index.js

"use strict";

const jimp = require("jimp");
const Delaunay = require("d3-delaunay").Delaunay;

const neighborLocations = [
    [-1, -1],
    [ 0, -1],
    [ 1, -1],
    [ 1,  0],
    [ 1,  1],
    [ 0,  1],
    [-1,  1],
    [-1,  0]
];

let argsArray = process.argv.slice(2);

let dbgMode = false;

for (let i = argsArray.length + 1; i >= 0; i--) {
    let arg = argsArray[i];
    if (arg == "-d") {
        dbgMode = true;
        argsArray.splice(i, 1);
    }
}

if (process.argv.length < 3) {
    console.log("pixelfix \"path to file\" to fix transparent pixels in file");
    console.log("pixelfix \"path to file\" \"path to file 2\" to fix transparent pixels in multiple files");
    console.log("pixelfix -d \"path to file\" to view debug output (will overwrite file)");
    return;
}

let promises = [];
for (let fileLocation of argsArray) {
    promises.push((async function() {
        let image = await jimp.read(fileLocation);

        let voronoiPoints = [];
        let voronoiColors = [];
        image.scan(0, 0, image.bitmap.width, image.bitmap.height, function(x, y, idx) {
            let alpha = this.bitmap.data[ idx + 3 ];
            if (alpha != 0) {
                let red   = this.bitmap.data[ idx + 0 ];
                let green = this.bitmap.data[ idx + 1 ];
                let blue  = this.bitmap.data[ idx + 2 ];
                // Voronoi
                for (let offset of neighborLocations) {
                    let neighborAlpha = this.bitmap.data[image.getPixelIndex(x + offset[0], y + offset[1]) + 3];
                    if (neighborAlpha == 0) {
                        voronoiPoints.push([x, y]);
                        voronoiColors.push([red, green, blue]);
                        break;
                    } 
                }
            }
        });
        if (voronoiPoints.length > 0) {
            let dela = Delaunay.from(voronoiPoints);
            image.scan(0, 0, image.bitmap.width, image.bitmap.height, function(x, y, idx) {
                let alpha = this.bitmap.data[ idx + 3 ];
                if (alpha == 0) { 
                    let closestIndex = dela.find(x, y);
                    if (closestIndex != -1) {
                        let color = voronoiColors[closestIndex];

                        this.bitmap.data[ idx + 0 ] = color[0];
                        this.bitmap.data[ idx + 1 ] = color[1];
                        this.bitmap.data[ idx + 2 ] = color[2];
                        if (dbgMode) {
                            this.bitmap.data[idx + 3] = 255;
                        }
                    }
                }
            });
            await image.writeAsync(fileLocation);
            console.log(`Written to ${fileLocation}`);
        } else {
            console.log(`No transparent pixels to fix in ${fileLocation}`);
        }
    })());
}

Promise.all(promises).then(() => {
    console.log("Press any key to exit");
    process.stdin.setRawMode(true);
    process.stdin.resume();
    process.stdin.on("data", process.exit.bind(process, 0));
});