nano9 0.1.0-alpha.4

A Pico-8 compatibility layer for Bevy
Documentation 
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use crate::pico8::Error;
use bevy::prelude::Reflect;
use bitvec::prelude::*;
use std::hash::Hash;

#[derive(Debug, Clone, Eq, Hash, PartialEq, Reflect)]
pub struct PalMap {
    remap: Vec<u8>,
    #[reflect(ignore)]
    pub transparency: BitVec<u8, Lsb0>,
}

impl Default for PalMap {
    fn default() -> Self {
        let mut pal = PalMap::with_capacity(16);
        pal.transparency.set(0, true);
        pal
    }
}

impl PalMap {
    pub fn with_capacity(count: usize) -> Self {
        let remap = (0..count).map(|x| x as u8).collect();
        let transparency = BitVec::repeat(false, count);
        Self {
            remap,
            transparency,
        }
    }

    pub fn remap(&mut self, mut original_index: usize, new_index: usize) {
        if original_index >= self.remap.len() {
            original_index %= self.remap.len();
        }
        self.remap[original_index] = new_index as u8;
    }

    pub fn map(&self, index: usize) -> Option<usize> {
        self.remap.get(index).map(|x| *x as usize)
    }

    pub fn map_or_mod(&self, index: usize) -> usize {
        self.map(index).unwrap_or_else(|| {
            // Find the highest bit.
            // Create a mask 0b0000h1111
            self.remap[index % self.remap.len()] as usize
        })
    }

    pub fn reset(&mut self) {
        let n = self.remap.len() as u8;
        self.remap.clear();
        self.remap.extend(0..n);
        self.reset_transparency();
    }

    pub fn reset_transparency(&mut self) {
        self.transparency.fill(false);
        self.transparency.set(0, true);
    }

    // pub fn from_image(image: &Image) -> Self {
    //     let size = image.size();
    //     let count = (size.x * size.y) as usize;
    //     let mut palette = Vec::with_capacity(count);
    //     for i in 0..size.x {
    //         for j in 0..size.y {
    //             let color = image.get_color_at(i, j).unwrap().to_srgba();
    //             let rgb = color.to_u8_array();
    //             palette.push(rgb);
    //         }
    //     }
    //     let remap = (0..count).map(|x| x as u8).collect();
    //     let transparency = BitVec::repeat(false, count);
    //     Self {
    //         palette,
    //         remap,
    //         transparency,
    //     }
    // }

    pub fn write_color(
        &self,
        palette: &[[u8; 4]],
        palette_index: u8,
        pixel_bytes: &mut [u8],
    ) -> Result<(), Error> {
        let pi = self.map_or_mod(palette_index as usize);
        // PERF: We should just set the 24 or 32 bits in one go, right?
        if *self
            .transparency
            .get(pi)
            .ok_or(Error::NoSuch("transparency bit".into()))?
        {
            pixel_bytes[0..=2].copy_from_slice(&palette[pi][0..=2]);
            pixel_bytes[3] = 0x00;
        } else {
            pixel_bytes[0..=3].copy_from_slice(&palette[pi]);
        }
        Ok(())
    }
}