meteor-assets.js

var fs = require("fs"),
  gm = require("gm").subClass({ imageMagick: true });

var icons = [
  { name: "app_store", size: "1024x1024" },
  { name: "iphone_2x", size: "120x120" },
  { name: "iphone_3x", size: "180x180" },
  { name: "ipad", size: "76x76" },
  { name: "ipad_2x", size: "152x152" },
  { name: "ipad_pro", size: "167x167" },
  { name: "ios_settings", size: "29x29" },
  { name: "ios_settings_2x", size: "58x58" },
  { name: "ios_settings_3x", size: "87x87" },
  { name: "ios_spotlight", size: "40x40" },
  { name: "ios_spotlight_2x", size: "80x80" },
  { name: "ios_spotlight_3x", size: "120x120" },
  { name: "ios_notification", size: "20x20" },
  { name: "ios_notification_2x", size: "40x40" },
  { name: "ios_notification_3x", size: "60x60" },
  { name: "iphone_legacy", size: "57x57" },
  { name: "iphone_legacy_2x", size: "114x114" },
  { name: "ipad_spotlight_legacy", size: "50x50" },
  { name: "ipad_spotlight_legacy_2x", size: "100x100" },
  { name: "ipad_app_legacy", size: "72x72" },
  { name: "ipad_app_legacy_2x", size: "144x144" },
  { name: "android_mdpi", size: "48x48" },
  { name: "android_hdpi", size: "72x72" },
  { name: "android_xhdpi", size: "96x96" },
  { name: "android_xxhdpi", size: "144x144" },
  { name: "android_xxxhdpi", size: "192x192" }
];

var splashes = [
  { name: "iphone", size: "320x480" },
  { name: "iphone_2x", size: "640x960" },
  { name: "iphone5", size: "640x1136" },
  { name: "iphone6", size: "750x1334" },
  { name: "iphone6p_portrait", size: "1242x2208" },
  { name: "iphone6p_landscape", size: "2208x1242" },
  { name: "iphoneX_portrait", size: "1125x2436" },
  { name: "iphoneX_landscape", size: "2436x1125" },
  { name: "ipad_portrait", size: "768x1024" },
  { name: "ipad_portrait_2x", size: "1536x2048" },
  { name: "ipad_landscape", size: "1024x768" },
  { name: "ipad_landscape_2x", size: "2048x1536" },
  { name: "android_ldpi_landscape", size: "318x198" },
  { name: "android_mdpi_portrait", size: "318x478" },
  { name: "android_mdpi_landscape", size: "478x318" },
  { name: "android_hdpi_portrait", size: "478x798" },
  { name: "android_hdpi_landscape", size: "798x478" },
  { name: "android_xhdpi_portrait", size: "718x1278" },
  { name: "android_xhdpi_landscape", size: "1278x718" },
  { name: "android_xxhdpi_portrait", size: "1078x1438" },
  { name: "android_xxhdpi_landscape", size: "1438x1078" },
  { name: "android_xxxhdpi_portrait", size: "1278x1918" },
  { name: "android_xxxhdpi_landscape", size: "1918x1278" }
];

function getSize(image) {
  var sizes = image.size.split("x");
  return { width: sizes[0], height: sizes[1] };
}

// source file, target directory, image profile
function resize(source, target, image) {
  var icon = gm(source);

  var imageSize = getSize(image);
  var width = imageSize.width;
  var height = imageSize.height;
  var name = image.name;

  icon.resize(width, height).write(target + name + ".png", function(err) {
    if (err) {
      console.log(err);
      console.log("Quitting because of an error");
    } else {
      console.log("Wrote " + name);
    }
  });
}

function crop(source, target, image) {
  var size;
  var splash = gm(source);

  var imageSize = getSize(image);
  var width = parseInt(imageSize.width);
  var height = parseInt(imageSize.height);
  var name = image.name;

  // square up so that it cuts off as little as possible
  if (height > width) {
    splash.resize(height, height);

    size = height;
  } else {
    splash.resize(width, width);

    size = width;
  }

  // calculate x and y offset
  var xOffset = size / 2 - width / 2;
  var yOffset = size / 2 - height / 2;

  splash
    .crop(width, height, xOffset, yOffset)
    .write(target + name + ".png", function(err) {
      if (err) {
        console.log(err);
        console.log("Quitting because of an error");
      } else {
        console.log("Wrote " + name);
      }
    });
}

// Run the code

if (!fs.existsSync(__dirname + "/resources/icons")) {
  fs.mkdirSync(__dirname + "/resources/icons");
}

if (!fs.existsSync(__dirname + "/resources/splashes")) {
  fs.mkdirSync(__dirname + "/resources/splashes");
}

icons.forEach(function(icon) {
  if (icon.name.indexOf("android") == 0) {
    resize("resources/icon-android.png", "resources/icons/", icon);
  } else {
    resize("resources/icon-ios.png", "resources/icons/", icon);
  }
});

splashes.forEach(function(splash) {
  if (splash.name.indexOf("android") == 0) {
    crop("resources/splash-android.png", "resources/splashes/", splash);
  } else {
    crop("resources/splash-ios.png", "resources/splashes/", splash);
  }
});