Display current distance snap and add button to update to use it

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

@@ -81,6 +81,12 @@ namespace osu.Game.Rulesets.Catch.Edit
             inputManager = GetContainingInputManager();
         }
 
+        protected override double ReadCurrentDistanceSnap(HitObject before, HitObject after)
+        {
+            // TODO: catch lol
+            return 1;
+        }
+
         protected override void Update()
         {
             base.Update();

osu.Game.Rulesets.Osu/Edit/OsuHitObjectComposer.cs

@@ -112,6 +112,14 @@ namespace osu.Game.Rulesets.Osu.Edit
 
         private RectangularPositionSnapGrid rectangularPositionSnapGrid;
 
+        protected override double ReadCurrentDistanceSnap(HitObject before, HitObject after)
+        {
+            float expectedDistance = DurationToDistance(before, after.StartTime - before.GetEndTime());
+            float actualDistance = Vector2.Distance(((OsuHitObject)before).EndPosition, ((OsuHitObject)after).Position);
+
+            return actualDistance / expectedDistance;
+        }
+
         protected override void Update()
         {
             base.Update();

osu.Game/Rulesets/Edit/DistancedHitObjectComposer.cs

@@ -3,6 +3,8 @@
 
 #nullable disable
 
+using System.Diagnostics;
+using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Bindables;
 using osu.Framework.Extensions;
@@ -13,7 +15,9 @@ using osu.Framework.Graphics.Shapes;
 using osu.Framework.Input.Bindings;
 using osu.Framework.Input.Events;
 using osu.Framework.Localisation;
+using osu.Framework.Utils;
 using osu.Game.Configuration;
+using osu.Game.Graphics.Sprites;
 using osu.Game.Graphics.UserInterface;
 using osu.Game.Input.Bindings;
 using osu.Game.Overlays;
@@ -32,7 +36,7 @@ namespace osu.Game.Rulesets.Edit
     {
         private const float adjust_step = 0.1f;
 
-        public Bindable<double> DistanceSpacingMultiplier { get; } = new BindableDouble(1.0)
+        public BindableDouble DistanceSpacingMultiplier { get; } = new BindableDouble(1.0)
         {
             MinValue = 0.1,
             MaxValue = 6.0,
@@ -44,6 +48,9 @@ namespace osu.Game.Rulesets.Edit
         protected ExpandingToolboxContainer RightSideToolboxContainer { get; private set; }
 
         private ExpandableSlider<double, SizeSlider<double>> distanceSpacingSlider;
+        private ExpandableButton readCurrentButton;
+
+        private OsuSpriteText currentDistanceSpacingDisplay;
 
         [Resolved(canBeNull: true)]
         private OnScreenDisplay onScreenDisplay { get; set; }
@@ -74,10 +81,29 @@ namespace osu.Game.Rulesets.Edit
                         Alpha = DistanceSpacingMultiplier.Disabled ? 0 : 1,
                         Child = new EditorToolboxGroup("snapping")
                         {
-                            Child = distanceSpacingSlider = new ExpandableSlider<double, SizeSlider<double>>
+                            Children = new Drawable[]
                             {
-                                Current = { BindTarget = DistanceSpacingMultiplier },
+                                distanceSpacingSlider = new ExpandableSlider<double, SizeSlider<double>>
-                                KeyboardStep = adjust_step,
+                                {
+                                    Current = { BindTarget = DistanceSpacingMultiplier },
+                                    KeyboardStep = adjust_step,
+                                },
+                                currentDistanceSpacingDisplay = new OsuSpriteText
+                                {
+                                },
+                                readCurrentButton = new ExpandableButton
+                                {
+                                    Text = "Use current",
+                                    Action = () =>
+                                    {
+                                        (HitObject before, HitObject after)? objects = getObjectsOnEitherSideOfCurrentTime();
+
+                                        Debug.Assert(objects != null);
+
+                                        DistanceSpacingMultiplier.Value = ReadCurrentDistanceSnap(objects.Value.before, objects.Value.after);
+                                    },
+                                    RelativeSizeAxes = Axes.X,
+                                }
                             }
                         }
                     }
@@ -85,6 +111,46 @@ namespace osu.Game.Rulesets.Edit
             });
         }
 
+        private (HitObject before, HitObject after)? getObjectsOnEitherSideOfCurrentTime()
+        {
+            HitObject lastBefore = Playfield.HitObjectContainer.AliveObjects.LastOrDefault(h => h.HitObject.GetEndTime() <= EditorClock.CurrentTime)?.HitObject;
+
+            if (lastBefore == null)
+                return null;
+
+            HitObject firstAfter = Playfield.HitObjectContainer.AliveObjects.FirstOrDefault(h => h.HitObject.StartTime >= EditorClock.CurrentTime)?.HitObject;
+
+            if (firstAfter == null)
+                return null;
+
+            if (lastBefore == firstAfter)
+                return null;
+
+            return (lastBefore, firstAfter);
+        }
+
+        protected abstract double ReadCurrentDistanceSnap(HitObject before, HitObject after);
+
+        protected override void Update()
+        {
+            base.Update();
+
+            (HitObject before, HitObject after)? objects = getObjectsOnEitherSideOfCurrentTime();
+
+            if (objects != null)
+            {
+                double currentSnap = ReadCurrentDistanceSnap(objects.Value.before, objects.Value.after);
+                readCurrentButton.Enabled.Value = Precision.AlmostEquals(currentSnap, DistanceSpacingMultiplier.Value, DistanceSpacingMultiplier.Precision);
+
+                currentDistanceSpacingDisplay.Text = $"Current {currentSnap:N1}x";
+            }
+            else
+            {
+                readCurrentButton.Enabled.Value = false;
+                currentDistanceSpacingDisplay.Text = "Current: -";
+            }
+        }
+
         protected override void LoadComplete()
         {
             base.LoadComplete();

osu.Game/Rulesets/Edit/ExpandableButton.cs

@@ -0,0 +1,36 @@
+// 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 osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Game.Graphics.Containers;
+using osu.Game.Graphics.UserInterfaceV2;
+
+namespace osu.Game.Rulesets.Edit
+{
+    internal class ExpandableButton : RoundedButton, IExpandable
+    {
+        public BindableBool Expanded { get; } = new BindableBool();
+
+        [Resolved(canBeNull: true)]
+        private IExpandingContainer? expandingContainer { get; set; }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            expandingContainer?.Expanded.BindValueChanged(containerExpanded =>
+            {
+                Expanded.Value = containerExpanded.NewValue;
+            }, true);
+
+            Expanded.BindValueChanged(expanded =>
+            {
+                if (expanded.NewValue)
+                    Show();
+                else
+                    Hide();
+            }, true);
+        }
+    }
+}