Implement singular change events for ControlPoint

osu.Game/Beatmaps/ControlPoints/ControlPoint.cs

@@ -11,8 +11,28 @@ namespace osu.Game.Beatmaps.ControlPoints
 {
     public abstract class ControlPoint : IComparable<ControlPoint>, IDeepCloneable<ControlPoint>, IEquatable<ControlPoint>, IControlPoint
     {
+        /// <summary>
+        /// Invoked when any of this <see cref="ControlPoint"/>'s properties have changed.
+        /// </summary>
+        public event Action<ControlPoint>? Changed;
+
+        protected void RaiseChanged() => Changed?.Invoke(this);
+
+        private double time;
+
         [JsonIgnore]
-        public double Time { get; set; }
+        public double Time
+        {
+            get => time;
+            set
+            {
+                if (time == value)
+                    return;
+
+                time = value;
+                RaiseChanged();
+            }
+        }
 
         public void AttachGroup(ControlPointGroup pointGroup) => Time = pointGroup.Time;
 

osu.Game/Beatmaps/ControlPoints/DifficultyControlPoint.cs

@@ -44,6 +44,11 @@ namespace osu.Game.Beatmaps.ControlPoints
             set => SliderVelocityBindable.Value = value;
         }
 
+        public DifficultyControlPoint()
+        {
+            SliderVelocityBindable.BindValueChanged(_ => RaiseChanged());
+        }
+
         public override bool IsRedundant(ControlPoint? existing)
             => existing is DifficultyControlPoint existingDifficulty
                && GenerateTicks == existingDifficulty.GenerateTicks

osu.Game/Beatmaps/ControlPoints/EffectControlPoint.cs

@@ -50,6 +50,12 @@ namespace osu.Game.Beatmaps.ControlPoints
             set => KiaiModeBindable.Value = value;
         }
 
+        public EffectControlPoint()
+        {
+            KiaiModeBindable.BindValueChanged(_ => RaiseChanged());
+            ScrollSpeedBindable.BindValueChanged(_ => RaiseChanged());
+        }
+
         public override bool IsRedundant(ControlPoint? existing)
             => existing is EffectControlPoint existingEffect
                && KiaiMode == existingEffect.KiaiMode

osu.Game/Beatmaps/ControlPoints/SampleControlPoint.cs

@@ -56,6 +56,12 @@ namespace osu.Game.Beatmaps.ControlPoints
             set => SampleVolumeBindable.Value = value;
         }
 
+        public SampleControlPoint()
+        {
+            SampleBankBindable.BindValueChanged(_ => RaiseChanged());
+            SampleVolumeBindable.BindValueChanged(_ => RaiseChanged());
+        }
+
         /// <summary>
         /// Create a SampleInfo based on the sample settings in this control point.
         /// </summary>

osu.Game/Beatmaps/ControlPoints/TimingControlPoint.cs

@@ -82,6 +82,13 @@ namespace osu.Game.Beatmaps.ControlPoints
         /// </summary>
         public double BPM => 60000 / BeatLength;
 
+        public TimingControlPoint()
+        {
+            TimeSignatureBindable.BindValueChanged(_ => RaiseChanged());
+            OmitFirstBarLineBindable.BindValueChanged(_ => RaiseChanged());
+            BeatLengthBindable.BindValueChanged(_ => RaiseChanged());
+        }
+
         // Timing points are never redundant as they can change the time signature.
         public override bool IsRedundant(ControlPoint? existing) => false;