Draws contour outlines in the image if thickness>=0 or fills area bounded by the contours if thickness<0


- externalColor (TColor)
- Color of the external contours
- holeColor (TColor)
- Color of internal contours (holes).
- maxLevel (Int32)
- Maximal level for drawn contours. If 0, only contour is drawn. If 1, the contour and all contours after it on the same level are drawn. If 2, all contours after and all contours one level below the contours are drawn, etc. If the value is negative, the function does not draw the contours following after contour but draws child contours of contour up to abs(maxLevel)-1 level
- thickness (Int32)
- Thickness of lines the contours are drawn with. If it is negative, the contour interiors are drawn