Allow OsuScreens to decide whether ruleset switching should be allowed.

Tidies up ToolbarModeSelector a lot by using DI.

osu.Game/OsuGame.cs

@@ -203,13 +203,7 @@ namespace osu.Game
             {
                 Depth = -3,
                 OnHome = delegate { intro?.ChildScreen?.MakeCurrent(); },
-                OnRulesetChange = r => Ruleset.Value = r,
+            }, overlayContent.Add);
-            }, t =>
-            {
-                Ruleset.ValueChanged += delegate { Toolbar.SetRuleset(Ruleset.Value); };
-                Ruleset.TriggerChange();
-                overlayContent.Add(Toolbar);
-            });
 
             options.StateChanged += delegate
             {

osu.Game/Overlays/Toolbar/Toolbar.cs

@@ -8,7 +8,6 @@ using osu.Framework.Graphics.Colour;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.Sprites;
 using osu.Framework.Input;
-using osu.Game.Database;
 using osu.Game.Graphics;
 using OpenTK;
 
@@ -20,7 +19,6 @@ namespace osu.Game.Overlays.Toolbar
         public const float TOOLTIP_HEIGHT = 30;
 
         public Action OnHome;
-        public Action<RulesetInfo> OnRulesetChange;
 
         private readonly ToolbarModeSelector modeSelector;
         private readonly ToolbarUserArea userArea;
@@ -53,13 +51,7 @@ namespace osu.Game.Overlays.Toolbar
                         {
                             Action = () => OnHome?.Invoke()
                         },
-                        modeSelector = new ToolbarModeSelector
+                        modeSelector = new ToolbarModeSelector()
-                        {
-                            OnRulesetChange = mode =>
-                            {
-                                OnRulesetChange?.Invoke(mode);
-                            }
-                        }
                     }
                 },
                 new FillFlowContainer
@@ -130,8 +122,6 @@ namespace osu.Game.Overlays.Toolbar
             }
         }
 
-        public void SetRuleset(RulesetInfo ruleset) => modeSelector.SetRuleset(ruleset);
-
         protected override void PopIn()
         {
             MoveToY(0, transition_time, EasingTypes.OutQuint);

osu.Game/Overlays/Toolbar/ToolbarModeSelector.cs

@@ -1,7 +1,6 @@
 // Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
 // Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
 
-using System;
 using System.Linq;
 using osu.Framework.Allocation;
 using osu.Framework.Caching;
@@ -12,6 +11,7 @@ using osu.Framework.Graphics.Sprites;
 using osu.Game.Database;
 using OpenTK;
 using OpenTK.Graphics;
+using osu.Framework.Configuration;
 
 namespace osu.Game.Overlays.Toolbar
 {
@@ -23,7 +23,7 @@ namespace osu.Game.Overlays.Toolbar
         private readonly Drawable modeButtonLine;
         private ToolbarModeButton activeButton;
 
-        public Action<RulesetInfo> OnRulesetChange;
+        private readonly Bindable<RulesetInfo> ruleset = new Bindable<RulesetInfo>();
 
         public ToolbarModeSelector()
         {
@@ -66,30 +66,36 @@ namespace osu.Game.Overlays.Toolbar
         }
 
         [BackgroundDependencyLoader]
-        private void load(RulesetDatabase rulesets)
+        private void load(RulesetDatabase rulesets, OsuGame game)
         {
-            foreach (var ruleset in rulesets.AllRulesets)
+            foreach (var r in rulesets.AllRulesets)
             {
                 modeButtons.Add(new ToolbarModeButton
                 {
-                    Ruleset = ruleset,
+                    Ruleset = r,
                     Action = delegate
                     {
-                        SetRuleset(ruleset);
+                        ruleset.Value = r;
-                        OnRulesetChange?.Invoke(ruleset);
                     }
                 });
             }
+
+            ruleset.ValueChanged += rulesetChanged;
+            ruleset.DisabledChanged += disabledChanged;
+            ruleset.BindTo(game.Ruleset);
         }
 
+        public override bool HandleInput => !ruleset.Disabled;
+
+        private void disabledChanged(bool isDisabled) => FadeColour(isDisabled ? Color4.Gray : Color4.White, 300);
+
         protected override void Update()
         {
             base.Update();
-
             Size = new Vector2(modeButtons.DrawSize.X, 1);
         }
 
-        public void SetRuleset(RulesetInfo ruleset)
+        private void rulesetChanged(RulesetInfo ruleset)
         {
             foreach (ToolbarModeButton m in modeButtons.Children.Cast<ToolbarModeButton>())
             {

osu.Game/Screens/OsuScreen.cs

@@ -5,6 +5,7 @@ using osu.Framework.Allocation;
 using osu.Framework.Configuration;
 using osu.Framework.Screens;
 using osu.Game.Beatmaps;
+using osu.Game.Database;
 using osu.Game.Graphics.Containers;
 
 namespace osu.Game.Screens
@@ -25,8 +26,12 @@ namespace osu.Game.Screens
 
         internal virtual bool HasLocalCursorDisplayed => false;
 
+        internal virtual bool AllowRulesetChange => true;
+
         private readonly Bindable<WorkingBeatmap> beatmap = new Bindable<WorkingBeatmap>();
 
+        private readonly Bindable<RulesetInfo> ruleset = new Bindable<RulesetInfo>();
+
         public WorkingBeatmap Beatmap
         {
             get
@@ -40,7 +45,7 @@ namespace osu.Game.Screens
         }
 
         [BackgroundDependencyLoader(permitNulls: true)]
-        private void load(OsuGameBase game)
+        private void load(OsuGameBase game, OsuGame osuGame)
         {
             if (game != null)
             {
@@ -52,11 +57,23 @@ namespace osu.Game.Screens
             }
 
             beatmap.ValueChanged += OnBeatmapChanged;
+
+            if (osuGame != null)
+                ruleset.BindTo(osuGame.Ruleset);
         }
 
+        /// <summary>
+        /// The global Beatmap was changed.
+        /// </summary>
         protected virtual void OnBeatmapChanged(WorkingBeatmap beatmap)
         {
+        }
 
+        protected override void Update()
+        {
+            if (!IsCurrentScreen) return;
+
+            ruleset.Disabled = !AllowRulesetChange;
         }
 
         protected override void OnEntering(Screen last)

osu.Game/Screens/Play/Player.cs

@@ -39,6 +39,8 @@ namespace osu.Game.Screens.Play
 
         public bool IsPaused => !interpolatedSourceClock.IsRunning;
 
+        internal override bool AllowRulesetChange => false;
+
         public bool HasFailed { get; private set; }
 
         public int RestartCount;

osu.Game/Screens/Play/PlayerLoader.cs

@@ -27,6 +27,8 @@ namespace osu.Game.Screens.Play
         private bool showOverlays = true;
         internal override bool ShowOverlays => showOverlays;
 
+        internal override bool AllowRulesetChange => false;
+
         protected override BackgroundScreen CreateBackground() => new BackgroundScreenBeatmap(Beatmap);
 
         public PlayerLoader(Player player)

osu.Game/Screens/Ranking/Results.cs

@@ -31,6 +31,8 @@ namespace osu.Game.Screens.Ranking
 
         private ResultModeTabControl modeChangeButtons;
 
+        internal override bool AllowRulesetChange => false;
+
         private Container currentPage;
 
         private static readonly Vector2 background_blur = new Vector2(20);