Merge branch 'master' into editor-song-end

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

@@ -14,7 +14,7 @@ using osu.Framework.Graphics.Primitives;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
-using osu.Framework.Timing;
+using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
@@ -25,52 +25,63 @@ namespace osu.Game.Screens.Edit.Compose.Components
 {
     /// <summary>
     /// A container which provides a "blueprint" display of hitobjects.
-    /// Includes selection and manipulation support via a <see cref="SelectionHandler"/>.
+    /// Includes selection and manipulation support via a <see cref="Components.SelectionHandler"/>.
     /// </summary>
     public abstract class BlueprintContainer : CompositeDrawable, IKeyBindingHandler<PlatformAction>
     {
-        public event Action<IEnumerable<HitObject>> SelectionChanged;
-
         protected DragBox DragBox { get; private set; }
 
-        protected Container<SelectionBlueprint> SelectionBlueprints { get; private set; }
+        public Container<SelectionBlueprint> SelectionBlueprints { get; private set; }
 
-        private SelectionHandler selectionHandler;
+        protected SelectionHandler SelectionHandler { get; private set; }
+
+        protected readonly HitObjectComposer Composer;
+
+        [Resolved(CanBeNull = true)]
+        private IEditorChangeHandler changeHandler { get; set; }
 
         [Resolved]
-        private IAdjustableClock adjustableClock { get; set; }
+        protected EditorClock EditorClock { get; private set; }
 
         [Resolved]
-        private EditorBeatmap beatmap { get; set; }
+        protected EditorBeatmap Beatmap { get; private set; }
 
         private readonly BindableList<HitObject> selectedHitObjects = new BindableList<HitObject>();
+        private readonly Dictionary<HitObject, SelectionBlueprint> blueprintMap = new Dictionary<HitObject, SelectionBlueprint>();
 
         [Resolved(canBeNull: true)]
-        private IDistanceSnapProvider snapProvider { get; set; }
+        private IPositionSnapProvider snapProvider { get; set; }
 
-        protected BlueprintContainer()
+        protected BlueprintContainer(HitObjectComposer composer)
         {
+            Composer = composer;
+
             RelativeSizeAxes = Axes.Both;
         }
 
         [BackgroundDependencyLoader]
         private void load()
         {
-            selectionHandler = CreateSelectionHandler();
-            selectionHandler.DeselectAll = deselectAll;
+            SelectionHandler = CreateSelectionHandler();
+            SelectionHandler.DeselectAll = deselectAll;
 
             AddRangeInternal(new[]
             {
-                DragBox = CreateDragBox(select),
-                selectionHandler,
+                DragBox = CreateDragBox(selectBlueprintsFromDragRectangle),
+                SelectionHandler,
                 SelectionBlueprints = CreateSelectionBlueprintContainer(),
+                SelectionHandler.CreateProxy(),
                 DragBox.CreateProxy().With(p => p.Depth = float.MinValue)
             });
 
-            foreach (var obj in beatmap.HitObjects)
-                AddBlueprintFor(obj);
+            // For non-pooled rulesets, hitobjects are already present in the playfield which allows the blueprints to be loaded in the async context.
+            if (Composer != null)
+            {
+                foreach (var obj in Composer.HitObjects)
+                    addBlueprintFor(obj.HitObject);
+            }
 
-            selectedHitObjects.BindTo(beatmap.SelectedHitObjects);
+            selectedHitObjects.BindTo(Beatmap.SelectedHitObjects);
             selectedHitObjects.CollectionChanged += (selectedObjects, args) =>
             {
                 switch (args.Action)
@@ -83,10 +94,9 @@ namespace osu.Game.Screens.Edit.Compose.Components
                     case NotifyCollectionChangedAction.Remove:
                         foreach (var o in args.OldItems)
                             SelectionBlueprints.FirstOrDefault(b => b.HitObject == o)?.Deselect();
+
                         break;
                 }
-
-                SelectionChanged?.Invoke(selectedHitObjects);
             };
         }
 
@@ -94,15 +104,24 @@ namespace osu.Game.Screens.Edit.Compose.Components
         {
             base.LoadComplete();
 
-            beatmap.HitObjectAdded += AddBlueprintFor;
-            beatmap.HitObjectRemoved += removeBlueprintFor;
+            Beatmap.HitObjectAdded += addBlueprintFor;
+            Beatmap.HitObjectRemoved += removeBlueprintFor;
+
+            if (Composer != null)
+            {
+                // For pooled rulesets, blueprints must be added for hitobjects already "current" as they would've not been "current" during the async load addition process above.
+                foreach (var obj in Composer.HitObjects)
+                    addBlueprintFor(obj.HitObject);
+
+                Composer.Playfield.HitObjectUsageBegan += addBlueprintFor;
+                Composer.Playfield.HitObjectUsageFinished += removeBlueprintFor;
+            }
         }
 
-        protected virtual Container<SelectionBlueprint> CreateSelectionBlueprintContainer() =>
-            new Container<SelectionBlueprint> { RelativeSizeAxes = Axes.Both };
+        protected virtual Container<SelectionBlueprint> CreateSelectionBlueprintContainer() => new HitObjectOrderedSelectionContainer { RelativeSizeAxes = Axes.Both };
 
         /// <summary>
-        /// Creates a <see cref="SelectionHandler"/> which outlines <see cref="DrawableHitObject"/>s and handles movement of selections.
+        /// Creates a <see cref="Components.SelectionHandler"/> which outlines <see cref="DrawableHitObject"/>s and handles movement of selections.
         /// </summary>
         protected virtual SelectionHandler CreateSelectionHandler() => new SelectionHandler();
 
@@ -116,20 +135,26 @@ 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;
         }
 
+        private SelectionBlueprint clickedBlueprint;
+
         protected override bool OnClick(ClickEvent e)
         {
             if (e.Button == MouseButton.Right)
                 return false;
 
+            // store for double-click handling
+            clickedBlueprint = SelectionHandler.SelectedBlueprints.FirstOrDefault(b => b.IsHovered);
+
             // Deselection should only occur if no selected blueprints are hovered
             // A special case for when a blueprint was selected via this click is added since OnClick() may occur outside the hitobject and should not trigger deselection
-            if (endClickSelection() || selectionHandler.SelectedBlueprints.Any(b => b.IsHovered))
+            if (endClickSelection() || clickedBlueprint != null)
                 return true;
 
             deselectAll();
@@ -141,12 +166,11 @@ namespace osu.Game.Screens.Edit.Compose.Components
             if (e.Button == MouseButton.Right)
                 return false;
 
-            SelectionBlueprint clickedBlueprint = selectionHandler.SelectedBlueprints.FirstOrDefault(b => b.IsHovered);
-
-            if (clickedBlueprint == null)
+            // ensure the blueprint which was hovered for the first click is still the hovered blueprint.
+            if (clickedBlueprint == null || SelectionHandler.SelectedBlueprints.FirstOrDefault(b => b.IsHovered) != clickedBlueprint)
                 return false;
 
-            adjustableClock?.Seek(clickedBlueprint.HitObject.StartTime);
+            EditorClock?.SeekSmoothlyTo(clickedBlueprint.HitObject.StartTime);
             return true;
         }
 
@@ -163,8 +187,12 @@ namespace osu.Game.Screens.Edit.Compose.Components
             if (e.Button == MouseButton.Right)
                 return false;
 
-            if (movementBlueprint != null)
+            if (movementBlueprints != null)
+            {
+                isDraggingBlueprint = true;
+                changeHandler?.BeginChange();
                 return true;
+            }
 
             if (DragBox.HandleDrag(e))
             {
@@ -191,11 +219,18 @@ namespace osu.Game.Screens.Edit.Compose.Components
             if (e.Button == MouseButton.Right)
                 return;
 
-            if (DragBox.State == Visibility.Visible)
+            if (isDraggingBlueprint)
             {
-                DragBox.Hide();
-                selectionHandler.UpdateVisibility();
+                // handle positional change etc.
+                foreach (var obj in selectedHitObjects)
+                    Beatmap.Update(obj);
+
+                changeHandler?.EndChange();
+                isDraggingBlueprint = false;
             }
+
+            if (DragBox.State == Visibility.Visible)
+                DragBox.Hide();
         }
 
         protected override bool OnKeyDown(KeyDownEvent e)
@@ -203,7 +238,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
             switch (e.Key)
             {
                 case Key.Escape:
-                    if (!selectionHandler.SelectedBlueprints.Any())
+                    if (!SelectionHandler.SelectedBlueprints.Any())
                         return false;
 
                     deselectAll();
@@ -231,30 +266,59 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
         #region Blueprint Addition/Removal
 
-        private void removeBlueprintFor(HitObject hitObject)
+        private void addBlueprintFor(HitObject hitObject)
         {
-            var blueprint = SelectionBlueprints.SingleOrDefault(m => m.HitObject == hitObject);
-            if (blueprint == null)
+            if (blueprintMap.ContainsKey(hitObject))
                 return;
 
-            blueprint.Deselect();
-
-            blueprint.Selected -= onBlueprintSelected;
-            blueprint.Deselected -= onBlueprintDeselected;
-
-            SelectionBlueprints.Remove(blueprint);
-        }
-
-        protected virtual void AddBlueprintFor(HitObject hitObject)
-        {
             var blueprint = CreateBlueprintFor(hitObject);
             if (blueprint == null)
                 return;
 
+            blueprintMap[hitObject] = blueprint;
+
             blueprint.Selected += onBlueprintSelected;
             blueprint.Deselected += onBlueprintDeselected;
 
+            if (Beatmap.SelectedHitObjects.Contains(hitObject))
+                blueprint.Select();
+
             SelectionBlueprints.Add(blueprint);
+
+            OnBlueprintAdded(hitObject);
+        }
+
+        private void removeBlueprintFor(HitObject hitObject)
+        {
+            if (!blueprintMap.Remove(hitObject, out var blueprint))
+                return;
+
+            blueprint.Deselect();
+            blueprint.Selected -= onBlueprintSelected;
+            blueprint.Deselected -= onBlueprintDeselected;
+
+            SelectionBlueprints.Remove(blueprint);
+
+            if (movementBlueprints?.Contains(blueprint) == true)
+                finishSelectionMovement();
+
+            OnBlueprintRemoved(hitObject);
+        }
+
+        /// <summary>
+        /// Called after a <see cref="HitObject"/> blueprint has been added.
+        /// </summary>
+        /// <param name="hitObject">The <see cref="HitObject"/> for which the blueprint has been added.</param>
+        protected virtual void OnBlueprintAdded(HitObject hitObject)
+        {
+        }
+
+        /// <summary>
+        /// Called after a <see cref="HitObject"/> blueprint has been removed.
+        /// </summary>
+        /// <param name="hitObject">The <see cref="HitObject"/> for which the blueprint has been removed.</param>
+        protected virtual void OnBlueprintRemoved(HitObject hitObject)
+        {
         }
 
         #endregion
@@ -270,26 +334,18 @@ 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)
+        /// <returns>Whether a selection was performed.</returns>
+        private bool beginClickSelection(MouseButtonEvent e)
         {
-            Debug.Assert(!clickSelectionBegan);
-
-            // Deselections are only allowed for control + left clicks
-            bool allowDeselection = e.ControlPressed && e.Button == MouseButton.Left;
-
-            // Todo: This is probably incorrectly disallowing multiple selections on stacked objects
-            if (!allowDeselection && selectionHandler.SelectedBlueprints.Any(s => s.IsHovered))
-                return;
-
-            foreach (SelectionBlueprint blueprint in SelectionBlueprints.AliveChildren)
+            // Iterate from the top of the input stack (blueprints closest to the front of the screen first).
+            foreach (SelectionBlueprint blueprint in SelectionBlueprints.AliveChildren.Reverse())
             {
-                if (blueprint.IsHovered)
-                {
-                    selectionHandler.HandleSelectionRequested(blueprint, e.CurrentState);
-                    clickSelectionBegan = true;
-                    break;
-                }
+                if (!blueprint.IsHovered) continue;
+
+                return clickSelectionBegan = SelectionHandler.HandleSelectionRequested(blueprint, e);
             }
+
+            return false;
         }
 
         /// <summary>
@@ -309,14 +365,26 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// 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>
-        private void select(RectangleF rect)
+        private void selectBlueprintsFromDragRectangle(RectangleF rect)
         {
             foreach (var blueprint in SelectionBlueprints)
             {
-                if (blueprint.IsAlive && blueprint.IsPresent && rect.Contains(blueprint.SelectionPoint))
-                    blueprint.Select();
-                else
-                    blueprint.Deselect();
+                // only run when utmost necessary to avoid unnecessary rect computations.
+                bool isValidForSelection() => blueprint.IsAlive && blueprint.IsPresent && rect.Contains(blueprint.ScreenSpaceSelectionPoint);
+
+                switch (blueprint.State)
+                {
+                    case SelectionState.NotSelected:
+                        if (isValidForSelection())
+                            blueprint.Select();
+                        break;
+
+                    case SelectionState.Selected:
+                        // if the editor is playing, we generally don't want to deselect objects even if outside the selection area.
+                        if (!EditorClock.IsRunning && !isValidForSelection())
+                            blueprint.Deselect();
+                        break;
+                }
             }
         }
 
@@ -325,52 +393,57 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// </summary>
         private void selectAll()
         {
-            SelectionBlueprints.ToList().ForEach(m => m.Select());
-            selectionHandler.UpdateVisibility();
+            Composer.Playfield.KeepAllAlive();
+
+            // Scheduled to allow the change in lifetime to take place.
+            Schedule(() => SelectionBlueprints.ToList().ForEach(m => m.Select()));
         }
 
         /// <summary>
         /// Deselects all selected <see cref="SelectionBlueprint"/>s.
         /// </summary>
-        private void deselectAll() => selectionHandler.SelectedBlueprints.ToList().ForEach(m => m.Deselect());
+        private void deselectAll() => SelectionHandler.SelectedBlueprints.ToList().ForEach(m => m.Deselect());
 
         private void onBlueprintSelected(SelectionBlueprint blueprint)
         {
-            selectionHandler.HandleSelected(blueprint);
+            SelectionHandler.HandleSelected(blueprint);
             SelectionBlueprints.ChangeChildDepth(blueprint, 1);
-            beatmap.SelectedHitObjects.Add(blueprint.HitObject);
+
+            Composer.Playfield.SetKeepAlive(blueprint.HitObject, true);
         }
 
         private void onBlueprintDeselected(SelectionBlueprint blueprint)
         {
-            selectionHandler.HandleDeselected(blueprint);
+            SelectionHandler.HandleDeselected(blueprint);
             SelectionBlueprints.ChangeChildDepth(blueprint, 0);
-            beatmap.SelectedHitObjects.Remove(blueprint.HitObject);
+
+            Composer.Playfield.SetKeepAlive(blueprint.HitObject, false);
         }
 
         #endregion
 
         #region Selection Movement
 
-        private Vector2? movementBlueprintOriginalPosition;
-        private SelectionBlueprint movementBlueprint;
+        private Vector2[] movementBlueprintOriginalPositions;
+        private SelectionBlueprint[] movementBlueprints;
+        private bool isDraggingBlueprint;
 
         /// <summary>
         /// Attempts to begin the movement of any selected blueprints.
         /// </summary>
         private void prepareSelectionMovement()
         {
-            if (!selectionHandler.SelectedBlueprints.Any())
+            if (!SelectionHandler.SelectedBlueprints.Any())
                 return;
 
             // Any selected blueprint that is hovered can begin the movement of the group, however only the earliest hitobject is used for movement
             // A special case is added for when a click selection occurred before the drag
-            if (!clickSelectionBegan && !selectionHandler.SelectedBlueprints.Any(b => b.IsHovered))
+            if (!clickSelectionBegan && !SelectionHandler.SelectedBlueprints.Any(b => b.IsHovered))
                 return;
 
             // Movement is tracked from the blueprint of the earliest hitobject, since it only makes sense to distance snap from that hitobject
-            movementBlueprint = selectionHandler.SelectedBlueprints.OrderBy(b => b.HitObject.StartTime).First();
-            movementBlueprintOriginalPosition = movementBlueprint.SelectionPoint; // todo: unsure if correct
+            movementBlueprints = SelectionHandler.SelectedBlueprints.OrderBy(b => b.HitObject.StartTime).ToArray();
+            movementBlueprintOriginalPositions = movementBlueprints.Select(m => m.ScreenSpaceSelectionPoint).ToArray();
         }
 
         /// <summary>
@@ -380,26 +453,50 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <returns>Whether a movement was active.</returns>
         private bool moveCurrentSelection(DragEvent e)
         {
-            if (movementBlueprint == null)
+            if (movementBlueprints == null)
                 return false;
 
-            Debug.Assert(movementBlueprintOriginalPosition != null);
-
-            HitObject draggedObject = movementBlueprint.HitObject;
-
-            // The final movement position, relative to screenSpaceMovementStartPosition
-            Vector2 movePosition = movementBlueprintOriginalPosition.Value + e.ScreenSpaceMousePosition - e.ScreenSpaceMouseDownPosition;
-
-            (Vector2 snappedPosition, double snappedTime) = snapProvider.GetSnappedPosition(ToLocalSpace(movePosition), draggedObject.StartTime);
-
-            // Move the hitobjects
-            if (!selectionHandler.HandleMovement(new MoveSelectionEvent(movementBlueprint, ToScreenSpace(snappedPosition))))
+            if (snapProvider == null)
                 return true;
 
-            // Apply the start time at the newly snapped-to position
-            double offset = snappedTime - draggedObject.StartTime;
-            foreach (HitObject obj in selectionHandler.SelectedHitObjects)
-                obj.StartTime += offset;
+            Debug.Assert(movementBlueprintOriginalPositions != null);
+
+            Vector2 distanceTravelled = e.ScreenSpaceMousePosition - e.ScreenSpaceMouseDownPosition;
+
+            // check for positional snap for every object in selection (for things like object-object snapping)
+            for (var i = 0; i < movementBlueprintOriginalPositions.Length; i++)
+            {
+                var testPosition = movementBlueprintOriginalPositions[i] + distanceTravelled;
+
+                var positionalResult = snapProvider.SnapScreenSpacePositionToValidPosition(testPosition);
+
+                if (positionalResult.ScreenSpacePosition == testPosition) continue;
+
+                // attempt to move the objects, and abort any time based snapping if we can.
+                if (SelectionHandler.HandleMovement(new MoveSelectionEvent(movementBlueprints[i], positionalResult.ScreenSpacePosition)))
+                    return true;
+            }
+
+            // if no positional snapping could be performed, try unrestricted snapping from the earliest
+            // hitobject in the selection.
+
+            // The final movement position, relative to movementBlueprintOriginalPosition.
+            Vector2 movePosition = movementBlueprintOriginalPositions.First() + distanceTravelled;
+
+            // Retrieve a snapped position.
+            var result = snapProvider.SnapScreenSpacePositionToValidTime(movePosition);
+
+            // Move the hitobjects.
+            if (!SelectionHandler.HandleMovement(new MoveSelectionEvent(movementBlueprints.First(), result.ScreenSpacePosition)))
+                return true;
+
+            if (result.Time.HasValue)
+            {
+                // Apply the start time at the newly snapped-to position
+                double offset = result.Time.Value - movementBlueprints.First().HitObject.StartTime;
+
+                Beatmap.PerformOnSelection(obj => obj.StartTime += offset);
+            }
 
             return true;
         }
@@ -410,11 +507,11 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <returns>Whether a movement was active.</returns>
         private bool finishSelectionMovement()
         {
-            if (movementBlueprint == null)
+            if (movementBlueprints == null)
                 return false;
 
-            movementBlueprintOriginalPosition = null;
-            movementBlueprint = null;
+            movementBlueprintOriginalPositions = null;
+            movementBlueprints = null;
 
             return true;
         }
@@ -425,10 +522,16 @@ namespace osu.Game.Screens.Edit.Compose.Components
         {
             base.Dispose(isDisposing);
 
-            if (beatmap != null)
+            if (Beatmap != null)
             {
-                beatmap.HitObjectAdded -= AddBlueprintFor;
-                beatmap.HitObjectRemoved -= removeBlueprintFor;
+                Beatmap.HitObjectAdded -= addBlueprintFor;
+                Beatmap.HitObjectRemoved -= removeBlueprintFor;
+            }
+
+            if (Composer != null)
+            {
+                Composer.Playfield.HitObjectUsageBegan -= addBlueprintFor;
+                Composer.Playfield.HitObjectUsageFinished -= removeBlueprintFor;
             }
         }
     }

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

@@ -3,14 +3,21 @@
 
 using System.Collections.Generic;
 using System.Linq;
+using Humanizer;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
 using osu.Framework.Input;
+using osu.Game.Audio;
+using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Edit.Tools;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.Objects.Types;
+using osu.Game.Screens.Edit.Components.TernaryButtons;
 using osuTK;
 
 namespace osu.Game.Screens.Edit.Compose.Components
@@ -20,21 +27,16 @@ namespace osu.Game.Screens.Edit.Compose.Components
     /// </summary>
     public class ComposeBlueprintContainer : BlueprintContainer
     {
-        [Resolved]
-        private HitObjectComposer composer { get; set; }
-
-        private PlacementBlueprint currentPlacement;
+        public override bool ReceivePositionalInputAt(Vector2 screenSpacePos) => true;
 
         private readonly Container<PlacementBlueprint> placementBlueprintContainer;
 
+        private PlacementBlueprint currentPlacement;
         private InputManager inputManager;
 
-        private readonly IEnumerable<DrawableHitObject> drawableHitObjects;
-
-        public ComposeBlueprintContainer(IEnumerable<DrawableHitObject> drawableHitObjects)
+        public ComposeBlueprintContainer(HitObjectComposer composer)
+            : base(composer)
         {
-            this.drawableHitObjects = drawableHitObjects;
-
             placementBlueprintContainer = new Container<PlacementBlueprint>
             {
                 RelativeSizeAxes = Axes.Both
@@ -44,6 +46,8 @@ namespace osu.Game.Screens.Edit.Compose.Components
         [BackgroundDependencyLoader]
         private void load()
         {
+            TernaryStates = CreateTernaryButtons().ToArray();
+
             AddInternal(placementBlueprintContainer);
         }
 
@@ -52,6 +56,90 @@ namespace osu.Game.Screens.Edit.Compose.Components
             base.LoadComplete();
 
             inputManager = GetContainingInputManager();
+
+            // updates to selected are handled for us by SelectionHandler.
+            NewCombo.BindTo(SelectionHandler.SelectionNewComboState);
+
+            // we are responsible for current placement blueprint updated based on state changes.
+            NewCombo.ValueChanged += _ => updatePlacementNewCombo();
+
+            // we own SelectionHandler so don't need to worry about making bindable copies (for simplicity)
+            foreach (var kvp in SelectionHandler.SelectionSampleStates)
+            {
+                kvp.Value.BindValueChanged(_ => updatePlacementSamples());
+            }
+        }
+
+        private void updatePlacementNewCombo()
+        {
+            if (currentPlacement?.HitObject is IHasComboInformation c)
+                c.NewCombo = NewCombo.Value == TernaryState.True;
+        }
+
+        private void updatePlacementSamples()
+        {
+            if (currentPlacement == null) return;
+
+            foreach (var kvp in SelectionHandler.SelectionSampleStates)
+                sampleChanged(kvp.Key, kvp.Value.Value);
+        }
+
+        private void sampleChanged(string sampleName, TernaryState state)
+        {
+            if (currentPlacement == null) return;
+
+            var samples = currentPlacement.HitObject.Samples;
+
+            var existingSample = samples.FirstOrDefault(s => s.Name == sampleName);
+
+            switch (state)
+            {
+                case TernaryState.False:
+                    if (existingSample != null)
+                        samples.Remove(existingSample);
+                    break;
+
+                case TernaryState.True:
+                    if (existingSample == null)
+                        samples.Add(new HitSampleInfo(sampleName));
+                    break;
+            }
+        }
+
+        public readonly Bindable<TernaryState> NewCombo = new Bindable<TernaryState> { Description = "New Combo" };
+
+        /// <summary>
+        /// A collection of states which will be displayed to the user in the toolbox.
+        /// </summary>
+        public TernaryButton[] TernaryStates { get; private set; }
+
+        /// <summary>
+        /// Create all ternary states required to be displayed to the user.
+        /// </summary>
+        protected virtual IEnumerable<TernaryButton> CreateTernaryButtons()
+        {
+            //TODO: this should only be enabled (visible?) for rulesets that provide combo-supporting HitObjects.
+            yield return new TernaryButton(NewCombo, "New combo", () => new SpriteIcon { Icon = FontAwesome.Regular.DotCircle });
+
+            foreach (var kvp in SelectionHandler.SelectionSampleStates)
+                yield return new TernaryButton(kvp.Value, kvp.Key.Replace("hit", string.Empty).Titleize(), () => getIconForSample(kvp.Key));
+        }
+
+        private Drawable getIconForSample(string sampleName)
+        {
+            switch (sampleName)
+            {
+                case HitSampleInfo.HIT_CLAP:
+                    return new SpriteIcon { Icon = FontAwesome.Solid.Hands };
+
+                case HitSampleInfo.HIT_WHISTLE:
+                    return new SpriteIcon { Icon = FontAwesome.Solid.Bullhorn };
+
+                case HitSampleInfo.HIT_FINISH:
+                    return new SpriteIcon { Icon = FontAwesome.Solid.DrumSteelpan };
+            }
+
+            return null;
         }
 
         #region Placement
@@ -65,12 +153,14 @@ namespace osu.Game.Screens.Edit.Compose.Components
             createPlacement();
         }
 
-        private void updatePlacementPosition(Vector2 screenSpacePosition)
+        private void updatePlacementPosition()
         {
-            Vector2 snappedGridPosition = composer.GetSnappedPosition(ToLocalSpace(screenSpacePosition), 0).position;
-            Vector2 snappedScreenSpacePosition = ToScreenSpace(snappedGridPosition);
+            var snapResult = Composer.SnapScreenSpacePositionToValidTime(inputManager.CurrentState.Mouse.Position);
 
-            currentPlacement.UpdatePosition(snappedScreenSpacePosition);
+            // if no time was found from positional snapping, we should still quantize to the beat.
+            snapResult.Time ??= Beatmap.SnapTime(EditorClock.CurrentTime, null);
+
+            currentPlacement.UpdateTimeAndPosition(snapResult);
         }
 
         #endregion
@@ -79,18 +169,20 @@ namespace osu.Game.Screens.Edit.Compose.Components
         {
             base.Update();
 
-            if (composer.CursorInPlacementArea)
+            if (Composer.CursorInPlacementArea)
                 createPlacement();
             else if (currentPlacement?.PlacementActive == false)
                 removePlacement();
 
             if (currentPlacement != null)
-                updatePlacementPosition(inputManager.CurrentState.Mouse.Position);
+            {
+                updatePlacementPosition();
+            }
         }
 
         protected sealed override SelectionBlueprint CreateBlueprintFor(HitObject hitObject)
         {
-            var drawable = drawableHitObjects.FirstOrDefault(d => d.HitObject == hitObject);
+            var drawable = Composer.HitObjects.FirstOrDefault(d => d.HitObject == hitObject);
 
             if (drawable == null)
                 return null;
@@ -100,10 +192,15 @@ namespace osu.Game.Screens.Edit.Compose.Components
 
         public virtual OverlaySelectionBlueprint CreateBlueprintFor(DrawableHitObject hitObject) => null;
 
-        protected override void AddBlueprintFor(HitObject hitObject)
+        protected override void OnBlueprintAdded(HitObject hitObject)
         {
+            base.OnBlueprintAdded(hitObject);
+
             refreshTool();
-            base.AddBlueprintFor(hitObject);
+
+            // on successful placement, the new combo button should be reset as this is the most common user interaction.
+            if (Beatmap.SelectedHitObjects.Count == 0)
+                NewCombo.Value = TernaryState.False;
         }
 
         private void createPlacement()
@@ -117,7 +214,11 @@ namespace osu.Game.Screens.Edit.Compose.Components
                 placementBlueprintContainer.Child = currentPlacement = blueprint;
 
                 // Fixes a 1-frame position discrepancy due to the first mouse move event happening in the next frame
-                updatePlacementPosition(inputManager.CurrentState.Mouse.Position);
+                updatePlacementPosition();
+
+                updatePlacementSamples();
+
+                updatePlacementNewCombo();
             }
         }
 

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

@@ -43,7 +43,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
         protected OsuColour Colours { get; private set; }
 
         [Resolved]
-        protected IDistanceSnapProvider SnapProvider { get; private set; }
+        protected IPositionSnapProvider SnapProvider { get; private set; }
 
         [Resolved]
         private EditorBeatmap beatmap { get; set; }

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

@@ -45,7 +45,7 @@ namespace osu.Game.Screens.Edit.Compose.Components
         {
             Masking = true,
             BorderColour = Color4.White,
-            BorderThickness = SelectionHandler.BORDER_RADIUS,
+            BorderThickness = SelectionBox.BORDER_RADIUS,
             Child = new Box
             {
                 RelativeSizeAxes = Axes.Both,
@@ -53,6 +53,8 @@ namespace osu.Game.Screens.Edit.Compose.Components
             }
         };
 
+        private RectangleF? dragRectangle;
+
         /// <summary>
         /// Handle a forwarded mouse event.
         /// </summary>
@@ -66,15 +68,14 @@ namespace osu.Game.Screens.Edit.Compose.Components
             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 rec = dragQuad.AABBFloat;
+            dragRectangle = rec;
 
-            var topLeft = ToLocalSpace(dragRectangle.TopLeft);
-            var bottomRight = ToLocalSpace(dragRectangle.BottomRight);
+            var topLeft = ToLocalSpace(rec.TopLeft);
+            var bottomRight = ToLocalSpace(rec.BottomRight);
 
             Box.Position = topLeft;
             Box.Size = bottomRight - topLeft;
-
-            PerformSelection?.Invoke(dragRectangle);
             return true;
         }
 
@@ -93,7 +94,19 @@ namespace osu.Game.Screens.Edit.Compose.Components
             }
         }
 
-        public override void Hide() => State = Visibility.Hidden;
+        protected override void Update()
+        {
+            base.Update();
+
+            if (dragRectangle != null)
+                PerformSelection?.Invoke(dragRectangle.Value);
+        }
+
+        public override void Hide()
+        {
+            State = Visibility.Hidden;
+            dragRectangle = null;
+        }
 
         public override void Show() => State = Visibility.Visible;
 

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

@@ -1,32 +0,0 @@
-// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
-// See the LICENCE file in the repository root for full licence text.
-
-using osu.Framework.Graphics;
-using osu.Framework.Graphics.Containers;
-using osu.Framework.Graphics.Shapes;
-using osuTK.Graphics;
-
-namespace osu.Game.Screens.Edit.Compose.Components
-{
-    /// <summary>
-    /// Provides a border around the playfield.
-    /// </summary>
-    public class EditorPlayfieldBorder : CompositeDrawable
-    {
-        public EditorPlayfieldBorder()
-        {
-            RelativeSizeAxes = Axes.Both;
-
-            Masking = true;
-            BorderColour = Color4.White;
-            BorderThickness = 2;
-
-            InternalChild = new Box
-            {
-                RelativeSizeAxes = Axes.Both,
-                Alpha = 0,
-                AlwaysPresent = true
-            };
-        }
-    }
-}

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

@@ -0,0 +1,77 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Generic;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Rulesets.Edit;
+using osu.Game.Rulesets.Objects;
+
+namespace osu.Game.Screens.Edit.Compose.Components
+{
+    /// <summary>
+    /// A container for <see cref="SelectionBlueprint"/> ordered by their <see cref="HitObject"/> start times.
+    /// </summary>
+    public sealed class HitObjectOrderedSelectionContainer : Container<SelectionBlueprint>
+    {
+        public override void Add(SelectionBlueprint drawable)
+        {
+            base.Add(drawable);
+            bindStartTime(drawable);
+        }
+
+        public override bool Remove(SelectionBlueprint drawable)
+        {
+            if (!base.Remove(drawable))
+                return false;
+
+            unbindStartTime(drawable);
+            return true;
+        }
+
+        public override void Clear(bool disposeChildren)
+        {
+            base.Clear(disposeChildren);
+            unbindAllStartTimes();
+        }
+
+        private readonly Dictionary<SelectionBlueprint, IBindable> startTimeMap = new Dictionary<SelectionBlueprint, IBindable>();
+
+        private void bindStartTime(SelectionBlueprint blueprint)
+        {
+            var bindable = blueprint.HitObject.StartTimeBindable.GetBoundCopy();
+
+            bindable.BindValueChanged(_ =>
+            {
+                if (LoadState >= LoadState.Ready)
+                    SortInternal();
+            });
+
+            startTimeMap[blueprint] = bindable;
+        }
+
+        private void unbindStartTime(SelectionBlueprint blueprint)
+        {
+            startTimeMap[blueprint].UnbindAll();
+            startTimeMap.Remove(blueprint);
+        }
+
+        private void unbindAllStartTimes()
+        {
+            foreach (var kvp in startTimeMap)
+                kvp.Value.UnbindAll();
+            startTimeMap.Clear();
+        }
+
+        protected override int Compare(Drawable x, Drawable y)
+        {
+            var xObj = (SelectionBlueprint)x;
+            var yObj = (SelectionBlueprint)y;
+
+            // Put earlier blueprints towards the end of the list, so they handle input first
+            int i = yObj.HitObject.StartTime.CompareTo(xObj.HitObject.StartTime);
+            return i == 0 ? CompareReverseChildID(x, y) : i;
+        }
+    }
+}

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

@@ -0,0 +1,273 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Input.Events;
+using osu.Game.Graphics;
+using osuTK;
+using osuTK.Input;
+
+namespace osu.Game.Screens.Edit.Compose.Components
+{
+    public class SelectionBox : CompositeDrawable
+    {
+        public Func<float, bool> OnRotation;
+        public Func<Vector2, Anchor, bool> OnScale;
+        public Func<Direction, bool> OnFlip;
+        public Func<bool> OnReverse;
+
+        public Action OperationStarted;
+        public Action OperationEnded;
+
+        private bool canReverse;
+
+        /// <summary>
+        /// Whether pattern reversing support should be enabled.
+        /// </summary>
+        public bool CanReverse
+        {
+            get => canReverse;
+            set
+            {
+                if (canReverse == value) return;
+
+                canReverse = value;
+                recreate();
+            }
+        }
+
+        private bool canRotate;
+
+        /// <summary>
+        /// Whether rotation support should be enabled.
+        /// </summary>
+        public bool CanRotate
+        {
+            get => canRotate;
+            set
+            {
+                if (canRotate == value) return;
+
+                canRotate = value;
+                recreate();
+            }
+        }
+
+        private bool canScaleX;
+
+        /// <summary>
+        /// Whether vertical scale support should be enabled.
+        /// </summary>
+        public bool CanScaleX
+        {
+            get => canScaleX;
+            set
+            {
+                if (canScaleX == value) return;
+
+                canScaleX = value;
+                recreate();
+            }
+        }
+
+        private bool canScaleY;
+
+        /// <summary>
+        /// Whether horizontal scale support should be enabled.
+        /// </summary>
+        public bool CanScaleY
+        {
+            get => canScaleY;
+            set
+            {
+                if (canScaleY == value) return;
+
+                canScaleY = value;
+                recreate();
+            }
+        }
+
+        private Container dragHandles;
+        private FillFlowContainer buttons;
+
+        public const float BORDER_RADIUS = 3;
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            RelativeSizeAxes = Axes.Both;
+
+            recreate();
+        }
+
+        protected override bool OnKeyDown(KeyDownEvent e)
+        {
+            if (e.Repeat || !e.ControlPressed)
+                return false;
+
+            switch (e.Key)
+            {
+                case Key.G:
+                    return CanReverse && OnReverse?.Invoke() == true;
+
+                case Key.H:
+                    return CanScaleX && OnFlip?.Invoke(Direction.Horizontal) == true;
+
+                case Key.J:
+                    return CanScaleY && OnFlip?.Invoke(Direction.Vertical) == true;
+            }
+
+            return base.OnKeyDown(e);
+        }
+
+        private void recreate()
+        {
+            if (LoadState < LoadState.Loading)
+                return;
+
+            InternalChildren = new Drawable[]
+            {
+                new Container
+                {
+                    Masking = true,
+                    BorderThickness = BORDER_RADIUS,
+                    BorderColour = colours.YellowDark,
+                    RelativeSizeAxes = Axes.Both,
+                    Children = new Drawable[]
+                    {
+                        new Box
+                        {
+                            RelativeSizeAxes = Axes.Both,
+
+                            AlwaysPresent = true,
+                            Alpha = 0
+                        },
+                    }
+                },
+                dragHandles = new Container
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    // ensures that the centres of all drag handles line up with the middle of the selection box border.
+                    Padding = new MarginPadding(BORDER_RADIUS / 2)
+                },
+                buttons = new FillFlowContainer
+                {
+                    Y = 20,
+                    AutoSizeAxes = Axes.Both,
+                    Direction = FillDirection.Horizontal,
+                    Anchor = Anchor.BottomCentre,
+                    Origin = Anchor.Centre
+                }
+            };
+
+            if (CanScaleX) addXScaleComponents();
+            if (CanScaleX && CanScaleY) addFullScaleComponents();
+            if (CanScaleY) addYScaleComponents();
+            if (CanRotate) addRotationComponents();
+            if (CanReverse) addButton(FontAwesome.Solid.Backward, "Reverse pattern (Ctrl-G)", () => OnReverse?.Invoke());
+        }
+
+        private void addRotationComponents()
+        {
+            const float separation = 40;
+
+            addButton(FontAwesome.Solid.Undo, "Rotate 90 degrees counter-clockwise", () => OnRotation?.Invoke(-90));
+            addButton(FontAwesome.Solid.Redo, "Rotate 90 degrees clockwise", () => OnRotation?.Invoke(90));
+
+            AddRangeInternal(new Drawable[]
+            {
+                new Box
+                {
+                    Depth = float.MaxValue,
+                    Colour = colours.YellowLight,
+                    Blending = BlendingParameters.Additive,
+                    Alpha = 0.3f,
+                    Size = new Vector2(BORDER_RADIUS, separation),
+                    Anchor = Anchor.TopCentre,
+                    Origin = Anchor.BottomCentre,
+                },
+                new SelectionBoxDragHandleButton(FontAwesome.Solid.Redo, "Free rotate")
+                {
+                    Anchor = Anchor.TopCentre,
+                    Y = -separation,
+                    HandleDrag = e => OnRotation?.Invoke(convertDragEventToAngleOfRotation(e)),
+                    OperationStarted = operationStarted,
+                    OperationEnded = operationEnded
+                }
+            });
+        }
+
+        private void addYScaleComponents()
+        {
+            addButton(FontAwesome.Solid.ArrowsAltV, "Flip vertically (Ctrl-J)", () => OnFlip?.Invoke(Direction.Vertical));
+
+            addDragHandle(Anchor.TopCentre);
+            addDragHandle(Anchor.BottomCentre);
+        }
+
+        private void addFullScaleComponents()
+        {
+            addDragHandle(Anchor.TopLeft);
+            addDragHandle(Anchor.TopRight);
+            addDragHandle(Anchor.BottomLeft);
+            addDragHandle(Anchor.BottomRight);
+        }
+
+        private void addXScaleComponents()
+        {
+            addButton(FontAwesome.Solid.ArrowsAltH, "Flip horizontally (Ctrl-H)", () => OnFlip?.Invoke(Direction.Horizontal));
+
+            addDragHandle(Anchor.CentreLeft);
+            addDragHandle(Anchor.CentreRight);
+        }
+
+        private void addButton(IconUsage icon, string tooltip, Action action)
+        {
+            buttons.Add(new SelectionBoxDragHandleButton(icon, tooltip)
+            {
+                OperationStarted = operationStarted,
+                OperationEnded = operationEnded,
+                Action = action
+            });
+        }
+
+        private void addDragHandle(Anchor anchor) => dragHandles.Add(new SelectionBoxDragHandle
+        {
+            Anchor = anchor,
+            HandleDrag = e => OnScale?.Invoke(e.Delta, anchor),
+            OperationStarted = operationStarted,
+            OperationEnded = operationEnded
+        });
+
+        private int activeOperations;
+
+        private float convertDragEventToAngleOfRotation(DragEvent e)
+        {
+            // Adjust coordinate system to the center of SelectionBox
+            float startAngle = MathF.Atan2(e.LastMousePosition.Y - DrawHeight / 2, e.LastMousePosition.X - DrawWidth / 2);
+            float endAngle = MathF.Atan2(e.MousePosition.Y - DrawHeight / 2, e.MousePosition.X - DrawWidth / 2);
+
+            return (endAngle - startAngle) * 180 / MathF.PI;
+        }
+
+        private void operationEnded()
+        {
+            if (--activeOperations == 0)
+                OperationEnded?.Invoke();
+        }
+
+        private void operationStarted()
+        {
+            if (activeOperations++ == 0)
+                OperationStarted?.Invoke();
+        }
+    }
+}

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

@@ -0,0 +1,105 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input.Events;
+using osu.Game.Graphics;
+using osuTK;
+
+namespace osu.Game.Screens.Edit.Compose.Components
+{
+    public class SelectionBoxDragHandle : Container
+    {
+        public Action OperationStarted;
+        public Action OperationEnded;
+
+        public Action<DragEvent> HandleDrag { get; set; }
+
+        private Circle circle;
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            Size = new Vector2(10);
+            Origin = Anchor.Centre;
+
+            InternalChildren = new Drawable[]
+            {
+                circle = new Circle
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Anchor = Anchor.Centre,
+                    Origin = Anchor.Centre,
+                },
+            };
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+            UpdateHoverState();
+        }
+
+        protected override bool OnHover(HoverEvent e)
+        {
+            UpdateHoverState();
+            return base.OnHover(e);
+        }
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            base.OnHoverLost(e);
+            UpdateHoverState();
+        }
+
+        protected bool HandlingMouse;
+
+        protected override bool OnMouseDown(MouseDownEvent e)
+        {
+            HandlingMouse = true;
+            UpdateHoverState();
+            return true;
+        }
+
+        protected override bool OnDragStart(DragStartEvent e)
+        {
+            OperationStarted?.Invoke();
+            return true;
+        }
+
+        protected override void OnDrag(DragEvent e)
+        {
+            HandleDrag?.Invoke(e);
+            base.OnDrag(e);
+        }
+
+        protected override void OnDragEnd(DragEndEvent e)
+        {
+            HandlingMouse = false;
+            OperationEnded?.Invoke();
+
+            UpdateHoverState();
+            base.OnDragEnd(e);
+        }
+
+        protected override void OnMouseUp(MouseUpEvent e)
+        {
+            HandlingMouse = false;
+            UpdateHoverState();
+            base.OnMouseUp(e);
+        }
+
+        protected virtual void UpdateHoverState()
+        {
+            circle.Colour = HandlingMouse ? colours.GrayF : (IsHovered ? colours.Red : colours.YellowDark);
+            this.ScaleTo(HandlingMouse || IsHovered ? 1.5f : 1, 100, Easing.OutQuint);
+        }
+    }
+}

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

@@ -0,0 +1,66 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System;
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Cursor;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Input.Events;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Screens.Edit.Compose.Components
+{
+    /// <summary>
+    /// A drag "handle" which shares the visual appearance but behaves more like a clickable button.
+    /// </summary>
+    public sealed class SelectionBoxDragHandleButton : SelectionBoxDragHandle, IHasTooltip
+    {
+        private SpriteIcon icon;
+
+        private readonly IconUsage iconUsage;
+
+        public Action Action;
+
+        public SelectionBoxDragHandleButton(IconUsage iconUsage, string tooltip)
+        {
+            this.iconUsage = iconUsage;
+
+            TooltipText = tooltip;
+
+            Anchor = Anchor.Centre;
+            Origin = Anchor.Centre;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            Size *= 2;
+            AddInternal(icon = new SpriteIcon
+            {
+                RelativeSizeAxes = Axes.Both,
+                Size = new Vector2(0.5f),
+                Icon = iconUsage,
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+            });
+        }
+
+        protected override bool OnClick(ClickEvent e)
+        {
+            OperationStarted?.Invoke();
+            Action?.Invoke();
+            OperationEnded?.Invoke();
+            return true;
+        }
+
+        protected override void UpdateHoverState()
+        {
+            base.UpdateHoverState();
+            icon.Colour = !HandlingMouse && IsHovered ? Color4.White : Color4.Black;
+        }
+
+        public string TooltipText { get; }
+    }
+}

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

@@ -4,7 +4,9 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Humanizer;
 using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Cursor;
@@ -12,14 +14,17 @@ using osu.Framework.Graphics.Shapes;
 using osu.Framework.Graphics.UserInterface;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
-using osu.Framework.Input.States;
+using osu.Framework.Input.Events;
 using osu.Game.Audio;
 using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Drawables;
+using osu.Game.Rulesets.Objects.Types;
 using osuTK;
+using osuTK.Input;
 
 namespace osu.Game.Screens.Edit.Compose.Components
 {
@@ -28,17 +33,22 @@ namespace osu.Game.Screens.Edit.Compose.Components
     /// </summary>
     public class SelectionHandler : CompositeDrawable, IKeyBindingHandler<PlatformAction>, IHasContextMenu
     {
-        public const float BORDER_RADIUS = 2;
-
         public IEnumerable<SelectionBlueprint> SelectedBlueprints => selectedBlueprints;
         private readonly List<SelectionBlueprint> selectedBlueprints;
 
-        public IEnumerable<HitObject> SelectedHitObjects => selectedBlueprints.Select(b => b.HitObject);
+        public int SelectedCount => selectedBlueprints.Count;
 
-        private Drawable outline;
+        private Drawable content;
+
+        private OsuSpriteText selectionDetailsText;
+
+        protected SelectionBox SelectionBox { get; private set; }
+
+        [Resolved]
+        protected EditorBeatmap EditorBeatmap { get; private set; }
 
         [Resolved(CanBeNull = true)]
-        private EditorBeatmap editorBeatmap { get; set; }
+        protected IEditorChangeHandler ChangeHandler { get; private set; }
 
         public SelectionHandler()
         {
@@ -52,29 +62,109 @@ namespace osu.Game.Screens.Edit.Compose.Components
         [BackgroundDependencyLoader]
         private void load(OsuColour colours)
         {
-            InternalChild = outline = new Container
+            createStateBindables();
+
+            InternalChild = content = new Container
             {
-                Masking = true,
-                BorderThickness = BORDER_RADIUS,
-                BorderColour = colours.Yellow,
-                Child = new Box
+                Children = new Drawable[]
                 {
-                    RelativeSizeAxes = Axes.Both,
-                    AlwaysPresent = true,
-                    Alpha = 0
+                    // todo: should maybe be inside the SelectionBox?
+                    new Container
+                    {
+                        Name = "info text",
+                        AutoSizeAxes = Axes.Both,
+                        Children = new Drawable[]
+                        {
+                            new Box
+                            {
+                                Colour = colours.YellowDark,
+                                RelativeSizeAxes = Axes.Both,
+                            },
+                            selectionDetailsText = new OsuSpriteText
+                            {
+                                Padding = new MarginPadding(2),
+                                Colour = colours.Gray0,
+                                Font = OsuFont.Default.With(size: 11)
+                            }
+                        }
+                    },
+                    SelectionBox = CreateSelectionBox(),
                 }
             };
         }
 
+        public SelectionBox CreateSelectionBox()
+            => new SelectionBox
+            {
+                OperationStarted = OnOperationBegan,
+                OperationEnded = OnOperationEnded,
+
+                OnRotation = HandleRotation,
+                OnScale = HandleScale,
+                OnFlip = HandleFlip,
+                OnReverse = HandleReverse,
+            };
+
+        /// <summary>
+        /// Fired when a drag operation ends from the selection box.
+        /// </summary>
+        protected virtual void OnOperationBegan()
+        {
+            ChangeHandler?.BeginChange();
+        }
+
+        /// <summary>
+        /// Fired when a drag operation begins from the selection box.
+        /// </summary>
+        protected virtual void OnOperationEnded()
+        {
+            ChangeHandler?.EndChange();
+        }
+
         #region User Input Handling
 
         /// <summary>
         /// Handles the selected <see cref="DrawableHitObject"/>s being moved.
         /// </summary>
+        /// <remarks>
+        /// Just returning true is enough to allow <see cref="HitObject.StartTime"/> updates to take place.
+        /// Custom implementation is only required if other attributes are to be considered, like changing columns.
+        /// </remarks>
         /// <param name="moveEvent">The move event.</param>
-        /// <returns>Whether any <see cref="DrawableHitObject"/>s were moved.</returns>
+        /// <returns>
+        /// Whether any <see cref="DrawableHitObject"/>s could be moved.
+        /// Returning true will also propagate StartTime changes provided by the closest <see cref="IPositionSnapProvider.SnapScreenSpacePositionToValidTime"/>.
+        /// </returns>
         public virtual bool HandleMovement(MoveSelectionEvent moveEvent) => false;
 
+        /// <summary>
+        /// Handles the selected <see cref="DrawableHitObject"/>s being rotated.
+        /// </summary>
+        /// <param name="angle">The delta angle to apply to the selection.</param>
+        /// <returns>Whether any <see cref="DrawableHitObject"/>s could be rotated.</returns>
+        public virtual bool HandleRotation(float angle) => false;
+
+        /// <summary>
+        /// Handles the selected <see cref="DrawableHitObject"/>s being scaled.
+        /// </summary>
+        /// <param name="scale">The delta scale to apply, in playfield local coordinates.</param>
+        /// <param name="anchor">The point of reference where the scale is originating from.</param>
+        /// <returns>Whether any <see cref="DrawableHitObject"/>s could be scaled.</returns>
+        public virtual bool HandleScale(Vector2 scale, Anchor anchor) => false;
+
+        /// <summary>
+        /// Handles the selected <see cref="DrawableHitObject"/>s being flipped.
+        /// </summary>
+        /// <param name="direction">The direction to flip</param>
+        /// <returns>Whether any <see cref="DrawableHitObject"/>s could be flipped.</returns>
+        public virtual bool HandleFlip(Direction direction) => false;
+
+        /// <summary>
+        /// Handles the selected <see cref="DrawableHitObject"/>s being reversed pattern-wise.
+        /// </summary>
+        /// <returns>Whether any <see cref="DrawableHitObject"/>s could be reversed.</returns>
+        public virtual bool HandleReverse() => false;
+
         public bool OnPressed(PlatformAction action)
         {
             switch (action.ActionMethod)
@@ -107,9 +197,10 @@ namespace osu.Game.Screens.Edit.Compose.Components
         internal void HandleSelected(SelectionBlueprint blueprint)
         {
             selectedBlueprints.Add(blueprint);
-            editorBeatmap.SelectedHitObjects.Add(blueprint.HitObject);
 
-            UpdateVisibility();
+            // there are potentially multiple SelectionHandlers active, but we only want to add hitobjects to the selected list once.
+            if (!EditorBeatmap.SelectedHitObjects.Contains(blueprint.HitObject))
+                EditorBeatmap.SelectedHitObjects.Add(blueprint.HitObject);
         }
 
         /// <summary>
@@ -119,41 +210,55 @@ namespace osu.Game.Screens.Edit.Compose.Components
         internal void HandleDeselected(SelectionBlueprint blueprint)
         {
             selectedBlueprints.Remove(blueprint);
-            editorBeatmap.SelectedHitObjects.Remove(blueprint.HitObject);
 
-            // We don't want to update visibility if > 0, since we may be deselecting blueprints during drag-selection
-            if (selectedBlueprints.Count == 0)
-                UpdateVisibility();
+            EditorBeatmap.SelectedHitObjects.Remove(blueprint.HitObject);
         }
 
         /// <summary>
         /// Handle a blueprint requesting selection.
         /// </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)
+        /// <param name="e">The mouse event responsible for selection.</param>
+        /// <returns>Whether a selection was performed.</returns>
+        internal bool HandleSelectionRequested(SelectionBlueprint blueprint, MouseButtonEvent e)
         {
-            if (state.Keyboard.ControlPressed)
+            if (e.ShiftPressed && e.Button == MouseButton.Right)
             {
-                if (blueprint.IsSelected)
-                    blueprint.Deselect();
-                else
-                    blueprint.Select();
+                handleQuickDeletion(blueprint);
+                return false;
             }
-            else
-            {
-                if (blueprint.IsSelected)
-                    return;
 
-                DeselectAll?.Invoke();
-                blueprint.Select();
-            }
+            if (e.ControlPressed && e.Button == MouseButton.Left)
+                blueprint.ToggleSelection();
+            else
+                ensureSelected(blueprint);
+
+            return true;
+        }
+
+        private void handleQuickDeletion(SelectionBlueprint blueprint)
+        {
+            if (blueprint.HandleQuickDeletion())
+                return;
+
+            if (!blueprint.IsSelected)
+                EditorBeatmap.Remove(blueprint.HitObject);
+            else
+                deleteSelected();
+        }
+
+        private void ensureSelected(SelectionBlueprint blueprint)
+        {
+            if (blueprint.IsSelected)
+                return;
+
+            DeselectAll?.Invoke();
+            blueprint.Select();
         }
 
         private void deleteSelected()
         {
-            foreach (var h in selectedBlueprints.ToList())
-                editorBeatmap.Remove(h.HitObject);
+            EditorBeatmap.RemoveRange(selectedBlueprints.Select(b => b.HitObject));
         }
 
         #endregion
@@ -163,12 +268,22 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <summary>
         /// Updates whether this <see cref="SelectionHandler"/> is visible.
         /// </summary>
-        internal void UpdateVisibility()
+        private void updateVisibility()
+        {
+            int count = selectedBlueprints.Count;
+
+            selectionDetailsText.Text = count > 0 ? count.ToString() : string.Empty;
+
+            this.FadeTo(count > 0 ? 1 : 0);
+            OnSelectionChanged();
+        }
+
+        /// <summary>
+        /// Triggered whenever the set of selected objects changes.
+        /// Should update the selection box's state to match supported operations.
+        /// </summary>
+        protected virtual void OnSelectionChanged()
         {
-            if (selectedBlueprints.Count > 0)
-                Show();
-            else
-                Hide();
         }
 
         protected override void Update()
@@ -191,8 +306,8 @@ namespace osu.Game.Screens.Edit.Compose.Components
             topLeft -= new Vector2(5);
             bottomRight += new Vector2(5);
 
-            outline.Size = bottomRight - topLeft;
-            outline.Position = topLeft;
+            content.Size = bottomRight - topLeft;
+            content.Position = topLeft;
         }
 
         #endregion
@@ -205,14 +320,32 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <param name="sampleName">The name of the hit sample.</param>
         public void AddHitSample(string sampleName)
         {
-            foreach (var h in SelectedHitObjects)
+            EditorBeatmap.PerformOnSelection(h =>
             {
                 // Make sure there isn't already an existing sample
                 if (h.Samples.Any(s => s.Name == sampleName))
-                    continue;
+                    return;
 
-                h.Samples.Add(new HitSampleInfo { Name = sampleName });
-            }
+                h.Samples.Add(new HitSampleInfo(sampleName));
+            });
+        }
+
+        /// <summary>
+        /// Set the new combo state of all selected <see cref="HitObject"/>s.
+        /// </summary>
+        /// <param name="state">Whether to set or unset.</param>
+        /// <exception cref="InvalidOperationException">Throws if any selected object doesn't implement <see cref="IHasComboInformation"/></exception>
+        public void SetNewCombo(bool state)
+        {
+            EditorBeatmap.PerformOnSelection(h =>
+            {
+                var comboInfo = h as IHasComboInformation;
+
+                if (comboInfo == null || comboInfo.NewCombo == state) return;
+
+                comboInfo.NewCombo = state;
+                EditorBeatmap.Update(h);
+            });
         }
 
         /// <summary>
@@ -221,76 +354,144 @@ namespace osu.Game.Screens.Edit.Compose.Components
         /// <param name="sampleName">The name of the hit sample.</param>
         public void RemoveHitSample(string sampleName)
         {
-            foreach (var h in SelectedHitObjects)
-                h.SamplesBindable.RemoveAll(s => s.Name == sampleName);
+            EditorBeatmap.PerformOnSelection(h => h.SamplesBindable.RemoveAll(s => s.Name == sampleName));
+        }
+
+        #endregion
+
+        #region Selection State
+
+        /// <summary>
+        /// The state of "new combo" for all selected hitobjects.
+        /// </summary>
+        public readonly Bindable<TernaryState> SelectionNewComboState = new Bindable<TernaryState>();
+
+        /// <summary>
+        /// The state of each sample type for all selected hitobjects. Keys match with <see cref="HitSampleInfo"/> constant specifications.
+        /// </summary>
+        public readonly Dictionary<string, Bindable<TernaryState>> SelectionSampleStates = new Dictionary<string, Bindable<TernaryState>>();
+
+        /// <summary>
+        /// Set up ternary state bindables and bind them to selection/hitobject changes (in both directions)
+        /// </summary>
+        private void createStateBindables()
+        {
+            foreach (var sampleName in HitSampleInfo.AllAdditions)
+            {
+                var bindable = new Bindable<TernaryState>
+                {
+                    Description = sampleName.Replace("hit", string.Empty).Titleize()
+                };
+
+                bindable.ValueChanged += state =>
+                {
+                    switch (state.NewValue)
+                    {
+                        case TernaryState.False:
+                            RemoveHitSample(sampleName);
+                            break;
+
+                        case TernaryState.True:
+                            AddHitSample(sampleName);
+                            break;
+                    }
+                };
+
+                SelectionSampleStates[sampleName] = bindable;
+            }
+
+            // new combo
+            SelectionNewComboState.ValueChanged += state =>
+            {
+                switch (state.NewValue)
+                {
+                    case TernaryState.False:
+                        SetNewCombo(false);
+                        break;
+
+                    case TernaryState.True:
+                        SetNewCombo(true);
+                        break;
+                }
+            };
+
+            // bring in updates from selection changes
+            EditorBeatmap.HitObjectUpdated += _ => Scheduler.AddOnce(UpdateTernaryStates);
+            EditorBeatmap.SelectedHitObjects.CollectionChanged += (sender, args) =>
+            {
+                Scheduler.AddOnce(updateVisibility);
+                Scheduler.AddOnce(UpdateTernaryStates);
+            };
+        }
+
+        /// <summary>
+        /// Called when context menu ternary states may need to be recalculated (selection changed or hitobject updated).
+        /// </summary>
+        protected virtual void UpdateTernaryStates()
+        {
+            SelectionNewComboState.Value = GetStateFromSelection(EditorBeatmap.SelectedHitObjects.OfType<IHasComboInformation>(), h => h.NewCombo);
+
+            foreach (var (sampleName, bindable) in SelectionSampleStates)
+            {
+                bindable.Value = GetStateFromSelection(EditorBeatmap.SelectedHitObjects, h => h.Samples.Any(s => s.Name == sampleName));
+            }
+        }
+
+        /// <summary>
+        /// Given a selection target and a function of truth, retrieve the correct ternary state for display.
+        /// </summary>
+        protected TernaryState GetStateFromSelection<T>(IEnumerable<T> selection, Func<T, bool> func)
+        {
+            if (selection.Any(func))
+                return selection.All(func) ? TernaryState.True : TernaryState.Indeterminate;
+
+            return TernaryState.False;
         }
 
         #endregion
 
         #region Context Menu
 
-        public virtual MenuItem[] ContextMenuItems
+        public MenuItem[] ContextMenuItems
         {
             get
             {
                 if (!selectedBlueprints.Any(b => b.IsHovered))
                     return Array.Empty<MenuItem>();
 
-                var items = new List<MenuItem>
+                var items = new List<MenuItem>();
+
+                items.AddRange(GetContextMenuItemsForSelection(selectedBlueprints));
+
+                if (selectedBlueprints.All(b => b.HitObject is IHasComboInformation))
                 {
-                    new OsuMenuItem("Sound")
-                    {
-                        Items = new[]
-                        {
-                            createHitSampleMenuItem("Whistle", HitSampleInfo.HIT_WHISTLE),
-                            createHitSampleMenuItem("Clap", HitSampleInfo.HIT_CLAP),
-                            createHitSampleMenuItem("Finish", HitSampleInfo.HIT_FINISH)
-                        }
-                    },
-                    new OsuMenuItem("Delete", MenuItemType.Destructive, deleteSelected),
-                };
+                    items.Add(new TernaryStateMenuItem("New combo") { State = { BindTarget = SelectionNewComboState } });
+                }
 
                 if (selectedBlueprints.Count == 1)
                     items.AddRange(selectedBlueprints[0].ContextMenuItems);
 
+                items.AddRange(new[]
+                {
+                    new OsuMenuItem("Sound")
+                    {
+                        Items = SelectionSampleStates.Select(kvp =>
+                            new TernaryStateMenuItem(kvp.Value.Description) { State = { BindTarget = kvp.Value } }).ToArray()
+                    },
+                    new OsuMenuItem("Delete", MenuItemType.Destructive, deleteSelected),
+                });
+
                 return items.ToArray();
             }
         }
 
-        private MenuItem createHitSampleMenuItem(string name, string sampleName)
-        {
-            return new TernaryStateMenuItem(name, MenuItemType.Standard, setHitSampleState)
-            {
-                State = { Value = getHitSampleState() }
-            };
-
-            void setHitSampleState(TernaryState state)
-            {
-                switch (state)
-                {
-                    case TernaryState.False:
-                        RemoveHitSample(sampleName);
-                        break;
-
-                    case TernaryState.True:
-                        AddHitSample(sampleName);
-                        break;
-                }
-            }
-
-            TernaryState getHitSampleState()
-            {
-                int countExisting = SelectedHitObjects.Count(h => h.Samples.Any(s => s.Name == sampleName));
-
-                if (countExisting == 0)
-                    return TernaryState.False;
-
-                if (countExisting < SelectedHitObjects.Count())
-                    return TernaryState.Indeterminate;
-
-                return TernaryState.True;
-            }
-        }
+        /// <summary>
+        /// Provide context menu items relevant to current selection. Calling base is not required.
+        /// </summary>
+        /// <param name="selection">The current selection.</param>
+        /// <returns>The relevant menu items.</returns>
+        protected virtual IEnumerable<MenuItem> GetContextMenuItemsForSelection(IEnumerable<SelectionBlueprint> selection)
+            => Enumerable.Empty<MenuItem>();
 
         #endregion
     }

osu.Game/Screens/Edit/Compose/Components/Timeline/CentreMarker.cs

@@ -12,14 +12,14 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
     public class CentreMarker : CompositeDrawable
     {
-        private const float triangle_width = 20;
+        private const float triangle_width = 15;
         private const float triangle_height = 10;
         private const float bar_width = 2;
 
         public CentreMarker()
         {
             RelativeSizeAxes = Axes.Y;
-            Size = new Vector2(20, 1);
+            Size = new Vector2(triangle_width, 1);
 
             Anchor = Anchor.Centre;
             Origin = Anchor.Centre;
@@ -39,6 +39,12 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                     Origin = Anchor.BottomCentre,
                     Size = new Vector2(triangle_width, triangle_height),
                     Scale = new Vector2(1, -1)
+                },
+                new Triangle
+                {
+                    Anchor = Anchor.BottomCentre,
+                    Origin = Anchor.BottomCentre,
+                    Size = new Vector2(triangle_width, triangle_height),
                 }
             };
         }
@@ -46,7 +52,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
         [BackgroundDependencyLoader]
         private void load(OsuColour colours)
         {
-            Colour = colours.Red;
+            Colour = colours.RedDark;
         }
     }
 }

osu.Game/Screens/Edit/Compose/Components/Timeline/DifficultyPointPiece.cs

@@ -0,0 +1,67 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
+using osuTK.Graphics;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    public class DifficultyPointPiece : CompositeDrawable
+    {
+        private readonly DifficultyControlPoint difficultyPoint;
+
+        private OsuSpriteText speedMultiplierText;
+        private readonly BindableNumber<double> speedMultiplier;
+
+        public DifficultyPointPiece(DifficultyControlPoint difficultyPoint)
+        {
+            this.difficultyPoint = difficultyPoint;
+            speedMultiplier = difficultyPoint.SpeedMultiplierBindable.GetBoundCopy();
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            RelativeSizeAxes = Axes.Y;
+            AutoSizeAxes = Axes.X;
+
+            Color4 colour = difficultyPoint.GetRepresentingColour(colours);
+
+            InternalChildren = new Drawable[]
+            {
+                new Box
+                {
+                    Colour = colour,
+                    Width = 2,
+                    RelativeSizeAxes = Axes.Y,
+                },
+                new Container
+                {
+                    AutoSizeAxes = Axes.Both,
+                    Children = new Drawable[]
+                    {
+                        new Box
+                        {
+                            Colour = colour,
+                            RelativeSizeAxes = Axes.Both,
+                        },
+                        speedMultiplierText = new OsuSpriteText
+                        {
+                            Font = OsuFont.Default.With(weight: FontWeight.Bold),
+                            Colour = Color4.White,
+                        }
+                    }
+                },
+            };
+
+            speedMultiplier.BindValueChanged(multiplier => speedMultiplierText.Text = $"{multiplier.NewValue:n2}x", true);
+        }
+    }
+}

osu.Game/Screens/Edit/Compose/Components/Timeline/SamplePointPiece.cs

@@ -0,0 +1,85 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Colour;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
+using osuTK.Graphics;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    public class SamplePointPiece : CompositeDrawable
+    {
+        private readonly SampleControlPoint samplePoint;
+
+        private readonly Bindable<string> bank;
+        private readonly BindableNumber<int> volume;
+
+        private OsuSpriteText text;
+        private Box volumeBox;
+
+        public SamplePointPiece(SampleControlPoint samplePoint)
+        {
+            this.samplePoint = samplePoint;
+            volume = samplePoint.SampleVolumeBindable.GetBoundCopy();
+            bank = samplePoint.SampleBankBindable.GetBoundCopy();
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            Origin = Anchor.TopLeft;
+            Anchor = Anchor.TopLeft;
+
+            AutoSizeAxes = Axes.X;
+            RelativeSizeAxes = Axes.Y;
+
+            Color4 colour = samplePoint.GetRepresentingColour(colours);
+
+            InternalChildren = new Drawable[]
+            {
+                new Container
+                {
+                    RelativeSizeAxes = Axes.Y,
+                    Width = 20,
+                    Children = new Drawable[]
+                    {
+                        volumeBox = new Box
+                        {
+                            X = 2,
+                            Anchor = Anchor.BottomLeft,
+                            Origin = Anchor.BottomLeft,
+                            Colour = ColourInfo.GradientVertical(colour, Color4.Black),
+                            RelativeSizeAxes = Axes.Both,
+                        },
+                        new Box
+                        {
+                            Colour = colour.Lighten(0.2f),
+                            Width = 2,
+                            RelativeSizeAxes = Axes.Y,
+                        },
+                    }
+                },
+                text = new OsuSpriteText
+                {
+                    X = 2,
+                    Y = -5,
+                    Anchor = Anchor.BottomLeft,
+                    Alpha = 0.9f,
+                    Rotation = -90,
+                    Font = OsuFont.Default.With(weight: FontWeight.SemiBold)
+                }
+            };
+
+            volume.BindValueChanged(volume => volumeBox.Height = volume.NewValue / 100f, true);
+            bank.BindValueChanged(bank => text.Text = bank.NewValue, true);
+        }
+    }
+}

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

@@ -8,65 +8,30 @@ using osu.Framework.Bindables;
 using osu.Framework.Extensions.Color4Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Audio;
+using osu.Framework.Graphics.Containers;
 using osu.Framework.Input.Events;
-using osu.Framework.Timing;
 using osu.Game.Beatmaps;
+using osu.Game.Configuration;
 using osu.Game.Graphics;
 using osu.Game.Rulesets.Edit;
 using osuTK;
 
 namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
-    [Cached(typeof(IDistanceSnapProvider))]
+    [Cached(typeof(IPositionSnapProvider))]
     [Cached]
-    public class Timeline : ZoomableScrollContainer, IDistanceSnapProvider
+    public class Timeline : ZoomableScrollContainer, IPositionSnapProvider
     {
         public readonly Bindable<bool> WaveformVisible = new Bindable<bool>();
+
+        public readonly Bindable<bool> ControlPointsVisible = new Bindable<bool>();
+
+        public readonly Bindable<bool> TicksVisible = new Bindable<bool>();
+
         public readonly IBindable<WorkingBeatmap> Beatmap = new Bindable<WorkingBeatmap>();
 
         [Resolved]
-        private IAdjustableClock adjustableClock { get; set; }
-
-        public Timeline()
-        {
-            ZoomDuration = 200;
-            ZoomEasing = Easing.OutQuint;
-            ScrollbarVisible = false;
-        }
-
-        private WaveformGraph waveform;
-
-        [BackgroundDependencyLoader]
-        private void load(IBindable<WorkingBeatmap> beatmap, OsuColour colours)
-        {
-            Add(waveform = new WaveformGraph
-            {
-                RelativeSizeAxes = Axes.Both,
-                Colour = colours.Blue.Opacity(0.2f),
-                LowColour = colours.BlueLighter,
-                MidColour = colours.BlueDark,
-                HighColour = colours.BlueDarker,
-                Depth = float.MaxValue
-            });
-
-            // We don't want the centre marker to scroll
-            AddInternal(new CentreMarker());
-
-            WaveformVisible.ValueChanged += visible => waveform.FadeTo(visible.NewValue ? 1 : 0, 200, Easing.OutQuint);
-
-            Beatmap.BindTo(beatmap);
-            Beatmap.BindValueChanged(b =>
-            {
-                waveform.Waveform = b.NewValue.Waveform;
-                track = b.NewValue.Track;
-
-                MinZoom = getZoomLevelForVisibleMilliseconds(10000);
-                MaxZoom = getZoomLevelForVisibleMilliseconds(500);
-                Zoom = getZoomLevelForVisibleMilliseconds(2000);
-            }, true);
-        }
-
-        private float getZoomLevelForVisibleMilliseconds(double milliseconds) => (float)(track.Length / milliseconds);
+        private EditorClock editorClock { get; set; }
 
         /// <summary>
         /// The timeline's scroll position in the last frame.
@@ -90,6 +55,77 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
         private Track track;
 
+        public Timeline()
+        {
+            ZoomDuration = 200;
+            ZoomEasing = Easing.OutQuint;
+            ScrollbarVisible = false;
+        }
+
+        private WaveformGraph waveform;
+
+        private TimelineTickDisplay ticks;
+
+        private TimelineControlPointDisplay controlPoints;
+
+        private Bindable<float> waveformOpacity;
+
+        [BackgroundDependencyLoader]
+        private void load(IBindable<WorkingBeatmap> beatmap, OsuColour colours, OsuConfigManager config)
+        {
+            AddRange(new Drawable[]
+            {
+                new Container
+                {
+                    RelativeSizeAxes = Axes.Both,
+                    Depth = float.MaxValue,
+                    Children = new Drawable[]
+                    {
+                        waveform = new WaveformGraph
+                        {
+                            RelativeSizeAxes = Axes.Both,
+                            BaseColour = colours.Blue.Opacity(0.2f),
+                            LowColour = colours.BlueLighter,
+                            MidColour = colours.BlueDark,
+                            HighColour = colours.BlueDarker,
+                        },
+                        ticks = new TimelineTickDisplay(),
+                        controlPoints = new TimelineControlPointDisplay(),
+                    }
+                },
+            });
+
+            // We don't want the centre marker to scroll
+            AddInternal(new CentreMarker { Depth = float.MaxValue });
+
+            waveformOpacity = config.GetBindable<float>(OsuSetting.EditorWaveformOpacity);
+            waveformOpacity.BindValueChanged(_ => updateWaveformOpacity(), true);
+
+            WaveformVisible.ValueChanged += _ => updateWaveformOpacity();
+            ControlPointsVisible.ValueChanged += visible => controlPoints.FadeTo(visible.NewValue ? 1 : 0, 200, Easing.OutQuint);
+            TicksVisible.ValueChanged += visible => ticks.FadeTo(visible.NewValue ? 1 : 0, 200, Easing.OutQuint);
+
+            Beatmap.BindTo(beatmap);
+            Beatmap.BindValueChanged(b =>
+            {
+                waveform.Waveform = b.NewValue.Waveform;
+                track = b.NewValue.Track;
+
+                // todo: i don't think this is safe, the track may not be loaded yet.
+                if (track.Length > 0)
+                {
+                    MaxZoom = getZoomLevelForVisibleMilliseconds(500);
+                    MinZoom = getZoomLevelForVisibleMilliseconds(10000);
+                    Zoom = getZoomLevelForVisibleMilliseconds(2000);
+                }
+            }, true);
+        }
+
+        private void updateWaveformOpacity() =>
+            waveform.FadeTo(WaveformVisible.Value ? waveformOpacity.Value : 0, 200, Easing.OutQuint);
+
+        private float getZoomLevelForVisibleMilliseconds(double milliseconds) => Math.Max(1, (float)(track.Length / milliseconds));
+
         protected override void Update()
         {
             base.Update();
@@ -98,31 +134,42 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             Content.Margin = new MarginPadding { Horizontal = DrawWidth / 2 };
 
             // This needs to happen after transforms are updated, but before the scroll position is updated in base.UpdateAfterChildren
-            if (adjustableClock.IsRunning)
+            if (editorClock.IsRunning)
                 scrollToTrackTime();
         }
 
+        protected override bool OnScroll(ScrollEvent e)
+        {
+            // if this is not a precision scroll event, let the editor handle the seek itself (for snapping support)
+            if (!e.AltPressed && !e.IsPrecise)
+                return false;
+
+            return base.OnScroll(e);
+        }
+
         protected override void UpdateAfterChildren()
         {
             base.UpdateAfterChildren();
 
             if (handlingDragInput)
                 seekTrackToCurrent();
-            else if (!adjustableClock.IsRunning)
+            else if (!editorClock.IsRunning)
             {
-                // The track isn't running. There are two cases we have to be wary of:
-                // 1) The user flick-drags on this timeline: We want the track to follow us
-                // 2) The user changes the track time through some other means (scrolling in the editor or overview timeline): We want to follow the track time
+                // The track isn't running. There are three cases we have to be wary of:
+                // 1) The user flick-drags on this timeline and we are applying an interpolated seek on the clock, until interrupted by 2 or 3.
+                // 2) The user changes the track time through some other means (scrolling in the editor or overview timeline; clicking a hitobject etc.). We want the timeline to track the clock's time.
+                // 3) An ongoing seek transform is running from an external seek. We want the timeline to track the clock's time.
 
-                // The simplest way to cover both cases is by checking whether the scroll position has changed and the audio hasn't been changed externally
-                if (Current != lastScrollPosition && adjustableClock.CurrentTime == lastTrackTime)
+                // The simplest way to cover the first two cases is by checking whether the scroll position has changed and the audio hasn't been changed externally
+                // Checking IsSeeking covers the third case, where the transform may not have been applied yet.
+                if (Current != lastScrollPosition && editorClock.CurrentTime == lastTrackTime && !editorClock.IsSeeking)
                     seekTrackToCurrent();
                 else
                     scrollToTrackTime();
             }
 
             lastScrollPosition = Current;
-            lastTrackTime = adjustableClock.CurrentTime;
+            lastTrackTime = editorClock.CurrentTime;
         }
 
         private void seekTrackToCurrent()
@@ -131,16 +178,20 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                 return;
 
             double target = Current / Content.DrawWidth * track.Length;
-
-            adjustableClock.Seek(Math.Min(track.Length, target));
+            editorClock.Seek(Math.Min(track.Length, target));
         }
 
         private void scrollToTrackTime()
         {
-            if (!track.IsLoaded)
+            if (!track.IsLoaded || track.Length == 0)
                 return;
 
-            ScrollTo((float)(adjustableClock.CurrentTime / track.Length) * Content.DrawWidth, false);
+            // covers the case where the user starts playback after a drag is in progress.
+            // we want to ensure the clock is always stopped during drags to avoid weird audio playback.
+            if (handlingDragInput)
+                editorClock.Stop();
+
+            ScrollTo((float)(editorClock.CurrentTime / track.Length) * Content.DrawWidth, false);
         }
 
         protected override bool OnMouseDown(MouseDownEvent e)
@@ -163,15 +214,15 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
         private void beginUserDrag()
         {
             handlingDragInput = true;
-            trackWasPlaying = adjustableClock.IsRunning;
-            adjustableClock.Stop();
+            trackWasPlaying = editorClock.IsRunning;
+            editorClock.Stop();
         }
 
         private void endUserDrag()
         {
             handlingDragInput = false;
             if (trackWasPlaying)
-                adjustableClock.Start();
+                editorClock.Start();
         }
 
         [Resolved]
@@ -180,11 +231,16 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
         [Resolved]
         private IBeatSnapProvider beatSnapProvider { get; set; }
 
-        public double GetTimeFromScreenSpacePosition(Vector2 position)
-            => getTimeFromPosition(Content.ToLocalSpace(position));
+        /// <summary>
+        /// The total amount of time visible on the timeline.
+        /// </summary>
+        public double VisibleRange => track.Length / Zoom;
 
-        public (Vector2 position, double time) GetSnappedPosition(Vector2 position, double time) =>
-            (position, beatSnapProvider.SnapTime(getTimeFromPosition(position)));
+        public SnapResult SnapScreenSpacePositionToValidPosition(Vector2 screenSpacePosition) =>
+            new SnapResult(screenSpacePosition, null);
+
+        public SnapResult SnapScreenSpacePositionToValidTime(Vector2 screenSpacePosition) =>
+            new SnapResult(screenSpacePosition, beatSnapProvider.SnapTime(getTimeFromPosition(Content.ToLocalSpace(screenSpacePosition))));
 
         private double getTimeFromPosition(Vector2 localPosition) =>
             (localPosition.X / Content.DrawWidth) * track.Length;

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineArea.cs

@@ -14,9 +14,9 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
     public class TimelineArea : Container
     {
-        private readonly Timeline timeline = new Timeline { RelativeSizeAxes = Axes.Both };
+        public readonly Timeline Timeline = new Timeline { RelativeSizeAxes = Axes.Both };
 
-        protected override Container<Drawable> Content => timeline;
+        protected override Container<Drawable> Content => Timeline;
 
         [BackgroundDependencyLoader]
         private void load()
@@ -25,6 +25,8 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             CornerRadius = 5;
 
             OsuCheckbox waveformCheckbox;
+            OsuCheckbox controlPointsCheckbox;
+            OsuCheckbox ticksCheckbox;
 
             InternalChildren = new Drawable[]
             {
@@ -57,12 +59,26 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                                         Origin = Anchor.CentreLeft,
                                         AutoSizeAxes = Axes.Y,
                                         Width = 160,
-                                        Padding = new MarginPadding { Horizontal = 15 },
+                                        Padding = new MarginPadding { Horizontal = 10 },
                                         Direction = FillDirection.Vertical,
                                         Spacing = new Vector2(0, 4),
                                         Children = new[]
                                         {
-                                            waveformCheckbox = new OsuCheckbox { LabelText = "Waveform" }
+                                            waveformCheckbox = new OsuCheckbox
+                                            {
+                                                LabelText = "Waveform",
+                                                Current = { Value = true },
+                                            },
+                                            controlPointsCheckbox = new OsuCheckbox
+                                            {
+                                                LabelText = "Control Points",
+                                                Current = { Value = true },
+                                            },
+                                            ticksCheckbox = new OsuCheckbox
+                                            {
+                                                LabelText = "Ticks",
+                                                Current = { Value = true },
+                                            }
                                         }
                                     }
                                 }
@@ -107,7 +123,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                                     }
                                 }
                             },
-                            timeline
+                            Timeline
                         },
                     },
                     ColumnDimensions = new[]
@@ -119,11 +135,11 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                 }
             };
 
-            waveformCheckbox.Current.Value = true;
-
-            timeline.WaveformVisible.BindTo(waveformCheckbox.Current);
+            Timeline.WaveformVisible.BindTo(waveformCheckbox.Current);
+            Timeline.ControlPointsVisible.BindTo(controlPointsCheckbox.Current);
+            Timeline.TicksVisible.BindTo(ticksCheckbox.Current);
         }
 
-        private void changeZoom(float change) => timeline.Zoom += change;
+        private void changeZoom(float change) => Timeline.Zoom += change;
     }
 }

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineBlueprintContainer.cs

@@ -9,10 +9,11 @@ using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Primitives;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Input.Events;
+using osu.Framework.Utils;
+using osu.Game.Graphics;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Screens.Edit.Components.Timelines.Summary.Parts;
-using osuTK;
 using osuTK.Graphics;
 
 namespace osu.Game.Screens.Edit.Compose.Components.Timeline
@@ -25,21 +26,25 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
         [Resolved]
         private EditorBeatmap beatmap { get; set; }
 
+        [Resolved]
+        private OsuColour colours { get; set; }
+
         private DragEvent lastDragEvent;
-
         private Bindable<HitObject> placement;
-
         private SelectionBlueprint placementBlueprint;
 
-        public TimelineBlueprintContainer()
+        private readonly Box backgroundBox;
+
+        public TimelineBlueprintContainer(HitObjectComposer composer)
+            : base(composer)
         {
             RelativeSizeAxes = Axes.Both;
             Anchor = Anchor.Centre;
             Origin = Anchor.Centre;
 
-            Height = 0.4f;
+            Height = 0.6f;
 
-            AddInternal(new Box
+            AddInternal(backgroundBox = new Box
             {
                 Colour = Color4.Black,
                 RelativeSizeAxes = Axes.Both,
@@ -78,6 +83,18 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
         protected override Container<SelectionBlueprint> CreateSelectionBlueprintContainer() => new TimelineSelectionBlueprintContainer { RelativeSizeAxes = Axes.Both };
 
+        protected override bool OnHover(HoverEvent e)
+        {
+            backgroundBox.FadeColour(colours.BlueLighter, 120, Easing.OutQuint);
+            return base.OnHover(e);
+        }
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            backgroundBox.FadeColour(Color4.Black, 600, Easing.OutQuint);
+            base.OnHoverLost(e);
+        }
+
         protected override void OnDrag(DragEvent e)
         {
             handleScrollViaDrag(e);
@@ -97,6 +114,12 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             if (lastDragEvent != null)
                 OnDrag(lastDragEvent);
 
+            if (Composer != null && timeline != null)
+            {
+                Composer.Playfield.PastLifetimeExtension = timeline.VisibleRange / 2;
+                Composer.Playfield.FutureLifetimeExtension = timeline.VisibleRange / 2;
+            }
+
             base.Update();
         }
 
@@ -137,8 +160,14 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
         private class TimelineDragBox : DragBox
         {
-            private Vector2 lastMouseDown;
-            private float localMouseDown;
+            // the following values hold the start and end X positions of the drag box in the timeline's local space,
+            // but with zoom unapplied in order to be able to compensate for positional changes
+            // while the timeline is being zoomed in/out.
+            private float? selectionStart;
+            private float selectionEnd;
+
+            [Resolved]
+            private Timeline timeline { get; set; }
 
             public TimelineDragBox(Action<RectangleF> performSelect)
                 : base(performSelect)
@@ -153,21 +182,34 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
             public override bool HandleDrag(MouseButtonEvent e)
             {
-                // store the original position of the mouse down, as we may be scrolled during selection.
-                if (lastMouseDown != e.ScreenSpaceMouseDownPosition)
-                {
-                    lastMouseDown = e.ScreenSpaceMouseDownPosition;
-                    localMouseDown = e.MouseDownPosition.X;
-                }
+                selectionStart ??= e.MouseDownPosition.X / timeline.CurrentZoom;
 
-                float selection1 = localMouseDown;
-                float selection2 = e.MousePosition.X;
+                // only calculate end when a transition is not in progress to avoid bouncing.
+                if (Precision.AlmostEquals(timeline.CurrentZoom, timeline.Zoom))
+                    selectionEnd = e.MousePosition.X / timeline.CurrentZoom;
 
-                Box.X = Math.Min(selection1, selection2);
-                Box.Width = Math.Abs(selection1 - selection2);
+                updateDragBoxPosition();
+                return true;
+            }
+
+            private void updateDragBoxPosition()
+            {
+                if (selectionStart == null)
+                    return;
+
+                float rescaledStart = selectionStart.Value * timeline.CurrentZoom;
+                float rescaledEnd = selectionEnd * timeline.CurrentZoom;
+
+                Box.X = Math.Min(rescaledStart, rescaledEnd);
+                Box.Width = Math.Abs(rescaledStart - rescaledEnd);
 
                 PerformSelection?.Invoke(Box.ScreenSpaceDrawQuad.AABBFloat);
-                return true;
+            }
+
+            public override void Hide()
+            {
+                base.Hide();
+                selectionStart = null;
             }
         }
 
@@ -177,7 +219,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
             public TimelineSelectionBlueprintContainer()
             {
-                AddInternal(new TimelinePart<SelectionBlueprint>(Content = new Container<SelectionBlueprint> { RelativeSizeAxes = Axes.Both }) { RelativeSizeAxes = Axes.Both });
+                AddInternal(new TimelinePart<SelectionBlueprint>(Content = new HitObjectOrderedSelectionContainer { RelativeSizeAxes = Axes.Both }) { RelativeSizeAxes = Axes.Both });
             }
         }
     }

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineControlPointDisplay.cs

@@ -0,0 +1,57 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using System.Collections.Specialized;
+using System.Linq;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Screens.Edit.Components.Timelines.Summary.Parts;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    /// <summary>
+    /// The part of the timeline that displays the control points.
+    /// </summary>
+    public class TimelineControlPointDisplay : TimelinePart<TimelineControlPointGroup>
+    {
+        private readonly IBindableList<ControlPointGroup> controlPointGroups = new BindableList<ControlPointGroup>();
+
+        public TimelineControlPointDisplay()
+        {
+            RelativeSizeAxes = Axes.Both;
+        }
+
+        protected override void LoadBeatmap(EditorBeatmap beatmap)
+        {
+            base.LoadBeatmap(beatmap);
+
+            controlPointGroups.UnbindAll();
+            controlPointGroups.BindTo(beatmap.ControlPointInfo.Groups);
+            controlPointGroups.BindCollectionChanged((sender, args) =>
+            {
+                switch (args.Action)
+                {
+                    case NotifyCollectionChangedAction.Reset:
+                        Clear();
+                        break;
+
+                    case NotifyCollectionChangedAction.Add:
+                        foreach (var group in args.NewItems.OfType<ControlPointGroup>())
+                            Add(new TimelineControlPointGroup(group));
+                        break;
+
+                    case NotifyCollectionChangedAction.Remove:
+                        foreach (var group in args.OldItems.OfType<ControlPointGroup>())
+                        {
+                            var matching = Children.SingleOrDefault(gv => gv.Group == group);
+
+                            matching?.Expire();
+                        }
+
+                        break;
+                }
+            }, true);
+        }
+    }
+}

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineControlPointGroup.cs

@@ -0,0 +1,62 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Graphics;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    public class TimelineControlPointGroup : CompositeDrawable
+    {
+        public readonly ControlPointGroup Group;
+
+        private readonly IBindableList<ControlPoint> controlPoints = new BindableList<ControlPoint>();
+
+        [Resolved]
+        private OsuColour colours { get; set; }
+
+        public TimelineControlPointGroup(ControlPointGroup group)
+        {
+            Group = group;
+
+            RelativePositionAxes = Axes.X;
+            RelativeSizeAxes = Axes.Y;
+            AutoSizeAxes = Axes.X;
+
+            X = (float)group.Time;
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            controlPoints.BindTo(Group.ControlPoints);
+            controlPoints.BindCollectionChanged((_, __) =>
+            {
+                ClearInternal();
+
+                foreach (var point in controlPoints)
+                {
+                    switch (point)
+                    {
+                        case DifficultyControlPoint difficultyPoint:
+                            AddInternal(new DifficultyPointPiece(difficultyPoint) { Depth = -2 });
+                            break;
+
+                        case TimingControlPoint timingPoint:
+                            AddInternal(new TimingPointPiece(timingPoint));
+                            break;
+
+                        case SampleControlPoint samplePoint:
+                            AddInternal(new SamplePointPiece(samplePoint) { Depth = -1 });
+                            break;
+                    }
+                }
+            }, true);
+        }
+    }
+}

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineHitObjectBlueprint.cs

@@ -7,15 +7,20 @@ using JetBrains.Annotations;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
+using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Effects;
 using osu.Framework.Graphics.Primitives;
 using osu.Framework.Graphics.Shapes;
 using osu.Framework.Input.Events;
+using osu.Framework.Utils;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.Objects.Types;
+using osu.Game.Skinning;
 using osuTK;
 using osuTK.Graphics;
 
@@ -23,22 +28,26 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
     public class TimelineHitObjectBlueprint : SelectionBlueprint
     {
-        private readonly Circle circle;
+        private const float thickness = 5;
+        private const float shadow_radius = 5;
+        private const float circle_size = 34;
+
+        public Action<DragEvent> OnDragHandled;
 
         [UsedImplicitly]
         private readonly Bindable<double> startTime;
 
-        public Action<DragEvent> OnDragHandled;
+        private Bindable<int> indexInCurrentComboBindable;
+        private Bindable<int> comboIndexBindable;
 
+        private readonly Circle circle;
         private readonly DragBar dragBar;
-
         private readonly List<Container> shadowComponents = new List<Container>();
+        private readonly Container mainComponents;
+        private readonly OsuSpriteText comboIndexText;
 
-        private const float thickness = 5;
-
-        private const float shadow_radius = 5;
-
-        private const float circle_size = 16;
+        [Resolved]
+        private ISkinSource skin { get; set; }
 
         public TimelineHitObjectBlueprint(HitObject hitObject)
             : base(hitObject)
@@ -54,14 +63,28 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
 
+            AddRangeInternal(new Drawable[]
+            {
+                mainComponents = new Container
+                {
+                    Anchor = Anchor.CentreLeft,
+                    Origin = Anchor.CentreLeft,
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
+                },
+                comboIndexText = new OsuSpriteText
+                {
+                    Anchor = Anchor.CentreLeft,
+                    Origin = Anchor.Centre,
+                    Font = OsuFont.Numeric.With(size: circle_size / 2, weight: FontWeight.Black),
+                },
+            });
+
             circle = new Circle
             {
                 Size = new Vector2(circle_size),
                 Anchor = Anchor.CentreLeft,
                 Origin = Anchor.Centre,
-                RelativePositionAxes = Axes.X,
-                AlwaysPresent = true,
-                Colour = Color4.White,
                 EdgeEffect = new EdgeEffectParameters
                 {
                     Type = EdgeEffectType.Shadow,
@@ -72,12 +95,12 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
             shadowComponents.Add(circle);
 
-            if (hitObject is IHasEndTime)
+            if (hitObject is IHasDuration)
             {
                 DragBar dragBarUnderlay;
                 Container extensionBar;
 
-                AddRangeInternal(new Drawable[]
+                mainComponents.AddRange(new Drawable[]
                 {
                     extensionBar = new Container
                     {
@@ -117,18 +140,89 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             }
             else
             {
-                AddInternal(circle);
+                mainComponents.Add(circle);
             }
 
             updateShadows();
         }
 
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            if (HitObject is IHasComboInformation comboInfo)
+            {
+                indexInCurrentComboBindable = comboInfo.IndexInCurrentComboBindable.GetBoundCopy();
+                indexInCurrentComboBindable.BindValueChanged(_ => updateComboIndex(), true);
+
+                comboIndexBindable = comboInfo.ComboIndexBindable.GetBoundCopy();
+                comboIndexBindable.BindValueChanged(_ => updateComboColour(), true);
+
+                skin.SourceChanged += updateComboColour;
+            }
+        }
+
+        private void updateComboIndex() => comboIndexText.Text = (indexInCurrentComboBindable.Value + 1).ToString();
+
+        private void updateComboColour()
+        {
+            if (!(HitObject is IHasComboInformation combo))
+                return;
+
+            var comboColours = skin.GetConfig<GlobalSkinColours, IReadOnlyList<Color4>>(GlobalSkinColours.ComboColours)?.Value ?? Array.Empty<Color4>();
+            var comboColour = combo.GetComboColour(comboColours);
+
+            if (HitObject is IHasDuration)
+                mainComponents.Colour = ColourInfo.GradientHorizontal(comboColour, Color4.White);
+            else
+                mainComponents.Colour = comboColour;
+
+            var col = mainComponents.Colour.TopLeft.Linear;
+            float brightness = col.R + col.G + col.B;
+
+            // decide the combo index colour based on brightness?
+            comboIndexText.Colour = brightness > 0.5f ? Color4.Black : Color4.White;
+        }
+
         protected override void Update()
         {
             base.Update();
 
             // no bindable so we perform this every update
-            Width = (float)(HitObject.GetEndTime() - HitObject.StartTime);
+            float duration = (float)(HitObject.GetEndTime() - HitObject.StartTime);
+
+            if (Width != duration)
+            {
+                Width = duration;
+
+                // kind of haphazard but yeah, no bindables.
+                if (HitObject is IHasRepeats repeats)
+                    updateRepeats(repeats);
+            }
+        }
+
+        private Container repeatsContainer;
+
+        private void updateRepeats(IHasRepeats repeats)
+        {
+            repeatsContainer?.Expire();
+
+            mainComponents.Add(repeatsContainer = new Container
+            {
+                RelativeSizeAxes = Axes.Both,
+            });
+
+            for (int i = 0; i < repeats.RepeatCount; i++)
+            {
+                repeatsContainer.Add(new Circle
+                {
+                    Size = new Vector2(circle_size / 2),
+                    Anchor = Anchor.CentreLeft,
+                    Origin = Anchor.Centre,
+                    RelativePositionAxes = Axes.X,
+                    X = (float)(i + 1) / (repeats.RepeatCount + 1),
+                });
+            }
         }
 
         protected override bool ShouldBeConsideredForInput(Drawable child) => true;
@@ -186,7 +280,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             }
         }
 
-        public override Vector2 SelectionPoint => ScreenSpaceDrawQuad.TopLeft;
+        public override Vector2 ScreenSpaceSelectionPoint => ScreenSpaceDrawQuad.TopLeft;
 
         public class DragBar : Container
         {
@@ -254,46 +348,54 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                 Colour = IsHovered || hasMouseDown ? Color4.OrangeRed : Color4.White;
             }
 
-            protected override bool OnDragStart(DragStartEvent e) => true;
-
             [Resolved]
             private EditorBeatmap beatmap { get; set; }
 
             [Resolved]
             private IBeatSnapProvider beatSnapProvider { get; set; }
 
+            [Resolved(CanBeNull = true)]
+            private IEditorChangeHandler changeHandler { get; set; }
+
+            protected override bool OnDragStart(DragStartEvent e)
+            {
+                changeHandler?.BeginChange();
+                return true;
+            }
+
             protected override void OnDrag(DragEvent e)
             {
                 base.OnDrag(e);
 
                 OnDragHandled?.Invoke(e);
 
-                var time = timeline.GetTimeFromScreenSpacePosition(e.ScreenSpaceMousePosition);
-
-                switch (hitObject)
+                if (timeline.SnapScreenSpacePositionToValidTime(e.ScreenSpaceMousePosition).Time is double time)
                 {
-                    case IHasRepeats repeatHitObject:
-                        // find the number of repeats which can fit in the requested time.
-                        var lengthOfOneRepeat = repeatHitObject.Duration / (repeatHitObject.RepeatCount + 1);
-                        var proposedCount = Math.Max(0, (int)((time - hitObject.StartTime) / lengthOfOneRepeat) - 1);
+                    switch (hitObject)
+                    {
+                        case IHasRepeats repeatHitObject:
+                            // find the number of repeats which can fit in the requested time.
+                            var lengthOfOneRepeat = repeatHitObject.Duration / (repeatHitObject.RepeatCount + 1);
+                            var proposedCount = Math.Max(0, (int)Math.Round((time - hitObject.StartTime) / lengthOfOneRepeat) - 1);
 
-                        if (proposedCount == repeatHitObject.RepeatCount)
-                            return;
+                            if (proposedCount == repeatHitObject.RepeatCount)
+                                return;
 
-                        repeatHitObject.RepeatCount = proposedCount;
-                        break;
+                            repeatHitObject.RepeatCount = proposedCount;
+                            beatmap.Update(hitObject);
+                            break;
 
-                    case IHasEndTime endTimeHitObject:
-                        var snappedTime = Math.Max(hitObject.StartTime, beatSnapProvider.SnapTime(time));
+                        case IHasDuration endTimeHitObject:
+                            var snappedTime = Math.Max(hitObject.StartTime, beatSnapProvider.SnapTime(time));
 
-                        if (endTimeHitObject.EndTime == snappedTime)
-                            return;
+                            if (endTimeHitObject.EndTime == snappedTime || Precision.AlmostEquals(snappedTime, hitObject.StartTime, beatmap.GetBeatLengthAtTime(snappedTime)))
+                                return;
 
-                        endTimeHitObject.EndTime = snappedTime;
-                        break;
+                            endTimeHitObject.Duration = snappedTime - hitObject.StartTime;
+                            beatmap.Update(hitObject);
+                            break;
+                    }
                 }
-
-                beatmap.UpdateHitObject(hitObject);
             }
 
             protected override void OnDragEnd(DragEndEvent e)
@@ -301,6 +403,7 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
                 base.OnDragEnd(e);
 
                 OnDragHandled?.Invoke(null);
+                changeHandler?.EndChange();
             }
         }
     }

osu.Game/Screens/Edit/Compose/Components/Timeline/TimelineTickDisplay.cs

@@ -1,9 +1,11 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
+using osu.Framework.Caching;
 using osu.Framework.Graphics;
 using osu.Game.Beatmaps;
 using osu.Game.Graphics;
@@ -12,7 +14,7 @@ using osu.Game.Screens.Edit.Components.Timelines.Summary.Visualisations;
 
 namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 {
-    public class TimelineTickDisplay : TimelinePart
+    public class TimelineTickDisplay : TimelinePart<PointVisualisation>
     {
         [Resolved]
         private EditorBeatmap beatmap { get; set; }
@@ -23,6 +25,9 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
         [Resolved]
         private BindableBeatDivisor beatDivisor { get; set; }
 
+        [Resolved(CanBeNull = true)]
+        private IEditorChangeHandler changeHandler { get; set; }
+
         [Resolved]
         private OsuColour colours { get; set; }
 
@@ -31,15 +36,72 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
             RelativeSizeAxes = Axes.Both;
         }
 
+        private readonly Cached tickCache = new Cached();
+
         [BackgroundDependencyLoader]
         private void load()
         {
-            beatDivisor.BindValueChanged(_ => createLines(), true);
+            beatDivisor.BindValueChanged(_ => invalidateTicks());
+
+            if (changeHandler != null)
+                // currently this is the best way to handle any kind of timing changes.
+                changeHandler.OnStateChange += invalidateTicks;
         }
 
-        private void createLines()
+        private void invalidateTicks()
         {
-            Clear();
+            tickCache.Invalidate();
+        }
+
+        /// <summary>
+        /// The visible time/position range of the timeline.
+        /// </summary>
+        private (float min, float max) visibleRange = (float.MinValue, float.MaxValue);
+
+        /// <summary>
+        /// The next time/position value to the left of the display when tick regeneration needs to be run.
+        /// </summary>
+        private float? nextMinTick;
+
+        /// <summary>
+        /// The next time/position value to the right of the display when tick regeneration needs to be run.
+        /// </summary>
+        private float? nextMaxTick;
+
+        [Resolved(canBeNull: true)]
+        private Timeline timeline { get; set; }
+
+        protected override void Update()
+        {
+            base.Update();
+
+            if (timeline != null)
+            {
+                var newRange = (
+                    (ToLocalSpace(timeline.ScreenSpaceDrawQuad.TopLeft).X - PointVisualisation.WIDTH * 2) / DrawWidth * Content.RelativeChildSize.X,
+                    (ToLocalSpace(timeline.ScreenSpaceDrawQuad.TopRight).X + PointVisualisation.WIDTH * 2) / DrawWidth * Content.RelativeChildSize.X);
+
+                if (visibleRange != newRange)
+                {
+                    visibleRange = newRange;
+
+                    // actual regeneration only needs to occur if we've passed one of the known next min/max tick boundaries.
+                    if (nextMinTick == null || nextMaxTick == null || (visibleRange.min < nextMinTick || visibleRange.max > nextMaxTick))
+                        tickCache.Invalidate();
+                }
+            }
+
+            if (!tickCache.IsValid)
+                createTicks();
+        }
+
+        private void createTicks()
+        {
+            int drawableIndex = 0;
+            int highestDivisor = BindableBeatDivisor.VALID_DIVISORS.Last();
+
+            nextMinTick = null;
+            nextMaxTick = null;
 
             for (var i = 0; i < beatmap.ControlPointInfo.TimingPoints.Count; i++)
             {
@@ -50,41 +112,78 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
                 for (double t = point.Time; t < until; t += point.BeatLength / beatDivisor.Value)
                 {
-                    var indexInBeat = beat % beatDivisor.Value;
+                    float xPos = (float)t;
 
-                    if (indexInBeat == 0)
-                    {
-                        Add(new PointVisualisation(t)
-                        {
-                            Colour = BindableBeatDivisor.GetColourFor(1, colours),
-                            Origin = Anchor.TopCentre,
-                        });
-                    }
+                    if (t < visibleRange.min)
+                        nextMinTick = xPos;
+                    else if (t > visibleRange.max)
+                        nextMaxTick ??= xPos;
                     else
                     {
+                        // if this is the first beat in the beatmap, there is no next min tick
+                        if (beat == 0 && i == 0)
+                            nextMinTick = float.MinValue;
+
+                        var indexInBar = beat % ((int)point.TimeSignature * beatDivisor.Value);
+
                         var divisor = BindableBeatDivisor.GetDivisorForBeatIndex(beat, beatDivisor.Value);
                         var colour = BindableBeatDivisor.GetColourFor(divisor, colours);
-                        var height = 0.1f - (float)divisor / BindableBeatDivisor.VALID_DIVISORS.Last() * 0.08f;
 
-                        Add(new PointVisualisation(t)
-                        {
-                            Colour = colour,
-                            Height = height,
-                            Origin = Anchor.TopCentre,
-                        });
+                        // even though "bar lines" take up the full vertical space, we render them in two pieces because it allows for less anchor/origin churn.
+                        var height = indexInBar == 0 ? 0.5f : 0.1f - (float)divisor / highestDivisor * 0.08f;
 
-                        Add(new PointVisualisation(t)
-                        {
-                            Colour = colour,
-                            Anchor = Anchor.BottomLeft,
-                            Origin = Anchor.BottomCentre,
-                            Height = height,
-                        });
+                        var topPoint = getNextUsablePoint();
+                        topPoint.X = xPos;
+                        topPoint.Colour = colour;
+                        topPoint.Height = height;
+                        topPoint.Anchor = Anchor.TopLeft;
+                        topPoint.Origin = Anchor.TopCentre;
+
+                        var bottomPoint = getNextUsablePoint();
+                        bottomPoint.X = xPos;
+                        bottomPoint.Colour = colour;
+                        bottomPoint.Anchor = Anchor.BottomLeft;
+                        bottomPoint.Origin = Anchor.BottomCentre;
+                        bottomPoint.Height = height;
                     }
 
                     beat++;
                 }
             }
+
+            int usedDrawables = drawableIndex;
+
+            // save a few drawables beyond the currently used for edge cases.
+            while (drawableIndex < Math.Min(usedDrawables + 16, Count))
+                Children[drawableIndex++].Hide();
+
+            // expire any excess
+            while (drawableIndex < Count)
+                Children[drawableIndex++].Expire();
+
+            tickCache.Validate();
+
+            Drawable getNextUsablePoint()
+            {
+                PointVisualisation point;
+                if (drawableIndex >= Count)
+                    Add(point = new PointVisualisation());
+                else
+                    point = Children[drawableIndex];
+
+                drawableIndex++;
+                point.Show();
+
+                return point;
+            }
+        }
+
+        protected override void Dispose(bool isDisposing)
+        {
+            base.Dispose(isDisposing);
+
+            if (changeHandler != null)
+                changeHandler.OnStateChange -= invalidateTicks;
         }
     }
 }

osu.Game/Screens/Edit/Compose/Components/Timeline/TimingPointPiece.cs

@@ -0,0 +1,63 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Colour;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Shapes;
+using osu.Game.Beatmaps.ControlPoints;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
+using osuTK.Graphics;
+
+namespace osu.Game.Screens.Edit.Compose.Components.Timeline
+{
+    public class TimingPointPiece : CompositeDrawable
+    {
+        private readonly TimingControlPoint point;
+
+        private readonly BindableNumber<double> beatLength;
+        private OsuSpriteText bpmText;
+
+        public TimingPointPiece(TimingControlPoint point)
+        {
+            this.point = point;
+            beatLength = point.BeatLengthBindable.GetBoundCopy();
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            Origin = Anchor.CentreLeft;
+            Anchor = Anchor.CentreLeft;
+
+            AutoSizeAxes = Axes.Both;
+
+            Color4 colour = point.GetRepresentingColour(colours);
+
+            InternalChildren = new Drawable[]
+            {
+                new Box
+                {
+                    Alpha = 0.9f,
+                    Colour = ColourInfo.GradientHorizontal(colour, colour.Opacity(0.5f)),
+                    RelativeSizeAxes = Axes.Both,
+                },
+                bpmText = new OsuSpriteText
+                {
+                    Alpha = 0.9f,
+                    Padding = new MarginPadding(3),
+                    Font = OsuFont.Default.With(size: 40)
+                }
+            };
+
+            beatLength.BindValueChanged(beatLength =>
+            {
+                bpmText.Text = $"{60000 / beatLength.NewValue:n1} BPM";
+            }, true);
+        }
+    }
+}

osu.Game/Screens/Edit/Compose/Components/Timeline/ZoomableScrollContainer.cs

@@ -29,9 +29,14 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
         private readonly Container zoomedContent;
         protected override Container<Drawable> Content => zoomedContent;
-
         private float currentZoom = 1;
 
+        /// <summary>
+        /// The current zoom level of <see cref="ZoomableScrollContainer" />.
+        /// It may differ from <see cref="Zoom" /> during transitions.
+        /// </summary>
+        public float CurrentZoom => currentZoom;
+
         [Resolved(canBeNull: true)]
         private IFrameBasedClock editorClock { get; set; }
 
@@ -108,19 +113,19 @@ namespace osu.Game.Screens.Edit.Compose.Components.Timeline
 
         protected override bool OnScroll(ScrollEvent e)
         {
-            if (e.IsPrecise)
+            if (e.AltPressed)
             {
-                // can't handle scroll correctly while playing.
-                // the editor will handle this case for us.
-                if (editorClock?.IsRunning == true)
-                    return false;
-
-                // for now, we don't support zoom when using a precision scroll device. this needs gesture support.
-                return base.OnScroll(e);
+                // zoom when holding alt.
+                setZoomTarget(zoomTarget + e.ScrollDelta.Y, zoomedContent.ToLocalSpace(e.ScreenSpaceMousePosition).X);
+                return true;
             }
 
-            setZoomTarget(zoomTarget + e.ScrollDelta.Y, zoomedContent.ToLocalSpace(e.ScreenSpaceMousePosition).X);
-            return true;
+            // can't handle scroll correctly while playing.
+            // the editor will handle this case for us.
+            if (editorClock?.IsRunning == true)
+                return false;
+
+            return base.OnScroll(e);
         }
 
         private void updateZoomedContentWidth() => zoomedContent.Width = DrawWidth * currentZoom;

osu.Game/Screens/Edit/Compose/ComposeScreen.cs

@@ -1,8 +1,13 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+using System.Diagnostics;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Game.Beatmaps;
+using osu.Game.Rulesets;
 using osu.Game.Rulesets.Edit;
 using osu.Game.Screens.Edit.Compose.Components.Timeline;
 using osu.Game.Skinning;
@@ -11,27 +16,61 @@ namespace osu.Game.Screens.Edit.Compose
 {
     public class ComposeScreen : EditorScreenWithTimeline
     {
+        [Resolved]
+        private IBindable<WorkingBeatmap> beatmap { get; set; }
+
         private HitObjectComposer composer;
 
+        public ComposeScreen()
+            : base(EditorScreenMode.Compose)
+        {
+        }
+
+        private Ruleset ruleset;
+
+        protected override IReadOnlyDependencyContainer CreateChildDependencies(IReadOnlyDependencyContainer parent)
+        {
+            var dependencies = new DependencyContainer(base.CreateChildDependencies(parent));
+
+            ruleset = parent.Get<IBindable<WorkingBeatmap>>().Value.BeatmapInfo.Ruleset?.CreateInstance();
+            composer = ruleset?.CreateHitObjectComposer();
+
+            // make the composer available to the timeline and other components in this screen.
+            if (composer != null)
+                dependencies.CacheAs(composer);
+
+            return dependencies;
+        }
+
         protected override Drawable CreateMainContent()
         {
-            var ruleset = Beatmap.Value.BeatmapInfo.Ruleset?.CreateInstance();
-            composer = ruleset?.CreateHitObjectComposer();
-
             if (ruleset == null || composer == null)
                 return new ScreenWhiteBox.UnderConstructionMessage(ruleset == null ? "This beatmap" : $"{ruleset.Description}'s composer");
 
-            var beatmapSkinProvider = new BeatmapSkinProvidingContainer(Beatmap.Value.Skin);
+            return wrapSkinnableContent(composer);
+        }
+
+        protected override Drawable CreateTimelineContent()
+        {
+            if (ruleset == null || composer == null)
+                return base.CreateTimelineContent();
+
+            return wrapSkinnableContent(new TimelineBlueprintContainer(composer));
+        }
+
+        private Drawable wrapSkinnableContent(Drawable content)
+        {
+            Debug.Assert(ruleset != null);
+
+            var beatmapSkinProvider = new BeatmapSkinProvidingContainer(beatmap.Value.Skin);
 
             // the beatmapSkinProvider is used as the fallback source here to allow the ruleset-specific skin implementation
             // full access to all skin sources.
-            var rulesetSkinProvider = new SkinProvidingContainer(ruleset.CreateLegacySkinProvider(beatmapSkinProvider));
+            var rulesetSkinProvider = new SkinProvidingContainer(ruleset.CreateLegacySkinProvider(beatmapSkinProvider, EditorBeatmap.PlayableBeatmap));
 
             // load the skinning hierarchy first.
             // this is intentionally done in two stages to ensure things are in a loaded state before exposing the ruleset to skin sources.
-            return beatmapSkinProvider.WithChild(rulesetSkinProvider.WithChild(composer));
+            return beatmapSkinProvider.WithChild(rulesetSkinProvider.WithChild(content));
         }
-
-        protected override Drawable CreateTimelineContent() => composer == null ? base.CreateTimelineContent() : new TimelineBlueprintContainer();
     }
 }