Merge branch 'master' into ParallaxContainerImprovement

osu.Game/Graphics/UserInterface/ScreenBreadcrumbControl.cs

@@ -0,0 +1,54 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System.Linq;
+using osu.Framework.Extensions.IEnumerableExtensions;
+using osu.Framework.Screens;
+
+namespace osu.Game.Graphics.UserInterface
+{
+    /// <summary>
+    /// A <see cref="BreadcrumbControl"/> which follows the active screen (and allows navigation) in a <see cref="Screen"/> stack.
+    /// </summary>
+    public class ScreenBreadcrumbControl : BreadcrumbControl<Screen>
+    {
+        private Screen last;
+
+        public ScreenBreadcrumbControl(Screen initialScreen)
+        {
+            Current.ValueChanged += newScreen =>
+            {
+                if (last != newScreen && !newScreen.IsCurrentScreen)
+                    newScreen.MakeCurrent();
+            };
+
+            onPushed(initialScreen);
+        }
+
+        private void screenChanged(Screen newScreen)
+        {
+            if (newScreen == null) return;
+
+            if (last != null)
+            {
+                last.Exited -= screenChanged;
+                last.ModePushed -= onPushed;
+            }
+
+            last = newScreen;
+
+            newScreen.Exited += screenChanged;
+            newScreen.ModePushed += onPushed;
+
+            Current.Value = newScreen;
+        }
+
+        private void onPushed(Screen screen)
+        {
+            Items.ToList().SkipWhile(i => i != Current.Value).Skip(1).ForEach(RemoveItem);
+            AddItem(screen);
+
+            screenChanged(screen);
+        }
+    }
+}