scale_factor.rs

/// A scaling factor between two different length units.
///
/// This is effectively a type-safe float, intended to be used in combination with the known-type
/// instances of Point2D, Rect, etc.
#[deriving(Clone, Decodable, Encodable, Eq)]
pub struct ScaleFactor<Src, Dst>(pub f32);

impl<Src, Dst> Deref<f32> for ScaleFactor<Src, Dst> {
    fn deref<'a>(&'a self) -> &'a f32 {
        let ScaleFactor(ref x) = *self;
        x
    }
}

impl<A,B,C> Mul<ScaleFactor<B, C>, ScaleFactor<A, C>> for ScaleFactor<A, B> {
    #[inline]
    fn mul(&self, other: &ScaleFactor<B, C>) -> ScaleFactor<A, C> {
        ScaleFactor(**self * **other)
    }
}

impl<Src, Dst> Mul<Src, Dst> for ScaleFactor<Src, Dst> {
    #[inline]
    fn mul(&self, other: &Src) -> Dst {
        **self * *other
    }
}