Use bindable flow for checking idle time

osu.Game/Input/IdleTracker.cs

@@ -1,6 +1,7 @@
 // Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
+using osu.Framework.Configuration;
 using osu.Framework.Graphics;
 using osu.Framework.Input;
 using osu.Framework.Input.Bindings;
@@ -8,10 +9,30 @@
 
 namespace osu.Game.Input
 {
+    /// <summary>
+    /// Track whether the end-user is in an idle state, based on their last interaction with the game.
+    /// </summary>
     public class IdleTracker : Component, IKeyBindingHandler<PlatformAction>, IHandleGlobalInput
     {
+        private readonly double timeToIdle;
+
         private double lastInteractionTime;
-        public double IdleTime => Clock.CurrentTime - lastInteractionTime;
+
+        protected double TimeSpentIdle => Clock.CurrentTime - lastInteractionTime;
+
+        /// <summary>
+        /// Whether the user is currently in an idle state.
+        /// </summary>
+        public BindableBool IsIdle = new BindableBool();
+
+        /// <summary>
+        /// Intstantiate a new <see cref="IdleTracker"/>.
+        /// </summary>
+        /// <param name="timeToIdle">The length in milliseconds until an idle state should be assumed.</param>
+        public IdleTracker(double timeToIdle)
+        {
+            this.timeToIdle = timeToIdle;
+        }
 
         private bool updateLastInteractionTime()
         {
@@ -19,6 +40,12 @@ private bool updateLastInteractionTime()
             return false;
         }
 
+        protected override void Update()
+        {
+            base.Update();
+            IsIdle.Value = TimeSpentIdle > timeToIdle;
+        }
+
         public bool OnPressed(PlatformAction action) => updateLastInteractionTime();
 
         public bool OnReleased(PlatformAction action) => updateLastInteractionTime();

osu.Game/OsuGame.cs

@@ -319,7 +319,7 @@ protected override void LoadComplete()
                 },
                 mainContent = new Container { RelativeSizeAxes = Axes.Both },
                 overlayContent = new Container { RelativeSizeAxes = Axes.Both, Depth = float.MinValue },
-                idleTracker = new IdleTracker { RelativeSizeAxes = Axes.Both }
+                idleTracker = new IdleTracker(6000) { RelativeSizeAxes = Axes.Both }
             });
 
             loadComponentSingleFile(screenStack = new Loader(), d =>

osu.Game/Screens/Menu/ButtonSystem.cs

@@ -8,6 +8,7 @@
 using osu.Framework.Allocation;
 using osu.Framework.Audio;
 using osu.Framework.Audio.Sample;
+using osu.Framework.Configuration;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Input.Bindings;
@@ -27,6 +28,8 @@ public class ButtonSystem : Container, IStateful<ButtonSystemState>, IKeyBinding
     {
         public event Action<ButtonSystemState> StateChanged;
 
+        private readonly BindableBool isIdle = new BindableBool();
+
         public Action OnEdit;
         public Action OnExit;
         public Action OnDirect;
@@ -65,8 +68,6 @@ public void SetOsuLogo(OsuLogo logo)
 
         private SampleChannel sampleBack;
 
-        private IdleTracker idleTracker;
-
         public ButtonSystem()
         {
             RelativeSizeAxes = Axes.Both;
@@ -108,10 +109,19 @@ public ButtonSystem()
         private void load(AudioManager audio, OsuGame game, IdleTracker idleTracker)
         {
             this.game = game;
-            this.idleTracker = idleTracker;
+
+            isIdle.ValueChanged += updateIdleState;
+            isIdle.BindTo(idleTracker.IsIdle);
+
             sampleBack = audio.Sample.Get(@"Menu/button-back-select");
         }
 
+        private void updateIdleState(bool isIdle)
+        {
+            if (isIdle && State != ButtonSystemState.Exit)
+                State = ButtonSystemState.Initial;
+        }
+
         public bool OnPressed(GlobalAction action)
         {
             switch (action)
@@ -270,9 +280,6 @@ private void updateLogoState(ButtonSystemState lastState = ButtonSystemState.Ini
 
         protected override void Update()
         {
-            if (idleTracker?.IdleTime > 6000 && State != ButtonSystemState.Exit)
-                State = ButtonSystemState.Initial;
-
             base.Update();
 
             if (logo != null)