Attempt to fix multiple selection movements

osu.Game.Rulesets.Mania/Edit/ManiaHitObjectComposer.cs

@@ -10,6 +10,7 @@ using osu.Framework.Allocation;
 using osu.Game.Rulesets.Mania.UI;
 using osu.Game.Rulesets.Mods;
 using osu.Game.Rulesets.UI;
+using osu.Game.Rulesets.UI.Scrolling;
 using osu.Game.Screens.Edit.Compose.Components;
 using osuTK;
 
@@ -37,7 +38,32 @@ namespace osu.Game.Rulesets.Mania.Edit
         protected override IReadOnlyDependencyContainer CreateChildDependencies(IReadOnlyDependencyContainer parent)
             => dependencies = new DependencyContainer(base.CreateChildDependencies(parent));
 
-        public int TotalColumns => ((ManiaPlayfield)drawableRuleset.Playfield).TotalColumns;
+        public ManiaPlayfield Playfield => ((ManiaPlayfield)drawableRuleset.Playfield);
+
+        public int TotalColumns => Playfield.TotalColumns;
+
+        public override (Vector2 position, double time) GetSnappedPosition(Vector2 position, double time)
+        {
+            var hoc = Playfield.GetColumn(0).HitObjectContainer;
+
+            position.Y -= ToLocalSpace(hoc.ScreenSpaceDrawQuad.TopLeft).Y;
+
+            float targetPosition = position.Y;
+
+            if (drawableRuleset.ScrollingInfo.Direction.Value == ScrollingDirection.Down)
+            {
+                // When scrolling downwards, the position is _negative_ when the object's start time is after the current time (e.g. in the middle of the stage).
+                // However all scrolling algorithms upwards scrolling, meaning that a positive (inverse) position is expected in the same scenario.
+                targetPosition = -targetPosition;
+            }
+
+            double targetTime = drawableRuleset.ScrollingInfo.Algorithm.TimeAt(targetPosition,
+                EditorClock.CurrentTime,
+                drawableRuleset.ScrollingInfo.TimeRange.Value,
+                hoc.DrawHeight);
+
+            return base.GetSnappedPosition(position, targetTime);
+        }
 
         protected override DrawableRuleset<ManiaHitObject> CreateDrawableRuleset(Ruleset ruleset, IBeatmap beatmap, IReadOnlyList<Mod> mods = null)
         {

osu.Game.Rulesets.Mania/Edit/ManiaSelectionHandler.cs

@@ -56,20 +56,6 @@ namespace osu.Game.Rulesets.Mania.Edit
                 // since the scrolling hitobject container requires at least one update frame to update the position.
                 // However the position needs to be valid for future movement events to calculate the correct deltas.
                 hitObject.Y += delta;
-
-                float targetPosition = hitObject.Position.Y;
-
-                if (scrollingInfo.Direction.Value == ScrollingDirection.Down)
-                {
-                    // When scrolling downwards, the position is _negative_ when the object's start time is after the current time (e.g. in the middle of the stage).
-                    // However all scrolling algorithms upwards scrolling, meaning that a positive (inverse) position is expected in the same scenario.
-                    targetPosition = -targetPosition;
-                }
-
-                hitObject.HitObject.StartTime = scrollingInfo.Algorithm.TimeAt(targetPosition,
-                    editorClock.CurrentTime,
-                    scrollingInfo.TimeRange.Value,
-                    objectParent.DrawHeight);
             }
         }
 

osu.Game.Rulesets.Mania/UI/ManiaPlayfield.cs

@@ -87,6 +87,22 @@ namespace osu.Game.Rulesets.Mania.UI
             return found;
         }
 
+        public Column GetColumn(int index)
+        {
+            foreach (var stage in stages)
+            {
+                if (index >= stage.Columns.Count)
+                {
+                    index -= stage.Columns.Count;
+                    continue;
+                }
+
+                return stage.Columns[index];
+            }
+
+            throw new ArgumentOutOfRangeException(nameof(index));
+        }
+
         /// <summary>
         /// Retrieves the total amount of columns across all stages in this playfield.
         /// </summary>

osu.Game/Screens/Edit/Compose/Components/BlueprintContainer.cs

@@ -401,18 +401,16 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
             HitObject draggedObject = movementBlueprint.HitObject;
 
-            // The final movement position, relative to movementBlueprintOriginalPosition
+            // The final movement position, relative to movementBlueprintOriginalPosition.
             Vector2 movePosition = movementBlueprintOriginalPosition.Value + e.ScreenSpaceMousePosition - e.ScreenSpaceMouseDownPosition;
 
-            (Vector2 snappedPosition, _) = snapProvider.GetSnappedPosition(ToLocalSpace(movePosition), draggedObject.StartTime);
+            // Retrieve a snapped position.
+            (Vector2 snappedPosition, double snappedTime) = snapProvider.GetSnappedPosition(ToLocalSpace(movePosition), draggedObject.StartTime);
 
-            // Move the hitobjects
+            // Move the hitobjects.
             if (!selectionHandler.HandleMovement(new MoveSelectionEvent(movementBlueprint, ToScreenSpace(snappedPosition))))
                 return true;
 
-            // Todo: Temp
-            (_, double snappedTime) = snapProvider.GetSnappedPosition(ToLocalSpace(snappedPosition), draggedObject.StartTime);
-
             // Apply the start time at the newly snapped-to position
             double offset = snappedTime - draggedObject.StartTime;
             foreach (HitObject obj in selectionHandler.SelectedHitObjects)