Move files to UI namespace

osu.Game/Graphics/Containers/ExpandingButtonContainer.cs

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+// 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.
+
+namespace osu.Game.Graphics.Containers
+{
+    /// <summary>
+    /// An <see cref="ExpandingContainer"/> with a long hover expansion delay.
+    /// </summary>
+    /// <remarks>
+    /// Mostly used for buttons with explanatory labels, in which the label would display after a "long hover".
+    /// </remarks>
+    public class ExpandingButtonContainer : ExpandingContainer
+    {
+        protected ExpandingButtonContainer(float contractedWidth, float expandedWidth)
+            : base(contractedWidth, expandedWidth)
+        {
+        }
+
+        protected override double HoverExpansionDelay => 750;
+    }
+}

osu.Game/Graphics/Containers/ExpandingContainer.cs

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+// 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.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Input.Events;
+using osu.Framework.Threading;
+
+namespace osu.Game.Graphics.Containers
+{
+    /// <summary>
+    /// Represents a <see cref="Container"/> with the ability to expand/contract on hover.
+    /// </summary>
+    public class ExpandingContainer : Container, IExpandingContainer
+    {
+        private readonly float contractedWidth;
+        private readonly float expandedWidth;
+
+        public BindableBool Expanded { get; } = new BindableBool();
+
+        /// <summary>
+        /// Delay before the container switches to expanded state from hover.
+        /// </summary>
+        protected virtual double HoverExpansionDelay => 0;
+
+        protected override Container<Drawable> Content => FillFlow;
+
+        protected FillFlowContainer FillFlow { get; }
+
+        protected ExpandingContainer(float contractedWidth, float expandedWidth)
+        {
+            this.contractedWidth = contractedWidth;
+            this.expandedWidth = expandedWidth;
+
+            RelativeSizeAxes = Axes.Y;
+            Width = contractedWidth;
+
+            InternalChild = new OsuScrollContainer
+            {
+                RelativeSizeAxes = Axes.Both,
+                ScrollbarVisible = false,
+                Child = FillFlow = new FillFlowContainer
+                {
+                    Origin = Anchor.CentreLeft,
+                    Anchor = Anchor.CentreLeft,
+                    RelativeSizeAxes = Axes.X,
+                    AutoSizeAxes = Axes.Y,
+                    Direction = FillDirection.Vertical,
+                },
+            };
+        }
+
+        private ScheduledDelegate hoverExpandEvent;
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            Expanded.BindValueChanged(v =>
+            {
+                this.ResizeWidthTo(v.NewValue ? expandedWidth : contractedWidth, 500, Easing.OutQuint);
+            }, true);
+        }
+
+        protected override bool OnHover(HoverEvent e)
+        {
+            updateHoverExpansion();
+            return true;
+        }
+
+        protected override bool OnMouseMove(MouseMoveEvent e)
+        {
+            updateHoverExpansion();
+            return base.OnMouseMove(e);
+        }
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            if (hoverExpandEvent != null)
+            {
+                hoverExpandEvent?.Cancel();
+                hoverExpandEvent = null;
+
+                Expanded.Value = false;
+                return;
+            }
+
+            base.OnHoverLost(e);
+        }
+
+        private void updateHoverExpansion()
+        {
+            hoverExpandEvent?.Cancel();
+
+            if (IsHovered && !Expanded.Value)
+                hoverExpandEvent = Scheduler.AddDelayed(() => Expanded.Value = true, HoverExpansionDelay);
+        }
+    }
+}

osu.Game/Graphics/Containers/IExpandable.cs

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+// 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.Bindables;
+using osu.Framework.Graphics;
+
+namespace osu.Game.Graphics.Containers
+{
+    /// <summary>
+    /// An interface for drawables with ability to expand/contract.
+    /// </summary>
+    public interface IExpandable : IDrawable
+    {
+        /// <summary>
+        /// Whether this drawable is in an expanded state.
+        /// </summary>
+        BindableBool Expanded { get; }
+    }
+}

osu.Game/Graphics/Containers/IExpandingContainer.cs

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+// 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.Graphics.Containers;
+using osu.Game.Overlays;
+
+namespace osu.Game.Graphics.Containers
+{
+    /// <summary>
+    /// A target expanding container that should be resolved by children <see cref="IExpandable"/>s to propagate state changes.
+    /// </summary>
+    [Cached(typeof(IExpandingContainer))]
+    public interface IExpandingContainer : IContainer, IExpandable
+    {
+    }
+}