Add helper method and update some other similar preempt calculations

osu.Game.Rulesets.Catch/CatchRuleset.cs

@@ -300,7 +300,7 @@ namespace osu.Game.Rulesets.Catch
                 Description = "Affects how early fruits fade in on the screen.",
                 AdditionalMetrics =
                 [
-                    new RulesetBeatmapAttribute.AdditionalMetric("Fade-in time", LocalisableString.Interpolate($@"{IBeatmapDifficultyInfo.DifficultyRange(effectiveDifficulty.ApproachRate, CatchHitObject.PREEMPT_RANGE):#,0.##} ms"))
+                    new RulesetBeatmapAttribute.AdditionalMetric("Fade-in time", LocalisableString.Interpolate($@"{IBeatmapDifficultyInfo.DifficultyRangeInt(effectiveDifficulty.ApproachRate, CatchHitObject.PREEMPT_RANGE):#,0.##} ms"))
                 ]
             };
             yield return new RulesetBeatmapAttribute(SongSelectStrings.HPDrain, @"HP", originalDifficulty.DrainRate, effectiveDifficulty.DrainRate, 10)

osu.Game.Rulesets.Catch/Objects/CatchHitObject.cs

@@ -150,7 +150,7 @@ namespace osu.Game.Rulesets.Catch.Objects
         {
             base.ApplyDefaultsToSelf(controlPointInfo, difficulty);
 
-            TimePreempt = (float)IBeatmapDifficultyInfo.DifficultyRange(difficulty.ApproachRate, PREEMPT_RANGE);
+            TimePreempt = IBeatmapDifficultyInfo.DifficultyRangeInt(difficulty.ApproachRate, PREEMPT_RANGE);
 
             Scale = LegacyRulesetExtensions.CalculateScaleFromCircleSize(difficulty.CircleSize);
         }

osu.Game.Rulesets.Osu/Objects/OsuHitObject.cs

@@ -171,7 +171,7 @@ namespace osu.Game.Rulesets.Osu.Objects
         {
             base.ApplyDefaultsToSelf(controlPointInfo, difficulty);
 
-            TimePreempt = (int)IBeatmapDifficultyInfo.DifficultyRange(difficulty.ApproachRate, PREEMPT_RANGE);
+            TimePreempt = IBeatmapDifficultyInfo.DifficultyRangeInt(difficulty.ApproachRate, PREEMPT_RANGE);
 
             // Preempt time can go below 450ms. Normally, this is achieved via the DT mod which uniformly speeds up all animations game wide regardless of AR.
             // This uniform speedup is hard to match 1:1, however we can at least make AR>10 (via mods) feel good by extending the upper linear function above.

osu.Game.Rulesets.Osu/OsuRuleset.cs

@@ -412,7 +412,8 @@ namespace osu.Game.Rulesets.Osu
                 Description = "Affects how early objects appear on screen relative to their hit time.",
                 AdditionalMetrics =
                 [
-                    new RulesetBeatmapAttribute.AdditionalMetric("Approach time", LocalisableString.Interpolate($@"{IBeatmapDifficultyInfo.DifficultyRange(effectiveDifficulty.ApproachRate, OsuHitObject.PREEMPT_RANGE):#,0.##} ms"))
+                    new RulesetBeatmapAttribute.AdditionalMetric("Approach time",
+                        LocalisableString.Interpolate($@"{IBeatmapDifficultyInfo.DifficultyRangeInt(effectiveDifficulty.ApproachRate, OsuHitObject.PREEMPT_RANGE):#,0.##} ms"))
                 ]
             };
 

osu.Game/Beatmaps/IBeatmapDifficultyInfo.cs

@@ -95,6 +95,31 @@ namespace osu.Game.Beatmaps
         static double DifficultyRange(double difficulty, DifficultyRange range)
             => DifficultyRange(difficulty, range.Min, range.Mid, range.Max);
 
+        /// <summary>
+        /// Maps a difficulty value [0, 10] to a two-piece linear range of values.
+        /// Floors the value to `int`, usually to match osu!stable spec.
+        /// </summary>
+        /// <param name="difficulty">The difficulty value to be mapped.</param>
+        /// <param name="range">The values that define the two linear ranges.
+        /// <list type="table">
+        ///   <item>
+        ///     <term>od0</term>
+        ///     <description>Minimum of the resulting range which will be achieved by a difficulty value of 0.</description>
+        ///   </item>
+        ///   <item>
+        ///     <term>od5</term>
+        ///     <description>Midpoint of the resulting range which will be achieved by a difficulty value of 5.</description>
+        ///   </item>
+        ///   <item>
+        ///     <term>od10</term>
+        ///     <description>Maximum of the resulting range which will be achieved by a difficulty value of 10.</description>
+        ///   </item>
+        /// </list>
+        /// </param>
+        /// <returns>Value to which the difficulty value maps in the specified range.</returns>
+        static int DifficultyRangeInt(double difficulty, DifficultyRange range)
+            => (int)DifficultyRange(difficulty, range.Min, range.Mid, range.Max);
+
         /// <summary>
         /// Inverse function to <see cref="DifficultyRange(double,double,double,double)"/>.
         /// Maps a value returned by the function above back to the difficulty that produced it.