45,7 +45,7 @@ namespace osu.Game.Rulesets.Catch.Tests
                 CircleSize = 0,
             };
 
-            trailContainer = new Container();
+            trailDisplay = new CatcherTrailDisplay();
             droppedObjectContainer = new DroppedObjectContainer();
 
             Child = new Container
@@ -54,8 +54,8 @@ namespace osu.Game.Rulesets.Catch.Tests
                 Children = new Drawable[]
                 {
                     droppedObjectContainer,
-                    catcher = new TestCatcher(trailContainer, droppedObjectContainer, difficulty),
+                    catcher = new TestCatcher(trailDisplay, droppedObjectContainer, difficulty),
-                    trailContainer,
+                    trailDisplay,
                 }
             };
         });
@@ -294,8 +294,8 @@ namespace osu.Game.Rulesets.Catch.Tests
         {
             public IEnumerable<CaughtObject> CaughtObjects => this.ChildrenOfType<CaughtObject>();
 
-            public TestCatcher(Container trailsTarget, DroppedObjectContainer droppedObjectTarget, BeatmapDifficulty difficulty)
+            public TestCatcher(CatcherTrailDisplay trails, DroppedObjectContainer droppedObjectTarget, BeatmapDifficulty difficulty)
-                : base(trailsTarget, droppedObjectTarget, difficulty)
+                : base(trails, droppedObjectTarget, difficulty)
             {
             }
         }

osu.Game.Rulesets.Catch.Tests/TestSceneCatcherArea.cs

@@ -121,11 +121,13 @@ namespace osu.Game.Rulesets.Catch.Tests
         {
             public TestCatcherArea(BeatmapDifficulty beatmapDifficulty)
             {
-                var droppedObjectContainer = new DroppedObjectContainer();
+                var trailDisplay = new CatcherTrailDisplay { Depth = -1 };
+                Add(trailDisplay);
 
+                var droppedObjectContainer = new DroppedObjectContainer();
                 Add(droppedObjectContainer);
 
-                Catcher = new Catcher(this, droppedObjectContainer, beatmapDifficulty)
+                Catcher = new Catcher(trailDisplay, droppedObjectContainer, beatmapDifficulty)
                 {
                     X = CatchPlayfield.CENTER_X
                 };

osu.Game.Rulesets.Catch.Tests/TestSceneHyperDashColouring.cs

@@ -113,30 +113,28 @@ namespace osu.Game.Rulesets.Catch.Tests
 
         private void checkHyperDashCatcherColour(ISkin skin, Color4 expectedCatcherColour, Color4? expectedEndGlowColour = null)
         {
-            Container trailsContainer = null;
-            Catcher catcher = null;
             CatcherTrailDisplay trails = null;
+            Catcher catcher = null;
 
             AddStep("create hyper-dashing catcher", () =>
             {
-                trailsContainer = new Container();
+                trails = new CatcherTrailDisplay();
                 Child = setupSkinHierarchy(new Container
                 {
                     Anchor = Anchor.Centre,
                     Children = new Drawable[]
                     {
-                        catcher = new Catcher(trailsContainer, new DroppedObjectContainer())
+                        catcher = new Catcher(trails, new DroppedObjectContainer())
                         {
                             Scale = new Vector2(4)
                         },
-                        trailsContainer
+                        trails
                     }
                 }, skin);
             });
 
-            AddStep("get trails container", () =>
+            AddStep("start hyper-dash", () =>
             {
-                trails = trailsContainer.OfType<CatcherTrailDisplay>().Single();
                 catcher.SetHyperDashState(2);
             });
 

osu.Game.Rulesets.Catch/UI/CatchPlayfield.cs

@@ -3,7 +3,6 @@
 
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
 using osu.Game.Beatmaps;
 using osu.Game.Rulesets.Catch.Objects;
 using osu.Game.Rulesets.Catch.Objects.Drawables;
@@ -45,14 +44,14 @@ namespace osu.Game.Rulesets.Catch.UI
         [BackgroundDependencyLoader]
         private void load()
         {
-            var trailContainer = new Container
+            var trailDisplay = new CatcherTrailDisplay
             {
                 Anchor = Anchor.BottomLeft,
                 Origin = Anchor.TopLeft
             };
             var droppedObjectContainer = new DroppedObjectContainer();
 
-            Catcher = new Catcher(trailContainer, droppedObjectContainer, difficulty)
+            Catcher = new Catcher(trailDisplay, droppedObjectContainer, difficulty)
             {
                 X = CENTER_X
             };
@@ -70,7 +69,7 @@ namespace osu.Game.Rulesets.Catch.UI
                     Origin = Anchor.TopLeft,
                     Catcher = Catcher,
                 },
-                trailContainer,
+                trailDisplay,
                 HitObjectContainer,
             });
 

osu.Game.Rulesets.Catch/UI/Catcher.cs

@@ -71,10 +71,10 @@ namespace osu.Game.Rulesets.Catch.UI
         /// </summary>
         private const float caught_fruit_scale_adjust = 0.5f;
 
-        [NotNull]
+        /// <summary>
-        private readonly Container trailsTarget;
+        /// Contains trails and afterimages (also called "end glow" in code) of the catcher.
-
+        /// </summary>
-        private CatcherTrailDisplay trails;
+        private readonly CatcherTrailDisplay trails;
 
         /// <summary>
         /// Contains caught objects on the plate.
@@ -92,20 +92,7 @@ namespace osu.Game.Rulesets.Catch.UI
             private set => Body.AnimationState.Value = value;
         }
 
-        private bool dashing;
+        public bool Dashing { get; set; }
-
-        public bool Dashing
-        {
-            get => dashing;
-            set
-            {
-                if (value == dashing) return;
-
-                dashing = value;
-
-                updateTrailVisibility();
-            }
-        }
 
         /// <summary>
         /// The currently facing direction.
@@ -138,9 +125,9 @@ namespace osu.Game.Rulesets.Catch.UI
         private readonly DrawablePool<CaughtBanana> caughtBananaPool;
         private readonly DrawablePool<CaughtDroplet> caughtDropletPool;
 
-        public Catcher([NotNull] Container trailsTarget, [NotNull] DroppedObjectContainer droppedObjectTarget, BeatmapDifficulty difficulty = null)
+        public Catcher([NotNull] CatcherTrailDisplay trails, [NotNull] DroppedObjectContainer droppedObjectTarget, BeatmapDifficulty difficulty = null)
         {
-            this.trailsTarget = trailsTarget;
+            this.trails = trails;
             this.droppedObjectTarget = droppedObjectTarget;
 
             Origin = Anchor.TopCentre;
@@ -177,15 +164,6 @@ namespace osu.Game.Rulesets.Catch.UI
         private void load(OsuConfigManager config)
         {
             hitLighting = config.GetBindable<bool>(OsuSetting.HitLighting);
-            trails = new CatcherTrailDisplay(this);
-        }
-
-        protected override void LoadComplete()
-        {
-            base.LoadComplete();
-
-            // don't add in above load as we may potentially modify a parent in an unsafe manner.
-            trailsTarget.Add(trails);
         }
 
         /// <summary>
@@ -313,7 +291,7 @@ namespace osu.Game.Rulesets.Catch.UI
 
                 if (!wasHyperDashing)
                 {
-                    trails.DisplayEndGlow();
+                    trails.DisplayEndGlow(CurrentState, X, Scale * Body.Scale);
                     runHyperDashStateTransition(true);
                 }
             }
@@ -331,13 +309,9 @@ namespace osu.Game.Rulesets.Catch.UI
 
         private void runHyperDashStateTransition(bool hyperDashing)
         {
-            updateTrailVisibility();
-
             this.FadeColour(hyperDashing ? hyperDashColour : Color4.White, HYPER_DASH_TRANSITION_DURATION, Easing.OutQuint);
         }
 
-        private void updateTrailVisibility() => trails.DisplayTrail = Dashing || HyperDashing;
-
         protected override void SkinChanged(ISkinSource skin)
         {
             base.SkinChanged(skin);
@@ -373,6 +347,15 @@ namespace osu.Game.Rulesets.Catch.UI
                 X = hyperDashTargetPosition;
                 SetHyperDashState();
             }
+
+            if (Dashing || HyperDashing)
+            {
+                double lastTrailTime = trails.LastDashTrail?.LifetimeStart ?? double.NegativeInfinity;
+                double generationInterval = HyperDashing ? 25 : 50;
+
+                if (Time.Current - lastTrailTime >= generationInterval)
+                    trails.DisplayDashTrail(CurrentState, X, Scale * Body.Scale, HyperDashing);
+            }
         }
 
         private void placeCaughtObject(DrawablePalpableCatchHitObject drawableObject, Vector2 position)

osu.Game.Rulesets.Catch/UI/CatcherTrailDisplay.cs

@@ -1,7 +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.Linq;
 using JetBrains.Annotations;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -17,7 +17,10 @@ namespace osu.Game.Rulesets.Catch.UI
     /// </summary>
     public class CatcherTrailDisplay : CompositeDrawable
     {
-        private readonly Catcher catcher;
+        [CanBeNull]
+        public CatcherTrail LastDashTrail => dashTrails.Concat(hyperDashTrails)
+                                                       .OrderByDescending(trail => trail.LifetimeStart)
+                                                       .FirstOrDefault();
 
         private readonly DrawablePool<CatcherTrail> trailPool;
 
@@ -55,30 +58,8 @@ namespace osu.Game.Rulesets.Catch.UI
             }
         }
 
-        private bool trail;
+        public CatcherTrailDisplay()
-
-        /// <summary>
-        /// Whether to start displaying trails following the catcher.
-        /// </summary>
-        public bool DisplayTrail
         {
-            get => trail;
-            set
-            {
-                if (trail == value)
-                    return;
-
-                trail = value;
-
-                if (trail)
-                    displayTrail();
-            }
-        }
-
-        public CatcherTrailDisplay([NotNull] Catcher catcher)
-        {
-            this.catcher = catcher ?? throw new ArgumentNullException(nameof(catcher));
-
             RelativeSizeAxes = Axes.Both;
 
             InternalChildren = new Drawable[]
@@ -93,9 +74,11 @@ namespace osu.Game.Rulesets.Catch.UI
         /// <summary>
         /// Displays a single end-glow catcher sprite.
         /// </summary>
-        public void DisplayEndGlow()
+        public void DisplayEndGlow(CatcherAnimationState animationState, float x, Vector2 scale)
         {
-            var endGlow = createTrailSprite(endGlowSprites);
+            var endGlow = createTrail(animationState, x, scale);
+
+            endGlowSprites.Add(endGlow);
 
             endGlow.MoveToOffset(new Vector2(0, -10), 1200, Easing.In);
             endGlow.ScaleTo(endGlow.Scale * 0.95f).ScaleTo(endGlow.Scale * 1.2f, 1200, Easing.In);
@@ -103,28 +86,26 @@ namespace osu.Game.Rulesets.Catch.UI
             endGlow.Expire(true);
         }
 
-        private void displayTrail()
+        public void DisplayDashTrail(CatcherAnimationState animationState, float x, Vector2 scale, bool hyperDashing)
         {
-            if (!DisplayTrail)
+            var sprite = createTrail(animationState, x, scale);
-                return;
 
-            var sprite = createTrailSprite(catcher.HyperDashing ? hyperDashTrails : dashTrails);
+            if (hyperDashing)
+                hyperDashTrails.Add(sprite);
+            else
+                dashTrails.Add(sprite);
 
             sprite.FadeTo(0.4f).FadeOut(800, Easing.OutQuint);
             sprite.Expire(true);
-
-            Scheduler.AddDelayed(displayTrail, catcher.HyperDashing ? 25 : 50);
         }
 
-        private CatcherTrail createTrailSprite(Container<CatcherTrail> target)
+        private CatcherTrail createTrail(CatcherAnimationState animationState, float x, Vector2 scale)
         {
             CatcherTrail sprite = trailPool.Get();
 
-            sprite.AnimationState = catcher.CurrentState;
+            sprite.AnimationState = animationState;
-            sprite.Scale = catcher.Scale * catcher.Body.Scale;
+            sprite.Scale = scale;
-            sprite.Position = catcher.Position;
+            sprite.Position = new Vector2(x, 0);
-
-            target.Add(sprite);
 
             return sprite;
         }