Add basic Queue based implementation of KPS

osu.Game.Tests/Visual/Gameplay/TestSceneKeysPerSecondCounter.cs

@@ -0,0 +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.
+
+namespace osu.Game.Tests.Visual.Gameplay
+{
+    public class TestSceneKeysPerSecondCounter
+    {
+        
+    }
+}

osu.Game/Screens/Play/HUD/KeysPerSecondCounter.cs

@@ -0,0 +1,125 @@
+// 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.Collections.Generic;
+using osu.Framework.Allocation;
+using osu.Framework.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Containers;
+using osu.Framework.Graphics.Sprites;
+using osu.Framework.Localisation;
+using osu.Game.Graphics;
+using osu.Game.Graphics.Sprites;
+using osu.Game.Graphics.UserInterface;
+using osu.Game.Skinning;
+using osuTK;
+
+namespace osu.Game.Screens.Play.HUD
+{
+    public class KeysPerSecondCounter : RollingCounter<int>, ISkinnableDrawable
+    {
+        private static Queue<DateTime>? timestamps;
+
+        private static event Action? onNewInput;
+        private readonly TimeSpan refreshSpan = TimeSpan.FromSeconds(1);
+
+        private const float alpha_when_invalid = 0.3f;
+        private readonly Bindable<bool> valid = new Bindable<bool>();
+
+        public static void AddTimestamp()
+        {
+            timestamps?.Enqueue(DateTime.Now);
+            onNewInput?.Invoke();
+        }
+
+        protected override double RollingDuration => 250;
+
+        public bool UsesFixedAnchor { get; set; }
+
+        public KeysPerSecondCounter()
+        {
+            timestamps ??= new Queue<DateTime>();
+            Current.Value = 0;
+            onNewInput += updateCounter;
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(OsuColour colours)
+        {
+            Colour = colours.BlueLighter;
+            valid.BindValueChanged(e =>
+                DrawableCount.FadeTo(e.NewValue ? 1 : alpha_when_invalid, 1000, Easing.OutQuint));
+        }
+
+        protected override void LoadComplete()
+        {
+            base.LoadComplete();
+
+            updateCounter();
+        }
+
+        protected override void Update()
+        {
+            if (timestamps != null)
+            {
+                if (timestamps.TryPeek(out var earliest) && DateTime.Now - earliest >= refreshSpan)
+                    timestamps.Dequeue();
+            }
+
+            updateCounter();
+
+            base.Update();
+        }
+
+        private void updateCounter()
+        {
+            valid.Value = timestamps != null;
+            Current.Value = timestamps?.Count ?? 0;
+        }
+
+        protected override IHasText CreateText() => new TextComponent
+        {
+            Alpha = alpha_when_invalid
+        };
+
+        private class TextComponent : CompositeDrawable, IHasText
+        {
+            public LocalisableString Text
+            {
+                get => text.Text;
+                set => text.Text = value;
+            }
+
+            private readonly OsuSpriteText text;
+
+            public TextComponent()
+            {
+                AutoSizeAxes = Axes.Both;
+
+                InternalChild = new FillFlowContainer
+                {
+                    AutoSizeAxes = Axes.Both,
+                    Spacing = new Vector2(2),
+                    Children = new Drawable[]
+                    {
+                        text = new OsuSpriteText
+                        {
+                            Anchor = Anchor.BottomLeft,
+                            Origin = Anchor.BottomLeft,
+                            Font = OsuFont.Numeric.With(size: 16, fixedWidth: true)
+                        },
+                        new OsuSpriteText
+                        {
+                            Anchor = Anchor.BottomLeft,
+                            Origin = Anchor.BottomLeft,
+                            Font = OsuFont.Numeric.With(size: 8, fixedWidth: true),
+                            Text = @"KPS",
+                            Padding = new MarginPadding { Bottom = 1.5f }, // align baseline better
+                        }
+                    }
+                };
+            }
+        }
+    }
+}

osu.Game/Screens/Play/KeyCounter.cs

@@ -10,6 +10,7 @@ using osu.Framework.Graphics.Sprites;
 using osu.Framework.Graphics.Textures;
 using osu.Game.Graphics;
 using osu.Game.Graphics.Sprites;
+using osu.Game.Screens.Play.HUD;
 using osuTK;
 using osuTK.Graphics;
 
@@ -55,6 +56,7 @@ namespace osu.Game.Screens.Play
 
         public void Increment()
         {
+            KeysPerSecondCounter.AddTimestamp();
             if (!IsCounting)
                 return;