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Diffstat (limited to 'vendor/image/src/color.rs')
| -rw-r--r-- | vendor/image/src/color.rs | 985 |
1 files changed, 985 insertions, 0 deletions
diff --git a/vendor/image/src/color.rs b/vendor/image/src/color.rs new file mode 100644 index 0000000..57a8511 --- /dev/null +++ b/vendor/image/src/color.rs @@ -0,0 +1,985 @@ +use std::ops::{Index, IndexMut}; + +use num_traits::{NumCast, ToPrimitive, Zero}; + +use crate::traits::{Enlargeable, Pixel, Primitive}; + +/// An enumeration over supported color types and bit depths +#[derive(Copy, PartialEq, Eq, Debug, Clone, Hash)] +#[non_exhaustive] +pub enum ColorType { + /// Pixel is 8-bit luminance + L8, + /// Pixel is 8-bit luminance with an alpha channel + La8, + /// Pixel contains 8-bit R, G and B channels + Rgb8, + /// Pixel is 8-bit RGB with an alpha channel + Rgba8, + + /// Pixel is 16-bit luminance + L16, + /// Pixel is 16-bit luminance with an alpha channel + La16, + /// Pixel is 16-bit RGB + Rgb16, + /// Pixel is 16-bit RGBA + Rgba16, + + /// Pixel is 32-bit float RGB + Rgb32F, + /// Pixel is 32-bit float RGBA + Rgba32F, +} + +impl ColorType { + /// Returns the number of bytes contained in a pixel of `ColorType` ```c``` + pub fn bytes_per_pixel(self) -> u8 { + match self { + ColorType::L8 => 1, + ColorType::L16 | ColorType::La8 => 2, + ColorType::Rgb8 => 3, + ColorType::Rgba8 | ColorType::La16 => 4, + ColorType::Rgb16 => 6, + ColorType::Rgba16 => 8, + ColorType::Rgb32F => 3 * 4, + ColorType::Rgba32F => 4 * 4, + } + } + + /// Returns if there is an alpha channel. + pub fn has_alpha(self) -> bool { + use ColorType::*; + match self { + L8 | L16 | Rgb8 | Rgb16 | Rgb32F => false, + La8 | Rgba8 | La16 | Rgba16 | Rgba32F => true, + } + } + + /// Returns false if the color scheme is grayscale, true otherwise. + pub fn has_color(self) -> bool { + use ColorType::*; + match self { + L8 | L16 | La8 | La16 => false, + Rgb8 | Rgb16 | Rgba8 | Rgba16 | Rgb32F | Rgba32F => true, + } + } + + /// Returns the number of bits contained in a pixel of `ColorType` ```c``` (which will always be + /// a multiple of 8). + pub fn bits_per_pixel(self) -> u16 { + <u16 as From<u8>>::from(self.bytes_per_pixel()) * 8 + } + + /// Returns the number of color channels that make up this pixel + pub fn channel_count(self) -> u8 { + let e: ExtendedColorType = self.into(); + e.channel_count() + } +} + +/// An enumeration of color types encountered in image formats. +/// +/// This is not exhaustive over all existing image formats but should be granular enough to allow +/// round tripping of decoding and encoding as much as possible. The variants will be extended as +/// necessary to enable this. +/// +/// Another purpose is to advise users of a rough estimate of the accuracy and effort of the +/// decoding from and encoding to such an image format. +#[derive(Copy, PartialEq, Eq, Debug, Clone, Hash)] +#[non_exhaustive] +pub enum ExtendedColorType { + /// Pixel is 8-bit alpha + A8, + /// Pixel is 1-bit luminance + L1, + /// Pixel is 1-bit luminance with an alpha channel + La1, + /// Pixel contains 1-bit R, G and B channels + Rgb1, + /// Pixel is 1-bit RGB with an alpha channel + Rgba1, + /// Pixel is 2-bit luminance + L2, + /// Pixel is 2-bit luminance with an alpha channel + La2, + /// Pixel contains 2-bit R, G and B channels + Rgb2, + /// Pixel is 2-bit RGB with an alpha channel + Rgba2, + /// Pixel is 4-bit luminance + L4, + /// Pixel is 4-bit luminance with an alpha channel + La4, + /// Pixel contains 4-bit R, G and B channels + Rgb4, + /// Pixel is 4-bit RGB with an alpha channel + Rgba4, + /// Pixel is 8-bit luminance + L8, + /// Pixel is 8-bit luminance with an alpha channel + La8, + /// Pixel contains 8-bit R, G and B channels + Rgb8, + /// Pixel is 8-bit RGB with an alpha channel + Rgba8, + /// Pixel is 16-bit luminance + L16, + /// Pixel is 16-bit luminance with an alpha channel + La16, + /// Pixel contains 16-bit R, G and B channels + Rgb16, + /// Pixel is 16-bit RGB with an alpha channel + Rgba16, + /// Pixel contains 8-bit B, G and R channels + Bgr8, + /// Pixel is 8-bit BGR with an alpha channel + Bgra8, + + // TODO f16 types? + /// Pixel is 32-bit float RGB + Rgb32F, + /// Pixel is 32-bit float RGBA + Rgba32F, + + /// Pixel is of unknown color type with the specified bits per pixel. This can apply to pixels + /// which are associated with an external palette. In that case, the pixel value is an index + /// into the palette. + Unknown(u8), +} + +impl ExtendedColorType { + /// Get the number of channels for colors of this type. + /// + /// Note that the `Unknown` variant returns a value of `1` since pixels can only be treated as + /// an opaque datum by the library. + pub fn channel_count(self) -> u8 { + match self { + ExtendedColorType::A8 + | ExtendedColorType::L1 + | ExtendedColorType::L2 + | ExtendedColorType::L4 + | ExtendedColorType::L8 + | ExtendedColorType::L16 + | ExtendedColorType::Unknown(_) => 1, + ExtendedColorType::La1 + | ExtendedColorType::La2 + | ExtendedColorType::La4 + | ExtendedColorType::La8 + | ExtendedColorType::La16 => 2, + ExtendedColorType::Rgb1 + | ExtendedColorType::Rgb2 + | ExtendedColorType::Rgb4 + | ExtendedColorType::Rgb8 + | ExtendedColorType::Rgb16 + | ExtendedColorType::Rgb32F + | ExtendedColorType::Bgr8 => 3, + ExtendedColorType::Rgba1 + | ExtendedColorType::Rgba2 + | ExtendedColorType::Rgba4 + | ExtendedColorType::Rgba8 + | ExtendedColorType::Rgba16 + | ExtendedColorType::Rgba32F + | ExtendedColorType::Bgra8 => 4, + } + } +} +impl From<ColorType> for ExtendedColorType { + fn from(c: ColorType) -> Self { + match c { + ColorType::L8 => ExtendedColorType::L8, + ColorType::La8 => ExtendedColorType::La8, + ColorType::Rgb8 => ExtendedColorType::Rgb8, + ColorType::Rgba8 => ExtendedColorType::Rgba8, + ColorType::L16 => ExtendedColorType::L16, + ColorType::La16 => ExtendedColorType::La16, + ColorType::Rgb16 => ExtendedColorType::Rgb16, + ColorType::Rgba16 => ExtendedColorType::Rgba16, + ColorType::Rgb32F => ExtendedColorType::Rgb32F, + ColorType::Rgba32F => ExtendedColorType::Rgba32F, + } + } +} + +macro_rules! define_colors { + {$( + $(#[$doc:meta])* + pub struct $ident:ident<T: $($bound:ident)*>([T; $channels:expr, $alphas:expr]) + = $interpretation:literal; + )*} => { + +$( // START Structure definitions + +$(#[$doc])* +#[derive(PartialEq, Eq, Clone, Debug, Copy, Hash)] +#[repr(C)] +#[allow(missing_docs)] +pub struct $ident<T> (pub [T; $channels]); + +impl<T: $($bound+)*> Pixel for $ident<T> { + type Subpixel = T; + + const CHANNEL_COUNT: u8 = $channels; + + #[inline(always)] + fn channels(&self) -> &[T] { + &self.0 + } + + #[inline(always)] + fn channels_mut(&mut self) -> &mut [T] { + &mut self.0 + } + + const COLOR_MODEL: &'static str = $interpretation; + + fn channels4(&self) -> (T, T, T, T) { + const CHANNELS: usize = $channels; + let mut channels = [T::DEFAULT_MAX_VALUE; 4]; + channels[0..CHANNELS].copy_from_slice(&self.0); + (channels[0], channels[1], channels[2], channels[3]) + } + + fn from_channels(a: T, b: T, c: T, d: T,) -> $ident<T> { + const CHANNELS: usize = $channels; + *<$ident<T> as Pixel>::from_slice(&[a, b, c, d][..CHANNELS]) + } + + fn from_slice(slice: &[T]) -> &$ident<T> { + assert_eq!(slice.len(), $channels); + unsafe { &*(slice.as_ptr() as *const $ident<T>) } + } + fn from_slice_mut(slice: &mut [T]) -> &mut $ident<T> { + assert_eq!(slice.len(), $channels); + unsafe { &mut *(slice.as_mut_ptr() as *mut $ident<T>) } + } + + fn to_rgb(&self) -> Rgb<T> { + let mut pix = Rgb([Zero::zero(), Zero::zero(), Zero::zero()]); + pix.from_color(self); + pix + } + + fn to_rgba(&self) -> Rgba<T> { + let mut pix = Rgba([Zero::zero(), Zero::zero(), Zero::zero(), Zero::zero()]); + pix.from_color(self); + pix + } + + fn to_luma(&self) -> Luma<T> { + let mut pix = Luma([Zero::zero()]); + pix.from_color(self); + pix + } + + fn to_luma_alpha(&self) -> LumaA<T> { + let mut pix = LumaA([Zero::zero(), Zero::zero()]); + pix.from_color(self); + pix + } + + fn map<F>(& self, f: F) -> $ident<T> where F: FnMut(T) -> T { + let mut this = (*self).clone(); + this.apply(f); + this + } + + fn apply<F>(&mut self, mut f: F) where F: FnMut(T) -> T { + for v in &mut self.0 { + *v = f(*v) + } + } + + fn map_with_alpha<F, G>(&self, f: F, g: G) -> $ident<T> where F: FnMut(T) -> T, G: FnMut(T) -> T { + let mut this = (*self).clone(); + this.apply_with_alpha(f, g); + this + } + + fn apply_with_alpha<F, G>(&mut self, mut f: F, mut g: G) where F: FnMut(T) -> T, G: FnMut(T) -> T { + const ALPHA: usize = $channels - $alphas; + for v in self.0[..ALPHA].iter_mut() { + *v = f(*v) + } + // The branch of this match is `const`. This way ensures that no subexpression fails the + // `const_err` lint (the expression `self.0[ALPHA]` would). + if let Some(v) = self.0.get_mut(ALPHA) { + *v = g(*v) + } + } + + fn map2<F>(&self, other: &Self, f: F) -> $ident<T> where F: FnMut(T, T) -> T { + let mut this = (*self).clone(); + this.apply2(other, f); + this + } + + fn apply2<F>(&mut self, other: &$ident<T>, mut f: F) where F: FnMut(T, T) -> T { + for (a, &b) in self.0.iter_mut().zip(other.0.iter()) { + *a = f(*a, b) + } + } + + fn invert(&mut self) { + Invert::invert(self) + } + + fn blend(&mut self, other: &$ident<T>) { + Blend::blend(self, other) + } +} + +impl<T> Index<usize> for $ident<T> { + type Output = T; + #[inline(always)] + fn index(&self, _index: usize) -> &T { + &self.0[_index] + } +} + +impl<T> IndexMut<usize> for $ident<T> { + #[inline(always)] + fn index_mut(&mut self, _index: usize) -> &mut T { + &mut self.0[_index] + } +} + +impl<T> From<[T; $channels]> for $ident<T> { + fn from(c: [T; $channels]) -> Self { + Self(c) + } +} + +)* // END Structure definitions + + } +} + +define_colors! { + /// RGB colors. + /// + /// For the purpose of color conversion, as well as blending, the implementation of `Pixel` + /// assumes an `sRGB` color space of its data. + pub struct Rgb<T: Primitive Enlargeable>([T; 3, 0]) = "RGB"; + /// Grayscale colors. + pub struct Luma<T: Primitive>([T; 1, 0]) = "Y"; + /// RGB colors + alpha channel + pub struct Rgba<T: Primitive Enlargeable>([T; 4, 1]) = "RGBA"; + /// Grayscale colors + alpha channel + pub struct LumaA<T: Primitive>([T; 2, 1]) = "YA"; +} + +/// Convert from one pixel component type to another. For example, convert from `u8` to `f32` pixel values. +pub trait FromPrimitive<Component> { + /// Converts from any pixel component type to this type. + fn from_primitive(component: Component) -> Self; +} + +impl<T: Primitive> FromPrimitive<T> for T { + fn from_primitive(sample: T) -> Self { + sample + } +} + +// from f32: +// Note that in to-integer-conversion we are performing rounding but NumCast::from is implemented +// as truncate towards zero. We emulate rounding by adding a bias. + +impl FromPrimitive<f32> for u8 { + fn from_primitive(float: f32) -> Self { + let inner = (float.clamp(0.0, 1.0) * u8::MAX as f32).round(); + NumCast::from(inner).unwrap() + } +} + +impl FromPrimitive<f32> for u16 { + fn from_primitive(float: f32) -> Self { + let inner = (float.clamp(0.0, 1.0) * u16::MAX as f32).round(); + NumCast::from(inner).unwrap() + } +} + +// from u16: + +impl FromPrimitive<u16> for u8 { + fn from_primitive(c16: u16) -> Self { + fn from(c: impl Into<u32>) -> u32 { + c.into() + } + // The input c is the numerator of `c / u16::MAX`. + // Derive numerator of `num / u8::MAX`, with rounding. + // + // This method is based on the inverse (see FromPrimitive<u8> for u16) and was tested + // exhaustively in Python. It's the same as the reference function: + // round(c * (2**8 - 1) / (2**16 - 1)) + NumCast::from((from(c16) + 128) / 257).unwrap() + } +} + +impl FromPrimitive<u16> for f32 { + fn from_primitive(int: u16) -> Self { + (int as f32 / u16::MAX as f32).clamp(0.0, 1.0) + } +} + +// from u8: + +impl FromPrimitive<u8> for f32 { + fn from_primitive(int: u8) -> Self { + (int as f32 / u8::MAX as f32).clamp(0.0, 1.0) + } +} + +impl FromPrimitive<u8> for u16 { + fn from_primitive(c8: u8) -> Self { + let x = c8.to_u64().unwrap(); + NumCast::from((x << 8) | x).unwrap() + } +} + +/// Provides color conversions for the different pixel types. +pub trait FromColor<Other> { + /// Changes `self` to represent `Other` in the color space of `Self` + fn from_color(&mut self, _: &Other); +} + +/// Copy-based conversions to target pixel types using `FromColor`. +// FIXME: this trait should be removed and replaced with real color space models +// rather than assuming sRGB. +pub(crate) trait IntoColor<Other> { + /// Constructs a pixel of the target type and converts this pixel into it. + fn into_color(&self) -> Other; +} + +impl<O, S> IntoColor<O> for S +where + O: Pixel + FromColor<S>, +{ + fn into_color(&self) -> O { + // Note we cannot use Pixel::CHANNELS_COUNT here to directly construct + // the pixel due to a current bug/limitation of consts. + #[allow(deprecated)] + let mut pix = O::from_channels(Zero::zero(), Zero::zero(), Zero::zero(), Zero::zero()); + pix.from_color(self); + pix + } +} + +/// Coefficients to transform from sRGB to a CIE Y (luminance) value. +const SRGB_LUMA: [u32; 3] = [2126, 7152, 722]; +const SRGB_LUMA_DIV: u32 = 10000; + +#[inline] +fn rgb_to_luma<T: Primitive + Enlargeable>(rgb: &[T]) -> T { + let l = <T::Larger as NumCast>::from(SRGB_LUMA[0]).unwrap() * rgb[0].to_larger() + + <T::Larger as NumCast>::from(SRGB_LUMA[1]).unwrap() * rgb[1].to_larger() + + <T::Larger as NumCast>::from(SRGB_LUMA[2]).unwrap() * rgb[2].to_larger(); + T::clamp_from(l / <T::Larger as NumCast>::from(SRGB_LUMA_DIV).unwrap()) +} + +// `FromColor` for Luma +impl<S: Primitive, T: Primitive> FromColor<Luma<S>> for Luma<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Luma<S>) { + let own = self.channels_mut(); + let other = other.channels(); + own[0] = T::from_primitive(other[0]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<LumaA<S>> for Luma<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &LumaA<S>) { + self.channels_mut()[0] = T::from_primitive(other.channels()[0]) + } +} + +impl<S: Primitive + Enlargeable, T: Primitive> FromColor<Rgb<S>> for Luma<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgb<S>) { + let gray = self.channels_mut(); + let rgb = other.channels(); + gray[0] = T::from_primitive(rgb_to_luma(rgb)); + } +} + +impl<S: Primitive + Enlargeable, T: Primitive> FromColor<Rgba<S>> for Luma<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgba<S>) { + let gray = self.channels_mut(); + let rgb = other.channels(); + let l = rgb_to_luma(rgb); + gray[0] = T::from_primitive(l); + } +} + +// `FromColor` for LumaA + +impl<S: Primitive, T: Primitive> FromColor<LumaA<S>> for LumaA<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &LumaA<S>) { + let own = self.channels_mut(); + let other = other.channels(); + own[0] = T::from_primitive(other[0]); + own[1] = T::from_primitive(other[1]); + } +} + +impl<S: Primitive + Enlargeable, T: Primitive> FromColor<Rgb<S>> for LumaA<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgb<S>) { + let gray_a = self.channels_mut(); + let rgb = other.channels(); + gray_a[0] = T::from_primitive(rgb_to_luma(rgb)); + gray_a[1] = T::DEFAULT_MAX_VALUE; + } +} + +impl<S: Primitive + Enlargeable, T: Primitive> FromColor<Rgba<S>> for LumaA<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgba<S>) { + let gray_a = self.channels_mut(); + let rgba = other.channels(); + gray_a[0] = T::from_primitive(rgb_to_luma(rgba)); + gray_a[1] = T::from_primitive(rgba[3]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<Luma<S>> for LumaA<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Luma<S>) { + let gray_a = self.channels_mut(); + gray_a[0] = T::from_primitive(other.channels()[0]); + gray_a[1] = T::DEFAULT_MAX_VALUE; + } +} + +// `FromColor` for RGBA + +impl<S: Primitive, T: Primitive> FromColor<Rgba<S>> for Rgba<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgba<S>) { + let own = &mut self.0; + let other = &other.0; + own[0] = T::from_primitive(other[0]); + own[1] = T::from_primitive(other[1]); + own[2] = T::from_primitive(other[2]); + own[3] = T::from_primitive(other[3]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<Rgb<S>> for Rgba<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgb<S>) { + let rgba = &mut self.0; + let rgb = &other.0; + rgba[0] = T::from_primitive(rgb[0]); + rgba[1] = T::from_primitive(rgb[1]); + rgba[2] = T::from_primitive(rgb[2]); + rgba[3] = T::DEFAULT_MAX_VALUE; + } +} + +impl<S: Primitive, T: Primitive> FromColor<LumaA<S>> for Rgba<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, gray: &LumaA<S>) { + let rgba = &mut self.0; + let gray = &gray.0; + rgba[0] = T::from_primitive(gray[0]); + rgba[1] = T::from_primitive(gray[0]); + rgba[2] = T::from_primitive(gray[0]); + rgba[3] = T::from_primitive(gray[1]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<Luma<S>> for Rgba<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, gray: &Luma<S>) { + let rgba = &mut self.0; + let gray = gray.0[0]; + rgba[0] = T::from_primitive(gray); + rgba[1] = T::from_primitive(gray); + rgba[2] = T::from_primitive(gray); + rgba[3] = T::DEFAULT_MAX_VALUE; + } +} + +// `FromColor` for RGB + +impl<S: Primitive, T: Primitive> FromColor<Rgb<S>> for Rgb<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgb<S>) { + let own = &mut self.0; + let other = &other.0; + own[0] = T::from_primitive(other[0]); + own[1] = T::from_primitive(other[1]); + own[2] = T::from_primitive(other[2]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<Rgba<S>> for Rgb<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Rgba<S>) { + let rgb = &mut self.0; + let rgba = &other.0; + rgb[0] = T::from_primitive(rgba[0]); + rgb[1] = T::from_primitive(rgba[1]); + rgb[2] = T::from_primitive(rgba[2]); + } +} + +impl<S: Primitive, T: Primitive> FromColor<LumaA<S>> for Rgb<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &LumaA<S>) { + let rgb = &mut self.0; + let gray = other.0[0]; + rgb[0] = T::from_primitive(gray); + rgb[1] = T::from_primitive(gray); + rgb[2] = T::from_primitive(gray); + } +} + +impl<S: Primitive, T: Primitive> FromColor<Luma<S>> for Rgb<T> +where + T: FromPrimitive<S>, +{ + fn from_color(&mut self, other: &Luma<S>) { + let rgb = &mut self.0; + let gray = other.0[0]; + rgb[0] = T::from_primitive(gray); + rgb[1] = T::from_primitive(gray); + rgb[2] = T::from_primitive(gray); + } +} + +/// Blends a color inter another one +pub(crate) trait Blend { + /// Blends a color in-place. + fn blend(&mut self, other: &Self); +} + +impl<T: Primitive> Blend for LumaA<T> { + fn blend(&mut self, other: &LumaA<T>) { + let max_t = T::DEFAULT_MAX_VALUE; + let max_t = max_t.to_f32().unwrap(); + let (bg_luma, bg_a) = (self.0[0], self.0[1]); + let (fg_luma, fg_a) = (other.0[0], other.0[1]); + + let (bg_luma, bg_a) = ( + bg_luma.to_f32().unwrap() / max_t, + bg_a.to_f32().unwrap() / max_t, + ); + let (fg_luma, fg_a) = ( + fg_luma.to_f32().unwrap() / max_t, + fg_a.to_f32().unwrap() / max_t, + ); + + let alpha_final = bg_a + fg_a - bg_a * fg_a; + if alpha_final == 0.0 { + return; + }; + let bg_luma_a = bg_luma * bg_a; + let fg_luma_a = fg_luma * fg_a; + + let out_luma_a = fg_luma_a + bg_luma_a * (1.0 - fg_a); + let out_luma = out_luma_a / alpha_final; + + *self = LumaA([ + NumCast::from(max_t * out_luma).unwrap(), + NumCast::from(max_t * alpha_final).unwrap(), + ]) + } +} + +impl<T: Primitive> Blend for Luma<T> { + fn blend(&mut self, other: &Luma<T>) { + *self = *other + } +} + +impl<T: Primitive> Blend for Rgba<T> { + fn blend(&mut self, other: &Rgba<T>) { + // http://stackoverflow.com/questions/7438263/alpha-compositing-algorithm-blend-modes#answer-11163848 + + if other.0[3].is_zero() { + return; + } + if other.0[3] == T::DEFAULT_MAX_VALUE { + *self = *other; + return; + } + + // First, as we don't know what type our pixel is, we have to convert to floats between 0.0 and 1.0 + let max_t = T::DEFAULT_MAX_VALUE; + let max_t = max_t.to_f32().unwrap(); + let (bg_r, bg_g, bg_b, bg_a) = (self.0[0], self.0[1], self.0[2], self.0[3]); + let (fg_r, fg_g, fg_b, fg_a) = (other.0[0], other.0[1], other.0[2], other.0[3]); + let (bg_r, bg_g, bg_b, bg_a) = ( + bg_r.to_f32().unwrap() / max_t, + bg_g.to_f32().unwrap() / max_t, + bg_b.to_f32().unwrap() / max_t, + bg_a.to_f32().unwrap() / max_t, + ); + let (fg_r, fg_g, fg_b, fg_a) = ( + fg_r.to_f32().unwrap() / max_t, + fg_g.to_f32().unwrap() / max_t, + fg_b.to_f32().unwrap() / max_t, + fg_a.to_f32().unwrap() / max_t, + ); + + // Work out what the final alpha level will be + let alpha_final = bg_a + fg_a - bg_a * fg_a; + if alpha_final == 0.0 { + return; + }; + + // We premultiply our channels by their alpha, as this makes it easier to calculate + let (bg_r_a, bg_g_a, bg_b_a) = (bg_r * bg_a, bg_g * bg_a, bg_b * bg_a); + let (fg_r_a, fg_g_a, fg_b_a) = (fg_r * fg_a, fg_g * fg_a, fg_b * fg_a); + + // Standard formula for src-over alpha compositing + let (out_r_a, out_g_a, out_b_a) = ( + fg_r_a + bg_r_a * (1.0 - fg_a), + fg_g_a + bg_g_a * (1.0 - fg_a), + fg_b_a + bg_b_a * (1.0 - fg_a), + ); + + // Unmultiply the channels by our resultant alpha channel + let (out_r, out_g, out_b) = ( + out_r_a / alpha_final, + out_g_a / alpha_final, + out_b_a / alpha_final, + ); + + // Cast back to our initial type on return + *self = Rgba([ + NumCast::from(max_t * out_r).unwrap(), + NumCast::from(max_t * out_g).unwrap(), + NumCast::from(max_t * out_b).unwrap(), + NumCast::from(max_t * alpha_final).unwrap(), + ]) + } +} + +impl<T: Primitive> Blend for Rgb<T> { + fn blend(&mut self, other: &Rgb<T>) { + *self = *other + } +} + +/// Invert a color +pub(crate) trait Invert { + /// Inverts a color in-place. + fn invert(&mut self); +} + +impl<T: Primitive> Invert for LumaA<T> { + fn invert(&mut self) { + let l = self.0; + let max = T::DEFAULT_MAX_VALUE; + + *self = LumaA([max - l[0], l[1]]) + } +} + +impl<T: Primitive> Invert for Luma<T> { + fn invert(&mut self) { + let l = self.0; + + let max = T::DEFAULT_MAX_VALUE; + let l1 = max - l[0]; + + *self = Luma([l1]) + } +} + +impl<T: Primitive> Invert for Rgba<T> { + fn invert(&mut self) { + let rgba = self.0; + + let max = T::DEFAULT_MAX_VALUE; + + *self = Rgba([max - rgba[0], max - rgba[1], max - rgba[2], rgba[3]]) + } +} + +impl<T: Primitive> Invert for Rgb<T> { + fn invert(&mut self) { + let rgb = self.0; + + let max = T::DEFAULT_MAX_VALUE; + + let r1 = max - rgb[0]; + let g1 = max - rgb[1]; + let b1 = max - rgb[2]; + + *self = Rgb([r1, g1, b1]) + } +} + +#[cfg(test)] +mod tests { + use super::{Luma, LumaA, Pixel, Rgb, Rgba}; + + #[test] + fn test_apply_with_alpha_rgba() { + let mut rgba = Rgba([0, 0, 0, 0]); + rgba.apply_with_alpha(|s| s, |_| 0xFF); + assert_eq!(rgba, Rgba([0, 0, 0, 0xFF])); + } + + #[test] + fn test_apply_with_alpha_rgb() { + let mut rgb = Rgb([0, 0, 0]); + rgb.apply_with_alpha(|s| s, |_| panic!("bug")); + assert_eq!(rgb, Rgb([0, 0, 0])); + } + + #[test] + fn test_map_with_alpha_rgba() { + let rgba = Rgba([0, 0, 0, 0]).map_with_alpha(|s| s, |_| 0xFF); + assert_eq!(rgba, Rgba([0, 0, 0, 0xFF])); + } + + #[test] + fn test_map_with_alpha_rgb() { + let rgb = Rgb([0, 0, 0]).map_with_alpha(|s| s, |_| panic!("bug")); + assert_eq!(rgb, Rgb([0, 0, 0])); + } + + #[test] + fn test_blend_luma_alpha() { + let ref mut a = LumaA([255 as u8, 255]); + let b = LumaA([255 as u8, 255]); + a.blend(&b); + assert_eq!(a.0[0], 255); + assert_eq!(a.0[1], 255); + + let ref mut a = LumaA([255 as u8, 0]); + let b = LumaA([255 as u8, 255]); + a.blend(&b); + assert_eq!(a.0[0], 255); + assert_eq!(a.0[1], 255); + + let ref mut a = LumaA([255 as u8, 255]); + let b = LumaA([255 as u8, 0]); + a.blend(&b); + assert_eq!(a.0[0], 255); + assert_eq!(a.0[1], 255); + + let ref mut a = LumaA([255 as u8, 0]); + let b = LumaA([255 as u8, 0]); + a.blend(&b); + assert_eq!(a.0[0], 255); + assert_eq!(a.0[1], 0); + } + + #[test] + fn test_blend_rgba() { + let ref mut a = Rgba([255 as u8, 255, 255, 255]); + let b = Rgba([255 as u8, 255, 255, 255]); + a.blend(&b); + assert_eq!(a.0, [255, 255, 255, 255]); + + let ref mut a = Rgba([255 as u8, 255, 255, 0]); + let b = Rgba([255 as u8, 255, 255, 255]); + a.blend(&b); + assert_eq!(a.0, [255, 255, 255, 255]); + + let ref mut a = Rgba([255 as u8, 255, 255, 255]); + let b = Rgba([255 as u8, 255, 255, 0]); + a.blend(&b); + assert_eq!(a.0, [255, 255, 255, 255]); + + let ref mut a = Rgba([255 as u8, 255, 255, 0]); + let b = Rgba([255 as u8, 255, 255, 0]); + a.blend(&b); + assert_eq!(a.0, [255, 255, 255, 0]); + } + + #[test] + fn test_apply_without_alpha_rgba() { + let mut rgba = Rgba([0, 0, 0, 0]); + rgba.apply_without_alpha(|s| s + 1); + assert_eq!(rgba, Rgba([1, 1, 1, 0])); + } + + #[test] + fn test_apply_without_alpha_rgb() { + let mut rgb = Rgb([0, 0, 0]); + rgb.apply_without_alpha(|s| s + 1); + assert_eq!(rgb, Rgb([1, 1, 1])); + } + + #[test] + fn test_map_without_alpha_rgba() { + let rgba = Rgba([0, 0, 0, 0]).map_without_alpha(|s| s + 1); + assert_eq!(rgba, Rgba([1, 1, 1, 0])); + } + + #[test] + fn test_map_without_alpha_rgb() { + let rgb = Rgb([0, 0, 0]).map_without_alpha(|s| s + 1); + assert_eq!(rgb, Rgb([1, 1, 1])); + } + + macro_rules! test_lossless_conversion { + ($a:ty, $b:ty, $c:ty) => { + let a: $a = [<$a as Pixel>::Subpixel::DEFAULT_MAX_VALUE >> 2; + <$a as Pixel>::CHANNEL_COUNT as usize] + .into(); + let b: $b = a.into_color(); + let c: $c = b.into_color(); + assert_eq!(a.channels(), c.channels()); + }; + } + + #[test] + fn test_lossless_conversions() { + use super::IntoColor; + use crate::traits::Primitive; + + test_lossless_conversion!(Luma<u8>, Luma<u16>, Luma<u8>); + test_lossless_conversion!(LumaA<u8>, LumaA<u16>, LumaA<u8>); + test_lossless_conversion!(Rgb<u8>, Rgb<u16>, Rgb<u8>); + test_lossless_conversion!(Rgba<u8>, Rgba<u16>, Rgba<u8>); + } + + #[test] + fn accuracy_conversion() { + use super::{Luma, Pixel, Rgb}; + let pixel = Rgb::from([13, 13, 13]); + let Luma([luma]) = pixel.to_luma(); + assert_eq!(luma, 13); + } +} |