Generates all the UWP icons with sensible naming, based of a couple initial files.

generate-icons.js

let imageConversion = require("image-conversion");
var fs = require("fs");
let jimp = require("jimp");
let ImageJs = require("image-js");

let output = "public/images/icon";

const scales = [100, 125, 150, 200, 240, 400];
const iconTargetSizes = [16,24,32,48,256];
const iconTargetDecorations = ['unplated_targetsize', 'targetsize'];

const icons = [
    makeIcon("square.png", "BadgeLogo", 24, 24, "png"),
    makeIcon("square.png", "StoreLogo", 50, 50, "png"),
    makeIcon("square.png", "Square30x30Logo", 30, 30, "png"),
    makeIcon("square.png", "Square44x44Logo", 44, 44, "png"),
    makeIcon("square.png", "Square70x70Logo", 70, 70, "png"),
    makeIcon("square.png", "Square71x71Logo", 71, 71, "png"),
    makeIcon("square.png", "Square150x150Logo", 150, 150, "png"),
    makeIcon("square.png", "Square310x310Logo", 310, 310, "png"),

    makeIcon("wide.png", "Wide310x150Logo", 310, 150, "jpg"),
    makeIcon("wide.png", "SplashScreen", 620, 300, "jpg"),
];

function makeIcon(source, name, width, height, extension) {
    return {
        source,
        name, 
        width: width,
        height: height,
        extension
    };
}

async function outputSingle(sourcePath, width, height, outputFile) {
            // Jimp seems better at resizing
            let jimpImg = await jimp.read(sourcePath);        
            jimpImg = jimpImg.resize(width, height);            
            jimpImg = await jimpImg.writeAsync(outputFile);

            // image-js seems better at file sizes
            let img2 = await ImageJs.read(outputFile);
            await ImageJs.write(outputFile, img2);

            console.log("Saved " + outputFile)
}

async function doIt() {
    for (var i=0;i<icons.length;i++) {
        let icon = icons[i];

        for (var j=0;j<scales.length;j++) {
            let scale = scales[j];

            let sourcePath = `raw-icons/${icon.source}`
            let outputFile = `${output}/${icon.name}.scale-${scale}.${icon.extension}`;
            let scaledWidth = Math.ceil((scale * icon.width)/100);
            let scaledHeight = Math.ceil((scale * icon.height)/100);

            await outputSingle(sourcePath, scaledWidth, scaledHeight, outputFile);
        }
    }
    
    for (var i=0;i<iconTargetSizes.length;i++) {
        let targetSize = iconTargetSizes[i];

        for (var j=0;j<iconTargetDecorations.length;j++) {
            let decoration = iconTargetDecorations[j];

            let sourcePath = `raw-icons/square.png`
            let outputFile = `${output}/Square44x44Logo-${decoration}-${targetSize}.png`;

            await outputSingle(sourcePath, targetSize, targetSize, outputFile);
        }
    }
}
doIt();