drawContoursAsync function
DrawContours draws contours outlines or filled contours.
For further details, please see: https:///docs.opencv.org/master/d6/d6e/group__imgproc__draw.html#ga746c0625f1781f1ffc9056259103edbc
Implementation
Future<Mat> drawContoursAsync(
  InputOutputArray image,
  Contours contours,
  int contourIdx,
  Scalar color, {
  int thickness = 1,
  int lineType = LINE_8,
  VecVec4i? hierarchy,
  int maxLevel = 0x3f3f3f3f,
  Point? offset,
}) {
  offset ??= Point(0, 0);
  hierarchy ??= VecVec4i();
  return cvRunAsync0(
    (callback) => cimgproc.cv_drawContours_1(
      image.ref,
      contours.ref,
      contourIdx,
      color.ref,
      thickness,
      lineType,
      hierarchy!.ref,
      maxLevel,
      offset!.ref,
      callback,
    ),
    (c) {
      return c.complete(image);
    },
  );
}