Add BackgroundMode stack.

osu.Game/GameModes/BackgroundMode.cs

@@ -0,0 +1,97 @@
+//Copyright (c) 2007-2016 ppy Pty Ltd <contact@ppy.sh>.
+//Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using osu.Framework.GameModes;
+using osu.Framework.Graphics.Transformations;
+using osu.Game.Graphics.Background;
+using OpenTK;
+
+namespace osu.Game.GameModes
+{
+    public abstract class BackgroundMode : GameMode, IEquatable<BackgroundMode>
+    {
+        public virtual bool Equals(BackgroundMode other)
+        {
+            return other?.GetType() == GetType();
+        }
+
+        const float transition_length = 500;
+        const float x_movement_amount = 50;
+
+        public override void Load()
+        {
+            base.Load();
+
+            Content.Scale *= 1 + (x_movement_amount / Size.X) * 2;
+        }
+
+        protected override void OnEntering(GameMode last)
+        {
+            Content.FadeOut();
+            Content.MoveToX(x_movement_amount);
+
+            Content.FadeIn(transition_length, EasingTypes.InOutQuart);
+            Content.MoveToX(0, transition_length, EasingTypes.InOutQuart);
+
+            base.OnEntering(last);
+        }
+
+        protected override void OnSuspending(GameMode next)
+        {
+            Content.MoveToX(-x_movement_amount, transition_length, EasingTypes.InOutQuart);
+            base.OnSuspending(next);
+        }
+
+        protected override void OnExiting(GameMode next)
+        {
+            Content.FadeOut(transition_length, EasingTypes.OutExpo);
+            Content.MoveToX(x_movement_amount, transition_length, EasingTypes.OutExpo);
+
+            base.OnExiting(next);
+        }
+
+        protected override void OnResuming(GameMode last)
+        {
+            Content.MoveToX(0, transition_length, EasingTypes.OutExpo);
+            base.OnResuming(last);
+        }
+    }
+
+    public class BackgroundModeDefault : BackgroundMode
+    {
+        public override void Load()
+        {
+            base.Load();
+
+            Add(new Background());
+        }
+    }
+
+    public class BackgroundModeCustom : BackgroundMode
+    {
+        private readonly string textureName;
+
+        public BackgroundModeCustom(string textureName)
+        {
+            this.textureName = textureName;
+        }
+
+        public override void Load()
+        {
+            base.Load();
+
+            Add(new Background(textureName));
+        }
+
+        public override bool Equals(BackgroundMode other)
+        {
+            return base.Equals(other) && textureName == ((BackgroundModeCustom)other).textureName;
+        }
+
+    }
+}