Make sliders respond to control point changes

osu.Game.Rulesets.Osu.Tests/TestCaseSliderSelectionMask.cs

@@ -18,7 +18,7 @@ namespace osu.Game.Rulesets.Osu.Tests
 {
     public class TestCaseSliderSelectionMask : HitObjectSelectionMaskTestCase
     {
-        public override IReadOnlyList<Type> RequiredTypes => new Type[]
+        public override IReadOnlyList<Type> RequiredTypes => new[]
         {
             typeof(SliderSelectionMask),
             typeof(SliderCircleSelectionMask),

osu.Game.Rulesets.Osu/Edit/Masks/SliderMasks/Components/ControlPointPiece.cs

@@ -72,11 +72,28 @@ namespace osu.Game.Rulesets.Osu.Edit.Masks.SliderMasks.Components
         protected override bool OnDragStart(DragStartEvent e) => true;
 
         protected override bool OnDrag(DragEvent e)
+        {
+            if (index == 0)
+            {
+                // Special handling for the head - only the position of the slider changes
+                slider.Position += e.Delta;
+
+                // Since control points are relative to the position of the slider, they all need to be offset backwards by the delta
+                var newControlPoints = slider.ControlPoints.ToArray();
+                for (int i = 1; i < newControlPoints.Length; i++)
+                    newControlPoints[i] -= e.Delta;
+
+                slider.ControlPoints = newControlPoints;
+                slider.Curve.Calculate(true);
+            }
+            else
             {
                 var newControlPoints = slider.ControlPoints.ToArray();
                 newControlPoints[index] += e.Delta;
 
                 slider.ControlPoints = newControlPoints;
+                slider.Curve.Calculate(true);
+            }
 
             return true;
         }

osu.Game.Rulesets.Osu/Edit/Masks/SliderMasks/Components/SliderBodyPiece.cs

@@ -46,6 +46,7 @@ namespace osu.Game.Rulesets.Osu.Edit.Masks.SliderMasks.Components
 
             // Need to cause one update
             body.UpdateProgress(0);
+            body.Refresh();
         }
     }
 }

osu.Game.Rulesets.Osu/Edit/Masks/SliderMasks/Components/SliderCirclePiece.cs

@@ -16,6 +16,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Masks.SliderMasks.Components
         {
             this.slider = slider;
             this.position = position;
+
+            slider.ControlPointsChanged += _ => UpdatePosition();
         }
 
         protected override void UpdatePosition()

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs

@@ -85,6 +85,8 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             }
 
             HitObject.PositionChanged += _ => Position = HitObject.StackedPosition;
+
+            slider.ControlPointsChanged += _ => Body.Refresh();
         }
 
         public override Color4 AccentColour

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderHead.cs

@@ -16,7 +16,10 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         {
             this.slider = slider;
 
-            Position = HitObject.Position - slider.Position;
+            h.PositionChanged += _ => updatePosition();
+            slider.ControlPointsChanged += _ => updatePosition();
+
+            updatePosition();
         }
 
         protected override void Update()
@@ -33,5 +36,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         public Action<double> OnShake;
 
         protected override void Shake(double maximumLength) => OnShake?.Invoke(maximumLength);
+
+        private void updatePosition() => Position = HitObject.Position - slider.Position;
     }
 }

osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSliderTail.cs

@@ -8,6 +8,8 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 {
     public class DrawableSliderTail : DrawableOsuHitObject, IRequireTracking
     {
+        private readonly Slider slider;
+
         /// <summary>
         /// The judgement text is provided by the <see cref="DrawableSlider"/>.
         /// </summary>
@@ -18,6 +20,8 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         public DrawableSliderTail(Slider slider, SliderTailCircle hitCircle)
             : base(hitCircle)
         {
+            this.slider = slider;
+
             Origin = Anchor.Centre;
 
             RelativeSizeAxes = Axes.Both;
@@ -25,7 +29,10 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
             AlwaysPresent = true;
 
-            Position = HitObject.Position - slider.Position;
+            hitCircle.PositionChanged += _ => updatePosition();
+            slider.ControlPointsChanged += _ => updatePosition();
+
+            updatePosition();
         }
 
         protected override void CheckForResult(bool userTriggered, double timeOffset)
@@ -33,5 +40,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             if (!userTriggered && timeOffset >= 0)
                 ApplyResult(r => r.Type = Tracking ? HitResult.Great : HitResult.Miss);
         }
+
+        private void updatePosition() => Position = HitObject.Position - slider.Position;
     }
 }

osu.Game.Rulesets.Osu/Objects/Drawables/Pieces/SnakingSliderBody.cs

@@ -45,15 +45,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
         [BackgroundDependencyLoader]
         private void load()
         {
-            // Generate the entire curve
+            Refresh();
-            slider.Curve.GetPathToProgress(CurrentCurve, 0, 1);
-            SetVertices(CurrentCurve);
-
-            // The body is sized to the full path size to avoid excessive autosize computations
-            Size = Path.Size;
-
-            snakedPosition = Path.PositionInBoundingBox(Vector2.Zero);
-            snakedPathOffset = Path.PositionInBoundingBox(Path.Vertices[0]);
         }
 
         public void UpdateProgress(double completionProgress)
@@ -80,6 +72,27 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables.Pieces
             setRange(start, end);
         }
 
+        public void Refresh()
+        {
+            // Generate the entire curve
+            slider.Curve.GetPathToProgress(CurrentCurve, 0, 1);
+            SetVertices(CurrentCurve);
+
+            // The body is sized to the full path size to avoid excessive autosize computations
+            Size = Path.Size;
+
+            snakedPosition = Path.PositionInBoundingBox(Vector2.Zero);
+            snakedPathOffset = Path.PositionInBoundingBox(Path.Vertices[0]);
+
+            var lastSnakedStart = SnakedStart ?? 0;
+            var lastSnakedEnd = SnakedEnd ?? 0;
+
+            SnakedStart = null;
+            SnakedEnd = null;
+
+            setRange(lastSnakedStart, lastSnakedEnd);
+        }
+
         private void setRange(double p0, double p1)
         {
             if (p0 > p1)

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

@@ -64,6 +64,9 @@ namespace osu.Game.Rulesets.Osu.Objects
                 Curve.ControlPoints = value;
 
                 ControlPointsChanged?.Invoke(value);
+
+                if (TailCircle != null)
+                    TailCircle.Position = EndPosition;
             }
         }
 

osu.Game/Rulesets/Objects/SliderCurve.cs

@@ -124,10 +124,33 @@ namespace osu.Game.Rulesets.Objects
             }
         }
 
-        public void Calculate()
+        private void calculateCumulativeLength()
+        {
+            double l = 0;
+
+            cumulativeLength.Clear();
+            cumulativeLength.Add(l);
+
+            for (int i = 0; i < calculatedPath.Count - 1; ++i)
+            {
+                Vector2 diff = calculatedPath[i + 1] - calculatedPath[i];
+                double d = diff.Length;
+
+                l += d;
+                cumulativeLength.Add(l);
+            }
+
+            Distance = l;
+        }
+
+        public void Calculate(bool updateDistance = false)
         {
             calculatePath();
+
+            if (!updateDistance)
                 calculateCumulativeLengthAndTrimPath();
+            else
+                calculateCumulativeLength();
         }
 
         private int indexOfDistance(double d)