From 0a45aa80cb011e658dc1d7c3504d2fe4ef12f079 Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 27 Jan 2022 16:16:49 +0900
Subject: [PATCH 1/3] Remove unnecessary double-schedule in `UpdateBeatmapSet`

---
 osu.Game/Screens/Select/BeatmapCarousel.cs | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/osu.Game/Screens/Select/BeatmapCarousel.cs b/osu.Game/Screens/Select/BeatmapCarousel.cs
index dff2c598c3..94e520ba1c 100644
--- a/osu.Game/Screens/Select/BeatmapCarousel.cs
+++ b/osu.Game/Screens/Select/BeatmapCarousel.cs
@@ -311,13 +311,10 @@ namespace osu.Game.Screens.Select
 
             itemsCache.Invalidate();
 
-            Schedule(() =>
-            {
-                if (!Scroll.UserScrolling)
-                    ScrollToSelected(true);
+            if (!Scroll.UserScrolling)
+                ScrollToSelected(true);
 
-                BeatmapSetsChanged?.Invoke();
-            });
+            BeatmapSetsChanged?.Invoke();
         });
 
         /// <summary>

From 449e9bcf5c123e1e1c92534f8f3a710412a5028d Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 27 Jan 2022 16:17:38 +0900
Subject: [PATCH 2/3] Ensure beatmap carousel scroll position is maintained
 during deletion operations

---
 osu.Game/Screens/Select/BeatmapCarousel.cs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/osu.Game/Screens/Select/BeatmapCarousel.cs b/osu.Game/Screens/Select/BeatmapCarousel.cs
index 94e520ba1c..c27915c383 100644
--- a/osu.Game/Screens/Select/BeatmapCarousel.cs
+++ b/osu.Game/Screens/Select/BeatmapCarousel.cs
@@ -286,6 +286,9 @@ namespace osu.Game.Screens.Select
 
             root.RemoveChild(existingSet);
             itemsCache.Invalidate();
+
+            if (!Scroll.UserScrolling)
+                ScrollToSelected(true);
         });
 
         public void UpdateBeatmapSet(BeatmapSetInfo beatmapSet) => Schedule(() =>

From f2cecad83b2e1df2b2e15c5cd49e04534cf55dca Mon Sep 17 00:00:00 2001
From: Dean Herbert <pe@ppy.sh>
Date: Thu, 27 Jan 2022 16:38:02 +0900
Subject: [PATCH 3/3] Add failing test coverage showing carousel deletions
 don't keep scroll position

---
 .../SongSelect/TestSceneBeatmapCarousel.cs    | 43 +++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs b/osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs
index 0298c3bea9..2f2001c4f2 100644
--- a/osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs
+++ b/osu.Game.Tests/Visual/SongSelect/TestSceneBeatmapCarousel.cs
@@ -9,6 +9,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Extensions.IEnumerableExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
+using osu.Framework.Utils;
 using osu.Game.Beatmaps;
 using osu.Game.Configuration;
 using osu.Game.Rulesets;
@@ -40,6 +41,36 @@ namespace osu.Game.Tests.Visual.SongSelect
             this.rulesets = rulesets;
         }
 
+        [Test]
+        public void TestScrollPositionMaintainedOnAdd()
+        {
+            loadBeatmaps(count: 1, randomDifficulties: false);
+
+            for (int i = 0; i < 10; i++)
+            {
+                AddRepeatStep("Add some sets", () => carousel.UpdateBeatmapSet(TestResources.CreateTestBeatmapSetInfo()), 4);
+
+                checkSelectionIsCentered();
+            }
+        }
+
+        [Test]
+        public void TestScrollPositionMaintainedOnDelete()
+        {
+            loadBeatmaps(count: 50, randomDifficulties: false);
+
+            for (int i = 0; i < 10; i++)
+            {
+                AddRepeatStep("Remove some sets", () =>
+                    carousel.RemoveBeatmapSet(carousel.Items.Select(item => item.Item)
+                                                      .OfType<CarouselBeatmapSet>()
+                                                      .OrderBy(item => item.GetHashCode())
+                                                      .First(item => item.State.Value != CarouselItemState.Selected && item.Visible).BeatmapSet), 4);
+
+                checkSelectionIsCentered();
+            }
+        }
+
         [Test]
         public void TestManyPanels()
         {
@@ -813,6 +844,18 @@ namespace osu.Game.Tests.Visual.SongSelect
                 carousel.Items.Count(s => (diff ? s.Item is CarouselBeatmap : s.Item is CarouselBeatmapSet) && s.Item.Visible) == count);
         }
 
+        private void checkSelectionIsCentered()
+        {
+            AddAssert("Selected panel is centered", () =>
+            {
+                return Precision.AlmostEquals(
+                    carousel.ScreenSpaceDrawQuad.Centre,
+                    carousel.Items
+                            .First(i => i.Item.State.Value == CarouselItemState.Selected)
+                            .ScreenSpaceDrawQuad.Centre, 100);
+            });
+        }
+
         private void checkNoSelection() => AddAssert("Selection is null", () => currentSelection == null);
 
         private void nextRandom() =>