Merge pull request #31764 from peppy/beatmap-carousel-v2-grouping

Add group support to beatmap carousel v2

osu.Game.Tests/Visual/SongSelect/BeatmapCarouselV2TestScene.cs

@@ -21,6 +21,7 @@ using osu.Game.Screens.SelectV2;
 using osu.Game.Tests.Beatmaps;
 using osu.Game.Tests.Resources;
 using osuTK.Graphics;
+using osuTK.Input;
 using BeatmapCarousel = osu.Game.Screens.SelectV2.BeatmapCarousel;
 
 namespace osu.Game.Tests.Visual.SongSelect
@@ -53,7 +54,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         }
 
         [SetUpSteps]
-        public void SetUpSteps()
+        public virtual void SetUpSteps()
         {
             RemoveAllBeatmaps();
 
@@ -129,12 +130,59 @@ namespace osu.Game.Tests.Visual.SongSelect
             });
         }
 
-        protected void SortBy(FilterCriteria criteria) => AddStep($"sort by {criteria.Sort}", () => Carousel.Filter(criteria));
+        protected void SortBy(FilterCriteria criteria) => AddStep($"sort {criteria.Sort} group {criteria.Group}", () => Carousel.Filter(criteria));
 
         protected void WaitForDrawablePanels() => AddUntilStep("drawable panels loaded", () => Carousel.ChildrenOfType<ICarouselPanel>().Count(), () => Is.GreaterThan(0));
         protected void WaitForSorting() => AddUntilStep("sorting finished", () => Carousel.IsFiltering, () => Is.False);
         protected void WaitForScrolling() => AddUntilStep("scroll finished", () => Scroll.Current, () => Is.EqualTo(Scroll.Target));
 
+        protected void SelectNextPanel() => AddStep("select next panel", () => InputManager.Key(Key.Down));
+        protected void SelectPrevPanel() => AddStep("select prev panel", () => InputManager.Key(Key.Up));
+        protected void SelectNextGroup() => AddStep("select next group", () => InputManager.Key(Key.Right));
+        protected void SelectPrevGroup() => AddStep("select prev group", () => InputManager.Key(Key.Left));
+
+        protected void Select() => AddStep("select", () => InputManager.Key(Key.Enter));
+
+        protected void CheckNoSelection() => AddAssert("has no selection", () => Carousel.CurrentSelection, () => Is.Null);
+        protected void CheckHasSelection() => AddAssert("has selection", () => Carousel.CurrentSelection, () => Is.Not.Null);
+
+        protected void WaitForGroupSelection(int group, int panel)
+        {
+            AddUntilStep($"selected is group{group} panel{panel}", () =>
+            {
+                var groupingFilter = Carousel.Filters.OfType<BeatmapCarouselFilterGrouping>().Single();
+
+                GroupDefinition g = groupingFilter.GroupItems.Keys.ElementAt(group);
+                CarouselItem item = groupingFilter.GroupItems[g].ElementAt(panel);
+
+                return ReferenceEquals(Carousel.CurrentSelection, item.Model);
+            });
+        }
+
+        protected void WaitForSelection(int set, int? diff = null)
+        {
+            AddUntilStep($"selected is set{set}{(diff.HasValue ? $" diff{diff.Value}" : "")}", () =>
+            {
+                if (diff != null)
+                    return ReferenceEquals(Carousel.CurrentSelection, BeatmapSets[set].Beatmaps[diff.Value]);
+
+                return BeatmapSets[set].Beatmaps.Contains(Carousel.CurrentSelection);
+            });
+        }
+
+        protected void ClickVisiblePanel<T>(int index)
+            where T : Drawable
+        {
+            AddStep($"click panel at index {index}", () =>
+            {
+                Carousel.ChildrenOfType<T>()
+                        .Where(p => ((ICarouselPanel)p).Item?.IsVisible == true)
+                        .Reverse()
+                        .ElementAt(index)
+                        .TriggerClick();
+            });
+        }
+
         /// <summary>
         /// Add requested beatmap sets count to list.
         /// </summary>

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarouselV2Basics.cs

@@ -32,6 +32,13 @@ namespace osu.Game.Tests.Visual.SongSelect
             RemoveAllBeatmaps();
         }
 
+        [Test]
+        public void TestOffScreenLoading()
+        {
+            AddStep("disable masking", () => Scroll.Masking = false);
+            AddStep("enable masking", () => Scroll.Masking = true);
+        }
+
         [Test]
         public void TestAddRemoveOneByOne()
         {
@@ -43,7 +50,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         public void TestSorting()
         {
             AddBeatmaps(10);
-            SortBy(new FilterCriteria { Sort = SortMode.Difficulty });
+            SortBy(new FilterCriteria { Group = GroupMode.Difficulty, Sort = SortMode.Difficulty });
             SortBy(new FilterCriteria { Sort = SortMode.Artist });
         }
 

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarouselV2GroupSelection.cs

@@ -0,0 +1,135 @@
+// 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.Linq;
+using NUnit.Framework;
+using osu.Framework.Testing;
+using osu.Game.Beatmaps;
+using osu.Game.Screens.Select;
+using osu.Game.Screens.Select.Filter;
+using osu.Game.Screens.SelectV2;
+
+namespace osu.Game.Tests.Visual.SongSelect
+{
+    [TestFixture]
+    public partial class TestSceneBeatmapCarouselV2GroupSelection : BeatmapCarouselV2TestScene
+    {
+        public override void SetUpSteps()
+        {
+            RemoveAllBeatmaps();
+
+            CreateCarousel();
+
+            SortBy(new FilterCriteria { Group = GroupMode.Difficulty, Sort = SortMode.Difficulty });
+        }
+
+        [Test]
+        public void TestOpenCloseGroupWithNoSelection()
+        {
+            AddBeatmaps(10, 5);
+            WaitForDrawablePanels();
+
+            AddAssert("no beatmaps visible", () => Carousel.ChildrenOfType<BeatmapPanel>().Count(p => p.Alpha > 0), () => Is.Zero);
+            CheckNoSelection();
+
+            ClickVisiblePanel<GroupPanel>(0);
+            AddUntilStep("some beatmaps visible", () => Carousel.ChildrenOfType<BeatmapPanel>().Count(p => p.Alpha > 0), () => Is.GreaterThan(0));
+            CheckNoSelection();
+
+            ClickVisiblePanel<GroupPanel>(0);
+            AddUntilStep("no beatmaps visible", () => Carousel.ChildrenOfType<BeatmapPanel>().Count(p => p.Alpha > 0), () => Is.Zero);
+            CheckNoSelection();
+        }
+
+        [Test]
+        public void TestCarouselRemembersSelection()
+        {
+            AddBeatmaps(10);
+            WaitForDrawablePanels();
+
+            SelectNextGroup();
+
+            object? selection = null;
+
+            AddStep("store drawable selection", () => selection = getSelectedPanel()?.Item?.Model);
+
+            CheckHasSelection();
+            AddAssert("drawable selection non-null", () => selection, () => Is.Not.Null);
+            AddAssert("drawable selection matches carousel selection", () => selection, () => Is.EqualTo(Carousel.CurrentSelection));
+
+            RemoveAllBeatmaps();
+            AddUntilStep("no drawable selection", getSelectedPanel, () => Is.Null);
+
+            AddBeatmaps(10);
+            WaitForDrawablePanels();
+
+            CheckHasSelection();
+            AddAssert("no drawable selection", getSelectedPanel, () => Is.Null);
+
+            AddStep("add previous selection", () => BeatmapSets.Add(((BeatmapInfo)selection!).BeatmapSet!));
+
+            AddAssert("selection matches original carousel selection", () => selection, () => Is.EqualTo(Carousel.CurrentSelection));
+            AddUntilStep("drawable selection restored", () => getSelectedPanel()?.Item?.Model, () => Is.EqualTo(selection));
+            AddAssert("carousel item is visible", () => getSelectedPanel()?.Item?.IsVisible, () => Is.True);
+
+            ClickVisiblePanel<GroupPanel>(0);
+            AddUntilStep("carousel item not visible", getSelectedPanel, () => Is.Null);
+
+            ClickVisiblePanel<GroupPanel>(0);
+            AddUntilStep("carousel item is visible", () => getSelectedPanel()?.Item?.IsVisible, () => Is.True);
+
+            BeatmapPanel? getSelectedPanel() => Carousel.ChildrenOfType<BeatmapPanel>().SingleOrDefault(p => p.Selected.Value);
+        }
+
+        [Test]
+        public void TestGroupSelectionOnHeader()
+        {
+            AddBeatmaps(10, 3);
+            WaitForDrawablePanels();
+
+            SelectNextGroup();
+            WaitForGroupSelection(0, 0);
+
+            SelectPrevPanel();
+            SelectPrevGroup();
+            WaitForGroupSelection(2, 9);
+        }
+
+        [Test]
+        public void TestKeyboardSelection()
+        {
+            AddBeatmaps(10, 3);
+            WaitForDrawablePanels();
+
+            SelectNextPanel();
+            SelectNextPanel();
+            SelectNextPanel();
+            SelectNextPanel();
+            CheckNoSelection();
+
+            // open first group
+            Select();
+            CheckNoSelection();
+            AddUntilStep("some beatmaps visible", () => Carousel.ChildrenOfType<BeatmapPanel>().Count(p => p.Alpha > 0), () => Is.GreaterThan(0));
+
+            SelectNextPanel();
+            Select();
+            WaitForGroupSelection(0, 0);
+
+            SelectNextGroup();
+            WaitForGroupSelection(0, 1);
+
+            SelectNextGroup();
+            WaitForGroupSelection(0, 2);
+
+            SelectPrevGroup();
+            WaitForGroupSelection(0, 1);
+
+            SelectPrevGroup();
+            WaitForGroupSelection(0, 0);
+
+            SelectPrevGroup();
+            WaitForGroupSelection(2, 9);
+        }
+    }
+}

osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarouselV2Selection.cs

@@ -22,10 +22,10 @@ namespace osu.Game.Tests.Visual.SongSelect
         {
             AddBeatmaps(10);
             WaitForDrawablePanels();
-            checkNoSelection();
+            CheckNoSelection();
 
-            select();
+            Select();
-            checkNoSelection();
+            CheckNoSelection();
 
             AddStep("press down arrow", () => InputManager.PressKey(Key.Down));
             checkSelectionIterating(false);
@@ -39,8 +39,8 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddStep("release up arrow", () => InputManager.ReleaseKey(Key.Up));
             checkSelectionIterating(false);
 
-            select();
+            Select();
-            checkHasSelection();
+            CheckHasSelection();
         }
 
         /// <summary>
@@ -52,7 +52,7 @@ namespace osu.Game.Tests.Visual.SongSelect
         {
             AddBeatmaps(10);
             WaitForDrawablePanels();
-            checkNoSelection();
+            CheckNoSelection();
 
             AddStep("press right arrow", () => InputManager.PressKey(Key.Right));
             checkSelectionIterating(true);
@@ -73,13 +73,13 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddBeatmaps(10);
             WaitForDrawablePanels();
 
-            selectNextGroup();
+            SelectNextGroup();
 
             object? selection = null;
 
             AddStep("store drawable selection", () => selection = getSelectedPanel()?.Item?.Model);
 
-            checkHasSelection();
+            CheckHasSelection();
             AddAssert("drawable selection non-null", () => selection, () => Is.Not.Null);
             AddAssert("drawable selection matches carousel selection", () => selection, () => Is.EqualTo(Carousel.CurrentSelection));
 
@@ -89,13 +89,14 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddBeatmaps(10);
             WaitForDrawablePanels();
 
-            checkHasSelection();
+            CheckHasSelection();
             AddAssert("no drawable selection", getSelectedPanel, () => Is.Null);
 
             AddStep("add previous selection", () => BeatmapSets.Add(((BeatmapInfo)selection!).BeatmapSet!));
 
+            AddAssert("selection matches original carousel selection", () => selection, () => Is.EqualTo(Carousel.CurrentSelection));
             AddUntilStep("drawable selection restored", () => getSelectedPanel()?.Item?.Model, () => Is.EqualTo(selection));
-            AddAssert("drawable selection matches carousel selection", () => selection, () => Is.EqualTo(Carousel.CurrentSelection));
+            AddAssert("carousel item is visible", () => getSelectedPanel()?.Item?.IsVisible, () => Is.True);
 
             BeatmapPanel? getSelectedPanel() => Carousel.ChildrenOfType<BeatmapPanel>().SingleOrDefault(p => p.Selected.Value);
         }
@@ -108,10 +109,10 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddBeatmaps(total_set_count);
             WaitForDrawablePanels();
 
-            selectNextGroup();
+            SelectNextGroup();
-            waitForSelection(0, 0);
+            WaitForSelection(0, 0);
-            selectPrevGroup();
+            SelectPrevGroup();
-            waitForSelection(total_set_count - 1, 0);
+            WaitForSelection(total_set_count - 1, 0);
         }
 
         [Test]
@@ -122,10 +123,25 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddBeatmaps(total_set_count);
             WaitForDrawablePanels();
 
-            selectPrevGroup();
+            SelectPrevGroup();
-            waitForSelection(total_set_count - 1, 0);
+            WaitForSelection(total_set_count - 1, 0);
-            selectNextGroup();
+            SelectNextGroup();
-            waitForSelection(0, 0);
+            WaitForSelection(0, 0);
+        }
+
+        [Test]
+        public void TestGroupSelectionOnHeader()
+        {
+            AddBeatmaps(10, 3);
+            WaitForDrawablePanels();
+
+            SelectNextGroup();
+            SelectNextGroup();
+            WaitForSelection(1, 0);
+
+            SelectPrevPanel();
+            SelectPrevGroup();
+            WaitForSelection(0, 0);
         }
 
         [Test]
@@ -134,71 +150,50 @@ namespace osu.Game.Tests.Visual.SongSelect
             AddBeatmaps(10, 3);
             WaitForDrawablePanels();
 
-            selectNextPanel();
+            SelectNextPanel();
-            selectNextPanel();
+            SelectNextPanel();
-            selectNextPanel();
+            SelectNextPanel();
-            selectNextPanel();
+            SelectNextPanel();
-            checkNoSelection();
+            CheckNoSelection();
 
-            select();
+            Select();
-            waitForSelection(3, 0);
+            WaitForSelection(3, 0);
 
-            selectNextPanel();
+            SelectNextPanel();
-            waitForSelection(3, 0);
+            WaitForSelection(3, 0);
 
-            select();
+            Select();
-            waitForSelection(3, 1);
+            WaitForSelection(3, 1);
 
-            selectNextPanel();
+            SelectNextPanel();
-            waitForSelection(3, 1);
+            WaitForSelection(3, 1);
 
-            select();
+            Select();
-            waitForSelection(3, 2);
+            WaitForSelection(3, 2);
 
-            selectNextPanel();
+            SelectNextPanel();
-            waitForSelection(3, 2);
+            WaitForSelection(3, 2);
 
-            select();
+            Select();
-            waitForSelection(4, 0);
+            WaitForSelection(4, 0);
         }
 
         [Test]
         public void TestEmptyTraversal()
         {
-            selectNextPanel();
+            SelectNextPanel();
-            checkNoSelection();
+            CheckNoSelection();
 
-            selectNextGroup();
+            SelectNextGroup();
-            checkNoSelection();
+            CheckNoSelection();
 
-            selectPrevPanel();
+            SelectPrevPanel();
-            checkNoSelection();
+            CheckNoSelection();
 
-            selectPrevGroup();
+            SelectPrevGroup();
-            checkNoSelection();
+            CheckNoSelection();
         }
 
-        private void waitForSelection(int set, int? diff = null)
-        {
-            AddUntilStep($"selected is set{set}{(diff.HasValue ? $" diff{diff.Value}" : "")}", () =>
-            {
-                if (diff != null)
-                    return ReferenceEquals(Carousel.CurrentSelection, BeatmapSets[set].Beatmaps[diff.Value]);
-
-                return BeatmapSets[set].Beatmaps.Contains(Carousel.CurrentSelection);
-            });
-        }
-
-        private void selectNextPanel() => AddStep("select next panel", () => InputManager.Key(Key.Down));
-        private void selectPrevPanel() => AddStep("select prev panel", () => InputManager.Key(Key.Up));
-        private void selectNextGroup() => AddStep("select next group", () => InputManager.Key(Key.Right));
-        private void selectPrevGroup() => AddStep("select prev group", () => InputManager.Key(Key.Left));
-
-        private void select() => AddStep("select", () => InputManager.Key(Key.Enter));
-
-        private void checkNoSelection() => AddAssert("has no selection", () => Carousel.CurrentSelection, () => Is.Null);
-        private void checkHasSelection() => AddAssert("has selection", () => Carousel.CurrentSelection, () => Is.Not.Null);
-
         private void checkSelectionIterating(bool isIterating)
         {
             object? selection = null;

osu.Game/Screens/SelectV2/BeatmapCarousel.cs

@@ -92,34 +92,102 @@ namespace osu.Game.Screens.SelectV2
 
         #region Selection handling
 
-        protected override void HandleItemSelected(object? model)
+        private GroupDefinition? lastSelectedGroup;
+        private BeatmapInfo? lastSelectedBeatmap;
+
+        protected override bool HandleItemSelected(object? model)
         {
             base.HandleItemSelected(model);
 
+            switch (model)
+            {
+                case GroupDefinition group:
+                    // Special case – collapsing an open group.
+                    if (lastSelectedGroup == group)
+                    {
+                        setVisibilityOfGroupItems(lastSelectedGroup, false);
+                        lastSelectedGroup = null;
+                        return false;
+                    }
+
+                    setVisibleGroup(group);
+                    return false;
+
+                case BeatmapSetInfo setInfo:
                     // Selecting a set isn't valid – let's re-select the first difficulty.
-            if (model is BeatmapSetInfo setInfo)
-            {
                     CurrentSelection = setInfo.Beatmaps.First();
-                return;
+                    return false;
-            }
 
-            if (model is BeatmapInfo beatmapInfo)
+                case BeatmapInfo beatmapInfo:
-                setVisibilityOfSetItems(beatmapInfo.BeatmapSet!, true);
-        }
 
-        protected override void HandleItemDeselected(object? model)
+                    // If we have groups, we need to account for them.
+                    if (Criteria.SplitOutDifficulties)
                     {
-            base.HandleItemDeselected(model);
+                        // Find the containing group. There should never be too many groups so iterating is efficient enough.
+                        GroupDefinition? group = grouping.GroupItems.SingleOrDefault(kvp => kvp.Value.Any(i => ReferenceEquals(i.Model, beatmapInfo))).Key;
 
-            if (model is BeatmapInfo beatmapInfo)
+                        if (group != null)
-                setVisibilityOfSetItems(beatmapInfo.BeatmapSet!, false);
+                            setVisibleGroup(group);
+                    }
+                    else
+                    {
+                        setVisibleSet(beatmapInfo);
+                    }
+
+                    return true;
+            }
+
+            return true;
+        }
+
+        protected override bool CheckValidForGroupSelection(CarouselItem item)
+        {
+            switch (item.Model)
+            {
+                case BeatmapSetInfo:
+                    return true;
+
+                case BeatmapInfo:
+                    return Criteria.SplitOutDifficulties;
+
+                case GroupDefinition:
+                    return false;
+
+                default:
+                    throw new ArgumentException($"Unsupported model type {item.Model}");
+            }
+        }
+
+        private void setVisibleGroup(GroupDefinition group)
+        {
+            if (lastSelectedGroup != null)
+                setVisibilityOfGroupItems(lastSelectedGroup, false);
+            lastSelectedGroup = group;
+            setVisibilityOfGroupItems(group, true);
+        }
+
+        private void setVisibilityOfGroupItems(GroupDefinition group, bool visible)
+        {
+            if (grouping.GroupItems.TryGetValue(group, out var items))
+            {
+                foreach (var i in items)
+                    i.IsVisible = visible;
+            }
+        }
+
+        private void setVisibleSet(BeatmapInfo beatmapInfo)
+        {
+            if (lastSelectedBeatmap != null)
+                setVisibilityOfSetItems(lastSelectedBeatmap.BeatmapSet!, false);
+            lastSelectedBeatmap = beatmapInfo;
+            setVisibilityOfSetItems(beatmapInfo.BeatmapSet!, true);
         }
 
         private void setVisibilityOfSetItems(BeatmapSetInfo set, bool visible)
         {
-            if (grouping.SetItems.TryGetValue(set, out var group))
+            if (grouping.SetItems.TryGetValue(set, out var items))
             {
-                foreach (var i in group)
+                foreach (var i in items)
                     i.IsVisible = visible;
             }
         }
@@ -143,9 +211,11 @@ namespace osu.Game.Screens.SelectV2
 
         private readonly DrawablePool<BeatmapPanel> beatmapPanelPool = new DrawablePool<BeatmapPanel>(100);
         private readonly DrawablePool<BeatmapSetPanel> setPanelPool = new DrawablePool<BeatmapSetPanel>(100);
+        private readonly DrawablePool<GroupPanel> groupPanelPool = new DrawablePool<GroupPanel>(100);
 
         private void setupPools()
         {
+            AddInternal(groupPanelPool);
             AddInternal(beatmapPanelPool);
             AddInternal(setPanelPool);
         }
@@ -154,7 +224,12 @@ namespace osu.Game.Screens.SelectV2
         {
             switch (item.Model)
             {
+                case GroupDefinition:
+                    return groupPanelPool.Get();
+
                 case BeatmapInfo:
+                    // TODO: if beatmap is a group selection target, it needs to be a different drawable
+                    // with more information attached.
                     return beatmapPanelPool.Get();
 
                 case BeatmapSetInfo:
@@ -166,4 +241,6 @@ namespace osu.Game.Screens.SelectV2
 
         #endregion
     }
+
+    public record GroupDefinition(string Title);
 }

osu.Game/Screens/SelectV2/BeatmapCarouselFilterGrouping.cs

@@ -8,6 +8,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using osu.Game.Beatmaps;
 using osu.Game.Screens.Select;
+using osu.Game.Screens.Select.Filter;
 
 namespace osu.Game.Screens.SelectV2
 {
@@ -18,7 +19,13 @@ namespace osu.Game.Screens.SelectV2
         /// </summary>
         public IDictionary<BeatmapSetInfo, HashSet<CarouselItem>> SetItems => setItems;
 
+        /// <summary>
+        /// Groups contain children which are group-selectable. This dictionary holds the relationships between groups-panels to allow expanding them on selection.
+        /// </summary>
+        public IDictionary<GroupDefinition, HashSet<CarouselItem>> GroupItems => groupItems;
+
         private readonly Dictionary<BeatmapSetInfo, HashSet<CarouselItem>> setItems = new Dictionary<BeatmapSetInfo, HashSet<CarouselItem>>();
+        private readonly Dictionary<GroupDefinition, HashSet<CarouselItem>> groupItems = new Dictionary<GroupDefinition, HashSet<CarouselItem>>();
 
         private readonly Func<FilterCriteria> getCriteria;
 
@@ -29,52 +36,99 @@ namespace osu.Game.Screens.SelectV2
 
         public async Task<IEnumerable<CarouselItem>> Run(IEnumerable<CarouselItem> items, CancellationToken cancellationToken) => await Task.Run(() =>
         {
+            bool groupSetsTogether;
+
+            setItems.Clear();
+            groupItems.Clear();
+
             var criteria = getCriteria();
-
-            if (criteria.SplitOutDifficulties)
-            {
-                foreach (var item in items)
-                {
-                    item.IsVisible = true;
-                    item.IsGroupSelectionTarget = true;
-                }
-
-                return items;
-            }
-
-            CarouselItem? lastItem = null;
-
             var newItems = new List<CarouselItem>(items.Count());
 
+            // Add criteria groups.
+            switch (criteria.Group)
+            {
+                default:
+                    groupSetsTogether = true;
+                    newItems.AddRange(items);
+                    break;
+
+                case GroupMode.Difficulty:
+                    groupSetsTogether = false;
+                    int starGroup = int.MinValue;
+
                     foreach (var item in items)
                     {
                         cancellationToken.ThrowIfCancellationRequested();
 
-                if (item.Model is BeatmapInfo b)
+                        var b = (BeatmapInfo)item.Model;
-                {
-                    // Add set header
-                    if (lastItem == null || (lastItem.Model is BeatmapInfo b2 && b2.BeatmapSet!.OnlineID != b.BeatmapSet!.OnlineID))
-                    {
-                        newItems.Add(new CarouselItem(b.BeatmapSet!)
-                        {
-                            DrawHeight = BeatmapSetPanel.HEIGHT,
-                            IsGroupSelectionTarget = true
-                        });
-                    }
 
-                    if (!setItems.TryGetValue(b.BeatmapSet!, out var related))
+                        if (b.StarRating > starGroup)
-                        setItems[b.BeatmapSet!] = related = new HashSet<CarouselItem>();
+                        {
-
+                            starGroup = (int)Math.Floor(b.StarRating);
-                    related.Add(item);
+                            newItems.Add(new CarouselItem(new GroupDefinition($"{starGroup} - {++starGroup} *")) { DrawHeight = GroupPanel.HEIGHT });
                         }
 
                         newItems.Add(item);
-                lastItem = item;
+                    }
 
-                item.IsGroupSelectionTarget = false;
+                    break;
+            }
+
+            // Add set headers wherever required.
+            CarouselItem? lastItem = null;
+
+            if (groupSetsTogether)
+            {
+                for (int i = 0; i < newItems.Count; i++)
+                {
+                    cancellationToken.ThrowIfCancellationRequested();
+
+                    var item = newItems[i];
+
+                    if (item.Model is BeatmapInfo beatmap)
+                    {
+                        bool newBeatmapSet = lastItem == null || (lastItem.Model is BeatmapInfo lastBeatmap && lastBeatmap.BeatmapSet!.ID != beatmap.BeatmapSet!.ID);
+
+                        if (newBeatmapSet)
+                        {
+                            newItems.Insert(i, new CarouselItem(beatmap.BeatmapSet!) { DrawHeight = BeatmapSetPanel.HEIGHT });
+                            i++;
+                        }
+
+                        if (!setItems.TryGetValue(beatmap.BeatmapSet!, out var related))
+                            setItems[beatmap.BeatmapSet!] = related = new HashSet<CarouselItem>();
+
+                        related.Add(item);
                         item.IsVisible = false;
                     }
 
+                    lastItem = item;
+                }
+            }
+
+            // Link group items to their headers.
+            GroupDefinition? lastGroup = null;
+
+            foreach (var item in newItems)
+            {
+                cancellationToken.ThrowIfCancellationRequested();
+
+                if (item.Model is GroupDefinition group)
+                {
+                    lastGroup = group;
+                    continue;
+                }
+
+                if (lastGroup != null)
+                {
+                    if (!groupItems.TryGetValue(lastGroup, out var groupRelated))
+                        groupItems[lastGroup] = groupRelated = new HashSet<CarouselItem>();
+                    groupRelated.Add(item);
+
+                    item.IsVisible = false;
+                }
+            }
+
             return newItems;
         }, cancellationToken).ConfigureAwait(false);
     }

osu.Game/Screens/SelectV2/BeatmapSetPanel.cs

@@ -67,7 +67,6 @@ namespace osu.Game.Screens.SelectV2
             base.PrepareForUse();
 
             Debug.Assert(Item != null);
-            Debug.Assert(Item.IsGroupSelectionTarget);
 
             var beatmapSetInfo = (BeatmapSetInfo)Item.Model;
 

osu.Game/Screens/SelectV2/Carousel.cs

@@ -8,6 +8,7 @@ using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
 using osu.Framework.Bindables;
+using osu.Framework.Caching;
 using osu.Framework.Extensions.TypeExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
@@ -130,7 +131,7 @@ namespace osu.Game.Screens.SelectV2
         ///
         /// A filter may add, mutate or remove items.
         /// </remarks>
-        protected IEnumerable<ICarouselFilter> Filters { get; init; } = Enumerable.Empty<ICarouselFilter>();
+        public IEnumerable<ICarouselFilter> Filters { get; init; } = Enumerable.Empty<ICarouselFilter>();
 
         /// <summary>
         /// All items which are to be considered for display in this carousel.
@@ -167,12 +168,18 @@ namespace osu.Game.Screens.SelectV2
         protected Drawable? GetMaterialisedDrawableForItem(CarouselItem item) =>
             scroll.Panels.SingleOrDefault(p => ((ICarouselPanel)p).Item == item);
 
+        /// <summary>
+        /// When a user is traversing the carousel via group selection keys, assert whether the item provided is a valid target.
+        /// </summary>
+        /// <param name="item">The candidate item.</param>
+        /// <returns>Whether the provided item is a valid group target. If <c>false</c>, more panels will be checked in the user's requested direction until a valid target is found.</returns>
+        protected virtual bool CheckValidForGroupSelection(CarouselItem item) => true;
+
         /// <summary>
         /// Called when an item is "selected".
         /// </summary>
-        protected virtual void HandleItemSelected(object? model)
+        /// <returns>Whether the item should be selected.</returns>
-        {
+        protected virtual bool HandleItemSelected(object? model) => true;
-        }
 
         /// <summary>
         /// Called when an item is "deselected".
@@ -205,7 +212,6 @@ namespace osu.Game.Screens.SelectV2
             InternalChild = scroll = new CarouselScrollContainer
             {
                 RelativeSizeAxes = Axes.Both,
-                Masking = false,
             };
 
             Items.BindCollectionChanged((_, _) => FilterAsync());
@@ -303,19 +309,19 @@ namespace osu.Game.Screens.SelectV2
                     return true;
 
                 case GlobalAction.SelectNext:
-                    selectNext(1, isGroupSelection: false);
+                    traverseKeyboardSelection(1);
-                    return true;
-
-                case GlobalAction.SelectNextGroup:
-                    selectNext(1, isGroupSelection: true);
                     return true;
 
                 case GlobalAction.SelectPrevious:
-                    selectNext(-1, isGroupSelection: false);
+                    traverseKeyboardSelection(-1);
+                    return true;
+
+                case GlobalAction.SelectNextGroup:
+                    traverseGroupSelection(1);
                     return true;
 
                 case GlobalAction.SelectPreviousGroup:
-                    selectNext(-1, isGroupSelection: true);
+                    traverseGroupSelection(-1);
                     return true;
             }
 
@@ -326,91 +332,99 @@ namespace osu.Game.Screens.SelectV2
         {
         }
 
-        /// <summary>
+        private void traverseKeyboardSelection(int direction)
-        /// Select the next valid selection relative to a current selection.
-        /// This is generally for keyboard based traversal.
-        /// </summary>
-        /// <param name="direction">Positive for downwards, negative for upwards.</param>
-        /// <param name="isGroupSelection">Whether the selection should traverse groups. Group selection updates the actual selection immediately, while non-group selection will only prepare a future keyboard selection.</param>
-        /// <returns>Whether selection was possible.</returns>
-        private bool selectNext(int direction, bool isGroupSelection)
         {
-            // Ensure sanity
+            if (carouselItems == null || carouselItems.Count == 0) return;
-            Debug.Assert(direction != 0);
-            direction = direction > 0 ? 1 : -1;
 
-            if (carouselItems == null || carouselItems.Count == 0)
+            int originalIndex;
-                return false;
 
-            // If the user has a different keyboard selection and requests
+            if (currentKeyboardSelection.Index != null)
-            // group selection, first transfer the keyboard selection to actual selection.
+                originalIndex = currentKeyboardSelection.Index.Value;
-            if (isGroupSelection && currentSelection.CarouselItem != currentKeyboardSelection.CarouselItem)
+            else if (direction > 0)
-            {
+                originalIndex = carouselItems.Count - 1;
-                TryActivateSelection();
+            else
-                return true;
+                originalIndex = 0;
-            }
 
-            CarouselItem? selectionItem = currentKeyboardSelection.CarouselItem;
+            int newIndex = originalIndex;
-            int selectionIndex = currentKeyboardSelection.Index ?? -1;
-
-            // To keep things simple, let's first handle the cases where there's no selection yet.
-            if (selectionItem == null || selectionIndex < 0)
-            {
-                // Start by selecting the first item.
-                selectionItem = carouselItems.First();
-                selectionIndex = 0;
-
-                // In the forwards case, immediately attempt selection of this panel.
-                // If selection fails, continue with standard logic to find the next valid selection.
-                if (direction > 0 && attemptSelection(selectionItem))
-                    return true;
-
-                // In the backwards direction we can just allow the selection logic to go ahead and loop around to the last valid.
-            }
-
-            Debug.Assert(selectionItem != null);
-
-            // As a second special case, if we're group selecting backwards and the current selection isn't a group,
-            // make sure to go back to the group header this item belongs to, so that the block below doesn't find it and stop too early.
-            if (isGroupSelection && direction < 0)
-            {
-                while (!carouselItems[selectionIndex].IsGroupSelectionTarget)
-                    selectionIndex--;
-            }
-
-            CarouselItem? newItem;
 
             // Iterate over every item back to the current selection, finding the first valid item.
             // The fail condition is when we reach the selection after a cyclic loop over every item.
             do
             {
-                selectionIndex += direction;
+                newIndex = (newIndex + direction + carouselItems.Count) % carouselItems.Count;
-                newItem = carouselItems[(selectionIndex + carouselItems.Count) % carouselItems.Count];
+                var newItem = carouselItems[newIndex];
 
-                if (attemptSelection(newItem))
+                if (newItem.IsVisible)
-                    return true;
-            } while (newItem != selectionItem);
-
-            return false;
-
-            bool attemptSelection(CarouselItem item)
                 {
-                if (!item.IsVisible || (isGroupSelection && !item.IsGroupSelectionTarget))
+                    setKeyboardSelection(newItem.Model);
-                    return false;
+                    return;
-
-                if (isGroupSelection)
-                    setSelection(item.Model);
-                else
-                    setKeyboardSelection(item.Model);
-
-                return true;
                 }
+            } while (newIndex != originalIndex);
+        }
+
+        /// <summary>
+        /// Select the next valid selection relative to a current selection.
+        /// This is generally for keyboard based traversal.
+        /// </summary>
+        /// <param name="direction">Positive for downwards, negative for upwards.</param>
+        /// <returns>Whether selection was possible.</returns>
+        private void traverseGroupSelection(int direction)
+        {
+            if (carouselItems == null || carouselItems.Count == 0) return;
+
+            // If the user has a different keyboard selection and requests
+            // group selection, first transfer the keyboard selection to actual selection.
+            if (currentSelection.CarouselItem != currentKeyboardSelection.CarouselItem)
+            {
+                TryActivateSelection();
+
+                // There's a chance this couldn't resolve, at which point continue with standard traversal.
+                if (currentSelection.CarouselItem == currentKeyboardSelection.CarouselItem)
+                    return;
+            }
+
+            int originalIndex;
+            int newIndex;
+
+            if (currentSelection.Index == null)
+            {
+                // If there's no current selection, start from either end of the full list.
+                newIndex = originalIndex = direction > 0 ? carouselItems.Count - 1 : 0;
+            }
+            else
+            {
+                newIndex = originalIndex = currentSelection.Index.Value;
+
+                // As a second special case, if we're group selecting backwards and the current selection isn't a group,
+                // make sure to go back to the group header this item belongs to, so that the block below doesn't find it and stop too early.
+                if (direction < 0)
+                {
+                    while (!CheckValidForGroupSelection(carouselItems[newIndex]))
+                        newIndex--;
+                }
+            }
+
+            // Iterate over every item back to the current selection, finding the first valid item.
+            // The fail condition is when we reach the selection after a cyclic loop over every item.
+            do
+            {
+                newIndex = (newIndex + direction + carouselItems.Count) % carouselItems.Count;
+                var newItem = carouselItems[newIndex];
+
+                if (CheckValidForGroupSelection(newItem))
+                {
+                    setSelection(newItem.Model);
+                    return;
+                }
+            } while (newIndex != originalIndex);
         }
 
         #endregion
 
         #region Selection handling
 
+        private readonly Cached selectionValid = new Cached();
+
         private Selection currentKeyboardSelection = new Selection();
         private Selection currentSelection = new Selection();
 
@@ -419,29 +433,22 @@ namespace osu.Game.Screens.SelectV2
             if (currentSelection.Model == model)
                 return;
 
-            var previousSelection = currentSelection;
+            if (HandleItemSelected(model))
+            {
+                if (currentSelection.Model != null)
+                    HandleItemDeselected(currentSelection.Model);
 
-            if (previousSelection.Model != null)
+                currentKeyboardSelection = new Selection(model);
-                HandleItemDeselected(previousSelection.Model);
+                currentSelection = currentKeyboardSelection;
+            }
 
-            currentSelection = currentKeyboardSelection = new Selection(model);
+            selectionValid.Invalidate();
-            HandleItemSelected(currentSelection.Model);
-
-            // `HandleItemSelected` can alter `CurrentSelection`, which will recursively call `setSelection()` again.
-            // if that happens, the rest of this method should be a no-op.
-            if (currentSelection.Model != model)
-                return;
-
-            refreshAfterSelection();
-            scrollToSelection();
         }
 
         private void setKeyboardSelection(object? model)
         {
             currentKeyboardSelection = new Selection(model);
-
+            selectionValid.Invalidate();
-            refreshAfterSelection();
-            scrollToSelection();
         }
 
         /// <summary>
@@ -526,6 +533,13 @@ namespace osu.Game.Screens.SelectV2
             if (carouselItems == null)
                 return;
 
+            if (!selectionValid.IsValid)
+            {
+                refreshAfterSelection();
+                scrollToSelection();
+                selectionValid.Validate();
+            }
+
             var range = getDisplayRange();
 
             if (range != displayedRange)

osu.Game/Screens/SelectV2/CarouselItem.cs

@@ -29,11 +29,6 @@ namespace osu.Game.Screens.SelectV2
         /// </summary>
         public float DrawHeight { get; set; } = DEFAULT_HEIGHT;
 
-        /// <summary>
-        /// Whether this item should be a valid target for user group selection hotkeys.
-        /// </summary>
-        public bool IsGroupSelectionTarget { get; set; }
-
         /// <summary>
         /// Whether this item is visible or collapsed (hidden).
         /// </summary>

osu.Game/Screens/SelectV2/GroupPanel.cs

@@ -0,0 +1,112 @@
+// 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.Diagnostics;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Extensions.Color4Extensions;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Pooling;
+using osu.Framework.Graphics.Shapes;
+using osu.Framework.Input.Events;
+using osu.Game.Graphics.Sprites;
+using osuTK;
+using osuTK.Graphics;
+
+namespace osu.Game.Screens.SelectV2
+{
+    public partial class GroupPanel : PoolableDrawable, ICarouselPanel
+    {
+        public const float HEIGHT = CarouselItem.DEFAULT_HEIGHT * 2;
+
+        [Resolved]
+        private BeatmapCarousel carousel { get; set; } = null!;
+
+        private Box activationFlash = null!;
+        private OsuSpriteText text = null!;
+
+        [BackgroundDependencyLoader]
+        private void load()
+        {
+            Size = new Vector2(500, HEIGHT);
+            Masking = true;
+
+            InternalChildren = new Drawable[]
+            {
+                new Box
+                {
+                    Colour = Color4.DarkBlue.Darken(5),
+                    Alpha = 0.8f,
+                    RelativeSizeAxes = Axes.Both,
+                },
+                activationFlash = new Box
+                {
+                    Colour = Color4.White,
+                    Blending = BlendingParameters.Additive,
+                    Alpha = 0,
+                    RelativeSizeAxes = Axes.Both,
+                },
+                text = new OsuSpriteText
+                {
+                    Padding = new MarginPadding(5),
+                    Anchor = Anchor.CentreLeft,
+                    Origin = Anchor.CentreLeft,
+                }
+            };
+
+            Selected.BindValueChanged(value =>
+            {
+                activationFlash.FadeTo(value.NewValue ? 0.2f : 0, 500, Easing.OutQuint);
+            });
+
+            KeyboardSelected.BindValueChanged(value =>
+            {
+                if (value.NewValue)
+                {
+                    BorderThickness = 5;
+                    BorderColour = Color4.Pink;
+                }
+                else
+                {
+                    BorderThickness = 0;
+                }
+            });
+        }
+
+        protected override void PrepareForUse()
+        {
+            base.PrepareForUse();
+
+            Debug.Assert(Item != null);
+
+            GroupDefinition group = (GroupDefinition)Item.Model;
+
+            text.Text = group.Title;
+
+            this.FadeInFromZero(500, Easing.OutQuint);
+        }
+
+        protected override bool OnClick(ClickEvent e)
+        {
+            carousel.CurrentSelection = Item!.Model;
+            return true;
+        }
+
+        #region ICarouselPanel
+
+        public CarouselItem? Item { get; set; }
+        public BindableBool Selected { get; } = new BindableBool();
+        public BindableBool KeyboardSelected { get; } = new BindableBool();
+
+        public double DrawYPosition { get; set; }
+
+        public void Activated()
+        {
+            // sets should never be activated.
+            throw new InvalidOperationException();
+        }
+
+        #endregion
+    }
+}