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//! 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;
//! ```
#![doc(html_logo_url = "https://kornel.ski/rgb-logo.png")]
#![no_std]

// std is required to run unit tests
#[cfg(test)]
#[macro_use] extern crate std;

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

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

/// BGR/BGRA alernative layouts & grayscale
///
/// BGR might be useful for some Windows or OpenGL APIs.
pub mod alt;

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

#[repr(C)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq, Ord, PartialOrd, Hash)]
/// The RGB pixel
///
/// 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)]
/// The RGBA pixel
///
/// 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>;

/// 8-bit RGBA, alpha is last. 0 = transparent, 255 = opaque.
pub type RGBA8 = RGBA<u8>;

/// 16-bit RGB in machine's native endian. 0 = transparent, 65535 = opaque.
///
/// 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!({let t: &[RGBA8] = rgb_bytes.as_pixels(); t}.len(), 0);
    assert_eq!(rgb, rgb_bytes.into_iter().cloned().collect());
    assert_eq!(&[rgb], rgb_bytes.as_rgb());
    assert_eq!(&[rgb], rgb_bytes.as_pixels());
    let mut rgb2 = [rgb];
    assert_eq!(rgb2.as_mut_slice().as_rgb_mut(), &mut [rgb]);
    assert_eq!(&mut [rgb], rgb2.as_mut_slice().as_pixels_mut());

    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[..]);
}