Mat.fromRange constructor
Implementation
factory Mat.fromRange(Mat mat, int rowStart, int rowEnd, {int colStart = 0, int? colEnd}) {
final p = calloc<cvg.Mat>();
colEnd ??= mat.cols;
cvRun(() => cffi.Mat_FromRange(mat.ref, rowStart, rowEnd, colStart, colEnd!, p));
return Mat._(p);
}