leptos-chartistry 0.2.3

Chartistry is a charting library for Leptos
Documentation 
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mod colourmaps;
mod scheme;

pub use colourmaps::*;
pub use scheme::{ColourScheme, DivergingGradient, LinearGradientSvg, SequentialGradient};

use std::str::FromStr;

/// A colour in RGB format.
#[derive(Copy, Clone, Debug, PartialEq)]
pub struct Colour {
    red: u8,
    green: u8,
    blue: u8,
}

impl Colour {
    /// Create a new colour with the given red, green, and blue values.
    #[deprecated(since = "0.1.1", note = "renamed to `from_rgb`")]
    pub const fn new(red: u8, green: u8, blue: u8) -> Self {
        Self::from_rgb(red, green, blue)
    }

    /// Create a new colour with the given red, green, and blue values.
    pub const fn from_rgb(red: u8, green: u8, blue: u8) -> Self {
        Self { red, green, blue }
    }

    fn interpolate(self, rhs: Self, ratio: f64) -> Self {
        let ratio = ratio.clamp(0.0, 1.0);
        let interpolate = |pre: u8, post: u8| {
            let pre = pre as f64;
            let post = post as f64;
            let diff = post - pre;
            (pre + (diff * ratio)).round() as u8
        };
        Colour {
            red: interpolate(self.red, rhs.red),
            green: interpolate(self.green, rhs.green),
            blue: interpolate(self.blue, rhs.blue),
        }
    }
}

impl std::fmt::Display for Colour {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "#{:02X}{:02X}{:02X}", self.red, self.green, self.blue)
    }
}

impl FromStr for Colour {
    type Err = String;

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let s = s.trim_start_matches('#');
        let len = s.len();
        if len != 6 {
            return Err(format!("expected 6 characters, got {}", len));
        }
        let red = u8::from_str_radix(&s[0..2], 16).map_err(|e| e.to_string())?;
        let green = u8::from_str_radix(&s[2..4], 16).map_err(|e| e.to_string())?;
        let blue = u8::from_str_radix(&s[4..6], 16).map_err(|e| e.to_string())?;
        Ok(Colour { red, green, blue })
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_colour_interpolation() {
        let black = Colour::from_rgb(0, 0, 0);
        let white = Colour::from_rgb(255, 255, 255);
        assert_eq!(black.interpolate(white, 1.0), white);
        assert_eq!(black.interpolate(white, 0.0), black);
        assert_eq!(white.interpolate(black, 1.0), black);
        assert_eq!(white.interpolate(black, 0.0), white);
        assert_eq!(black.interpolate(white, 0.2), Colour::from_rgb(51, 51, 51));
        assert_eq!(
            white.interpolate(black, 0.2),
            Colour::from_rgb(204, 204, 204)
        );
        let other = Colour::from_rgb(34, 202, 117);
        assert_eq!(black.interpolate(other, 0.4), Colour::from_rgb(14, 81, 47));
        assert_eq!(
            white.interpolate(other, 0.2),
            Colour::from_rgb(211, 244, 227)
        );
        assert_eq!(
            white.interpolate(other, 0.8),
            Colour::from_rgb(78, 213, 145)
        );
    }
}