rgb 0.8.1

`struct RGB` for sharing pixels between crates. Allows no-copy high-level interoperability. Also adds common convenience methods and implements standard Rust traits to make RGB/RGBA pixels first-class Rust objects.
Documentation 
//! Basic struct for `RGB` and `RGBA` pixels. Packed, with red first, alpha last.
//!
//! This crate is intended to be the lowest common denominator for sharing `RGB`/`RGBA` bitmaps between other crates.
//!
//! The crate includes convenience functions for converting between the struct and bytes,
//! and overloaded operators that work on all channels at once.
//!
//! This crate intentionally doesn't implement color management (due to complexity of the problem),
//! but the structs can be parametrized to implement this if necessary. Other colorspaces are out of scope.
//!
//! ```rust
//! # use rgb::*;
//! let pixel = RGB8 {r:0, g:100, b:255};
//!
//! let pixel_rgba = pixel.alpha(255);
//! let pixel = pixel_rgba.rgb();
//!
//! let pixels = vec![pixel; 100];
//! let bytes = pixels.as_bytes();
//!
//! let half_bright = pixel.map(|channel| channel / 2);
//! let doubled = half_bright * 2;
//! # let _ = doubled;
//! ```

#[cfg(feature = "serde")]
#[macro_use] extern crate serde;

mod internal {
    pub mod rgb;
    pub mod rgba;
    pub mod pixel;
    pub mod ops;
    pub mod convert;
}

pub use internal::rgb::*;
pub use internal::rgba::*;
pub use internal::pixel::*;
pub use internal::ops::*;
pub use internal::convert::*;

#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
/// This is it. The component type can be `u8` (aliased as `RGB8`), `u16` (aliased as `RGB16`), or any other type (but simple copyable types are recommended.)
pub struct RGB<ComponentType> {
    /// Red
    pub r:ComponentType,
    /// Green
    pub g:ComponentType,
    /// Blue
    pub b:ComponentType,
}

#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
/// This is it. The component type can be `u8` (aliased as `RGBA8`), `u16` (aliased as `RGBA16`), or any other type (but simple copyable types are recommended.)
///
/// You can specify a different type for alpha, but it's only for special cases (e.g. if you use a newtype like RGBA<LinearLight<u16>, u16>).
pub struct RGBA<ComponentType, AlphaComponentType=ComponentType> {
    /// Red
    pub r:ComponentType,
    /// Green
    pub g:ComponentType,
    /// Blue
    pub b:ComponentType,
    /// Alpha
    pub a:AlphaComponentType,
}

/// 8-bit RGB. The colorspace is techincally undefined, but generally sRGB is assumed.
pub type RGB8 = RGB<u8>;

/// 16-bit RGB in machine's native endian. Be careful to perform byte-swapping when reading from files.
pub type RGB16 = RGB<u16>;

/// Alpha is last. The crate doesn't impose which value represents transparency, but usually it's 0 = transparent, 255 = opaque.
pub type RGBA8 = RGBA<u8>;

/// 16-bit RGB in machine's native endian. Alpha is last.
pub type RGBA16 = RGBA<u16>;

#[test]
fn rgb_works() {
    let rgb = RGB{r:0u8,g:128,b:255}.clone();
    assert_eq!(rgb.b, 255);

    assert_eq!(rgb, rgb.iter().map(|ch| ch).collect());

    assert_eq!(0, [rgb].as_bytes()[0]);
    assert_eq!(128, [rgb].as_bytes()[1]);
    assert_eq!(255, [rgb].as_bytes()[2]);

    let rgb = RGB16{r:0u16,g:0x7F7F,b:65535};
    assert_eq!(rgb.b, 65535);
    assert_eq!(rgb.as_slice()[1], 0x7F7F);

    assert_eq!(0, [rgb].as_bytes()[0]);
    assert_eq!(0, [rgb].as_bytes()[1]);
    assert_eq!(0x7F, [rgb].as_bytes()[2]);
    assert_eq!(0x7F, [rgb].as_bytes()[3]);
    assert_eq!(0xFF, [rgb].as_bytes()[4]);
    assert_eq!(0xFF, [rgb].as_bytes()[5]);

    assert_eq!("rgb(1,2,3)", format!("{}", RGB::new(1,2,3)));
}

#[test]
fn sub_floats() {
    assert_eq!(RGBA{r:2.5_f64, g:-1.5, b:0., a:5.}, RGBA{r:3.5_f64, g:-0.5, b:-2., a:0.} - RGBA{r:1.0_f64, g:1., b:-2., a:-5.});
}

#[test]
fn into() {
    let a:RGB8 = RGB{r:0,g:1,b:2};
    let b:RGB<i16> = a.into();
    let c:RGB<f32> = b.into();
    let d:RGB<f32> = a.into();
    assert_eq!(c, d);
}

#[test]
fn rgba_works() {
    let rgba = RGBA{r:0u8,g:128,b:255,a:33}.clone();
    assert_eq!(rgba.b, 255);
    assert_eq!(rgba.a, 33);

    assert_eq!(rgba, rgba.iter().map(|ch| ch).collect());

    assert_eq!("rgba(1,2,3,4)", format!("{}", RGBA::new(1,2,3,4)));

    assert_eq!(rgba - rgba, RGBA::new(0,0,0,0));
}

#[test]
fn bytes() {
    let rgb = RGB8::new(1,2,3);
    let rgb_arr = [rgb];
    let rgb_bytes = rgb_arr.as_bytes();
    assert_eq!(&[1,2,3], rgb_bytes);
    assert_eq!(rgb_bytes.as_rgba().len(), 0);
    assert_eq!(rgb, rgb_bytes.into_iter().cloned().collect());
    assert_eq!(&[rgb], rgb_bytes.as_rgb());
    let mut rgb2 = [rgb];
    assert_eq!(rgb2.as_mut_slice().as_rgb_mut(), &mut [rgb]);

    let rgba = RGBA8::new(1,2,3,4);
    let mut rgba_arr = [rgba];
    {
        let rgba_bytes = rgba_arr.as_bytes_mut();
        assert_eq!(&[1,2,3,4], rgba_bytes);
        assert_eq!(&[rgba], rgba_bytes.as_rgba());
        rgba_bytes[3] = 99;
    }
    assert_eq!(RGBA8::new(1,2,3,99), rgba_arr.as_bytes().into_iter().cloned().collect());

    let rgb = RGB16::new(1,2,3);
    let rgb_slice = rgb.as_slice();
    assert_eq!(&[1,2,3], rgb_slice);
    assert_eq!(rgb_slice.as_rgba(), &[]);
    assert_eq!(&[rgb], rgb_slice.as_rgb());
    assert_eq!(rgb, rgb_slice.into_iter().cloned().collect());

    let rgba = RGBA16::new(1,2,3,4);
    let rgba_slice = rgba.as_slice();
    assert_eq!(&[1,2,3,4], rgba_slice);
    assert_eq!(&[1,2,3], rgba_slice.as_rgb()[0].as_slice());
    assert_eq!(&[rgba], rgba_slice.as_rgba());
    assert_eq!(rgba, rgba_slice.into_iter().cloned().collect());
    let mut rgba2 = [rgba];
    assert_eq!(rgba2.as_mut_slice().as_rgba_mut(), &mut [rgba]);

    let mut foo = vec![0u8; 8];
    foo.as_rgba_mut()[1] = RGBA::new(1,2,3,4);
    assert_eq!(&[0u8,0,0,0,1,2,3,4], &foo[..]);
}