col method
Creates a matrix header for the specified matrix column.
The method makes a new header for the specified matrix column and returns it. This is an O(1) operation, regardless of the matrix size. The underlying data of the new matrix is shared with the original matrix. See also the Mat::row description.
x: A 0-based column index.
https://docs.opencv.org/4.x/d3/d63/classcv_1_1Mat.html#a23df02a07ffbfa4aa59c19bc003919fe
Implementation
Mat col(int x) {
final p = calloc<cvg.Mat>();
cvRun(() => cffi.Mat_Col(ref, x, p));
return Mat._(p);
}