Merge pull request #2329 from smoogipoo/selectionlayer-rewrite

Rewrite editor selections to better handle selection and movement logic

osu.Game.Rulesets.Osu/Edit/Layers/Selection/Overlays/HitCircleMask.cs

@@ -21,6 +21,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Layers.Selection.Overlays
             Size = hitCircle.Size;
             Scale = hitCircle.Scale;
 
+            CornerRadius = Size.X / 2;
+
             AddInternal(new RingPiece());
 
             hitCircle.HitObject.PositionChanged += _ => Position = hitCircle.Position;

osu.Game.Rulesets.Osu/Edit/Layers/Selection/Overlays/SliderCircleMask.cs

@@ -38,6 +38,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Layers.Selection.Overlays
             Scale = slider.HeadCircle.Scale;
 
             AddInternal(new RingPiece());
+
+            Select();
         }
 
         [BackgroundDependencyLoader]
@@ -52,5 +54,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Layers.Selection.Overlays
 
             RelativeAnchorPosition = hitObject.RelativeAnchorPosition;
         }
+
+        // Todo: This is temporary, since the slider circle masks don't do anything special yet. In the future they will handle input.
+        public override bool HandleMouseInput => false;
     }
 }

osu.Game.Rulesets.Osu/Edit/Layers/Selection/Overlays/SliderMask.cs

@@ -3,6 +3,7 @@
 
 using osu.Framework.Allocation;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Primitives;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Osu.Objects;
@@ -59,5 +60,8 @@ namespace osu.Game.Rulesets.Osu.Edit.Layers.Selection.Overlays
         }
 
         public override bool ReceiveMouseInputAt(Vector2 screenSpacePos) => body.ReceiveMouseInputAt(screenSpacePos);
+
+        public override Vector2 SelectionPoint => ToScreenSpace(OriginPosition);
+        public override Quad SelectionQuad => body.PathDrawQuad;
     }
 }

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

@@ -10,7 +10,6 @@ using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Graphics.Containers;
 using osu.Game.Rulesets.Osu.Judgements;
-using osu.Framework.Graphics.Primitives;
 using osu.Game.Configuration;
 using osu.Game.Rulesets.Scoring;
 using OpenTK.Graphics;
@@ -177,8 +176,5 @@ namespace osu.Game.Rulesets.Osu.Objects.Drawables
         public Drawable ProxiedLayer => HeadCircle.ApproachCircle;
 
         public override bool ReceiveMouseInputAt(Vector2 screenSpacePos) => Body.ReceiveMouseInputAt(screenSpacePos);
-
-        public override Vector2 SelectionPoint => ToScreenSpace(OriginPosition);
-        public override Quad SelectionQuad => Body.PathDrawQuad;
     }
 }

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

@@ -7,10 +7,11 @@ using osu.Game.Rulesets.Objects;
 using OpenTK;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Rulesets.Edit.Types;
 
 namespace osu.Game.Rulesets.Osu.Objects
 {
-    public abstract class OsuHitObject : HitObject, IHasComboInformation, IHasPosition
+    public abstract class OsuHitObject : HitObject, IHasComboInformation, IHasEditablePosition
     {
         public const double OBJECT_RADIUS = 64;
 

osu.Game.Tests/Visual/TestCaseHitObjectComposer.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using JetBrains.Annotations;
 using NUnit.Framework;
 using osu.Framework.Allocation;
 using osu.Framework.Timing;
@@ -12,7 +13,6 @@ using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Osu;
 using osu.Game.Rulesets.Osu.Edit;
-using osu.Game.Rulesets.Osu.Edit.Layers.Selection.Overlays;
 using osu.Game.Rulesets.Osu.Objects;
 using osu.Game.Screens.Edit.Screens.Compose.Layers;
 using osu.Game.Tests.Beatmaps;
@@ -20,19 +20,16 @@ using osu.Game.Tests.Beatmaps;
 namespace osu.Game.Tests.Visual
 {
     [TestFixture]
-    public class TestCaseEditorSelectionLayer : OsuTestCase
+    public class TestCaseHitObjectComposer : OsuTestCase
     {
         public override IReadOnlyList<Type> RequiredTypes => new[]
         {
-            typeof(SelectionLayer),
-            typeof(SelectionBox),
+            typeof(MaskSelection),
+            typeof(DragLayer),
             typeof(HitObjectComposer),
             typeof(OsuHitObjectComposer),
             typeof(HitObjectMaskLayer),
-            typeof(HitObjectMask),
-            typeof(HitCircleMask),
-            typeof(SliderMask),
-            typeof(SliderCircleMask)
+            typeof(NotNullAttribute)
         };
 
         private DependencyContainer dependencies;

osu.Game/Rulesets/Edit/HitObjectComposer.cs

@@ -65,9 +65,6 @@ namespace osu.Game.Rulesets.Edit
                 return;
             }
 
-            HitObjectMaskLayer hitObjectMaskLayer = new HitObjectMaskLayer(this);
-            SelectionLayer selectionLayer = new SelectionLayer(rulesetContainer.Playfield);
-
             var layerBelowRuleset = new BorderLayer
             {
                 RelativeSizeAxes = Axes.Both,
@@ -75,12 +72,7 @@ namespace osu.Game.Rulesets.Edit
             };
 
             var layerAboveRuleset = CreateLayerContainer();
-            layerAboveRuleset.Children = new Drawable[]
-            {
-                selectionLayer, // Below object overlays for input
-                hitObjectMaskLayer,
-                selectionLayer.CreateProxy() // Proxy above object overlays for selections
-            };
+            layerAboveRuleset.Child = new HitObjectMaskLayer(rulesetContainer.Playfield, this);
 
             layerContainers.Add(layerBelowRuleset);
             layerContainers.Add(layerAboveRuleset);
@@ -122,11 +114,6 @@ namespace osu.Game.Rulesets.Edit
                 }
             };
 
-            selectionLayer.ObjectSelected += hitObjectMaskLayer.AddOverlay;
-            selectionLayer.ObjectDeselected += hitObjectMaskLayer.RemoveOverlay;
-            selectionLayer.SelectionCleared += hitObjectMaskLayer.RemoveSelectionOverlay;
-            selectionLayer.SelectionFinished += hitObjectMaskLayer.AddSelectionOverlay;
-
             toolboxCollection.Items =
                 CompositionTools.Select(t => new RadioButton(t.Name, () => setCompositionTool(t)))
                 .Prepend(new RadioButton("Select", () => setCompositionTool(null)))
@@ -261,11 +248,10 @@ namespace osu.Game.Rulesets.Edit
         public virtual HitObjectMask CreateMaskFor(DrawableHitObject hitObject) => null;
 
         /// <summary>
-        /// Creates a <see cref="SelectionBox"/> which outlines <see cref="DrawableHitObject"/>s
-        /// and handles all hitobject movement/pattern adjustments.
+        /// Creates a <see cref="MaskSelection"/> which outlines <see cref="DrawableHitObject"/>s
+        /// and handles hitobject pattern adjustments.
         /// </summary>
-        /// <param name="overlays">The <see cref="DrawableHitObject"/> overlays.</param>
-        public virtual SelectionBox CreateSelectionOverlay(IReadOnlyList<HitObjectMask> overlays) => new SelectionBox(overlays);
+        public virtual MaskSelection CreateMaskSelection() => new MaskSelection();
 
         /// <summary>
         /// Creates a <see cref="ScalableContainer"/> which provides a layer above or below the <see cref="Playfield"/>.

osu.Game/Rulesets/Edit/HitObjectMask.cs

@@ -1,21 +1,146 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using System;
+using osu.Framework;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Primitives;
+using osu.Framework.Input;
 using osu.Game.Rulesets.Objects.Drawables;
+using OpenTK;
 
 namespace osu.Game.Rulesets.Edit
 {
     /// <summary>
     /// A mask placed above a <see cref="DrawableHitObject"/> adding editing functionality.
     /// </summary>
-    public class HitObjectMask : Container
+    public class HitObjectMask : CompositeDrawable, IStateful<SelectionState>
     {
+        /// <summary>
+        /// Invoked when this <see cref="HitObjectMask"/> has been selected.
+        /// </summary>
+        public event Action<HitObjectMask> Selected;
+
+        /// <summary>
+        /// Invoked when this <see cref="HitObjectMask"/> has been deselected.
+        /// </summary>
+        public event Action<HitObjectMask> Deselected;
+
+        /// <summary>
+        /// Invoked when this <see cref="HitObjectMask"/> has requested selection.
+        /// Will fire even if already selected. Does not actually perform selection.
+        /// </summary>
+        public event Action<HitObjectMask, InputState> SelectionRequested;
+
+        /// <summary>
+        /// Invoked when this <see cref="HitObjectMask"/> has requested drag.
+        /// </summary>
+        public event Action<HitObjectMask, InputState> DragRequested;
+
+        /// <summary>
+        /// The <see cref="DrawableHitObject"/> which this <see cref="HitObjectMask"/> applies to.
+        /// </summary>
         public readonly DrawableHitObject HitObject;
 
+        protected override bool ShouldBeAlive => HitObject.IsAlive && HitObject.IsPresent || State == SelectionState.Selected;
+        public override bool HandleMouseInput => ShouldBeAlive;
+        public override bool RemoveWhenNotAlive => false;
+
         public HitObjectMask(DrawableHitObject hitObject)
         {
             HitObject = hitObject;
+
+            AlwaysPresent = true;
+            Alpha = 0;
         }
+
+        private SelectionState state;
+
+        public event Action<SelectionState> StateChanged;
+
+        public SelectionState State
+        {
+            get => state;
+            set
+            {
+                if (state == value) return;
+
+                state = value;
+                switch (state)
+                {
+                    case SelectionState.Selected:
+                        Show();
+                        Selected?.Invoke(this);
+                        break;
+                    case SelectionState.NotSelected:
+                        Hide();
+                        Deselected?.Invoke(this);
+                        break;
+                }
+            }
+        }
+
+        /// <summary>
+        /// Selects this <see cref="HitObjectMask"/>, causing it to become visible.
+        /// </summary>
+        public void Select() => State = SelectionState.Selected;
+
+        /// <summary>
+        /// Deselects this <see cref="HitObjectMask"/>, causing it to become invisible.
+        /// </summary>
+        public void Deselect() => State = SelectionState.NotSelected;
+
+        public bool IsSelected => State == SelectionState.Selected;
+
+        private bool selectionRequested;
+
+        protected override bool OnMouseDown(InputState state, MouseDownEventArgs args)
+        {
+            selectionRequested = false;
+
+            if (State == SelectionState.NotSelected)
+            {
+                SelectionRequested?.Invoke(this, state);
+                selectionRequested = true;
+            }
+
+            return IsSelected;
+        }
+
+        protected override bool OnClick(InputState state)
+        {
+            if (State == SelectionState.Selected && !selectionRequested)
+            {
+                selectionRequested = true;
+                SelectionRequested?.Invoke(this, state);
+                return true;
+            }
+
+            return base.OnClick(state);
+        }
+
+        protected override bool OnDragStart(InputState state) => true;
+
+        protected override bool OnDrag(InputState state)
+        {
+            DragRequested?.Invoke(this, state);
+            return true;
+        }
+
+        /// <summary>
+        /// The screen-space point that causes this <see cref="HitObjectMask"/> to be selected.
+        /// </summary>
+        public virtual Vector2 SelectionPoint => ScreenSpaceDrawQuad.Centre;
+
+        /// <summary>
+        /// The screen-space quad that outlines this <see cref="HitObjectMask"/> for selections.
+        /// </summary>
+        public virtual Quad SelectionQuad => ScreenSpaceDrawQuad;
+    }
+
+    public enum SelectionState
+    {
+        NotSelected,
+        Selected
     }
 }

osu.Game/Rulesets/Objects/Drawables/DrawableHitObject.cs

@@ -6,14 +6,12 @@ using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Configuration;
-using osu.Framework.Graphics.Primitives;
 using osu.Game.Audio;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Judgements;
 using osu.Game.Rulesets.Objects.Types;
 using osu.Game.Rulesets.Scoring;
 using osu.Game.Skinning;
-using OpenTK;
 using OpenTK.Graphics;
 
 namespace osu.Game.Rulesets.Objects.Drawables
@@ -231,16 +229,6 @@ namespace osu.Game.Rulesets.Objects.Drawables
         protected virtual void CheckForJudgements(bool userTriggered, double timeOffset)
         {
         }
-
-        /// <summary>
-        /// The screen-space point that causes this <see cref="DrawableHitObject"/> to be selected in the Editor.
-        /// </summary>
-        public virtual Vector2 SelectionPoint => ScreenSpaceDrawQuad.Centre;
-
-        /// <summary>
-        /// The screen-space quad that outlines this <see cref="DrawableHitObject"/> for selections in the Editor.
-        /// </summary>
-        public virtual Quad SelectionQuad => ScreenSpaceDrawQuad;
     }
 
     public abstract class DrawableHitObject<TObject> : DrawableHitObject

osu.Game/Screens/Edit/Screens/Compose/Layers/DragLayer.cs

@@ -0,0 +1,92 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Primitives;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input;
+using osu.Game.Rulesets.Edit;
+using OpenTK.Graphics;
+
+namespace osu.Game.Screens.Edit.Screens.Compose.Layers
+{
+    /// <summary>
+    /// A layer that handles and displays drag selection for a collection of <see cref="HitObjectMask"/>s.
+    /// </summary>
+    public class DragLayer : CompositeDrawable
+    {
+        private readonly Action<RectangleF> performSelection;
+
+        /// <summary>
+        /// Invoked when the drag selection has finished.
+        /// </summary>
+        public event Action DragEnd;
+
+        private Drawable box;
+
+        /// <summary>
+        /// Creates a new <see cref="DragLayer"/>.
+        /// </summary>
+        /// <param name="maskContainer">The selectable <see cref="HitObjectMask"/>s.</param>
+        public DragLayer(Action<RectangleF> performSelection)
+        {
+            this.performSelection = performSelection;
+
+            RelativeSizeAxes = Axes.Both;
+            AlwaysPresent = true;
+            Alpha = 0;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            InternalChild = box = new Container
+            {
+                Masking = true,
+                BorderColour = Color4.White,
+                BorderThickness = MaskSelection.BORDER_RADIUS,
+                Child = new Box
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Alpha = 0.1f
+                }
+            };
+        }
+
+        protected override bool OnDragStart(InputState state)
+        {
+            this.FadeIn(250, Easing.OutQuint);
+            return true;
+        }
+
+        protected override bool OnDrag(InputState state)
+        {
+            var dragPosition = state.Mouse.NativeState.Position;
+            var dragStartPosition = state.Mouse.NativeState.PositionMouseDown ?? dragPosition;
+
+            var dragQuad = new Quad(dragStartPosition.X, dragStartPosition.Y, dragPosition.X - dragStartPosition.X, dragPosition.Y - dragStartPosition.Y);
+
+            // We use AABBFloat instead of RectangleF since it handles negative sizes for us
+            var dragRectangle = dragQuad.AABBFloat;
+
+            var topLeft = ToLocalSpace(dragRectangle.TopLeft);
+            var bottomRight = ToLocalSpace(dragRectangle.BottomRight);
+
+            box.Position = topLeft;
+            box.Size = bottomRight - topLeft;
+
+            performSelection?.Invoke(dragRectangle);
+            return true;
+        }
+
+        protected override bool OnDragEnd(InputState state)
+        {
+            this.FadeOut(250, Easing.OutQuint);
+            DragEnd?.Invoke();
+            return true;
+        }
+    }
+}

osu.Game/Screens/Edit/Screens/Compose/Layers/HitObjectMaskLayer.cs

@@ -2,65 +2,92 @@
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
 using System.Linq;
+using osu.Framework.Allocation;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Input;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.UI;
 
 namespace osu.Game.Screens.Edit.Screens.Compose.Layers
 {
     public class HitObjectMaskLayer : CompositeDrawable
     {
+        private readonly Playfield playfield;
         private readonly HitObjectComposer composer;
-        private readonly Container<HitObjectMask> overlayContainer;
 
-        public HitObjectMaskLayer(HitObjectComposer composer)
+        private MaskContainer maskContainer;
+
+        public HitObjectMaskLayer(Playfield playfield, HitObjectComposer composer)
         {
+            // we need the playfield as HitObjects may not be initialised until its BDL.
+            this.playfield = playfield;
+
             this.composer = composer;
+
             RelativeSizeAxes = Axes.Both;
+        }
 
-            InternalChild = overlayContainer = new Container<HitObjectMask> { RelativeSizeAxes = Axes.Both };
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            maskContainer = new MaskContainer();
+
+            var maskSelection = composer.CreateMaskSelection();
+
+            maskContainer.MaskSelected += maskSelection.HandleSelected;
+            maskContainer.MaskDeselected += maskSelection.HandleDeselected;
+            maskContainer.MaskSelectionRequested += maskSelection.HandleSelectionRequested;
+            maskContainer.MaskDragRequested += maskSelection.HandleDrag;
+
+            maskSelection.DeselectAll = maskContainer.DeselectAll;
+
+            var dragLayer = new DragLayer(maskContainer.Select);
+            dragLayer.DragEnd += () => maskSelection.UpdateVisibility();
+
+            InternalChildren = new Drawable[]
+            {
+                dragLayer,
+                maskSelection,
+                maskContainer,
+                dragLayer.CreateProxy()
+            };
+
+            foreach (var obj in playfield.HitObjects.Objects)
+                addMask(obj);
+        }
+
+        protected override bool OnMouseDown(InputState state, MouseDownEventArgs args)
+        {
+            maskContainer.DeselectAll();
+            return true;
         }
 
         /// <summary>
-        /// Adds an overlay for a <see cref="DrawableHitObject"/> which adds movement support.
+        /// Adds a mask for a <see cref="DrawableHitObject"/> which adds movement support.
         /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to create an overlay for.</param>
-        public void AddOverlay(DrawableHitObject hitObject)
+        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to create a mask for.</param>
+        private void addMask(DrawableHitObject hitObject)
         {
-            var overlay = composer.CreateMaskFor(hitObject);
-            if (overlay == null)
+            var mask = composer.CreateMaskFor(hitObject);
+            if (mask == null)
                 return;
 
-            overlayContainer.Add(overlay);
+            maskContainer.Add(mask);
         }
 
         /// <summary>
-        /// Removes the overlay for a <see cref="DrawableHitObject"/>.
+        /// Removes the mask for a <see cref="DrawableHitObject"/>.
         /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to remove the overlay for.</param>
-        public void RemoveOverlay(DrawableHitObject hitObject)
+        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to remove the mask for.</param>
+        private void removeMask(DrawableHitObject hitObject)
         {
-            var existing = overlayContainer.FirstOrDefault(h => h.HitObject == hitObject);
-            if (existing == null)
+            var mask = maskContainer.FirstOrDefault(h => h.HitObject == hitObject);
+            if (mask == null)
                 return;
 
-            existing.Hide();
-            existing.Expire();
-        }
-
-        private SelectionBox currentSelectionBox;
-
-        public void AddSelectionOverlay()
-        {
-            if (overlayContainer.Count > 0)
-                AddInternal(currentSelectionBox = composer.CreateSelectionOverlay(overlayContainer));
-        }
-
-        public void RemoveSelectionOverlay()
-        {
-            currentSelectionBox?.Hide();
-            currentSelectionBox?.Expire();
+            maskContainer.Remove(mask);
         }
     }
 }

osu.Game/Screens/Edit/Screens/Compose/Layers/MaskContainer.cs

@@ -0,0 +1,123 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Input;
+using osu.Game.Rulesets.Edit;
+using RectangleF = osu.Framework.Graphics.Primitives.RectangleF;
+
+namespace osu.Game.Screens.Edit.Screens.Compose.Layers
+{
+    public class MaskContainer : Container<HitObjectMask>
+    {
+        /// <summary>
+        /// Invoked when any <see cref="HitObjectMask"/> is selected.
+        /// </summary>
+        public event Action<HitObjectMask> MaskSelected;
+
+        /// <summary>
+        /// Invoked when any <see cref="HitObjectMask"/> is deselected.
+        /// </summary>
+        public event Action<HitObjectMask> MaskDeselected;
+
+        /// <summary>
+        /// Invoked when any <see cref="HitObjectMask"/> requests selection.
+        /// </summary>
+        public event Action<HitObjectMask, InputState> MaskSelectionRequested;
+
+        /// <summary>
+        /// Invoked when any <see cref="HitObjectMask"/> requests drag.
+        /// </summary>
+        public event Action<HitObjectMask, InputState> MaskDragRequested;
+
+        private IEnumerable<HitObjectMask> aliveMasks => AliveInternalChildren.Cast<HitObjectMask>();
+
+        public MaskContainer()
+        {
+            RelativeSizeAxes = Axes.Both;
+        }
+
+        public override void Add(HitObjectMask drawable)
+        {
+            base.Add(drawable);
+
+            drawable.Selected += onMaskSelected;
+            drawable.Deselected += onMaskDeselected;
+            drawable.SelectionRequested += onSelectionRequested;
+            drawable.DragRequested += onDragRequested;
+        }
+
+        public override bool Remove(HitObjectMask drawable)
+        {
+            var result = base.Remove(drawable);
+
+            if (result)
+            {
+                drawable.Selected -= onMaskSelected;
+                drawable.Deselected -= onMaskDeselected;
+                drawable.SelectionRequested -= onSelectionRequested;
+                drawable.DragRequested -= onDragRequested;
+            }
+
+            return result;
+        }
+
+        /// <summary>
+        /// Select all masks in a given rectangle selection area.
+        /// </summary>
+        /// <param name="rect">The rectangle to perform a selection on in screen-space coordinates.</param>
+        public void Select(RectangleF rect)
+        {
+            foreach (var mask in aliveMasks.ToList())
+            {
+                if (mask.IsPresent && rect.Contains(mask.SelectionPoint))
+                    mask.Select();
+                else
+                    mask.Deselect();
+            }
+        }
+
+        /// <summary>
+        /// Deselects all selected <see cref="HitObjectMask"/>s.
+        /// </summary>
+        public void DeselectAll() => aliveMasks.ToList().ForEach(m => m.Deselect());
+
+        private void onMaskSelected(HitObjectMask mask)
+        {
+            MaskSelected?.Invoke(mask);
+            ChangeChildDepth(mask, 1);
+        }
+
+        private void onMaskDeselected(HitObjectMask mask)
+        {
+            MaskDeselected?.Invoke(mask);
+            ChangeChildDepth(mask, 0);
+        }
+
+        private void onSelectionRequested(HitObjectMask mask, InputState state) => MaskSelectionRequested?.Invoke(mask, state);
+        private void onDragRequested(HitObjectMask mask, InputState state) => MaskDragRequested?.Invoke(mask, state);
+
+        protected override int Compare(Drawable x, Drawable y)
+        {
+            if (!(x is HitObjectMask xMask) || !(y is HitObjectMask yMask))
+                return base.Compare(x, y);
+            return Compare(xMask, yMask);
+        }
+
+        public int Compare(HitObjectMask x, HitObjectMask y)
+        {
+            // dpeth is used to denote selected status (we always want selected masks to handle input first).
+            int d = x.Depth.CompareTo(y.Depth);
+            if (d != 0)
+                return d;
+
+            // Put earlier hitobjects towards the end of the list, so they handle input first
+            int i = y.HitObject.HitObject.StartTime.CompareTo(x.HitObject.HitObject.StartTime);
+            return i == 0 ? CompareReverseChildID(x, y) : i;
+        }
+    }
+}

osu.Game/Screens/Edit/Screens/Compose/Layers/MaskSelection.cs

@@ -0,0 +1,164 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input;
+using osu.Game.Graphics;
+using osu.Game.Rulesets.Edit;
+using osu.Game.Rulesets.Edit.Types;
+using OpenTK;
+
+namespace osu.Game.Screens.Edit.Screens.Compose.Layers
+{
+    /// <summary>
+    /// A box which surrounds <see cref="HitObjectMask"/>s and provides interactive handles, context menus etc.
+    /// </summary>
+    public class MaskSelection : CompositeDrawable
+    {
+        public const float BORDER_RADIUS = 2;
+
+        private readonly List<HitObjectMask> selectedMasks;
+
+        private Drawable outline;
+
+        public MaskSelection()
+        {
+            selectedMasks = new List<HitObjectMask>();
+
+            RelativeSizeAxes = Axes.Both;
+            AlwaysPresent = true;
+            Alpha = 0;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            InternalChild = outline = new Container
+            {
+                Masking = true,
+                BorderThickness = BORDER_RADIUS,
+                BorderColour = colours.Yellow,
+                Child = new Box
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    AlwaysPresent = true,
+                    Alpha = 0
+                }
+            };
+        }
+
+        #region User Input Handling
+
+        public void HandleDrag(HitObjectMask m, InputState state)
+        {
+            // Todo: Various forms of snapping
+
+            foreach (var mask in selectedMasks)
+            {
+                switch (mask.HitObject.HitObject)
+                {
+                    case IHasEditablePosition editablePosition:
+                        editablePosition.OffsetPosition(state.Mouse.Delta);
+                        break;
+                }
+            }
+        }
+
+        #endregion
+
+        #region Selection Handling
+
+        /// <summary>
+        /// Bind an action to deselect all selected masks.
+        /// </summary>
+        public Action DeselectAll { private get; set; }
+
+        /// <summary>
+        /// Handle a mask becoming selected.
+        /// </summary>
+        /// <param name="mask">The mask.</param>
+        public void HandleSelected(HitObjectMask mask) => selectedMasks.Add(mask);
+
+        /// <summary>
+        /// Handle a mask becoming deselected.
+        /// </summary>
+        /// <param name="mask">The mask.</param>
+        public void HandleDeselected(HitObjectMask mask)
+        {
+            selectedMasks.Remove(mask);
+
+            // We don't want to update visibility if > 0, since we may be deselecting masks during drag-selection
+            if (selectedMasks.Count == 0)
+                UpdateVisibility();
+        }
+
+        /// <summary>
+        /// Handle a mask requesting selection.
+        /// </summary>
+        /// <param name="mask">The mask.</param>
+        public void HandleSelectionRequested(HitObjectMask mask, InputState state)
+        {
+            if (state.Keyboard.ControlPressed)
+            {
+                if (mask.IsSelected)
+                    mask.Deselect();
+                else
+                    mask.Select();
+            }
+            else
+            {
+                if (mask.IsSelected)
+                    return;
+
+                DeselectAll?.Invoke();
+                mask.Select();
+            }
+
+            UpdateVisibility();
+        }
+
+        #endregion
+
+        /// <summary>
+        /// Updates whether this <see cref="MaskSelection"/> is visible.
+        /// </summary>
+        internal void UpdateVisibility()
+        {
+            if (selectedMasks.Count > 0)
+                Show();
+            else
+                Hide();
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            if (selectedMasks.Count == 0)
+                return;
+
+            // Move the rectangle to cover the hitobjects
+            var topLeft = new Vector2(float.MaxValue, float.MaxValue);
+            var bottomRight = new Vector2(float.MinValue, float.MinValue);
+
+            bool hasSelection = false;
+
+            foreach (var mask in selectedMasks)
+            {
+                topLeft = Vector2.ComponentMin(topLeft, ToLocalSpace(mask.SelectionQuad.TopLeft));
+                bottomRight = Vector2.ComponentMax(bottomRight, ToLocalSpace(mask.SelectionQuad.BottomRight));
+            }
+
+            topLeft -= new Vector2(5);
+            bottomRight += new Vector2(5);
+
+            outline.Size = bottomRight - topLeft;
+            outline.Position = topLeft;
+        }
+    }
+}

osu.Game/Screens/Edit/Screens/Compose/Layers/SelectionBox.cs

@@ -1,102 +0,0 @@
-// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
-// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
-
-using System.Collections.Generic;
-using System.Linq;
-using osu.Framework.Allocation;
-using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Shapes;
-using osu.Framework.Input;
-using osu.Game.Graphics;
-using osu.Game.Rulesets.Edit;
-using osu.Game.Rulesets.Edit.Types;
-using osu.Game.Rulesets.Objects.Drawables;
-using OpenTK;
-
-namespace osu.Game.Screens.Edit.Screens.Compose.Layers
-{
-    /// <summary>
-    /// A box which surrounds <see cref="DrawableHitObject"/>s and provides interactive handles, context menus etc.
-    /// </summary>
-    public class SelectionBox : VisibilityContainer
-    {
-        private readonly IReadOnlyList<HitObjectMask> overlays;
-
-        public const float BORDER_RADIUS = 2;
-
-        public SelectionBox(IReadOnlyList<HitObjectMask> overlays)
-        {
-            this.overlays = overlays;
-
-            Masking = true;
-            BorderThickness = BORDER_RADIUS;
-
-            InternalChild = new Box
-            {
-                RelativeSizeAxes = Axes.Both,
-                AlwaysPresent = true,
-                Alpha = 0
-            };
-
-            State = Visibility.Visible;
-        }
-
-        [BackgroundDependencyLoader]
-        private void load(OsuColour colours)
-        {
-            BorderColour = colours.Yellow;
-        }
-
-        protected override void Update()
-        {
-            base.Update();
-
-            // Todo: We might need to optimise this
-
-            // Move the rectangle to cover the hitobjects
-            var topLeft = new Vector2(float.MaxValue, float.MaxValue);
-            var bottomRight = new Vector2(float.MinValue, float.MinValue);
-
-            foreach (var obj in overlays)
-            {
-                topLeft = Vector2.ComponentMin(topLeft, Parent.ToLocalSpace(obj.HitObject.SelectionQuad.TopLeft));
-                bottomRight = Vector2.ComponentMax(bottomRight, Parent.ToLocalSpace(obj.HitObject.SelectionQuad.BottomRight));
-            }
-
-            topLeft -= new Vector2(5);
-            bottomRight += new Vector2(5);
-
-            Size = bottomRight - topLeft;
-            Position = topLeft;
-        }
-
-        public override bool ReceiveMouseInputAt(Vector2 screenSpacePos) => overlays.Any(o => o.ReceiveMouseInputAt(screenSpacePos));
-
-        protected override bool OnMouseDown(InputState state, MouseDownEventArgs args) => true;
-
-        protected override bool OnDragStart(InputState state) => true;
-
-        protected override bool OnDrag(InputState state)
-        {
-            // Todo: Various forms of snapping
-            foreach (var hitObject in overlays.Select(o => o.HitObject.HitObject))
-            {
-                switch (hitObject)
-                {
-                    case IHasEditablePosition editablePosition:
-                        editablePosition.OffsetPosition(state.Mouse.Delta);
-                        break;
-                }
-            }
-            return true;
-        }
-
-        protected override bool OnDragEnd(InputState state) => true;
-
-        public override bool DisposeOnDeathRemoval => true;
-
-        protected override void PopIn() => this.FadeIn();
-        protected override void PopOut() => this.FadeOut();
-    }
-}

osu.Game/Screens/Edit/Screens/Compose/Layers/SelectionLayer.cs

@@ -1,240 +0,0 @@
-// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
-// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using osu.Framework.Extensions.IEnumerableExtensions;
-using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Primitives;
-using osu.Framework.Graphics.Shapes;
-using osu.Framework.Input;
-using osu.Game.Rulesets.Objects.Drawables;
-using osu.Game.Rulesets.UI;
-using OpenTK;
-using OpenTK.Graphics;
-using RectangleF = osu.Framework.Graphics.Primitives.RectangleF;
-
-namespace osu.Game.Screens.Edit.Screens.Compose.Layers
-{
-    public class SelectionLayer : CompositeDrawable
-    {
-        /// <summary>
-        /// Invoked when a <see cref="DrawableHitObject"/> is selected.
-        /// </summary>
-        public event Action<DrawableHitObject> ObjectSelected;
-
-        /// <summary>
-        /// Invoked when a <see cref="DrawableHitObject"/> is deselected.
-        /// </summary>
-        public event Action<DrawableHitObject> ObjectDeselected;
-
-        /// <summary>
-        /// Invoked when the selection has been cleared.
-        /// </summary>
-        public event Action SelectionCleared;
-
-        /// <summary>
-        /// Invoked when the user has finished selecting all <see cref="DrawableHitObject"/>s.
-        /// </summary>
-        public event Action SelectionFinished;
-
-        private readonly Playfield playfield;
-
-        public SelectionLayer(Playfield playfield)
-        {
-            this.playfield = playfield;
-
-            RelativeSizeAxes = Axes.Both;
-        }
-
-        private DragBox dragBox;
-
-        private readonly HashSet<DrawableHitObject> selectedHitObjects = new HashSet<DrawableHitObject>();
-
-        protected override bool OnMouseDown(InputState state, MouseDownEventArgs args)
-        {
-            DeselectAll();
-            return true;
-        }
-
-        protected override bool OnDragStart(InputState state)
-        {
-            AddInternal(dragBox = new DragBox());
-            return true;
-        }
-
-        protected override bool OnDrag(InputState state)
-        {
-            dragBox.Show();
-
-            var dragPosition = state.Mouse.NativeState.Position;
-            var dragStartPosition = state.Mouse.NativeState.PositionMouseDown ?? dragPosition;
-
-            var screenSpaceDragQuad = new Quad(dragStartPosition.X, dragStartPosition.Y, dragPosition.X - dragStartPosition.X, dragPosition.Y - dragStartPosition.Y);
-
-            dragBox.SetDragRectangle(screenSpaceDragQuad.AABBFloat);
-            selectQuad(screenSpaceDragQuad);
-
-            return true;
-        }
-
-        protected override bool OnDragEnd(InputState state)
-        {
-            dragBox.Hide();
-            dragBox.Expire();
-
-            finishSelection();
-
-            return true;
-        }
-
-        protected override bool OnClick(InputState state)
-        {
-            selectPoint(state.Mouse.NativeState.Position);
-            finishSelection();
-
-            return true;
-        }
-
-        /// <summary>
-        /// Selects a <see cref="DrawableHitObject"/>.
-        /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to select.</param>
-        public void Select(DrawableHitObject hitObject)
-        {
-            if (!select(hitObject))
-                return;
-
-            clearSelection();
-            finishSelection();
-        }
-
-        /// <summary>
-        /// Selects a <see cref="DrawableHitObject"/> without performing capture updates.
-        /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to select.</param>
-        /// <returns>Whether <paramref name="hitObject"/> was selected.</returns>
-        private bool select(DrawableHitObject hitObject)
-        {
-            if (!selectedHitObjects.Add(hitObject))
-                return false;
-
-            ObjectSelected?.Invoke(hitObject);
-            return true;
-        }
-
-        /// <summary>
-        /// Deselects a <see cref="DrawableHitObject"/>.
-        /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to deselect.</param>
-        public void Deselect(DrawableHitObject hitObject)
-        {
-            if (!deselect(hitObject))
-                return;
-
-            clearSelection();
-            finishSelection();
-        }
-
-        /// <summary>
-        /// Deselects a <see cref="DrawableHitObject"/> without performing capture updates.
-        /// </summary>
-        /// <param name="hitObject">The <see cref="DrawableHitObject"/> to deselect.</param>
-        /// <returns>Whether the <see cref="DrawableHitObject"/> was deselected.</returns>
-        private bool deselect(DrawableHitObject hitObject)
-        {
-            if (!selectedHitObjects.Remove(hitObject))
-                return false;
-
-            ObjectDeselected?.Invoke(hitObject);
-            return true;
-        }
-
-        /// <summary>
-        /// Deselects all selected <see cref="DrawableHitObject"/>s.
-        /// </summary>
-        public void DeselectAll()
-        {
-            selectedHitObjects.ForEach(h => ObjectDeselected?.Invoke(h));
-            selectedHitObjects.Clear();
-
-            clearSelection();
-        }
-
-        /// <summary>
-        /// Selects all hitobjects that are present within the area of a <see cref="Quad"/>.
-        /// </summary>
-        /// <param name="screenSpaceQuad">The selection <see cref="Quad"/>.</param>
-        // Todo: If needed we can severely reduce allocations in this method
-        private void selectQuad(Quad screenSpaceQuad)
-        {
-            var expectedSelection = playfield.HitObjects.Objects.Where(h => h.IsAlive && h.IsPresent && screenSpaceQuad.Contains(h.SelectionPoint)).ToList();
-
-            var toRemove = selectedHitObjects.Except(expectedSelection).ToList();
-            foreach (var obj in toRemove)
-                deselect(obj);
-
-            expectedSelection.ForEach(h => select(h));
-        }
-
-        /// <summary>
-        /// Selects the top-most hitobject that is present under a specific point.
-        /// </summary>
-        /// <param name="screenSpacePoint">The <see cref="Vector2"/> to select at.</param>
-        private void selectPoint(Vector2 screenSpacePoint)
-        {
-            var target = playfield.HitObjects.Objects.Reverse().Where(h => h.IsAlive && h.IsPresent).FirstOrDefault(h => h.ReceiveMouseInputAt(screenSpacePoint));
-            if (target == null)
-                return;
-
-            select(target);
-        }
-
-        private void clearSelection() => SelectionCleared?.Invoke();
-
-        private void finishSelection()
-        {
-            if (selectedHitObjects.Count == 0)
-                return;
-            SelectionFinished?.Invoke();
-        }
-
-        /// <summary>
-        /// A box that represents a drag selection.
-        /// </summary>
-        private class DragBox : VisibilityContainer
-        {
-            /// <summary>
-            /// Creates a new <see cref="DragBox"/>.
-            /// </summary>
-            public DragBox()
-            {
-                Masking = true;
-                BorderColour = Color4.White;
-                BorderThickness = SelectionBox.BORDER_RADIUS;
-
-                Child = new Box
-                {
-                    RelativeSizeAxes = Axes.Both,
-                    Alpha = 0.1f
-                };
-            }
-
-            public void SetDragRectangle(RectangleF rectangle)
-            {
-                var topLeft = Parent.ToLocalSpace(rectangle.TopLeft);
-                var bottomRight = Parent.ToLocalSpace(rectangle.BottomRight);
-
-                Position = topLeft;
-                Size = bottomRight - topLeft;
-            }
-
-            public override bool DisposeOnDeathRemoval => true;
-
-            protected override void PopIn() => this.FadeIn(250, Easing.OutQuint);
-            protected override void PopOut() => this.FadeOut(250, Easing.OutQuint);
-        }
-    }
-}