private static Chord CalculateLongestPerpendicularChord(List<Point> coordinates, Chord longestChord, double margin = 0)
{
double length = 0;
double rotation = 0;
Point StartingPoint = new Point();
Point EndingPoint = new Point();
foreach (Point p1 in coordinates)
{
foreach (Point p2 in coordinates)
{
if (p1.Equals(p2)) continue;
//if (p2.X > p1.X) continue;
//if (p2.Y > p1.Y) continue;
double slope = (-1.0d / ((p2.Y - p1.Y) / ((double)(p2.X - p1.X))));
double slopeTarget = (longestChord.Rotation);
if (!(slope >= slopeTarget * (1.0d - margin) && slope <= slopeTarget * (1.0d + margin))) continue;
double lengthCurrentChord = Math.Sqrt(Math.Pow(p1.X - p2.X, 2) + Math.Pow(p1.Y - p2.Y, 2));
if (lengthCurrentChord > length)
{
length = lengthCurrentChord;
rotation = (p2.Y - p1.Y) / ((double)(p2.X - p1.X));
StartingPoint = p1;
EndingPoint = p2;
}
}
}
return new Chord(length, rotation, StartingPoint, EndingPoint);
}
public static Chord Calculate(Image image, Chord longestChord)
{
List<Point> coordinates = ObjectOuterPixels.OuterPoints(image);
Chord lpc;
double margin = 0;
do
{
lpc = CalculateLongestPerpendicularChord(coordinates, longestChord, margin); //Tries to calculate with the current margin (starts without a margin)
margin += 0.01d; //update margin
} while (lpc.Length <= 0 && margin < 1); //while we didnt find a perpendicular chord, and the margin is still smaller then 1:
//ObjectOuterPixels.SaveOuterPixelsAsImageWithChords(longestChord, lpc, coordinates, image.Size);
return lpc;
}
/// <summary>
/// Save the with chords (useful for debugging)
/// </summary>
/// <param name="longestChord"></param>
/// <param name="lpc"></param>
/// <param name="coordinates"></param>
/// <param name="size"></param>
public static void SaveOuterPixelsAsImageWithChords(Chord longestChord, Chord lpc, List<Point> coordinates, Size size)
{
Bitmap b = new Bitmap(size.Width, size.Height);
foreach(Point p in coordinates)
{
b.SetPixel(p.X, p.Y, Color.Black);
}
Pen red = new Pen(Color.Red, 1);
using (var graphics = Graphics.FromImage(b))
{
graphics.DrawLine(red, longestChord.StartingPoint, longestChord.EndingPoint);
graphics.DrawLine(red, lpc.StartingPoint, lpc.EndingPoint);
b.Save(Image.GetFileName("Chords through object"), System.Drawing.Imaging.ImageFormat.Png);
//Image image = new Image(b);
//image.Save("Chords through object");
}
//Doesnt work quite yet...not sure why.
}
