Mat.fromMat constructor
Implementation
factory Mat.fromMat(Mat mat, {bool copy = false, Rect? roi}) {
roi ??= Rect(0, 0, mat.cols, mat.rows);
final p = calloc<cvg.Mat>();
cvRun(() => ccore.cv_Mat_create_13(mat.ref, roi!.ref, p, ffi.nullptr));
final dst = Mat._(p, false);
if (copy) return dst.clone();
return dst;
}