private static Tuple <double, Point[]> GetPercentCovered(Point[] polygon, Rect rect)
{
// Figure out the intersected polygon
Point[] intersection = Math2D.GetIntersection_Polygon_Polygon(
polygon,
new Point[] { rect.TopLeft, rect.TopRight, rect.BottomRight, rect.BottomLeft });
if (intersection == null || intersection.Length == 0)
{
return(null);
}
// Calculate the area of the polygon
double areaPolygon = Math2D.GetAreaPolygon(intersection);
double areaRect = rect.Width * rect.Height;
if (areaPolygon > areaRect)
{
if (areaPolygon > areaRect * 1.01)
{
throw new ApplicationException(string.Format("Area of intersected polygon is larger than the rectangle that clipped it: polygon={0}, rectangle={1}", areaPolygon.ToString(), areaRect.ToString()));
}
areaPolygon = areaRect;
}
return(Tuple.Create(areaPolygon / areaRect, intersection));
}