/// <summary>
/// Create Polygon from a group of points
private static Path FromGroup(Path area)
{
Rect box = BoundBox(area);
BitMatrix bm = Polygonizer.DrawPoints(area, box); // The matrix holding the points
Path polygon = new Path(); // the result
// find highest & leftmost point
int i = 0;
for (i = 0; i < bm.bits.Length; i++)
{
if (bm.bits[i])
{
break;
}
i++;
}
IntPoint currP = new IntPoint();
IntPoint nextP = new IntPoint();
IntPoint guessP = new IntPoint();
Direction currDirBack = Direction.NE; // since the first point is uppermost & leftmost, prevDirBack can never be W
Direction nextDirBack = Direction.E; // a random direction different from prevDirBack
// extract the coordinate
currP.X = i % bm.width;
currP.Y = i / bm.width;
IntPoint startP = new IntPoint(currP);
// the position to look at based on the curr point
// NE SE SE
// NE CT SW
// NW NW SW
do
{
// make guessP the next moore neighbor
switch (currDirBack)
{
case Direction.N: goto case Direction.NE;
case Direction.NE:
guessP.X = currP.X + 1;
guessP.Y = currP.Y + 1;
break;
case Direction.E: goto case Direction.SE;
case Direction.SE:
guessP.X = currP.X - 1;
guessP.Y = currP.Y + 1;
break;
case Direction.S: goto case Direction.SW;
case Direction.SW:
guessP.X = currP.X - 1;
guessP.Y = currP.Y - 1;
break;
case Direction.W: goto case Direction.NW;
case Direction.NW:
guessP.X = currP.X + 1;
guessP.Y = currP.Y - 1;
break;
}
nextP = bm.nextNeighbour(currP, guessP);
nextDirBack = BitMatrix.getDirection(nextP, currP);
// only add the curr point if it is a true vertex
if (nextDirBack != currDirBack)
{
polygon.Add(new IntPoint(currP.X + box.xMin, currP.Y + box.yMin));
currDirBack = nextDirBack;
}
currP = nextP;
} while (nextP != startP);
RDP(polygon);
return(polygon);
}
