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//! Color blending and blending equations. //! //! Palette offers both OpenGL style blending equations, as well as most of the //! SVG composition operators (also common in photo manipulation software). The //! composition operators are all implemented in the //! [`Blend`](crate::Blend) trait, and ready to use with any appropriate //! color type: //! //! ``` //! use palette::{LinSrgba, Blend}; //! //! let a = LinSrgba::new(0.2, 0.5, 0.1, 0.8); //! let b = LinSrgba::new(0.6, 0.3, 0.5, 0.1); //! let c = a.overlay(b); //! ``` //! //! Blending equations can be defined using the //! [`Equations`](crate::blend::Equations) type, which is then passed to the //! `blend` function, from the `Blend` trait: //! //! ``` //! use palette::{LinSrgba, Blend}; //! use palette::blend::{Equations, Parameter}; //! //! let blend_mode = Equations::from_parameters( //! Parameter::SourceAlpha, //! Parameter::OneMinusSourceAlpha //! ); //! //! let a = LinSrgba::new(0.2, 0.5, 0.1, 0.8); //! let b = LinSrgba::new(0.6, 0.3, 0.5, 0.1); //! let c = a.blend(b, blend_mode); //! ``` //! //! Note that blending will use [premultiplied alpha](crate::blend::PreAlpha), //! which may result in loss of some color information in some cases. One such //! case is that a completely transparent resultant color will become black. use crate::float::Float; use crate::ComponentWise; pub use self::blend::Blend; pub use self::equations::{Equation, Equations, Parameter, Parameters}; pub use self::pre_alpha::PreAlpha; mod blend; mod equations; mod pre_alpha; #[cfg(test)] mod test; /// A trait for custom blend functions. pub trait BlendFunction<C: Blend<Color = C> + ComponentWise> where C::Scalar: Float, { /// Apply this blend function to a pair of colors. fn apply_to( self, source: PreAlpha<C, C::Scalar>, destination: PreAlpha<C, C::Scalar>, ) -> PreAlpha<C, C::Scalar>; } impl<C, F> BlendFunction<C> for F where C: Blend<Color = C> + ComponentWise, C::Scalar: Float, F: FnOnce(PreAlpha<C, C::Scalar>, PreAlpha<C, C::Scalar>) -> PreAlpha<C, C::Scalar>, { fn apply_to( self, source: PreAlpha<C, C::Scalar>, destination: PreAlpha<C, C::Scalar>, ) -> PreAlpha<C, C::Scalar> { (self)(source, destination) } }