Function offset_index

perro_editor/res/scripts/scene/editor_nav.rs:1249–1258

(current: usize, len: usize, delta: isize)

    .unwrap_or(false);
    if changed {
        refresh_all(ctx);
    }
}

pub fn offset_index(current: usize, len: usize, delta: isize) -> usize {
    if len == 0 {
        return 0;
    }
    if delta < 0 {
        current.saturating_sub(delta.unsigned_abs())
    } else {
        (current + delta as usize).min(len - 1)
    }