From 3db995c7782c0f643239c97798c9bbc90aafd843 Mon Sep 17 00:00:00 2001
From: smoogipoo <smoogipoo@smgi.me>
Date: Mon, 24 May 2021 17:15:57 +0900
Subject: [PATCH] Fix sliders jumping around the screen on movement

---
 .../Sliders/SliderSelectionBlueprint.cs         |  7 ++++++-
 .../Objects/Drawables/DrawableSlider.cs         | 17 +++++++++--------
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderSelectionBlueprint.cs b/osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderSelectionBlueprint.cs
index ec97f1fd78..e810d2fe0c 100644
--- a/osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderSelectionBlueprint.cs
+++ b/osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderSelectionBlueprint.cs
@@ -16,6 +16,7 @@ using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components;
 using osu.Game.Rulesets.Osu.Objects;
+using osu.Game.Rulesets.Osu.Objects.Drawables;
 using osu.Game.Screens.Edit;
 using osu.Game.Screens.Edit.Compose;
 using osuTK;
@@ -25,6 +26,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders
 {
     public class SliderSelectionBlueprint : OsuSelectionBlueprint<Slider>
     {
+        protected new DrawableSlider DrawableObject => (DrawableSlider)base.DrawableObject;
+
         protected SliderBodyPiece BodyPiece { get; private set; }
         protected SliderCircleOverlay HeadOverlay { get; private set; }
         protected SliderCircleOverlay TailOverlay { get; private set; }
@@ -236,7 +239,9 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders
             new OsuMenuItem("Add control point", MenuItemType.Standard, () => addControlPoint(rightClickPosition)),
         };
 
-        public override Vector2 ScreenSpaceSelectionPoint => BodyPiece.ToScreenSpace(BodyPiece.PathStartLocation);
+        // Always refer to the drawable object's slider body so subsequent movement deltas are calculated with updated positions.
+        public override Vector2 ScreenSpaceSelectionPoint => DrawableObject.SliderBody?.ToScreenSpace(DrawableObject.SliderBody.PathOffset)
+                                                             ?? BodyPiece.ToScreenSpace(BodyPiece.PathStartLocation);
 
         public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) =>
             BodyPiece.ReceivePositionalInputAt(screenSpacePos) || ControlPointVisualiser?.Pieces.Any(p => p.ReceivePositionalInputAt(screenSpacePos)) == true;
diff --git a/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs b/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs
index 82b5492de6..0bec33bf77 100644
--- a/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs
+++ b/osu.Game.Rulesets.Osu/Objects/Drawables/DrawableSlider.cs
@@ -34,7 +34,8 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
 
         public override bool DisplayResult => !HitObject.OnlyJudgeNestedObjects;
 
-        private PlaySliderBody sliderBody => Body.Drawable as PlaySliderBody;
+        [CanBeNull]
+        public PlaySliderBody SliderBody => Body.Drawable as PlaySliderBody;
 
         public IBindable<int> PathVersion => pathVersion;
         private readonly Bindable<int> pathVersion = new Bindable<int>();
@@ -215,16 +216,16 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             double completionProgress = Math.Clamp((Time.Current - HitObject.StartTime) / HitObject.Duration, 0, 1);
 
             Ball.UpdateProgress(completionProgress);
-            sliderBody?.UpdateProgress(completionProgress);
+            SliderBody?.UpdateProgress(completionProgress);
 
             foreach (DrawableHitObject hitObject in NestedHitObjects)
             {
-                if (hitObject is ITrackSnaking s) s.UpdateSnakingPosition(HitObject.Path.PositionAt(sliderBody?.SnakedStart ?? 0), HitObject.Path.PositionAt(sliderBody?.SnakedEnd ?? 0));
+                if (hitObject is ITrackSnaking s) s.UpdateSnakingPosition(HitObject.Path.PositionAt(SliderBody?.SnakedStart ?? 0), HitObject.Path.PositionAt(SliderBody?.SnakedEnd ?? 0));
                 if (hitObject is IRequireTracking t) t.Tracking = Ball.Tracking;
             }
 
-            Size = sliderBody?.Size ?? Vector2.Zero;
-            OriginPosition = sliderBody?.PathOffset ?? Vector2.Zero;
+            Size = SliderBody?.Size ?? Vector2.Zero;
+            OriginPosition = SliderBody?.PathOffset ?? Vector2.Zero;
 
             if (DrawSize != Vector2.Zero)
             {
@@ -238,7 +239,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         public override void OnKilled()
         {
             base.OnKilled();
-            sliderBody?.RecyclePath();
+            SliderBody?.RecyclePath();
         }
 
         protected override void ApplySkin(ISkinSource skin, bool allowFallback)
@@ -324,7 +325,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             {
                 case ArmedState.Hit:
                     Ball.ScaleTo(HitObject.Scale * 1.4f, fade_out_time, Easing.Out);
-                    if (sliderBody?.SnakingOut.Value == true)
+                    if (SliderBody?.SnakingOut.Value == true)
                         Body.FadeOut(40); // short fade to allow for any body colour to smoothly disappear.
                     break;
             }
@@ -332,7 +333,7 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
             this.FadeOut(fade_out_time, Easing.OutQuint).Expire();
         }
 
-        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => sliderBody?.ReceivePositionalInputAt(screenSpacePos) ?? base.ReceivePositionalInputAt(screenSpacePos);
+        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => SliderBody?.ReceivePositionalInputAt(screenSpacePos) ?? base.ReceivePositionalInputAt(screenSpacePos);
 
         private class DefaultSliderBody : PlaySliderBody
         {