For one of the projects I need to calculate some simple vector arithmetics like the Euclidean distance. I also need other properties of the Point and Rect structs that aren't built-in the Silverlight framework. As you might know I'm a huge fan of extension methods for extending built-in functionality (1, 2). That's why I wrote a few extension methods for the Point and Rect structs that might come handy.

**Rect**

public static class RectExtensions { // Calculates the center point of this rectangle. public static Point Center(this Rect rect) { return new Point(rect.X + rect.Width * 0.5, rect.Y + rect.Height * 0.5); } // Tests if this rectangle intersects with the other. public static bool IntersectsWith(this Rect rect, Rect other) { // Test for separating axis if (other.Bottom < rect.Top || other.Right < rect.Left || other.Top > rect.Bottom || other.Left > rect.Right) { return false; } return true; } }

The usage should be pretty obvious.

Rect r = new Rect(0, 0, 200, 300); Point center = r.Center(); bool isIntersecting = r.IntersectsWith(new Rect(500, 600, 100, 50));

**Point**

public static class PointExtensions { // Calculates the distance vector of the points. public static Point Distance(this Point p1, Point p2) { return new Point(p1.X - p2.X, p1.Y - p2.Y); } // Calculates the length of the vector. public static double Length(this Point p) { return Math.Sqrt(p.X * p.X + p.Y * p.Y); } // Calculates the square length of the vector. public static double LengthSquare(this Point p) { return p.X * p.X + p.Y * p.Y; } }

The squared length saves some cycles if this information is only needed for comparison.

Point p1 = new Point(200, 300); Point p2 = new Point(400, 500); Point distance = p1.Distance(p2); double length = distance.Length(); double lengthSq = distance.LengthSquare(); length = Math.Sqrt(lengthSq);

**Source Code**

You can download the two C# files from here.