more refactoring

Sledgemapper/SpriteSheet.cs

@@ -0,0 +1,37 @@
+using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework.Content;
+using Microsoft.Xna.Framework.Graphics;
+using System;
+using System.Collections.Generic;
+
+namespace Sledgemapper
+{
+    internal class SpriteSheet
+    {
+        internal Texture2D Texture;
+        internal Dictionary<String, Rectangle> index;
+
+        public void LoadContent(ContentManager content, string spriteIndex, string texture)
+        {
+            index = content.Load<Dictionary<String, Rectangle>>(spriteIndex);
+            Texture = content.Load<Texture2D>(texture);
+        }
+
+        internal Rectangle? SourceRectangle(string spriteName)
+        {
+            Rectangle r;
+            bool hasValue = index.TryGetValue(spriteName, out r);
+
+            if (hasValue)
+            {
+                return r;
+            }
+            else
+            {
+                throw new Exception("value doesn't exist");
+            }
+        }
+    }
+
+
+}