Refactor to avoid DI / event flow

There's always one active smoke segment and it's the direct child of
`SmokeContainer`. This can be simplified as such.

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

@@ -14,7 +14,6 @@
 using osu.Framework.Graphics.Shaders;
 using osu.Framework.Graphics.Textures;
 using osu.Framework.Utils;
-using osu.Game.Rulesets.Osu.UI;
 using osuTK;
 using osuTK.Graphics;
 
@@ -54,7 +53,6 @@ protected float Radius
 
         private float totalDistance;
         private Vector2? lastPosition;
-        private SmokeContainer? smokeContainer;
 
         private const int max_point_count = 18_000;
 
@@ -84,9 +82,8 @@ protected float Radius
         private const float max_rotation = 0.25f;
 
         [BackgroundDependencyLoader]
-        private void load(SmokeContainer container, ShaderManager shaders)
+        private void load(ShaderManager shaders)
         {
-            smokeContainer = container;
             RoundedTextureShader = shaders.Load(VertexShaderDescriptor.TEXTURE_2, FragmentShaderDescriptor.TEXTURE_ROUNDED);
             TextureShader = shaders.Load(VertexShaderDescriptor.TEXTURE_2, FragmentShaderDescriptor.TEXTURE);
         }
@@ -100,14 +97,6 @@ protected override void LoadComplete()
             SmokeStartTime = Time.Current;
 
             totalDistance = PointInterval;
-
-            if (smokeContainer != null)
-            {
-                smokeContainer.SmokeMoved += onSmokeMoved;
-                smokeContainer.SmokeEnded += onSmokeEnded;
-
-                onSmokeMoved(smokeContainer.LastMousePosition, Time.Current);
-            }
         }
 
         private Vector2 nextPointDirection()
@@ -116,7 +105,7 @@ private Vector2 nextPointDirection()
             return new Vector2(MathF.Sin(angle), -MathF.Cos(angle));
         }
 
-        private void onSmokeMoved(Vector2 position, double time)
+        public void AddPosition(Vector2 position, double time)
         {
             lastPosition ??= position;
 
@@ -158,17 +147,11 @@ private void onSmokeMoved(Vector2 position, double time)
             lastPosition = position;
 
             if (SmokePoints.Count >= max_point_count)
-                onSmokeEnded(time);
+                FinishDrawing(time);
         }
 
-        private void onSmokeEnded(double time)
+        public void FinishDrawing(double time)
         {
-            if (smokeContainer != null)
-            {
-                smokeContainer.SmokeMoved -= onSmokeMoved;
-                smokeContainer.SmokeEnded -= onSmokeEnded;
-            }
-
             SmokeEndTime = time;
         }
 
@@ -181,17 +164,6 @@ protected override void Update()
             Invalidate(Invalidation.DrawNode);
         }
 
-        protected override void Dispose(bool isDisposing)
-        {
-            base.Dispose(isDisposing);
-
-            if (smokeContainer != null)
-            {
-                smokeContainer.SmokeMoved -= onSmokeMoved;
-                smokeContainer.SmokeEnded -= onSmokeEnded;
-            }
-        }
-
         protected struct SmokePoint
         {
             public Vector2 Position;

osu.Game.Rulesets.Osu/UI/SmokeContainer.cs

@@ -1,13 +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.
 
-using System;
-using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
+using osu.Game.Rulesets.Osu.Skinning;
 using osu.Game.Rulesets.Osu.Skinning.Default;
 using osu.Game.Skinning;
 using osuTK;
@@ -17,15 +16,11 @@ namespace osu.Game.Rulesets.Osu.UI
     /// <summary>
     /// Manages smoke trails generated from user input.
     /// </summary>
-    [Cached]
     public class SmokeContainer : Container, IRequireHighFrequencyMousePosition, IKeyBindingHandler<OsuAction>
     {
-        public event Action<Vector2, double>? SmokeMoved;
-        public event Action<double>? SmokeEnded;
-
         public Vector2 LastMousePosition;
 
-        private bool isSmoking;
+        private SkinnableDrawable? currentSegment;
 
         public override bool ReceivePositionalInputAt(Vector2 _) => true;
 
@@ -33,21 +28,22 @@ public bool OnPressed(KeyBindingPressEvent<OsuAction> e)
         {
             if (e.Action == OsuAction.Smoke)
             {
-                isSmoking = true;
+                AddInternal(currentSegment = new SkinnableDrawable(new OsuSkinComponent(OsuSkinComponents.SmokeTrail), _ => new DefaultSmokeSegment()));
-                AddInternal(new SkinnableDrawable(new OsuSkinComponent(OsuSkinComponents.SmokeTrail), _ => new DefaultSmokeSegment()));
+                addPosition(LastMousePosition, Time.Current);
-
                 return true;
             }
 
             return false;
         }
 
+        private void addPosition(Vector2 position, double timeCurrent) => (currentSegment?.Drawable as SmokeSegment)?.AddPosition(position, timeCurrent);
+
         public void OnReleased(KeyBindingReleaseEvent<OsuAction> e)
         {
             if (e.Action == OsuAction.Smoke)
             {
-                isSmoking = false;
+                (currentSegment?.Drawable as SmokeSegment)?.FinishDrawing(Time.Current);
-                SmokeEnded?.Invoke(Time.Current);
+                currentSegment = null;
 
                 foreach (Drawable child in Children)
                 {
@@ -59,11 +55,10 @@ public void OnReleased(KeyBindingReleaseEvent<OsuAction> e)
 
         protected override bool OnMouseMove(MouseMoveEvent e)
         {
-            if (isSmoking)
+            if (currentSegment != null)
-                SmokeMoved?.Invoke(e.MousePosition, Time.Current);
+                addPosition(e.MousePosition, Time.Current);
 
             LastMousePosition = e.MousePosition;
-
             return base.OnMouseMove(e);
         }
     }