//! What a drawing can be taken out of, and what it cannot.

use iris::core::{UiRegion, UiScalar, UiSpan};

/// A box `size` tall whose top is `rel` of the way down the window.
fn fixed(rel: f32, size: f32) -> UiRegion {
    UiRegion::new(
        UiSpan::FULL,
        UiSpan::new(UiScalar { rel, abs: 0.0 }, UiScalar { rel, abs: size }),
    )
}

#[test]
fn a_fixed_length_cannot_be_stretched_out_of() {
    assert!(!fixed(0.0, 164.0).stretchable());
    assert!(!fixed(0.5, 164.0).stretchable());
    assert!(UiRegion::FULL.stretchable());
}

#[test]
fn a_stretch_keeps_each_part_at_its_fraction() {
    let to = fixed(0.0, 98.0);
    // A part filling the window fills what replaced it.
    assert_eq!(UiRegion::FULL.stretch(&UiRegion::FULL, &to), to);
    // And the middle half of it stays the middle half.
    let half = UiRegion::new(
        UiSpan::FULL,
        UiSpan::new(UiScalar::rel(0.25), UiScalar::rel(0.75)),
    );
    assert_eq!(
        half.stretch(&UiRegion::FULL, &to),
        UiRegion::new(
            UiSpan::FULL,
            UiSpan::new(
                UiScalar {
                    rel: 0.0,
                    abs: 24.5
                },
                UiScalar {
                    rel: 0.0,
                    abs: 73.5
                }
            )
        )
    );
}