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.
