@bashbers/astro-image-dithering/dist/lib.js

Astro image dithering plugin - converts png's in project to dithered.pngs and uses them inside markdown files.

import { readdirSync, statSync } from "fs";
import path from 'node:path';
function colorClamp(value) {
    if (value < 0)
        return 0;
    else if (value > 255)
        return 255;
    return value;
}
var bayerMatrix8x8 = [
    [1, 49, 13, 61, 4, 52, 16, 64],
    [33, 17, 45, 29, 36, 20, 48, 32],
    [9, 57, 5, 53, 12, 60, 8, 56],
    [41, 25, 37, 21, 44, 28, 40, 24],
    [3, 51, 15, 63, 2, 50, 14, 62],
    [35, 19, 47, 31, 34, 18, 46, 30],
    [11, 59, 7, 55, 10, 58, 6, 54],
    [43, 27, 39, 23, 42, 26, 38, 22]
];
const pattern = [
    [0, 32, 8, 40, 2, 34, 10, 42], /* 8x8 Bayer ordered dithering  */
    [48, 16, 56, 24, 50, 18, 58, 26], /* pattern.  Each input pixel   */
    [12, 44, 4, 36, 14, 46, 6, 38], /* is scaled to the 0..63 range */
    [60, 28, 52, 20, 62, 30, 54, 22], /* before looking in this table */
    [3, 35, 11, 43, 1, 33, 9, 41], /* to determine the action.     */
    [51, 19, 59, 27, 49, 17, 57, 25],
    [15, 47, 7, 39, 13, 45, 5, 37],
    [63, 31, 55, 23, 61, 29, 53, 21]
];
// int r, int g, int b, int[][] palette, int paletteLength
function getClosestPaletteColorIndex(r, g, b, palette, paletteLength) {
    var minDistance = 195076;
    var diffR, diffG, diffB;
    var distanceSquared;
    var bestIndex = 0;
    var paletteChannels;
    for (var i = 0; i < paletteLength; i++) {
        paletteChannels = palette[i];
        diffR = r - paletteChannels[0];
        diffG = g - paletteChannels[1];
        diffB = b - paletteChannels[2];
        distanceSquared = diffR * diffR + diffG * diffG + diffB * diffB;
        if (distanceSquared < minDistance) {
            bestIndex = i;
            minDistance = distanceSquared;
        }
    }
    return bestIndex;
}
export function BayerDithering(inPixels, width, height, palette) {
    var offset = 0;
    var indexedOffset = 0;
    var r, g, b;
    var pixel, threshold, index;
    var paletteLength = palette.length;
    var matrix = pattern;
    var indexedPixels = new Uint8Array(width * height);
    var modI = 8;
    var modJ = 8;
    for (var j = 0; j < height; j++) {
        var modj = j % modJ;
        for (var i = 0; i < width; i++) {
            threshold = matrix[i % modI][modj];
            r = colorClamp(inPixels[offset] + threshold);
            g = colorClamp(inPixels[offset + 1] + threshold);
            b = colorClamp(inPixels[offset + 2] + threshold);
            offset += 4;
            index = getClosestPaletteColorIndex(r, g, b, palette, paletteLength);
            indexedPixels[indexedOffset++] = index;
        }
    }
    return indexedPixels;
}
export function recursiveFindByExtension(base, ext, files, result) {
    files = files || readdirSync(base);
    result = result || [];
    files.forEach(function (file) {
        var newbase = path.join(base, file);
        if (statSync(newbase).isDirectory()) {
            result = recursiveFindByExtension(newbase, ext, readdirSync(newbase), result);
        }
        else {
            if (file.substr(-1 * (ext.length + 1)) == '.' + ext) {
                result.push(newbase);
            }
        }
    });
    return result;
}