public void Click(Point p)
 {
     if (this.FirstPoint.IsEmpty)
     {
         this.FirstPoint = p;
     }
     else if (this.SecondPoint.IsEmpty)
     {
         this.SecondPoint = p;
         RedCircle redCircle = new RedCircle(this.FirstPoint, this.distance(this.FirstPoint, this.SecondPoint));
         if (!this.checkCollisions(redCircle))
         {
             this.Circles.Add(redCircle);
         }
         this.FirstPoint  = Point.Empty;
         this.SecondPoint = Point.Empty;
     }
 }
 private bool checkCollisions(Circle redCircle)
 {
     using (List <RedCircle> .Enumerator enumerator = this.Circles.GetEnumerator())
     {
         while (true)
         {
             if (!enumerator.MoveNext())
             {
                 break;
             }
             RedCircle current = enumerator.Current;
             if (current.IsColiding(redCircle))
             {
                 return(true);
             }
         }
     }
     return(false);
 }