From 8f995a30af27f3cd90df67d1c45e434e028daf5d Mon Sep 17 00:00:00 2001
From: Dan Balasescu <smoogipoo@smgi.me>
Date: Thu, 8 Feb 2024 00:20:32 +0900
Subject: [PATCH] Fix legacy coverage metrics

---
 .../Mods/ManiaModHidden.cs                    | 29 +++++++++++++++----
 .../Mods/ManiaModWithPlayfieldCover.cs        |  4 ++-
 .../UI/PlayfieldCoveringWrapper.cs            | 14 ++++++---
 3 files changed, 37 insertions(+), 10 deletions(-)

diff --git a/osu.Game.Rulesets.Mania/Mods/ManiaModHidden.cs b/osu.Game.Rulesets.Mania/Mods/ManiaModHidden.cs
index 9def29f82b..211f21513d 100644
--- a/osu.Game.Rulesets.Mania/Mods/ManiaModHidden.cs
+++ b/osu.Game.Rulesets.Mania/Mods/ManiaModHidden.cs
@@ -6,20 +6,21 @@ using System.Linq;
 using osu.Framework.Localisation;
 using osu.Game.Rulesets.Mania.UI;
 using osu.Framework.Bindables;
+using osu.Framework.Graphics;
 using osu.Game.Rulesets.Scoring;
 
 namespace osu.Game.Rulesets.Mania.Mods
 {
-    public class ManiaModHidden : ManiaModWithPlayfieldCover
+    public partial class ManiaModHidden : ManiaModWithPlayfieldCover
     {
         /// <summary>
         /// osu!stable is referenced to 768px.
         /// </summary>
-        private const float playfield_height = 768;
+        private const float reference_playfield_height = 768;
 
-        private const float min_coverage = 160f / playfield_height;
-        private const float max_coverage = 400f / playfield_height;
-        private const float coverage_increase_per_combo = 0.5f / playfield_height;
+        private const float min_coverage = 160 / reference_playfield_height;
+        private const float max_coverage = 400f / reference_playfield_height;
+        private const float coverage_increase_per_combo = 0.5f / reference_playfield_height;
 
         public override LocalisableString Description => @"Keys fade out before you hit them!";
         public override double ScoreMultiplier => 1;
@@ -43,5 +44,23 @@ namespace osu.Game.Rulesets.Mania.Mods
             combo.BindTo(scoreProcessor.Combo);
             combo.BindValueChanged(c => Coverage.Value = Math.Min(max_coverage, min_coverage + c.NewValue * coverage_increase_per_combo), true);
         }
+
+        protected override PlayfieldCoveringWrapper CreateCover(Drawable content) => new LegacyPlayfieldCover(content);
+
+        private partial class LegacyPlayfieldCover : PlayfieldCoveringWrapper
+        {
+            public LegacyPlayfieldCover(Drawable content)
+                : base(content)
+            {
+            }
+
+            protected override float GetHeight(float coverage)
+            {
+                if (DrawHeight == 0)
+                    return base.GetHeight(coverage);
+
+                return base.GetHeight(coverage) * reference_playfield_height / DrawHeight;
+            }
+        }
     }
 }
diff --git a/osu.Game.Rulesets.Mania/Mods/ManiaModWithPlayfieldCover.cs b/osu.Game.Rulesets.Mania/Mods/ManiaModWithPlayfieldCover.cs
index bb5807269a..864ef6c3d6 100644
--- a/osu.Game.Rulesets.Mania/Mods/ManiaModWithPlayfieldCover.cs
+++ b/osu.Game.Rulesets.Mania/Mods/ManiaModWithPlayfieldCover.cs
@@ -38,7 +38,7 @@ namespace osu.Game.Rulesets.Mania.Mods
                 Container hocParent = (Container)hoc.Parent!;
 
                 hocParent.Remove(hoc, false);
-                hocParent.Add(new PlayfieldCoveringWrapper(hoc).With(c =>
+                hocParent.Add(CreateCover(hoc).With(c =>
                 {
                     c.RelativeSizeAxes = Axes.Both;
                     c.Direction = ExpandDirection;
@@ -47,6 +47,8 @@ namespace osu.Game.Rulesets.Mania.Mods
             }
         }
 
+        protected virtual PlayfieldCoveringWrapper CreateCover(Drawable content) => new PlayfieldCoveringWrapper(content);
+
         protected override void ApplyIncreasedVisibilityState(DrawableHitObject hitObject, ArmedState state)
         {
         }
diff --git a/osu.Game.Rulesets.Mania/UI/PlayfieldCoveringWrapper.cs b/osu.Game.Rulesets.Mania/UI/PlayfieldCoveringWrapper.cs
index f0ac18d7ca..2b70c527ae 100644
--- a/osu.Game.Rulesets.Mania/UI/PlayfieldCoveringWrapper.cs
+++ b/osu.Game.Rulesets.Mania/UI/PlayfieldCoveringWrapper.cs
@@ -43,6 +43,8 @@ namespace osu.Game.Rulesets.Mania.UI
 
         private readonly IBindable<ScrollingDirection> scrollDirection = new Bindable<ScrollingDirection>();
 
+        private float currentCoverage;
+
         public PlayfieldCoveringWrapper(Drawable content)
         {
             InternalChild = new BufferedContainer
@@ -112,15 +114,19 @@ namespace osu.Game.Rulesets.Mania.UI
         {
             base.Update();
 
-            updateHeight((float)Interpolation.DampContinuously(filled.Height, Coverage.Value, 25, Math.Abs(Time.Elapsed)));
+            updateHeight((float)Interpolation.DampContinuously(currentCoverage, Coverage.Value, 25, Math.Abs(Time.Elapsed)));
         }
 
-        private void updateHeight(float height)
+        private void updateHeight(float coverage)
         {
-            filled.Height = height;
-            gradient.Y = -height;
+            filled.Height = GetHeight(coverage);
+            gradient.Y = -GetHeight(coverage);
+
+            currentCoverage = coverage;
         }
 
+        protected virtual float GetHeight(float coverage) => coverage;
+
         private void onScrollDirectionChanged(ValueChangedEvent<ScrollingDirection> direction)
             => cover.Rotation = direction.NewValue == ScrollingDirection.Up ? 0 : 180f;