Question

I have a class that contains a Rectangle, and I fill up a list with these objects. Here’s an example of what I’m trying to do:

class Foo 
{ 
   Rectangle rect; 
   public Foo(Rectangle r) { rect = r; }
}

List<Foo> listFoo = new List<Foo>();
// Call the next three Rectangles 'A' 'B' and 'C'.
listFoo.Add(new Foo(new Rectangle(0, 0, 5, 5)));    // Rect 'A' intersects with B
listFoo.Add(new Foo(new Rectangle(3, 3, 5, 5)));    // Rect 'B' intersects with A & C
listFoo.Add(new Foo(new Rectangle(6, 6, 5, 5)));    // Rect 'C' intersects with B

var query = ???;

foreach (Rectangle r in query) 
{ 
    // Should give two results
    // Rectangle(3, 3, 2, 2);   A & B
    // Rectangle(6, 6, 2, 2);   B & C
}

Can I write a single query that will use Rectangle.Intersect() to return a list of unique intersections in listFoo, with no duplicates from things like .Intersect(A,B) and .Intersect(B,A)?

Answer 1

 var q = (from f1 in listFoo
          from f2 in listFoo
          let r = Rectangle.Intersect(f1.rect,f2.rect)
          where f1 != f2 && r != Rectangle.Empty
          select r).Distinct();