Fix AdjustedAttributesTooltip being broken by design

Fixes issue described in the following comment:
https://github.com/ppy/osu/pull/25759#issuecomment-1855954637

That is just not how the tooltip system is supposed to be used.

To name the individual sins:

- Caching and returning a tooltip instance like the classes that used
  tooltips is incorrect. The lifetime of tooltip instances is managed by
  the tooltip container. `GetCustomTooltip()` is called by it
  exclusively. It should return a fresh instance every time.

- Not putting actual data in `IHasCustomTooltip.TooltipContent` is
  wrong.

- Having `Tooltip.SetContent()` be a no-op is *grossly and flagrantly*
  wrong.

I'm not even sure which particular combination of the above
transgressions caused the issue as it presented itself, but at this time
I frankly do not care.

osu.Game/Overlays/Mods/AdjustedAttributesTooltip.cs

@@ -16,14 +16,13 @@ using osuTK;
 
 namespace osu.Game.Overlays.Mods
 {
-    public partial class AdjustedAttributesTooltip : VisibilityContainer, ITooltip
+    public partial class AdjustedAttributesTooltip : VisibilityContainer, ITooltip<AdjustedAttributesTooltip.Data?>
     {
         private FillFlowContainer attributesFillFlow = null!;
 
         private Container content = null!;
 
-        private BeatmapDifficulty? originalDifficulty;
-        private BeatmapDifficulty? adjustedDifficulty;
+        private Data? data;
 
         [Resolved]
         private OsuColour colours { get; set; } = null!;
@@ -73,26 +72,17 @@ namespace osu.Game.Overlays.Mods
             updateDisplay();
         }
 
-        public void UpdateAttributes(BeatmapDifficulty original, BeatmapDifficulty adjusted)
-        {
-            originalDifficulty = original;
-            adjustedDifficulty = adjusted;
-
-            if (IsLoaded)
-                updateDisplay();
-        }
-
         private void updateDisplay()
         {
             attributesFillFlow.Clear();
 
-            if (originalDifficulty == null || adjustedDifficulty == null)
-                return;
-
-            attemptAdd("CS", bd => bd.CircleSize);
-            attemptAdd("HP", bd => bd.DrainRate);
-            attemptAdd("OD", bd => bd.OverallDifficulty);
-            attemptAdd("AR", bd => bd.ApproachRate);
+            if (data != null)
+            {
+                attemptAdd("CS", bd => bd.CircleSize);
+                attemptAdd("HP", bd => bd.DrainRate);
+                attemptAdd("OD", bd => bd.OverallDifficulty);
+                attemptAdd("AR", bd => bd.ApproachRate);
+            }
 
             if (attributesFillFlow.Any())
                 content.Show();
@@ -101,16 +91,21 @@ namespace osu.Game.Overlays.Mods
 
             void attemptAdd(string name, Func<BeatmapDifficulty, double> lookup)
             {
-                double a = lookup(originalDifficulty);
-                double b = lookup(adjustedDifficulty);
+                double originalValue = lookup(data.OriginalDifficulty);
+                double adjustedValue = lookup(data.AdjustedDifficulty);
 
-                if (!Precision.AlmostEquals(a, b))
-                    attributesFillFlow.Add(new AttributeDisplay(name, a, b));
+                if (!Precision.AlmostEquals(originalValue, adjustedValue))
+                    attributesFillFlow.Add(new AttributeDisplay(name, originalValue, adjustedValue));
             }
         }
 
-        public void SetContent(object content)
+        public void SetContent(Data? data)
         {
+            if (this.data == data)
+                return;
+
+            this.data = data;
+            updateDisplay();
         }
 
         protected override void PopIn() => this.FadeIn(200, Easing.OutQuint);
@@ -118,6 +113,18 @@ namespace osu.Game.Overlays.Mods
 
         public void Move(Vector2 pos) => Position = pos;
 
+        public class Data
+        {
+            public BeatmapDifficulty OriginalDifficulty { get; }
+            public BeatmapDifficulty AdjustedDifficulty { get; }
+
+            public Data(BeatmapDifficulty originalDifficulty, BeatmapDifficulty adjustedDifficulty)
+            {
+                OriginalDifficulty = originalDifficulty;
+                AdjustedDifficulty = adjustedDifficulty;
+            }
+        }
+
         private partial class AttributeDisplay : CompositeDrawable
         {
             public AttributeDisplay(string name, double original, double adjusted)

osu.Game/Overlays/Mods/BeatmapAttributesDisplay.cs

@@ -27,7 +27,7 @@ namespace osu.Game.Overlays.Mods
     /// On the mod select overlay, this provides a local updating view of BPM, star rating and other
     /// difficulty attributes so the user can have a better insight into what mods are changing.
     /// </summary>
-    public partial class BeatmapAttributesDisplay : ModFooterInformationDisplay, IHasCustomTooltip
+    public partial class BeatmapAttributesDisplay : ModFooterInformationDisplay, IHasCustomTooltip<AdjustedAttributesTooltip.Data?>
     {
         private StarRatingDisplay starRatingDisplay = null!;
         private BPMDisplay bpmDisplay = null!;
@@ -57,11 +57,9 @@ namespace osu.Game.Overlays.Mods
         private CancellationTokenSource? cancellationSource;
         private IBindable<StarDifficulty?> starDifficulty = null!;
 
-        private AdjustedAttributesTooltip rateAdjustTooltip = null!;
+        public ITooltip<AdjustedAttributesTooltip.Data?> GetCustomTooltip() => new AdjustedAttributesTooltip();
 
-        public ITooltip GetCustomTooltip() => rateAdjustTooltip;
-
-        public object TooltipContent => this;
+        public AdjustedAttributesTooltip.Data? TooltipContent { get; private set; }
 
         private const float transition_duration = 250;
 
@@ -70,8 +68,6 @@ namespace osu.Game.Overlays.Mods
         {
             const float shear = ShearedOverlayContainer.SHEAR;
 
-            rateAdjustTooltip = new AdjustedAttributesTooltip();
-
             LeftContent.AddRange(new Drawable[]
             {
                 starRatingDisplay = new StarRatingDisplay(default, animated: true)
@@ -182,7 +178,7 @@ namespace osu.Game.Overlays.Mods
             Ruleset ruleset = gameRuleset.Value.CreateInstance();
             BeatmapDifficulty adjustedDifficulty = ruleset.GetRateAdjustedDisplayDifficulty(originalDifficulty, rate);
 
-            rateAdjustTooltip.UpdateAttributes(originalDifficulty, adjustedDifficulty);
+            TooltipContent = new AdjustedAttributesTooltip.Data(originalDifficulty, adjustedDifficulty);
 
             approachRateDisplay.AdjustType.Value = VerticalAttributeDisplay.CalculateEffect(originalDifficulty.ApproachRate, adjustedDifficulty.ApproachRate);
             overallDifficultyDisplay.AdjustType.Value = VerticalAttributeDisplay.CalculateEffect(originalDifficulty.OverallDifficulty, adjustedDifficulty.OverallDifficulty);

osu.Game/Screens/Select/Details/AdvancedStats.cs

@@ -30,7 +30,7 @@ using osu.Game.Overlays.Mods;
 
 namespace osu.Game.Screens.Select.Details
 {
-    public partial class AdvancedStats : Container, IHasCustomTooltip
+    public partial class AdvancedStats : Container, IHasCustomTooltip<AdjustedAttributesTooltip.Data>
     {
         [Resolved]
         private BeatmapDifficultyCache difficultyCache { get; set; }
@@ -46,9 +46,8 @@ namespace osu.Game.Screens.Select.Details
         protected readonly StatisticRow FirstValue, HpDrain, Accuracy, ApproachRate;
         private readonly StatisticRow starDifficulty;
 
-        private AdjustedAttributesTooltip rateAdjustTooltip;
-        public ITooltip GetCustomTooltip() => rateAdjustTooltip;
-        public object TooltipContent => this;
+        public ITooltip<AdjustedAttributesTooltip.Data> GetCustomTooltip() => new AdjustedAttributesTooltip();
+        public AdjustedAttributesTooltip.Data TooltipContent { get; private set; }
 
         private IBeatmapInfo beatmapInfo;
 
@@ -86,7 +85,6 @@ namespace osu.Game.Screens.Select.Details
         private void load(OsuColour colours)
         {
             starDifficulty.AccentColour = colours.Yellow;
-            rateAdjustTooltip = new AdjustedAttributesTooltip();
         }
 
         protected override void LoadComplete()
@@ -144,7 +142,7 @@ namespace osu.Game.Screens.Select.Details
 
                     adjustedDifficulty = ruleset.CreateInstance().GetRateAdjustedDisplayDifficulty(originalDifficulty, rate);
 
-                    rateAdjustTooltip.UpdateAttributes(originalDifficulty, adjustedDifficulty);
+                    TooltipContent = new AdjustedAttributesTooltip.Data(originalDifficulty, adjustedDifficulty);
                 }
             }