Move circle visual implementation to new class

Allows for more precise skin control over state animations.

osu.Game.Rulesets.Osu/Objects/Drawables/Pieces/MainCirclePiece.cs

@@ -0,0 +1,94 @@
+// 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.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Objects.Drawables;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
+{
+    public class MainCirclePiece : CompositeDrawable
+    {
+        private readonly CirclePiece circle;
+        private readonly RingPiece ring;
+        private readonly FlashPiece flash;
+        private readonly ExplodePiece explode;
+        private readonly NumberPiece number;
+        private readonly GlowPiece glow;
+
+        public MainCirclePiece(int index)
+        {
+            Size = new Vector2(OsuHitObject.OBJECT_RADIUS * 2);
+
+            Anchor = Anchor.Centre;
+            Origin = Anchor.Centre;
+
+            InternalChildren = new Drawable[]
+            {
+                glow = new GlowPiece(),
+                circle = new CirclePiece(),
+                number = new NumberPiece
+                {
+                    Text = (index + 1).ToString(),
+                },
+                ring = new RingPiece(),
+                flash = new FlashPiece(),
+                explode = new ExplodePiece(),
+            };
+        }
+
+        private readonly IBindable<ArmedState> state = new Bindable<ArmedState>();
+
+        private readonly Bindable<Color4> accentColour = new Bindable<Color4>();
+
+        [BackgroundDependencyLoader]
+        private void load(DrawableHitObject drawableObject)
+        {
+            state.BindTo(drawableObject.State);
+            state.BindValueChanged(updateState, true);
+
+            accentColour.BindTo(drawableObject.AccentColour);
+            accentColour.BindValueChanged(colour =>
+            {
+                explode.Colour = colour.NewValue;
+                glow.Colour = colour.NewValue;
+                circle.Colour = colour.NewValue;
+            }, true);
+        }
+
+        private void updateState(ValueChangedEvent<ArmedState> state)
+        {
+            glow.FadeOut(400);
+
+            switch (state.NewValue)
+            {
+                case ArmedState.Hit:
+                    const double flash_in = 40;
+                    const double flash_out = 100;
+
+                    flash.FadeTo(0.8f, flash_in)
+                         .Then()
+                         .FadeOut(flash_out);
+
+                    explode.FadeIn(flash_in);
+                    this.ScaleTo(1.5f, 400, Easing.OutQuad);
+
+                    using (BeginDelayedSequence(flash_in, true))
+                    {
+                        //after the flash, we can hide some elements that were behind it
+                        ring.FadeOut();
+                        circle.FadeOut();
+                        number.FadeOut();
+
+                        this.FadeOut(800);
+                    }
+
+                    break;
+            }
+        }
+    }
+}