convert Vector2D into value type

MBS.Framework/Drawing/Vector.cs

@@ -5,28 +5,54 @@ using System.Text;
 
 namespace MBS.Framework.Drawing
 {
-	public abstract class Vector
+	public struct Vector2D : IEquatable<Vector2D>
 	{
-	}
-	public class Vector2D
-	{
-		private double mvarX = 0.0;
-		public double X { get { return mvarX; } set { mvarX = value; } }
-		private double mvarY = 0.0;
-		public double Y { get { return mvarY; } set { mvarY = value; } }
+		private bool _IsNotEmpty;
+		public bool IsEmpty { get { return !_IsNotEmpty; } }
+
+		public static Vector2D Empty = new Vector2D();
+
+		public double X { get; set; }
+		public double Y { get; set; }
 
-		public Vector2D()
-		{
-		}
 		public Vector2D(double x, double y)
 		{
-			mvarX = x;
-			mvarY = y;
+			X = x;
+			Y = y;
+			_IsNotEmpty = true;
 		}
 
 		public override string ToString()
 		{
 			return String.Format("({0}, {1})", X, Y);
 		}
+
+		#region IEquatable implementation
+
+		public bool Equals(Vector2D other)
+		{
+			return (this.X.Equals(other.X) && this.Y.Equals(other.Y));
+		}
+
+		public static bool operator ==(Vector2D left, Vector2D right)
+		{
+			return left.Equals(right);
+		}
+		public static bool operator !=(Vector2D left, Vector2D right)
+		{
+			return !left.Equals(right);
+		}
+		public override bool Equals(object obj)
+		{
+			if (obj is Vector2D)
+			{
+				Vector2D other = (Vector2D)obj;
+				return X.Equals(other.X) && Y.Equals(other.Y) && IsEmpty.Equals(other.IsEmpty);
+			}
+			return base.Equals(obj);
+		}
+
+		#endregion
+
 	}
 }