Add the ability to delete slider control points using shift+right click

Closes https://github.com/ppy/osu/issues/10672.

In two minds about how this should be implemented but went in this
direction initially. The other way would be to add local handling of
Shift-Right Click inside PathControlPointPiece (which is already doing
mouse handling itself).

osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/Components/PathControlPointVisualiser.cs

@@ -18,6 +18,7 @@ using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Osu.Objects;
+using osuTK;
 using osuTK.Input;
 
 namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
@@ -105,7 +106,7 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
             switch (action.ActionMethod)
             {
                 case PlatformActionMethod.Delete:
-                    return deleteSelected();
+                    return DeleteSelected();
             }
 
             return false;
@@ -115,6 +116,9 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
         {
         }
 
+        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) =>
+            Pieces.Any(p => p.ReceivePositionalInputAt(screenSpacePos));
+
         private void selectPiece(PathControlPointPiece piece, MouseButtonEvent e)
         {
             if (e.Button == MouseButton.Left && inputManager.CurrentState.Keyboard.ControlPressed)
@@ -126,7 +130,7 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
             }
         }
 
-        private bool deleteSelected()
+        public bool DeleteSelected()
         {
             List<PathControlPoint> toRemove = Pieces.Where(p => p.IsSelected.Value).Select(p => p.ControlPoint).ToList();
 
@@ -169,7 +173,7 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders.Components
 
                 return new MenuItem[]
                 {
-                    new OsuMenuItem($"Delete {"control point".ToQuantity(count, count > 1 ? ShowQuantityAs.Numeric : ShowQuantityAs.None)}", MenuItemType.Destructive, () => deleteSelected()),
+                    new OsuMenuItem($"Delete {"control point".ToQuantity(count, count > 1 ? ShowQuantityAs.Numeric : ShowQuantityAs.None)}", MenuItemType.Destructive, () => DeleteSelected()),
                     new OsuMenuItem("Curve type")
                     {
                         Items = items

osu.Game.Rulesets.Osu/Edit/Blueprints/Sliders/SliderSelectionBlueprint.cs

@@ -3,6 +3,7 @@
 
 using System.Collections.Generic;
 using System.Diagnostics;
+using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -72,6 +73,18 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders
             BodyPiece.UpdateFrom(HitObject);
         }
 
+        public override bool HandleQuickDeletion()
+        {
+            var hoveredControlPoint = ControlPointVisualiser.Pieces.FirstOrDefault(p => p.IsHovered);
+
+            if (hoveredControlPoint == null)
+                return false;
+
+            hoveredControlPoint.IsSelected.Value = true;
+            ControlPointVisualiser.DeleteSelected();
+            return true;
+        }
+
         protected override void Update()
         {
             base.Update();
@@ -216,7 +229,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Blueprints.Sliders
 
         public override Vector2 ScreenSpaceSelectionPoint => BodyPiece.ToScreenSpace(BodyPiece.PathStartLocation);
 
-        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => BodyPiece.ReceivePositionalInputAt(screenSpacePos);
+        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) =>
+            BodyPiece.ReceivePositionalInputAt(screenSpacePos) || ControlPointVisualiser?.ReceivePositionalInputAt(screenSpacePos) == true;
 
         protected virtual SliderCircleSelectionBlueprint CreateCircleSelectionBlueprint(DrawableSlider slider, SliderPosition position) => new SliderCircleSelectionBlueprint(slider, position);
     }

osu.Game/Rulesets/Edit/SelectionBlueprint.cs

@@ -143,5 +143,11 @@ namespace osu.Game.Rulesets.Edit
         public virtual Quad SelectionQuad => ScreenSpaceDrawQuad;
 
         public virtual Vector2 GetInstantDelta(Vector2 screenSpacePosition) => Parent.ToLocalSpace(screenSpacePosition) - Position;
+
+        /// <summary>
+        /// Handle to perform a partial deletion when the user requests a quick delete (Shift+Right Click).
+        /// </summary>
+        /// <returns>True if the deletion operation was handled by this blueprint. Returning false will delete the full blueprint.</returns>
+        public virtual bool HandleQuickDeletion() => false;
     }
 }

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

@@ -116,7 +116,8 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
         protected override bool OnMouseDown(MouseDownEvent e)
         {
-            beginClickSelection(e);
+            if (beginClickSelection(e)) return true;
+
             prepareSelectionMovement();
 
             return e.Button == MouseButton.Left;
@@ -291,19 +292,23 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// Attempts to select any hovered blueprints.
         /// </summary>
         /// <param name="e">The input event that triggered this selection.</param>
-        private void beginClickSelection(MouseButtonEvent e)
+        private bool beginClickSelection(MouseButtonEvent e)
         {
             Debug.Assert(!clickSelectionBegan);
 
+            bool rightClickHandled = false;
+
             foreach (SelectionBlueprint blueprint in SelectionBlueprints.AliveChildren)
             {
                 if (blueprint.IsHovered)
                 {
-                    SelectionHandler.HandleSelectionRequested(blueprint, e.CurrentState);
+                    rightClickHandled |= SelectionHandler.HandleSelectionRequested(blueprint, e.CurrentState);
                     clickSelectionBegan = true;
                     break;
                 }
             }
+
+            return rightClickHandled;
         }
 
         /// <summary>

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

@@ -219,18 +219,28 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// </summary>
         /// <param name="blueprint">The blueprint.</param>
         /// <param name="state">The input state at the point of selection.</param>
-        internal void HandleSelectionRequested(SelectionBlueprint blueprint, InputState state)
+        /// <returns>Whether right click was handled.</returns>
+        internal bool HandleSelectionRequested(SelectionBlueprint blueprint, InputState state)
         {
             if (state.Keyboard.ShiftPressed && state.Mouse.IsPressed(MouseButton.Right))
+            {
                 handleQuickDeletion(blueprint);
-            else if (state.Keyboard.ControlPressed && state.Mouse.IsPressed(MouseButton.Left))
+                return true;
+            }
+
+            if (state.Keyboard.ControlPressed && state.Mouse.IsPressed(MouseButton.Left))
                 blueprint.ToggleSelection();
             else
                 ensureSelected(blueprint);
+
+            return false;
         }
 
         private void handleQuickDeletion(SelectionBlueprint blueprint)
         {
+            if (blueprint.HandleQuickDeletion())
+                return;
+
             if (!blueprint.IsSelected)
                 EditorBeatmap.Remove(blueprint.HitObject);
             else