/// <summary> A submethod of Add. Adds the specified rectangle to this polygon, skipping overlap checking with the first i elements of this polygon. </summary>
/// <param name="rect"> The rectangle to add to this collection. </param>
/// <param name="i"> The number of rectangles in this collection with which the specified rectangle is guaranteed not overlap with. </param>
private void Add(Rect rect, int i)
{
if (rect.Height == 0 || rect.Width == 0)
{
return;
}
Contract.Assert(i == 0 || this.rectangles.Take(i - 1).All(element =>
{
bool intersectsIncludingBoundaries = element.IntersectsWith(rect);
if (!intersectsIncludingBoundaries)
{
return(true);
}
var original = element; //else check if boundaries intersect (which don't count as intersections)
element.Intersect(rect);
return(element.Width == 0 || element.Height == 0 || element == Rect.Empty);
}), "The specified rectangle may not intersect with the first i elements");
for (; i < this.rectangles.Count; i++)
{
Rect elementAti = this[i];
Rect[] remainder = RectangleExtensions.Subtract(rect, ref elementAti);
this[i] = elementAti;
if (remainder.Length == 1 && remainder[0] == rect) //if no part of rect was subtracted
{
continue; //then continue with the next rectangle in this collection
}
//otherwise a part of rect was subtracted and isn't contained in the remainder any more
//that means the remainder doesn't intersect with the first i + 1 rectangles in this collection and the remainder is added accordingly
for (int j = 0; j < remainder.Length; j++)
{
this.Add(remainder[j], i + 1); //is correct even considering the swap this[i] = elementAti
}
return;
}
//this can only be reached if the continue statement was reached for every rectangle in this collection.
//That implies rect does not intersect with any rectangle in this collection and can therefore simply be added
this.rectangles.Add(rect);
}
/// <summary> Removes the area in the specified rectangle from the current polygon. </summary>
/// <param name="rect"></param>
public void Remove(Rect rect)
{
this.rectangles = this.rectangles.Select(r => RectangleExtensions.Subtract(r, rect)).Concat().ToList();
this.Simplify(); //this simplications are probably redundant, but are added for the sake of robustness
}