Function check_board_monotony 

pub fn check_board_monotony(corners: &[(f32, f32)], w: usize, h: usize) -> bool

Port of OpenCV icvCheckBoardMonotony.

corners are in row-major order with w columns and h rows. For each row and each column, the intermediate corners must project monotonically (and within [0, 1]) onto the segment between that row’s/column’s endpoints — i.e. the board maps to a non-self-intersecting grid.