Add function of computing position range occupied by hit objects

osu.Game.Rulesets.Catch/Edit/CatchHitObjectUtils.cs

@@ -1,7 +1,10 @@
 // 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.Collections.Generic;
+using System.Linq;
 using osu.Game.Rulesets.Catch.Objects;
+using osu.Game.Rulesets.Catch.UI;
 using osu.Game.Rulesets.Objects;
 using osu.Game.Rulesets.UI.Scrolling;
 using osuTK;
@@ -20,5 +23,41 @@ namespace osu.Game.Rulesets.Catch.Edit
         {
             return new Vector2(hitObject.OriginalX, hitObjectContainer.PositionAtTime(hitObject.StartTime));
         }
+
+        /// <summary>
+        /// Get the range of horizontal position occupied by the hit object.
+        /// </summary>
+        /// <remarks>
+        /// <see cref="TinyDroplet"/>s are excluded and returns <see cref="PositionRange.EMPTY"/>.
+        /// </remarks>
+        public static PositionRange GetPositionRange(HitObject hitObject)
+        {
+            switch (hitObject)
+            {
+                case Fruit fruit:
+                    return new PositionRange(fruit.OriginalX);
+
+                case Droplet droplet:
+                    return droplet is TinyDroplet ? PositionRange.EMPTY : new PositionRange(droplet.OriginalX);
+
+                case JuiceStream _:
+                    return GetPositionRange(hitObject.NestedHitObjects);
+
+                case BananaShower _:
+                    // A banana shower occupies the whole screen width.
+                    return new PositionRange(0, CatchPlayfield.WIDTH);
+
+                default:
+                    return PositionRange.EMPTY;
+            }
+        }
+
+        /// <summary>
+        /// Get the range of horizontal position occupied by the hit objects.
+        /// </summary>
+        /// <remarks>
+        /// <see cref="TinyDroplet"/>s are excluded.
+        /// </remarks>
+        public static PositionRange GetPositionRange(IEnumerable<HitObject> hitObjects) => hitObjects.Select(GetPositionRange).Aggregate(PositionRange.EMPTY, PositionRange.Union);
     }
 }

osu.Game.Rulesets.Catch/Edit/PositionRange.cs

@@ -0,0 +1,33 @@
+// 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;
+
+#nullable enable
+
+namespace osu.Game.Rulesets.Catch.Edit
+{
+    /// <summary>
+    /// Represents a closed interval of horizontal positions in the playfield.
+    /// </summary>
+    public readonly struct PositionRange
+    {
+        public readonly float Min;
+        public readonly float Max;
+
+        public PositionRange(float value)
+            : this(value, value)
+        {
+        }
+
+        public PositionRange(float min, float max)
+        {
+            Min = min;
+            Max = max;
+        }
+
+        public static PositionRange Union(PositionRange a, PositionRange b) => new PositionRange(Math.Min(a.Min, b.Min), Math.Max(a.Max, b.Max));
+
+        public static readonly PositionRange EMPTY = new PositionRange(float.PositiveInfinity, float.NegativeInfinity);
+    }
+}