zng_color/mix.rs
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use super::{clamp_normal, Hsla, Hsva, PreMulRgba, Rgba};
use zng_layout::unit::Factor;
use paste::*;
/// Webrender [`MixBlendMode`].
pub type RenderMixBlendMode = zng_view_api::MixBlendMode;
macro_rules! impl_mix {
(
separable {$(
$(#[$meta:meta])*
$Mode:ident => |$fg:ident, $bg:ident, $ca0:ident, $ca1:ident| $mix:expr,
)+}
non_separable {$(
$(#[$ns_meta:meta])*
$NsMode:ident => |[$fgh:ident, $fgs:ident, $fgl:ident], [$bgh:ident, $bgs:ident, $bgl:ident]| $ns_mix:expr,
)+}
) => {
/// Color mix blend mode.
#[repr(u8)]
#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub enum MixBlendMode {
$(
$(#[$meta])*
$Mode,
)+
$(
$(#[$ns_meta])*
$NsMode,
)+
}
impl From<MixBlendMode> for RenderMixBlendMode {
fn from(mode: MixBlendMode) -> Self {
match mode {
$(MixBlendMode::$Mode => RenderMixBlendMode::$Mode,)+
$(MixBlendMode::$NsMode => RenderMixBlendMode::$NsMode,)+
}
}
}
/// Color mix and adjustment methods.
pub trait MixAdjust {
/// MixAdjust `background` over `self` using the `mode`.
fn mix(self, mode: MixBlendMode, background: Self) -> Self where Self:Sized {
match mode {
$(MixBlendMode::$Mode => paste!(self.[<mix_ $Mode:lower>](background)),)+
$(MixBlendMode::$NsMode => paste!(self.[<mix_ $NsMode:lower>](background)),)+
}
}
$(
paste! {
#[doc = "MixAdjust `background` over `self` using the [`MixBlendMode::" $Mode "`]."]
///
$(#[$meta])*
fn [<mix_ $Mode:lower>](self, background: Self) -> Self;
}
)+
$(
paste! {
#[doc = "MixAdjust `self` over `background` using the [`MixBlendMode::`" $NsMode "`]."]
///
$(#[$ns_meta])*
///
/// This method converts both inputs to [`Hsla`] and the result back to `Rgba`.
fn [<mix_ $NsMode:lower>](self, background: Self) -> Self;
}
)+
/// Adds the `amount` to the color *lightness*.
///
/// # Examples
///
/// Add `10%` of the current lightness to the `DARK_RED` color:
///
/// ```
/// # use zng_color::*;
/// # use zng_layout::unit::*;
/// web_colors::DARK_RED.lighten(10.pct())
/// # ;
/// ```
fn lighten<A: Into<Factor>>(self, amount: A) -> Self;
/// Subtracts the `amount` from the color *lightness*.
///
/// # Examples
///
/// Removes `10%` of the current lightness from the `DARK_RED` color:
///
/// ```
/// # use zng_color::*;
/// # use zng_layout::unit::*;
/// web_colors::DARK_RED.darken(10.pct())
/// # ;
fn darken<A: Into<Factor>>(self, amount: A) -> Self;
/// Subtracts the `amount` from the color *saturation*.
///
/// # Examples
///
/// Removes `10%` of the current saturation from the `RED` color:
///
/// ```
/// # use zng_color::*;
/// # use zng_layout::unit::*;
/// colors::RED.desaturate(10.pct())
/// # ;
fn desaturate<A: Into<Factor>>(self, amount: A) -> Self;
/// Returns a copy of this color with a new `lightness`.
fn with_lightness<L: Into<Factor>>(self, lightness: L) -> Self;
}
impl PreMulRgba {
$(
paste! {
fn [<mix_ $Mode:lower _impl>](self, background: PreMulRgba) -> PreMulRgba {
PreMulRgba {
red: {
let $fg = self.red;
let $bg = background.red;
let $ca0 = self.alpha;
let $ca1 = background.alpha;
$mix
},
green: {
let $fg = self.green;
let $bg = background.green;
let $ca0 = self.alpha;
let $ca1 = background.alpha;
$mix
},
blue: {
let $fg = self.blue;
let $bg = background.blue;
let $ca0 = self.alpha;
let $ca1 = background.alpha;
$mix
},
alpha: {
let fga = self.alpha;
let bga = background.alpha;
(fga + bga - fga * bga).max(0.0).min(1.0)
},
}
}
}
)+
}
impl Hsla {
$(
paste! {
fn [<mix_ $NsMode:lower _impl>](self, background: Hsla) -> Hsla {
let $fgh = self.hue;
let $fgs = self.saturation;
let $fgl = self.lightness;
let $bgh = background.hue;
let $bgs = background.saturation;
let $bgl = background.lightness;
let [h, s, l] = { $ns_mix };
Hsla {
hue: h,
saturation: s,
lightness: l,
alpha: {
let fga = self.alpha;
let bga = background.alpha;
(fga + bga - fga * bga).max(0.0).min(1.0)
}
}
}
}
)+
}
impl MixAdjust for PreMulRgba {
$(
paste! {
fn [<mix_ $Mode:lower>](self, background: Self) -> Self {
self.[<mix_ $Mode:lower _impl>](background)
}
}
)+
$(
paste! {
fn [<mix_ $NsMode:lower>](self, background: Self) -> Self {
Hsla::from(self).[<mix_ $NsMode:lower>](Hsla::from(background)).into()
}
}
)+
fn lighten<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).lighten(amount.into()).into()
}
fn darken<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).darken(amount.into()).into()
}
fn desaturate<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).desaturate(amount).into()
}
fn with_lightness<L: Into<Factor>>(self, lightness: L) -> Self {
Hsla::from(self).with_lightness(lightness).into()
}
}
impl MixAdjust for Hsla {
$(
paste! {
fn [<mix_ $Mode:lower>](self, background: Self) -> Self {
PreMulRgba::from(self).[<mix_ $Mode:lower>](PreMulRgba::from(background)).into()
}
}
)+
$(
paste! {
fn [<mix_ $NsMode:lower>](self, background: Self) -> Self {
self.[<mix_ $NsMode:lower _impl>](background)
}
}
)+
fn lighten<A: Into<Factor>>(self, amount: A) -> Self {
let mut lighter = self;
lighter.lightness = clamp_normal(lighter.lightness + (lighter.lightness * amount.into().0));
lighter
}
fn darken<A: Into<Factor>>(self, amount: A) -> Self {
let mut darker = self;
darker.lightness = clamp_normal(darker.lightness - (darker.lightness * amount.into().0));
darker
}
fn desaturate<A: Into<Factor>>(self, amount: A) -> Self {
let mut d = self;
d.saturation = clamp_normal(d.saturation - (d.saturation * amount.into().0));
d
}
fn with_lightness<L: Into<Factor>>(mut self, lightness: L) -> Self {
self.set_lightness(lightness);
self
}
}
impl MixAdjust for Rgba {
$(
paste! {
fn [<mix_ $Mode:lower>](self, background: Self) -> Self {
PreMulRgba::from(self).[<mix_ $Mode:lower>](PreMulRgba::from(background)).into()
}
}
)+
$(
paste! {
fn [<mix_ $NsMode:lower>](self, background: Self) -> Self {
Hsla::from(self).[<mix_ $NsMode:lower>](Hsla::from(background)).into()
}
}
)+
fn lighten<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).lighten(amount.into()).into()
}
fn darken<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).darken(amount.into()).into()
}
fn desaturate<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).desaturate(amount).into()
}
fn with_lightness<L: Into<Factor>>(self, lightness: L) -> Self {
Hsla::from(self).with_lightness(lightness).into()
}
}
impl MixAdjust for Hsva {
$(
paste! {
fn [<mix_ $Mode:lower>](self, background: Self) -> Self {
PreMulRgba::from(self).[<mix_ $Mode:lower>](PreMulRgba::from(background)).into()
}
}
)+
$(
paste! {
fn [<mix_ $NsMode:lower>](self, background: Self) -> Self {
Hsla::from(self).[<mix_ $NsMode:lower>](Hsla::from(background)).into()
}
}
)+
fn lighten<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).lighten(amount.into()).into()
}
fn darken<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).darken(amount.into()).into()
}
fn desaturate<A: Into<Factor>>(self, amount: A) -> Self {
Hsla::from(self).desaturate(amount).into()
}
fn with_lightness<L: Into<Factor>>(self, lightness: L) -> Self {
Hsla::from(self).with_lightness(lightness).into()
}
}
};
}
impl_mix! {
separable {
/// Normal alpha blend of the foreground color over the background.
Normal => |fg, bg, fga, _bga| fg + bg * (1.0 - fga),
/// Multiply the colors.
///
/// The resultant color is always at least as dark as either color.
/// Multiplying any color with black results in black.
/// Multiplying any color with white preserves the original color.
Multiply => |fg, bg, fga, bga| fg * bg + fg * (1.0 - bga) + bg * (1.0 - fga),
/// Multiply the colors, then complements the result.
///
/// The result color is always at least as light as either of the two constituent colors.
/// Screening any color with white produces white; screening with black leaves the original color unchanged.
/// The effect is similar to projecting multiple photographic slides simultaneously onto a single screen.
Screen => |fg, bg, _fga, _bga| fg + bg - fg * bg,
/// Multiplies or screens the colors, depending on the background color value.
///
/// Foreground color overlays the background while preserving its highlights and shadows.
/// The background color is not replaced but is mixed with the foreground color to reflect the lightness or darkness
/// of the background.
///
/// This is the inverse of *hardlight*.
Overlay => |fg, bg, fga, bga| if bg * 2.0 <= bga {
2.0 * fg * bg + fg * (1.0 - bga) + bg * (1.0 - fga)
} else {
fg * (1.0 + bga) + bg * (1.0 + fga) - 2.0 * fg * bg - fga * bga
},
/// Selects the darker of the colors.
///
/// The background color is replaced with the foreground where the background is darker; otherwise, it is left unchanged.
Darken => |fg, bg, fga, bga| (fg * bga).min(bg * fga) + fg * (1.0 - bga) + bg * (1.0 - fga),
/// Selects the lighter of the colors.
///
/// The background color is replaced with the foreground where the background is lighter; otherwise, it is left unchanged.
Lighten => |fg, bg, fga, bga| (fg * bga).max(bg * fga) + fg * (1.0 - bga) + bg * (1.0 - fga),
/// Brightens the background color to reflect the foreground color. Painting with black produces no changes.
ColorDodge => |fg, bg, fga, bga| if fg == fga {
fga * bga + fg * (1.0 - bga) + bg * (1.0 - fga)
} else {
fga * bga * 1.0_f32.min((bg / bga) * fga / (fga - fg)) + fg * (1.0 - bga) + bg * (1.0 - fga)
},
/// Darkens the background color to reflect the foreground color. Painting with white produces no change.
ColorBurn => |fg, bg, fga, bga| fga * bga * (1.0 - 1.0_f32.min((1.0 - bg / bga) * fga / fg)) + fg * (1.0 - bga) + bg * (1.0 - fga),
/// Multiplies or screens the colors, depending on the foreground color value.
///
/// The effect is similar to shining a harsh spotlight on the background color.
HardLight => |fg, bg, fga, bga| if fg * 2.0 <= fga {
2.0 * fg * bg + fg * (1.0 - bga) + bg * (1.0 - fga)
} else {
fg * (1.0 + bga) + bg * (1.0 + fga) - 2.0 * fg * bg - fga * bga
},
/// Darkens or lightens the colors, depending on the foreground color value.
///
/// The effect is similar to shining a diffused spotlight on the background color.
SoftLight => |fg, bg, fga, bga| {
let m = bg / bga;
if fg * 2.0 <= fga {
bg * (fga + (2.0 * fg - fga) * (1.0 - m)) + fg * (1.0 - bga) + bg * (1.0 - fga)
} else if bg * 4.0 <= bga {
let m2 = m * m;
let m3 = m2 * m;
bga * (2.0 * fg - fga) * (m3 * 16.0 - m2 * 12.0 - m * 3.0) + fg - fg * bga + bg
} else {
bga * (2.0 * fg - fga) * (m.sqrt() - m) + fg - fg * bga + bg
}
},
/// Subtracts the darker of the two constituent colors from the lighter color.
///
/// Painting with white inverts the background color; painting with black produces no change.
Difference => |fg, bg, fga, bga| fg + bg - 2.0 * (fg * bga).min(bg * fga),
/// Produces an effect similar to that of the *difference* mode but lower in contrast.
///
/// Painting with white inverts the background color; painting with black produces no change.
Exclusion => |fg, bg, _fga, _bga| fg + bg - 2.0 * fg * bg,
}
non_separable {
/// Creates a color with the hue of the foreground color and the saturation and luminosity of the background color.
Hue => |[fgh, _fgs, _fgl], [_bgh, bgs, bgl]| [fgh, bgs, bgl],
/// Creates a color with the saturation of the foreground color and the hue and luminosity of the background color.
Saturation => |[_fgh, fgs, _fgl], [bgh, _bgs, bgl]| [bgh, fgs, bgl],
/// Creates a color with the hue and saturation of the foreground color and the luminosity of the background color.
Color => |[fgh, fgs, _fgl], [_bgh, _bgs, bgl]| [fgh, fgs, bgl],
/// Creates a color with the luminosity of the foreground color and the hue and saturation of the background color.
Luminosity => |[fgh, _fgs, _fbl], [bgh, bgs, _bgl]| [bgh, bgs, fgh],
}
}
#[expect(clippy::derivable_impls)] // macro generated enum
impl Default for MixBlendMode {
fn default() -> Self {
MixBlendMode::Normal
}
}