Index

• Custom Gradient
• Preset Gradients
• Parsing GIMP Gradient
• Using the Gradient
• Examples
• Similar Projects
• Projects using colorgrad

Usage

Add this to your Cargo.toml

colorgrad = "0.7.0"

Custom Gradient

Basic

let g = colorgrad::GradientBuilder::new().build::<colorgrad::LinearGradient>()?;

Custom Colors

use colorgrad::Color;

let g = colorgrad::GradientBuilder::new()
    .colors(&[
        Color::from_rgba8(0, 206, 209, 255),
        Color::from_rgba8(255, 105, 180, 255),
        Color::new(0.274, 0.5, 0.7, 1.0),
        Color::from_hsva(50.0, 1.0, 1.0, 1.0),
        Color::from_hsva(348.0, 0.9, 0.8, 1.0),
    ])
    .build::<colorgrad::LinearGradient>()?;

Using Web Color Format

.html_colors() method accepts named colors, hexadecimal (#rgb, #rgba, #rrggbb, #rrggbbaa), rgb(), rgba(), hsl(), hsla(), hwb(), and hsv().

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["#C41189", "#00BFFF", "#FFD700"])
    .build::<colorgrad::LinearGradient>()?;

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["gold", "hotpink", "darkturquoise"])
    .build::<colorgrad::LinearGradient>()?;

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["rgb(125,110,221)", "rgb(90%,45%,97%)", "hsl(229,79%,85%)"])
    .build::<colorgrad::LinearGradient>()?;

Using CSS Gradient Format

let g = colorgrad::GradientBuilder::new()
    .css("blue, cyan, gold, purple 70%, tomato 70%, 90%, #ff0")
    .build::<colorgrad::CatmullRomGradient>()?;

Domain & Color Position

Default domain is [0..1].

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["deeppink", "gold", "seagreen"])
    .build::<colorgrad::LinearGradient>()?;

assert_eq!(g.domain(), (0.0, 1.0));

Set the domain to [0..100].

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["deeppink", "gold", "seagreen"])
    .domain(&[0.0, 100.0])
    .build::<colorgrad::LinearGradient>()?;

assert_eq!(g.domain(), (0.0, 100.0));

Set the domain to [-1..1].

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["deeppink", "gold", "seagreen"])
    .domain(&[-1.0, 1.0])
    .build::<colorgrad::LinearGradient>()?;

assert_eq!(g.domain(), (-1.0, 1.0));

Set exact position for each color. The domain is [0..1].

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["deeppink", "gold", "seagreen"])
    .domain(&[0.0, 0.7, 1.0])
    .build::<colorgrad::LinearGradient>()?;

assert_eq!(g.domain(), (0.0, 1.0));

Set exact position for each color. The domain is [15..80].

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["deeppink", "gold", "seagreen"])
    .domain(&[15.0, 30.0, 80.0])
    .build::<colorgrad::LinearGradient>()?;

assert_eq!(g.domain(), (15.0, 80.0));

Blending Mode

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["#FFF", "#00F"])
    .mode(colorgrad::BlendMode::Rgb)
    .build::<colorgrad::LinearGradient>()?;

Interpolation Mode

let g = colorgrad::GradientBuilder::new()
    .html_colors(&["#C41189", "#00BFFF", "#FFD700"])
    .build::<colorgrad::BasisGradient>()?;

Preset Gradients

See PRESET.md

Parsing GIMP Gradient

use colorgrad::{Color, GimpGradient};
use std::fs::File;
use std::io::BufReader;

let input = File::open("examples/Abstract_1.ggr")?;
let buf = BufReader::new(input);
let col = Color::default();
let grad = GimpGradient::new(buf, &col, &col)?;

assert_eq!(grad.name(), "Abstract 1");

Using the Gradient

Get the domain

let grad = colorgrad::preset::rainbow();

assert_eq!(grad.domain(), (0.0, 1.0));

Get single color at certain position

use colorgrad::Gradient;

let grad = colorgrad::preset::blues();

assert_eq!(grad.at(0.0).to_rgba8(), [247, 251, 255, 255]);
assert_eq!(grad.at(0.5).to_rgba8(), [109, 174, 213, 255]);
assert_eq!(grad.at(1.0).to_rgba8(), [8,   48,  107, 255]);

assert_eq!(grad.at(0.3).to_rgba8(), grad.repeat_at(0.3).to_rgba8());
assert_eq!(grad.at(0.3).to_rgba8(), grad.reflect_at(0.3).to_rgba8());

assert_eq!(grad.at(0.7).to_rgba8(), grad.repeat_at(0.7).to_rgba8());
assert_eq!(grad.at(0.7).to_rgba8(), grad.reflect_at(0.7).to_rgba8());

The difference of at(), repeat_at() and reflect_at().

Get n colors evenly spaced across gradient

use colorgrad::Gradient;

let grad = colorgrad::preset::rainbow();

for c in grad.colors(10) {
    println!("{}", c.to_hex_string());
}

Output:

#6e40aa
#c83dac
#ff5375
#ff8c38
#c9d33a
#7cf659
#5dea8d
#48b8d0
#4775de
#6e40aa

Hard-Edged Gradient

Convert gradient to hard-edged gradient with 11 segments and 0 smoothness.

let g = colorgrad::preset::rainbow().sharp(11, 0.0);

This is the effect of different smoothness.

Examples

Gradient Image

use colorgrad::Gradient;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let width = 1300.0;
    let height = 70.0;

    // custom gradient
    let grad = colorgrad::GradientBuilder::new()
        .html_colors(&["deeppink", "gold", "seagreen"])
        .build::<colorgrad::CatmullRomGradient>()?;

    let imgbuf = image::ImageBuffer::from_fn(width as u32, height as u32, |x, _| {
        image::Rgba(grad.at(x as f32 / width).to_rgba8())
    });
    imgbuf.save("gradient.png")?;

    Ok(())
}

Example output:

Colored Noise

use colorgrad::Gradient;
use noise::NoiseFn;

fn main() {
    let scale = 0.015;

    let grad = colorgrad::preset::rainbow().sharp(5, 0.15);
    let ns = noise::OpenSimplex::new(0);

    let imgbuf = image::ImageBuffer::from_fn(600, 350, |x, y| {
        let t = ns.get([x as f64 * scale, y as f64 * scale]);
        image::Rgba(grad.at(norm(t as f32, -0.5, 0.5)).to_rgba8())
    });
    imgbuf.save("noise.png").unwrap();
}

fn norm(t: f32, a: f32, b: f32) -> f32 {
    (t - a) * (1.0 / (b - a))
}

Example output:

Features

Default

• named-colors: Enables parsing from named colors. Requires phf.
• preset: Preset gradients.

Can be disabled using default-features = false.

Optional

• lab: Blending colors in Lab colorspace.
• ggr: Parsing GIMP gradient format.

Similar Projects

• colorgrad (Go version of this library)
• colorous (Rust)
• chroma.js (Javascript)
• d3-scale-chromatic (Javascript)

Projects using colorgrad

• binocle - A graphical tool to visualize binary data
• bytehound - A memory profiler for Linux
• cosmic-bg - COSMIC session service which applies backgrounds to displays
• eruption - A Linux user-mode input and LED driver for keyboards, mice and other devices
• gradient - A command line tool for playing with color gradient
• lcat - lolcat clone
• lolcrab - lolcat but with noise (lcat fork)
• rust-fractal - Mandelbrot fractal visualizer
• WezTerm - A GPU-accelerated cross-platform terminal emulator and multiplexer
• and many others..

Links

• Color Blindness Simulator
• Visual System Simulator