/// <summary>
/// Somewhat optimized rectangle puller
/// Courtesy http://www.drdobbs.com/database/the-maximal-rectangle-problem/184410529
/// </summary>
/// <returns></returns>
public HashSet<BoundingBox> GetAllRectangles(HashSet<Location> locations, BoundingBox boundingBox)
{
//Console.WriteLine("Entering GetAllRectangles");
DateTime start = DateTime.Now;
HashSet<BoundingBox> result = new HashSet<BoundingBox>();
while (locations.Count > 0)
{
bool[,] boolArray = new bool[boundingBox.LowerRight.X + 1, boundingBox.LowerRight.Y + 1];
foreach (Location location in locations)
{
boolArray[location.Point.X, location.Point.Y] = true;
}
BoundingBox best = new BoundingBox();
for (int upperLeftX = BoundingBox.UpperLeft.X; upperLeftX < boundingBox.LowerRight.X + 1; upperLeftX++)
{
for (int upperLeftY = BoundingBox.UpperLeft.Y; upperLeftY < boundingBox.LowerRight.Y + 1; upperLeftY++)
{
if (!boolArray[upperLeftX, upperLeftY])
{
continue;
}
BoundingBox candidate = GrowOnes(new SxzPoint(upperLeftX, upperLeftY), boundingBox, boolArray);
if (candidate.Area() > best.Area())
{
best = candidate;
}
}
}
if (best.UpperLeft.X == -1)
{
break;
}
result.Add(best);
//Console.WriteLine("Have total rectangles " + result.Count);
//Console.WriteLine("Have remaining locations " + locations.Count);
foreach (Location location in new HashSet<Location>(locations))
{
if (best.Contains(location.Point.X, location.Point.Y))
{
locations.Remove(location);
}
}
}
//Console.WriteLine("Leaving GetAllRectangles with time " + (DateTime.Now - start).Milliseconds + " ms");
return result;
}
private static BoundingBox GrowOnes(SxzPoint upperLeft, BoundingBox boundingBox, bool[,] boolArray)
{
SxzPoint lowerRight = new SxzPoint(upperLeft.X, upperLeft.Y);
BoundingBox best = new BoundingBox();
best.UpperLeft = upperLeft;
best.LowerRight = upperLeft;
int maxX = boundingBox.LowerRight.X;
int y = upperLeft.Y - 1;
while ((y + 1) < (boundingBox.LowerRight.Y + 1) && boolArray[upperLeft.X, y + 1])
{
y++;
int x = upperLeft.X;
while ((x + 1) <= maxX && boolArray[x + 1, y])
{
x++;
}
maxX = x;
BoundingBox candidate = new BoundingBox();
candidate.UpperLeft = upperLeft;
candidate.LowerRight.X = x;
candidate.LowerRight.Y = y;
if (candidate.Area() > best.Area())
{
best = candidate;
}
}
return best;
}
