Function quad_point_count 

pub fn quad_point_count(array: Option<&Array>) -> usize

How many complete quadrilaterals an array holds; a trailing partial one is ignored.

use pdfrum_doc::annot::quad_point_count;
use pdfrum_object::Array;

let one = Array::of([0, 8, 10, 8, 0, 0, 10, 0]);
assert_eq!(quad_point_count(Some(&one)), 1);
// A trailing partial quadrilateral does not count.
let partial = Array::of([0, 8, 10, 8, 0]);
assert_eq!(quad_point_count(Some(&partial)), 0);
assert_eq!(quad_point_count(None), 0);