Add basic background display system.

osu.Game/Graphics/Background/Background.cs

@@ -0,0 +1,36 @@
+//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 osu.Framework.Graphics;
+using osu.Framework.Graphics.Sprites;
+using osu.Game.Graphics.Containers;
+using OpenTK;
+using OpenTK.Graphics;
+
+namespace osu.Game.Graphics.Background
+{
+    class Background : OsuLargeContainer
+    {
+        protected Sprite BackgroundSprite;
+
+        public override void Load()
+        {
+            base.Load();
+
+            Add(BackgroundSprite = new Sprite
+            {
+                Texture = Game.Textures.Get(@"Menu/background"),
+                Anchor = Anchor.Centre,
+                Origin = Anchor.Centre,
+                Colour = Color4.DarkGray
+            });
+        }
+
+        protected override void Update()
+        {
+            base.Update();
+            BackgroundSprite.Scale = new Vector2(Math.Max(ActualSize.X / BackgroundSprite.Size.X, ActualSize.Y / BackgroundSprite.Size.Y));
+        }
+    }
+}