Enforce `IBeatmap.Breaks` to be sorted chronologically

osu.Game/Beatmaps/Beatmap.cs

@@ -8,6 +8,7 @@
 using System.Linq;
 using osu.Game.Beatmaps.ControlPoints;
 using Newtonsoft.Json;
+using osu.Framework.Lists;
 using osu.Game.IO.Serialization.Converters;
 
 namespace osu.Game.Beatmaps
@@ -61,7 +62,7 @@ public Beatmap()
 
         public ControlPointInfo ControlPointInfo { get; set; } = new ControlPointInfo();
 
-        public List<BreakPeriod> Breaks { get; set; } = new List<BreakPeriod>();
+        public SortedList<BreakPeriod> Breaks { get; set; } = new SortedList<BreakPeriod>();
 
         public List<string> UnhandledEventLines { get; set; } = new List<string>();
 

osu.Game/Beatmaps/BeatmapConverter.cs

@@ -7,6 +7,8 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
+using osu.Framework.Lists;
+using osu.Game.Beatmaps.Timing;
 using osu.Game.Rulesets;
 using osu.Game.Rulesets.Objects;
 
@@ -50,7 +52,8 @@ public IBeatmap Convert(CancellationToken cancellationToken = default)
             original.ControlPointInfo = original.ControlPointInfo.DeepClone();
 
             // Used in osu!mania conversion.
-            original.Breaks = original.Breaks.ToList();
+            original.Breaks = new SortedList<BreakPeriod>(Comparer<BreakPeriod>.Default);
+            original.Breaks.AddRange(Beatmap.Breaks);
 
             return ConvertBeatmap(original, cancellationToken);
         }

osu.Game/Beatmaps/IBeatmap.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using osu.Framework.Lists;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Beatmaps.Timing;
 using osu.Game.Rulesets.Objects;
@@ -40,7 +41,7 @@ public interface IBeatmap
         /// <summary>
         /// The breaks in this beatmap.
         /// </summary>
-        List<BreakPeriod> Breaks { get; set; }
+        SortedList<BreakPeriod> Breaks { get; set; }
 
         /// <summary>
         /// All lines from the [Events] section which aren't handled in the encoding process yet.

osu.Game/Beatmaps/Timing/BreakPeriod.cs

@@ -6,7 +6,7 @@
 
 namespace osu.Game.Beatmaps.Timing
 {
-    public class BreakPeriod : IEquatable<BreakPeriod>
+    public class BreakPeriod : IEquatable<BreakPeriod>, IComparable<BreakPeriod>
     {
         /// <summary>
         /// The minimum gap between the start of the break and the previous object.
@@ -76,5 +76,17 @@ public virtual bool Equals(BreakPeriod? other) =>
             && EndTime == other.EndTime;
 
         public override int GetHashCode() => HashCode.Combine(StartTime, EndTime);
+
+        public int CompareTo(BreakPeriod? other)
+        {
+            if (ReferenceEquals(this, other)) return 0;
+            if (ReferenceEquals(null, other)) return 1;
+
+            int result = StartTime.CompareTo(other.StartTime);
+            if (result != 0)
+                return result;
+
+            return EndTime.CompareTo(other.EndTime);
+        }
     }
 }

osu.Game/Rulesets/Difficulty/DifficultyCalculator.cs

@@ -10,6 +10,7 @@
 using JetBrains.Annotations;
 using osu.Framework.Audio.Track;
 using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Framework.Lists;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Beatmaps.Timing;
@@ -327,7 +328,7 @@ public BeatmapDifficulty Difficulty
                 set => baseBeatmap.Difficulty = value;
             }
 
-            public List<BreakPeriod> Breaks
+            public SortedList<BreakPeriod> Breaks
             {
                 get => baseBeatmap.Breaks;
                 set => baseBeatmap.Breaks = value;

osu.Game/Screens/Edit/EditorBeatmap.cs

@@ -10,6 +10,7 @@
 using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
+using osu.Framework.Lists;
 using osu.Game.Beatmaps;
 using osu.Game.Beatmaps.ControlPoints;
 using osu.Game.Beatmaps.Legacy;
@@ -111,7 +112,11 @@ public EditorBeatmap(IBeatmap playableBeatmap, ISkin beatmapSkin = null, Beatmap
                 trackStartTime(obj);
 
             Breaks = new BindableList<BreakPeriod>(playableBeatmap.Breaks);
-            Breaks.BindCollectionChanged((_, _) => playableBeatmap.Breaks = Breaks.ToList());
+            Breaks.BindCollectionChanged((_, _) =>
+            {
+                playableBeatmap.Breaks.Clear();
+                playableBeatmap.Breaks.AddRange(Breaks);
+            });
 
             PreviewTime = new BindableInt(BeatmapInfo.Metadata.PreviewTime);
             PreviewTime.BindValueChanged(s =>
@@ -177,7 +182,7 @@ public ControlPointInfo ControlPointInfo
 
         public readonly BindableList<BreakPeriod> Breaks;
 
-        List<BreakPeriod> IBeatmap.Breaks
+        SortedList<BreakPeriod> IBeatmap.Breaks
         {
             get => PlayableBeatmap.Breaks;
             set => PlayableBeatmap.Breaks = value;