Windows Phone: Are you Game? Part 1

using System;
using System.Collections.Generic;
using Microsoft.Xna.Framework.Graphics;
using Microsoft.Xna.Framework;

namespace Harlinn.WindowsPhone.XNA.Engine.Extensions
{
  public static class RectangleEx
  {

    public static Rectangle Intersection(Rectangle firstRectangle, Rectangle secondRectangle)
    {
      int x1 = Math.Max(firstRectangle.X, secondRectangle.X);
      int x2 = Math.Min(firstRectangle.X + firstRectangle.Width, secondRectangle.X + secondRectangle.Width);
      int y1 = Math.Max(firstRectangle.Y, secondRectangle.Y);
      int y2 = Math.Min(firstRectangle.Y + firstRectangle.Height, secondRectangle.Y + secondRectangle.Height);

      if ((x2 >= x1) && (y2 >= y1))
      {
        return new Rectangle(x1, y1, x2 - x1, y2 - y1);
      }
      return Rectangle.Empty;
    }

    public static void Intersect(this Rectangle rectangle, Rectangle otherRectangle)
    {
      Rectangle result = Intersection(otherRectangle, rectangle);

      rectangle.X = result.X;
      rectangle.Y = result.Y;
      rectangle.Width = result.Width;
      rectangle.Height = result.Height;
    }
  }
}