From fc5832ce67d7af1b32f88109b705788c4bf07e07 Mon Sep 17 00:00:00 2001
From: Salman Alshamrani <frenzibyte@gmail.com>
Date: Wed, 5 Feb 2025 04:44:06 -0500
Subject: [PATCH] Support variable spacing between carousel items

---
 osu.Game/Screens/SelectV2/BeatmapCarousel.cs | 11 +++++++
 osu.Game/Screens/SelectV2/Carousel.cs        | 33 +++++++++++++-------
 2 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/osu.Game/Screens/SelectV2/BeatmapCarousel.cs b/osu.Game/Screens/SelectV2/BeatmapCarousel.cs
index 9f62780dda..12660d8642 100644
--- a/osu.Game/Screens/SelectV2/BeatmapCarousel.cs
+++ b/osu.Game/Screens/SelectV2/BeatmapCarousel.cs
@@ -20,12 +20,23 @@ namespace osu.Game.Screens.SelectV2
     [Cached]
     public partial class BeatmapCarousel : Carousel<BeatmapInfo>
     {
+        public const float SPACING = 5f;
+
         private IBindableList<BeatmapSetInfo> detachedBeatmaps = null!;
 
         private readonly LoadingLayer loading;
 
         private readonly BeatmapCarouselFilterGrouping grouping;
 
+        protected override float GetSpacingBetweenPanels(CarouselItem top, CarouselItem bottom)
+        {
+            if (top.Model is BeatmapInfo || bottom.Model is BeatmapInfo)
+                // Beatmap difficulty panels do not overlap with themselves or any other panel.
+                return SPACING;
+
+            return -SPACING;
+        }
+
         public BeatmapCarousel()
         {
             DebounceDelay = 100;
diff --git a/osu.Game/Screens/SelectV2/Carousel.cs b/osu.Game/Screens/SelectV2/Carousel.cs
index 608ef207d9..d7b6f251c3 100644
--- a/osu.Game/Screens/SelectV2/Carousel.cs
+++ b/osu.Game/Screens/SelectV2/Carousel.cs
@@ -50,11 +50,6 @@ namespace osu.Game.Screens.SelectV2
         /// </summary>
         public float DistanceOffscreenToPreload { get; set; }
 
-        /// <summary>
-        /// Vertical space between panel layout. Negative value can be used to create an overlapping effect.
-        /// </summary>
-        protected float SpacingBetweenPanels { get; set; } = -5;
-
         /// <summary>
         /// When a new request arrives to change filtering, the number of milliseconds to wait before performing the filter.
         /// Regardless of any external debouncing, this is a safety measure to avoid triggering too many threaded operations.
@@ -116,6 +111,11 @@ namespace osu.Game.Screens.SelectV2
             }
         }
 
+        /// <summary>
+        /// Returns the vertical spacing between two given carousel items. Negative value can be used to create an overlapping effect.
+        /// </summary>
+        protected virtual float GetSpacingBetweenPanels(CarouselItem top, CarouselItem bottom) => 0f;
+
         #endregion
 
         #region Properties and methods concerning implementations
@@ -260,7 +260,7 @@ namespace osu.Game.Screens.SelectV2
                     }
 
                     log("Updating Y positions");
-                    updateYPositions(items, visibleHalfHeight, SpacingBetweenPanels);
+                    updateYPositions(items, visibleHalfHeight);
                 }
                 catch (OperationCanceledException)
                 {
@@ -283,17 +283,26 @@ namespace osu.Game.Screens.SelectV2
             void log(string text) => Logger.Log($"Carousel[op {cts.GetHashCode().ToString()}] {stopwatch.ElapsedMilliseconds} ms: {text}");
         }
 
-        private static void updateYPositions(IEnumerable<CarouselItem> carouselItems, float offset, float spacing)
+        private void updateYPositions(IEnumerable<CarouselItem> carouselItems, float offset)
         {
+            CarouselItem? previousVisible = null;
+
             foreach (var item in carouselItems)
-                updateItemYPosition(item, ref offset, spacing);
+                updateItemYPosition(item, ref previousVisible, ref offset);
         }
 
-        private static void updateItemYPosition(CarouselItem item, ref float offset, float spacing)
+        private void updateItemYPosition(CarouselItem item, ref CarouselItem? previousVisible, ref float offset)
         {
+            float spacing = previousVisible == null || !item.IsVisible ? 0 : GetSpacingBetweenPanels(previousVisible, item);
+
+            offset += spacing;
             item.CarouselYPosition = offset;
+
             if (item.IsVisible)
-                offset += item.DrawHeight + spacing;
+            {
+                offset += item.DrawHeight;
+                previousVisible = item;
+            }
         }
 
         #endregion
@@ -470,7 +479,7 @@ namespace osu.Game.Screens.SelectV2
                 return;
             }
 
-            float spacing = SpacingBetweenPanels;
+            CarouselItem? lastVisible = null;
             int count = carouselItems.Count;
 
             Selection prevKeyboard = currentKeyboardSelection;
@@ -482,7 +491,7 @@ namespace osu.Game.Screens.SelectV2
             {
                 var item = carouselItems[i];
 
-                updateItemYPosition(item, ref yPos, spacing);
+                updateItemYPosition(item, ref lastVisible, ref yPos);
 
                 if (ReferenceEquals(item.Model, currentKeyboardSelection.Model))
                     currentKeyboardSelection = new Selection(item.Model, item, item.CarouselYPosition, i);