Add basic implementation of a toggleable menu item

osu.Game/Graphics/UserInterface/DrawableToggleMenuItem.cs

@@ -0,0 +1,60 @@
+// 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.Bindables;
+using osu.Framework.Graphics;
+using osu.Framework.Graphics.Sprites;
+using osuTK;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    public class DrawableToggleMenuItem : DrawableOsuMenuItem
+    {
+        protected new ToggleMenuItem Item => (ToggleMenuItem)base.Item;
+
+        public DrawableToggleMenuItem(ToggleMenuItem item)
+            : base(item)
+        {
+        }
+
+        protected override TextContainer CreateTextContainer() => new ToggleTextContainer
+        {
+            State = { BindTarget = Item.State }
+        };
+
+        private class ToggleTextContainer : TextContainer
+        {
+            public readonly Bindable<bool> State = new Bindable<bool>();
+
+            private readonly SpriteIcon checkmark;
+
+            public ToggleTextContainer()
+            {
+                Add(checkmark = new SpriteIcon
+                {
+                    Anchor = Anchor.CentreLeft,
+                    Origin = Anchor.CentreLeft,
+                    Icon = FontAwesome.Solid.Check,
+                    Size = new Vector2(10),
+                    Margin = new MarginPadding { Horizontal = MARGIN_HORIZONTAL },
+                    AlwaysPresent = true,
+                });
+            }
+
+            protected override void LoadComplete()
+            {
+                base.LoadComplete();
+
+                State.BindValueChanged(state => checkmark.Alpha = state.NewValue ? 1 : 0, true);
+            }
+
+            protected override void Update()
+            {
+                base.Update();
+
+                // Todo: This is bad. This can maybe be done better with a refactor of DrawableOsuMenuItem.
+                checkmark.X = BoldText.DrawWidth + 10;
+            }
+        }
+    }
+}