hayro-interpret 0.8.0

use super::{ToLuma, ToRgb, U8Lookup};
use hayro_syntax::object::Dict;
use hayro_syntax::object::dict::keys::{BLACK_POINT, GAMMA, WHITE_POINT};

#[derive(Debug, Clone)]
pub(crate) struct CalGray {
    white_point: [f32; 3],
    black_point: [f32; 3],
    gamma: f32,
    lookup: U8Lookup<u8>,
}

// See <https://github.com/mozilla/pdf.js/blob/06f44916c8936b92f464d337fe3a0a6b2b78d5b4/src/core/colorspace.js#L752>
impl CalGray {
    pub(super) fn new(dict: &Dict<'_>) -> Option<Self> {
        let white_point = dict.get::<[f32; 3]>(WHITE_POINT).unwrap_or([1.0, 1.0, 1.0]);
        let black_point = dict.get::<[f32; 3]>(BLACK_POINT).unwrap_or([0.0, 0.0, 0.0]);
        let gamma = dict.get::<f32>(GAMMA).unwrap_or(1.0);

        Some(Self {
            white_point,
            black_point,
            gamma,
            lookup: U8Lookup::default(),
        })
    }

    fn convert_value(&self, input: u8) -> u8 {
        let g = self.gamma;
        let (_xw, yw, _zw) = {
            let wp = self.white_point;
            (wp[0], wp[1], wp[2])
        };
        let (_xb, _yb, _zb) = {
            let bp = self.black_point;
            (bp[0], bp[1], bp[2])
        };

        let a = input as f32 / 255.0;
        let ag = a.powf(g);
        let l = yw * ag;
        (0.0_f32.max(295.8 * l.powf(0.333_333_34) - 40.8) + 0.5) as u8
    }

    fn u8_lookup(&self) -> Option<&[u8; 256]> {
        self.lookup.get_or_init_with(|input| {
            Some(Box::new(core::array::from_fn(|index| {
                self.convert_value(input[index])
            })))
        })
    }
}

impl ToRgb for CalGray {
    fn convert(&self, input: &[u8], output: &mut [u8]) -> Option<()> {
        let lookup = self.u8_lookup()?;
        for (input, output) in input.iter().zip(output.chunks_exact_mut(3)) {
            output.fill(lookup[*input as usize]);
        }

        Some(())
    }
}

impl ToLuma for CalGray {
    fn to_luma(&self, input: &mut [u8]) -> Option<()> {
        let lookup = self.u8_lookup()?;
        for value in input {
            *value = lookup[*value as usize];
        }

        Some(())
    }
}