Move aspect adjustments out of CatchPlayfield

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

@@ -33,14 +33,7 @@ public CatchPlayfield(BeatmapDifficulty difficulty, Func<CatchHitObject, Drawabl
 
             Size = new Vector2(0.86f); // matches stable's vertical offset for catcher plate
 
-            InternalChild = new Container
+            InternalChild = new PlayfieldLayer
-            {
-                Anchor = Anchor.Centre,
-                Origin = Anchor.Centre,
-                RelativeSizeAxes = Axes.Both,
-                FillMode = FillMode.Fit,
-                FillAspectRatio = 4f / 3,
-                Child = new PlayfieldLayer
             {
                 RelativeSizeAxes = Axes.Both,
                 Children = new Drawable[]
@@ -58,7 +51,6 @@ public CatchPlayfield(BeatmapDifficulty difficulty, Func<CatchHitObject, Drawabl
                     },
                     HitObjectContainer
                 }
-                }
             };
         }
 

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

@@ -1,12 +1,34 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using OpenTK;
 
 namespace osu.Game.Rulesets.Catch.UI
 {
     public class PlayfieldLayer : Container
+    {
+        protected override Container<Drawable> Content => content;
+        private readonly Container content;
+
+        public PlayfieldLayer()
+        {
+            InternalChild = new Container
+            {
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                RelativeSizeAxes = Axes.Both,
+                FillMode = FillMode.Fit,
+                FillAspectRatio = 4f / 3,
+                Child = content = new ScalingContainer { RelativeSizeAxes = Axes.Both }
+            };
+        }
+
+        /// <summary>
+        /// A <see cref="Container"/> which scales its content relative to a target width.
+        /// </summary>
+        private class ScalingContainer : Container
         {
             protected override void Update()
             {
@@ -17,3 +39,4 @@ protected override void Update()
             }
         }
     }
+}