2024-06-29 16:55:37 +00:00
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use image::RgbImage;
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2024-07-16 23:55:59 +00:00
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use palette::{cast::FromComponents, color_difference::Ciede2000, IntoColor, Lab, Oklch, Srgb};
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2024-06-29 16:55:37 +00:00
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/// Palette used on the display; pixels can be one of these colors.
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///
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/// The RGB values are slightly adjusted to improve accuracy.
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const DISPLAY_PALETTE: [Srgb; 7] = [
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Srgb::new(0.047, 0.047, 0.055), // Black
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Srgb::new(0.824, 0.824, 0.816), // White
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Srgb::new(0.118, 0.376, 0.122), // Green
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Srgb::new(0.114, 0.118, 0.667), // Blue
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Srgb::new(0.549, 0.106, 0.114), // Red
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Srgb::new(0.827, 0.788, 0.239), // Yellow
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Srgb::new(0.757, 0.443, 0.165), // Orange
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];
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// fn octcolor_rgb(color: &OctColor) -> &Srgb<u8> {
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// match color {
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// OctColor::Black => &DISPLAY_PALETTE[0],
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// OctColor::White => &DISPLAY_PALETTE[1],
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// OctColor::Green => &DISPLAY_PALETTE[2],
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// OctColor::Blue => &DISPLAY_PALETTE[3],
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// OctColor::Red => &DISPLAY_PALETTE[4],
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// OctColor::Yellow => &DISPLAY_PALETTE[5],
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// OctColor::Orange => &DISPLAY_PALETTE[6],
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// OctColor::HiZ => &DISPLAY_PALETTE[1],
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// }
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// }
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#[derive(Debug, Clone, Copy, PartialEq, Eq)]
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pub enum DisplayColor {
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Black,
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White,
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Green,
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Blue,
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Red,
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Yellow,
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Orange,
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}
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2024-07-02 15:57:29 +00:00
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impl From<DisplayColor> for Srgb {
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fn from(value: DisplayColor) -> Self {
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DISPLAY_PALETTE[value as usize]
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}
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}
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impl DisplayColor {
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fn from_u8(value: u8) -> Self {
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match value {
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0 => Self::Black,
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1 => Self::White,
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2 => Self::Green,
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3 => Self::Blue,
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4 => Self::Red,
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5 => Self::Yellow,
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6 => Self::Orange,
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_ => panic!("unexpected DisplayColor {value}"),
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}
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}
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fn into_byte(color1: Self, color2: Self) -> u8 {
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let upper: u8 = color1.into();
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let lower: u8 = color2.into();
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upper << 4 | lower
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}
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}
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impl From<DisplayColor> for u8 {
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fn from(value: DisplayColor) -> Self {
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value as Self
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}
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}
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/// Buffer to be sent to the ``EInk`` display.
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#[derive(Debug)]
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pub struct EInkBuffer(Vec<DisplayColor>);
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impl EInkBuffer {
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#[must_use]
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pub fn into_display_buffer(&self) -> Vec<u8> {
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let mut buf = Vec::with_capacity(self.0.len() / 2);
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for colors in self.0.chunks_exact(2) {
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buf.push(DisplayColor::into_byte(colors[0], colors[1]));
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}
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buf
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}
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#[must_use]
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pub fn new(width: usize, height: usize) -> Self {
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let v = vec![DisplayColor::Black; width * height];
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Self(v)
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}
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}
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// impl EInkBuffer {
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// /// Converts the EInkBuffer into data that can be sent over the SPI API
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// /// Bin-packs the two 4-bit colors into bytes.
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// pub fn into_buffer(&self) -> Vec<u8> {
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// vec![]
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// }
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//
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// pub fn new(width: usize, height: usize) -> EInkBuffer {
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// EInkBuffer {
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// data: vec![DisplayColor::Black; width * height],
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// width,
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// height,
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// }
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// }
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// pub fn set(&mut self, x: usize, y: usize, value: DisplayColor) {
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// self.data[x + y * self.width] = value;
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// }
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// pub fn get(&self, x:usize, y:usize) -> DisplayColor {
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// self.data[x
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// }
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// }
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pub trait Ditherer {
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fn dither(&mut self, img: &RgbImage, output: &mut EInkBuffer);
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}
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// fn color_distance(c1: LinSrgb, c2: LinSrgb) -> f32 {
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// let r2 = (c2.red - c1.red).powf(2.0);
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// let g2 = (c2.green - c1.green).powf(2.0);
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// let b2 = (c2.blue - c1.blue).powf(2.0);
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//
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// (r2 + g2 + b2).sqrt()
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// }
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/// Find the closest approximate palette color to the given sRGB value.
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/// This uses euclidian distance in linear space.
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pub fn nearest_neighbor(input_color: Lab) -> (DisplayColor, Lab) {
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let (nearest, _, color_diff) = DISPLAY_PALETTE
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.iter()
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.enumerate()
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.map(|(idx, p_color)| {
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let c: Lab = (*p_color).into_color();
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(idx, input_color.difference(c), input_color - c)
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})
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.min_by(|(_, a, _), (_, b, _)| a.total_cmp(b))
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.unwrap();
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(DisplayColor::from_u8(nearest as u8), color_diff)
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}
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pub struct NNDither();
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impl Ditherer for NNDither {
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fn dither(&mut self, img: &RgbImage, output: &mut EInkBuffer) {
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assert!(img.width() == 800);
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assert!(img.height() == 480);
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// sRGB view into the given image. zero copy!
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let srgb = <&[Srgb<u8>]>::from_components(&**img);
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for (idx, pixel) in srgb.iter().enumerate() {
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let (n, _) = nearest_neighbor(pixel.into_format().into_color());
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output.0[idx] = n;
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}
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}
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}
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pub struct FloydSteinbergDither();
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impl Ditherer for FloydSteinbergDither {
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fn dither(&mut self, img: &RgbImage, output: &mut EInkBuffer) {
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// create a copy of the image in Lab space, mutable.
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let srgb = <&[Srgb<u8>]>::from_components(&**img);
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let mut temp_img: Vec<Lab> = Vec::new();
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for pix in srgb {
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temp_img.push(pix.into_format().into_color());
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}
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}
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}
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