/// <summary>
/// Finds the interior contours of the area.
/// </summary>
/// <param name="area">The area to analyze.</param>
/// <param name="neighborhood">What type of neighborhood to segerate contours by.</param>
/// <returns>
/// A list of the contours. Each index corresponds to the distance from the outer edge (0 is right next to it, 1 is futher inside, etc).
/// </returns>
public static IReadOnlyList <IReadOnlySet <Position> > DetermineInteriorContours(
this ConnectedArea area,
Neighborhood neighborhood)
{
Func <Position, IEnumerable <Position> > getNeighborhood =
neighborhood == Neighborhood.Moore
? PositionExtensions.GetMooreNeighbors
: PositionExtensions.GetVonNeumannNeighbors;
HashSet <Position> remainingPositions = new(area);
List <IReadOnlySet <Position> > edges = new();
// Find outer edge
var outerEdge = remainingPositions.Where(p => getNeighborhood(p).Any(p => !area.Contains(p))).ToHashSet();
edges.Add(outerEdge);
remainingPositions.ExceptWith(outerEdge);
// Find remaining boundaries
while (remainingPositions.Any())
{
var lastEdge = edges.Last();
var edge = remainingPositions.Where(p => getNeighborhood(p).Any(lastEdge.Contains)).ToHashSet();
edges.Add(edge);
remainingPositions.ExceptWith(edge);
}
return(edges);
}
public static IReadOnlyDictionary <Position, int> DetermineInteriorEdgeDistance(
this ConnectedArea area,
Neighborhood neighborhood)
{
var edges = DetermineInteriorContours(area, neighborhood);
var output = new Dictionary <Position, int>();
for (int distance = 0; distance < edges.Count; distance++)
{
foreach (var p in edges[distance])
{
output.Add(p, distance);
}
}
return(output);
}