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use colorous::{
// Sequential single-hue
BLUES,
// Sequential multi-hue (ColorBrewer)
BLUE_GREEN,
BLUE_PURPLE,
// Diverging
BROWN_GREEN,
CIVIDIS,
COOL,
CUBEHELIX,
GREENS,
GREEN_BLUE,
GREYS,
INFERNO,
MAGMA,
ORANGES,
ORANGE_RED,
PINK_GREEN,
PLASMA,
PURPLES,
PURPLE_BLUE,
PURPLE_BLUE_GREEN,
PURPLE_GREEN,
PURPLE_ORANGE,
PURPLE_RED,
// Cyclical
RAINBOW,
REDS,
RED_BLUE,
RED_GREY,
RED_PURPLE,
RED_YELLOW_BLUE,
RED_YELLOW_GREEN,
SINEBOW,
SPECTRAL,
// Sequential multi-hue (perceptual)
TURBO,
VIRIDIS,
WARM,
YELLOW_GREEN,
YELLOW_GREEN_BLUE,
YELLOW_ORANGE_BROWN,
YELLOW_ORANGE_RED,
};
use std::sync::Arc;
const HEX_DIGITS: &[u8; 16] = b"0123456789abcdef";
/// Convert an RGB triplet to a 7-byte hex color string (`#rrggbb`).
/// Avoids `format!` overhead in hot loops (heatmaps, 2D histograms).
#[inline]
pub(crate) fn rgb_hex(r: u8, g: u8, b: u8) -> String {
let bytes = [
b'#',
HEX_DIGITS[(r >> 4) as usize],
HEX_DIGITS[(r & 0xf) as usize],
HEX_DIGITS[(g >> 4) as usize],
HEX_DIGITS[(g & 0xf) as usize],
HEX_DIGITS[(b >> 4) as usize],
HEX_DIGITS[(b & 0xf) as usize],
];
// SAFETY: all bytes are ASCII
unsafe { String::from_utf8_unchecked(bytes.to_vec()) }
}
fn cmap_str(gradient: colorous::Gradient, value: f64) -> String {
let rgb = gradient.eval_continuous(value.clamp(0.0, 1.0));
rgb_hex(rgb.r, rgb.g, rgb.b)
}
fn cmap_rgb(gradient: colorous::Gradient, value: f64) -> (u8, u8, u8) {
let rgb = gradient.eval_continuous(value.clamp(0.0, 1.0));
(rgb.r, rgb.g, rgb.b)
}
/// Color map used to encode numeric cell values as colors.
///
/// Values are normalized to `[0.0, 1.0]` relative to the data min/max before
/// the map is applied. Used by [`Heatmap`](crate::plot::Heatmap),
/// [`Histogram2D`](crate::plot::Histogram2D), and
/// [`CalendarPlot`](crate::plot::CalendarPlot).
///
/// # Choosing a color map
///
/// | Category | Variants | Use when |
/// |----------|----------|----------|
/// | Sequential (perceptual) | `Viridis`, `Inferno`, `Magma`, `Plasma`, `Cividis`, `Turbo`, `Warm`, `Cool`, `Cubehelix` | General-purpose continuous data; colorblind-safe options |
/// | Sequential (ColorBrewer) | `BlueGreen`, `BluePurple`, `GreenBlue`, `OrangeRed`, `PurpleBlue`, `PurpleBlueGreen`, `PurpleRed`, `RedPurple`, `YellowGreen`, `YellowGreenBlue`, `YellowOrangeBrown`, `YellowOrangeRed` | Themed sequential scales from [ColorBrewer](https://colorbrewer2.org/) |
/// | Sequential (single-hue) | `Blues`, `Greens`, `Grayscale`, `Oranges`, `Purples`, `Reds` | Monochromatic; print-friendly |
/// | Diverging | `BrownGreen`, `PinkGreen`, `PurpleGreen`, `PurpleOrange`, `RedBlue`, `RedGrey`, `RedYellowBlue`, `RedYellowGreen`, `Spectral` | Data with a meaningful midpoint (e.g. fold-change, correlation) |
/// | Cyclical | `Rainbow`, `Sinebow` | Periodic data (phase, angle, time-of-day) |
/// | Custom | `Custom` | Full control over color encoding |
#[derive(Clone)]
pub enum ColorMap {
// ── Sequential multi-hue (perceptual) ──────────────────────────────────
/// Improved rainbow; perceptually uniform; colorblind-safe.
Turbo,
/// Blue → green → yellow; perceptually uniform; default for most plots.
Viridis,
/// Black → purple → yellow; high-contrast; works in greyscale.
Inferno,
/// Black → purple → orange; similar to Inferno.
Magma,
/// Blue → purple → yellow; bright and perceptually uniform.
Plasma,
/// Blue → grey → yellow; optimized for color-vision deficiency.
Cividis,
/// Warm perceptual rainbow (180° rotation of Cool).
Warm,
/// Cool perceptual rainbow.
Cool,
/// Green's default Cubehelix spiral.
Cubehelix,
// ── Sequential multi-hue (ColorBrewer) ────────────────────────────────
/// White → blue-green.
BlueGreen,
/// White → blue-purple.
BluePurple,
/// White → green-blue.
GreenBlue,
/// White → orange-red.
OrangeRed,
/// White → purple-blue-green.
PurpleBlueGreen,
/// White → purple-blue.
PurpleBlue,
/// White → purple-red.
PurpleRed,
/// White → red-purple.
RedPurple,
/// White → yellow-green-blue.
YellowGreenBlue,
/// White → yellow-green.
YellowGreen,
/// White → yellow-orange-brown.
YellowOrangeBrown,
/// White → yellow-orange-red.
YellowOrangeRed,
// ── Sequential single-hue ─────────────────────────────────────────────
/// White → blue.
Blues,
/// White → green.
Greens,
/// White → black; print-friendly.
Grayscale,
/// White → orange.
Oranges,
/// White → purple.
Purples,
/// White → red.
Reds,
// ── Diverging ─────────────────────────────────────────────────────────
/// Brown ← 0 → green.
BrownGreen,
/// Pink ← 0 → green.
PinkGreen,
/// Purple ← 0 → green.
PurpleGreen,
/// Purple ← 0 → orange.
PurpleOrange,
/// Red ← 0 → blue.
RedBlue,
/// Red ← 0 → grey.
RedGrey,
/// Red ← 0 → yellow → blue.
RedYellowBlue,
/// Red ← 0 → yellow → green.
RedYellowGreen,
/// Red → orange → yellow → green → blue → purple.
Spectral,
// ── Cyclical ──────────────────────────────────────────────────────────
/// Less-angry rainbow; suitable for cyclical data.
Rainbow,
/// Smooth sinusoidal rainbow.
Sinebow,
// ── Custom ────────────────────────────────────────────────────────────
/// User-defined mapping from a normalized `[0.0, 1.0]` value to a CSS
/// color string. Wrap the function in `Arc` for cloneability.
///
/// ```rust,no_run
/// use std::sync::Arc;
/// use kuva::plot::ColorMap;
///
/// // Custom blue-to-red diverging scale
/// let cmap = ColorMap::Custom(Arc::new(|t: f64| {
/// let r = (t * 255.0) as u8;
/// let b = ((1.0 - t) * 255.0) as u8;
/// format!("rgb({r},0,{b})")
/// }));
/// ```
Custom(Arc<dyn Fn(f64) -> String + Send + Sync>),
}
impl std::fmt::Debug for ColorMap {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let name = match self {
ColorMap::Turbo => "Turbo",
ColorMap::Viridis => "Viridis",
ColorMap::Inferno => "Inferno",
ColorMap::Magma => "Magma",
ColorMap::Plasma => "Plasma",
ColorMap::Cividis => "Cividis",
ColorMap::Warm => "Warm",
ColorMap::Cool => "Cool",
ColorMap::Cubehelix => "Cubehelix",
ColorMap::BlueGreen => "BlueGreen",
ColorMap::BluePurple => "BluePurple",
ColorMap::GreenBlue => "GreenBlue",
ColorMap::OrangeRed => "OrangeRed",
ColorMap::PurpleBlueGreen => "PurpleBlueGreen",
ColorMap::PurpleBlue => "PurpleBlue",
ColorMap::PurpleRed => "PurpleRed",
ColorMap::RedPurple => "RedPurple",
ColorMap::YellowGreenBlue => "YellowGreenBlue",
ColorMap::YellowGreen => "YellowGreen",
ColorMap::YellowOrangeBrown => "YellowOrangeBrown",
ColorMap::YellowOrangeRed => "YellowOrangeRed",
ColorMap::Blues => "Blues",
ColorMap::Greens => "Greens",
ColorMap::Grayscale => "Grayscale",
ColorMap::Oranges => "Oranges",
ColorMap::Purples => "Purples",
ColorMap::Reds => "Reds",
ColorMap::BrownGreen => "BrownGreen",
ColorMap::PinkGreen => "PinkGreen",
ColorMap::PurpleGreen => "PurpleGreen",
ColorMap::PurpleOrange => "PurpleOrange",
ColorMap::RedBlue => "RedBlue",
ColorMap::RedGrey => "RedGrey",
ColorMap::RedYellowBlue => "RedYellowBlue",
ColorMap::RedYellowGreen => "RedYellowGreen",
ColorMap::Spectral => "Spectral",
ColorMap::Rainbow => "Rainbow",
ColorMap::Sinebow => "Sinebow",
ColorMap::Custom(_) => return write!(f, "ColorMap::Custom(<fn>)"),
};
write!(f, "ColorMap::{name}")
}
}
impl ColorMap {
/// Map a normalized value in `[0.0, 1.0]` to a CSS color string.
pub fn map(&self, value: f64) -> String {
match self {
ColorMap::Turbo => cmap_str(TURBO, value),
ColorMap::Viridis => cmap_str(VIRIDIS, value),
ColorMap::Inferno => cmap_str(INFERNO, value),
ColorMap::Magma => cmap_str(MAGMA, value),
ColorMap::Plasma => cmap_str(PLASMA, value),
ColorMap::Cividis => cmap_str(CIVIDIS, value),
ColorMap::Warm => cmap_str(WARM, value),
ColorMap::Cool => cmap_str(COOL, value),
ColorMap::Cubehelix => cmap_str(CUBEHELIX, value),
ColorMap::BlueGreen => cmap_str(BLUE_GREEN, value),
ColorMap::BluePurple => cmap_str(BLUE_PURPLE, value),
ColorMap::GreenBlue => cmap_str(GREEN_BLUE, value),
ColorMap::OrangeRed => cmap_str(ORANGE_RED, value),
ColorMap::PurpleBlueGreen => cmap_str(PURPLE_BLUE_GREEN, value),
ColorMap::PurpleBlue => cmap_str(PURPLE_BLUE, value),
ColorMap::PurpleRed => cmap_str(PURPLE_RED, value),
ColorMap::RedPurple => cmap_str(RED_PURPLE, value),
ColorMap::YellowGreenBlue => cmap_str(YELLOW_GREEN_BLUE, value),
ColorMap::YellowGreen => cmap_str(YELLOW_GREEN, value),
ColorMap::YellowOrangeBrown => cmap_str(YELLOW_ORANGE_BROWN, value),
ColorMap::YellowOrangeRed => cmap_str(YELLOW_ORANGE_RED, value),
ColorMap::Blues => cmap_str(BLUES, value),
ColorMap::Greens => cmap_str(GREENS, value),
ColorMap::Grayscale => cmap_str(GREYS, value),
ColorMap::Oranges => cmap_str(ORANGES, value),
ColorMap::Purples => cmap_str(PURPLES, value),
ColorMap::Reds => cmap_str(REDS, value),
ColorMap::BrownGreen => cmap_str(BROWN_GREEN, value),
ColorMap::PinkGreen => cmap_str(PINK_GREEN, value),
ColorMap::PurpleGreen => cmap_str(PURPLE_GREEN, value),
ColorMap::PurpleOrange => cmap_str(PURPLE_ORANGE, value),
ColorMap::RedBlue => cmap_str(RED_BLUE, value),
ColorMap::RedGrey => cmap_str(RED_GREY, value),
ColorMap::RedYellowBlue => cmap_str(RED_YELLOW_BLUE, value),
ColorMap::RedYellowGreen => cmap_str(RED_YELLOW_GREEN, value),
ColorMap::Spectral => cmap_str(SPECTRAL, value),
ColorMap::Rainbow => cmap_str(RAINBOW, value),
ColorMap::Sinebow => cmap_str(SINEBOW, value),
ColorMap::Custom(f) => f(value),
}
}
/// Map a normalized value to `(r, g, b)` bytes, avoiding string allocation.
/// Returns `None` for `Custom` colormaps (which must go through `map()`).
pub fn map_rgb(&self, value: f64) -> Option<(u8, u8, u8)> {
Some(match self {
ColorMap::Turbo => cmap_rgb(TURBO, value),
ColorMap::Viridis => cmap_rgb(VIRIDIS, value),
ColorMap::Inferno => cmap_rgb(INFERNO, value),
ColorMap::Magma => cmap_rgb(MAGMA, value),
ColorMap::Plasma => cmap_rgb(PLASMA, value),
ColorMap::Cividis => cmap_rgb(CIVIDIS, value),
ColorMap::Warm => cmap_rgb(WARM, value),
ColorMap::Cool => cmap_rgb(COOL, value),
ColorMap::Cubehelix => cmap_rgb(CUBEHELIX, value),
ColorMap::BlueGreen => cmap_rgb(BLUE_GREEN, value),
ColorMap::BluePurple => cmap_rgb(BLUE_PURPLE, value),
ColorMap::GreenBlue => cmap_rgb(GREEN_BLUE, value),
ColorMap::OrangeRed => cmap_rgb(ORANGE_RED, value),
ColorMap::PurpleBlueGreen => cmap_rgb(PURPLE_BLUE_GREEN, value),
ColorMap::PurpleBlue => cmap_rgb(PURPLE_BLUE, value),
ColorMap::PurpleRed => cmap_rgb(PURPLE_RED, value),
ColorMap::RedPurple => cmap_rgb(RED_PURPLE, value),
ColorMap::YellowGreenBlue => cmap_rgb(YELLOW_GREEN_BLUE, value),
ColorMap::YellowGreen => cmap_rgb(YELLOW_GREEN, value),
ColorMap::YellowOrangeBrown => cmap_rgb(YELLOW_ORANGE_BROWN, value),
ColorMap::YellowOrangeRed => cmap_rgb(YELLOW_ORANGE_RED, value),
ColorMap::Blues => cmap_rgb(BLUES, value),
ColorMap::Greens => cmap_rgb(GREENS, value),
ColorMap::Grayscale => cmap_rgb(GREYS, value),
ColorMap::Oranges => cmap_rgb(ORANGES, value),
ColorMap::Purples => cmap_rgb(PURPLES, value),
ColorMap::Reds => cmap_rgb(REDS, value),
ColorMap::BrownGreen => cmap_rgb(BROWN_GREEN, value),
ColorMap::PinkGreen => cmap_rgb(PINK_GREEN, value),
ColorMap::PurpleGreen => cmap_rgb(PURPLE_GREEN, value),
ColorMap::PurpleOrange => cmap_rgb(PURPLE_ORANGE, value),
ColorMap::RedBlue => cmap_rgb(RED_BLUE, value),
ColorMap::RedGrey => cmap_rgb(RED_GREY, value),
ColorMap::RedYellowBlue => cmap_rgb(RED_YELLOW_BLUE, value),
ColorMap::RedYellowGreen => cmap_rgb(RED_YELLOW_GREEN, value),
ColorMap::Spectral => cmap_rgb(SPECTRAL, value),
ColorMap::Rainbow => cmap_rgb(RAINBOW, value),
ColorMap::Sinebow => cmap_rgb(SINEBOW, value),
ColorMap::Custom(_) => return None,
})
}
}