Kaba class ViewPort ed

class ViewPort
    var area: rect

    # constructors
    func mut __init__()

    # functions
    func range() -> Range
    func sample2screen(s: f32) -> f32
    func sample2screen64(s: f64) -> f64
    func screen2sample(s: f32) -> f32
    func screen2sample64(s: f64) -> f64
    func mut set_range(r: Range)