Implement input handling behaviour of beatmap card dropdown

osu.Game/Beatmaps/Drawables/Cards/BeatmapCard.cs

@@ -44,6 +44,8 @@ namespace osu.Game.Beatmaps.Drawables.Cards
 
         private readonly BeatmapDownloadTracker downloadTracker;
 
+        private BeatmapCardDropdown dropdown = null!;
+
         private BeatmapCardThumbnail thumbnail = null!;
 
         private Container rightAreaBackground = null!;
@@ -80,7 +82,7 @@ namespace osu.Game.Beatmaps.Drawables.Cards
             GridContainer titleContainer;
             GridContainer artistContainer;
 
-            InternalChild = new BeatmapCardDropdown(height)
+            InternalChild = dropdown = new BeatmapCardDropdown(height)
             {
                 Body = new Container
                 {
@@ -277,6 +279,14 @@ namespace osu.Game.Beatmaps.Drawables.Cards
                                                     ChildrenEnumerable = createStatistics()
                                                 },
                                                 new BeatmapCardExtraInfoRow(beatmapSet)
+                                                {
+                                                    Hovered = _ =>
+                                                    {
+                                                        dropdown.ScheduleShow();
+                                                        return false;
+                                                    },
+                                                    Unhovered = _ => dropdown.ScheduleHide()
+                                                }
                                             }
                                         },
                                         downloadProgressBar = new BeatmapCardDownloadProgressBar

osu.Game/Beatmaps/Drawables/Cards/BeatmapCardDropdown.cs

@@ -1,12 +1,15 @@
 // 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.
 
+#nullable enable
+
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Effects;
 using osu.Framework.Graphics.Shapes;
+using osu.Framework.Threading;
 using osu.Game.Overlays;
 using osuTK;
 
@@ -37,13 +40,13 @@ namespace osu.Game.Beatmaps.Drawables.Cards
             RelativeSizeAxes = Axes.X;
             Height = height;
 
-            InternalChild = content = new Container
+            InternalChild = content = new HoverHandlingContainer
             {
                 RelativeSizeAxes = Axes.X,
                 AutoSizeAxes = Axes.Y,
                 CornerRadius = BeatmapCard.CORNER_RADIUS,
                 Masking = true,
-
+                Unhovered = _ => checkForHide(),
                 Children = new Drawable[]
                 {
                     background = new Box
@@ -57,12 +60,18 @@ namespace osu.Game.Beatmaps.Drawables.Cards
                         CornerRadius = BeatmapCard.CORNER_RADIUS,
                         Masking = true,
                     },
-                    dropdownContent = new Container
+                    dropdownContent = new HoverHandlingContainer
                     {
                         RelativeSizeAxes = Axes.X,
                         AutoSizeAxes = Axes.Y,
                         Margin = new MarginPadding { Top = height },
-                        Alpha = 0
+                        Alpha = 0,
+                        Hovered = _ =>
+                        {
+                            keep();
+                            return true;
+                        },
+                        Unhovered = _ => checkForHide()
                     },
                     borderContainer = new Container
                     {
@@ -95,6 +104,41 @@ namespace osu.Game.Beatmaps.Drawables.Cards
             FinishTransforms(true);
         }
 
+        private ScheduledDelegate? scheduledExpandedChange;
+
+        public void ScheduleShow()
+        {
+            scheduledExpandedChange?.Cancel();
+            if (Expanded.Value)
+                return;
+
+            scheduledExpandedChange = Scheduler.AddDelayed(() => Expanded.Value = true, 100);
+        }
+
+        public void ScheduleHide()
+        {
+            scheduledExpandedChange?.Cancel();
+            if (!Expanded.Value)
+                return;
+
+            scheduledExpandedChange = Scheduler.AddDelayed(() => Expanded.Value = false, 500);
+        }
+
+        private void checkForHide()
+        {
+            if (content.IsHovered || dropdownContent.IsHovered)
+                return;
+
+            scheduledExpandedChange?.Cancel();
+            Expanded.Value = false;
+        }
+
+        private void keep()
+        {
+            scheduledExpandedChange?.Cancel();
+            Expanded.Value = true;
+        }
+
         private void updateState()
         {
             background.FadeTo(Expanded.Value ? 1 : 0, BeatmapCard.TRANSITION_DURATION, Easing.OutQuint);

osu.Game/Beatmaps/Drawables/Cards/BeatmapCardExtraInfoRow.cs

@@ -8,14 +8,14 @@ using osuTK;
 
 namespace osu.Game.Beatmaps.Drawables.Cards
 {
-    public class BeatmapCardExtraInfoRow : CompositeDrawable
+    public class BeatmapCardExtraInfoRow : HoverHandlingContainer
     {
         public BeatmapCardExtraInfoRow(APIBeatmapSet beatmapSet)
         {
             RelativeSizeAxes = Axes.X;
             AutoSizeAxes = Axes.Y;
 
-            InternalChild = new FillFlowContainer
+            Child = new FillFlowContainer
             {
                 RelativeSizeAxes = Axes.X,
                 AutoSizeAxes = Axes.Y,

osu.Game/Beatmaps/Drawables/Cards/HoverHandlingContainer.cs

@@ -0,0 +1,27 @@
+// 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.
+
+#nullable enable
+
+using System;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Input.Events;
+
+namespace osu.Game.Beatmaps.Drawables.Cards
+{
+    public class HoverHandlingContainer : Container
+    {
+        public Func<HoverEvent, bool>? Hovered { get; set; }
+        public Action<HoverLostEvent>? Unhovered { get; set; }
+
+        protected override bool OnHover(HoverEvent e) => Hovered?.Invoke(e) ?? base.OnHover(e);
+
+        protected override void OnHoverLost(HoverLostEvent e)
+        {
+            if (Unhovered != null)
+                Unhovered?.Invoke(e);
+            else
+                base.OnHoverLost(e);
+        }
+    }
+}