Convert @6x to @4x, @3x, and @2x (xhdpi to hdpi, mdpi, and ldpi) - For Android assets/resource

resize.js

String.prototype.endsWith = function(suffix) {
    return this.indexOf(suffix, this.length - suffix.length) !== -1;
};

var gm = require('gm');
var fs = require('fs');
var path = require('path');

function getFiles(dir, files_) {
    files_ = files_ || [];
    var files = fs.readdirSync(dir);
    for (var i in files) {
        var name = dir + '/' + files[i];
        if (name.endsWith("@6x.png"))
            files_.push(name);
    }
    return files_;
}

var resize = function(fileName) {
    console.dir('--' + fileName);
    var name4x = fileName.replace("6x", "4x");
    var name3x = fileName.replace("6x", "3x");
    var name2x = fileName.replace("6x", "2x");

    gm(fileName)
        .resize("66.666666667%")
        .write(name4x, function(err) {
            if (err) return console.dir(err);
            console.log('Done - ' + name4x);
        });
    gm(fileName)
        .resize("50%")
        .write(name3x, function(err) {
            if (err) return console.dir(err);
            console.log('Done - ' + name3x);
        });
    gm(fileName)
        .resize("33.33333333%")
        .write(name2x, function(err) {
            if (err) return console.dir(err);
            console.log('Done - ' + name2x);
        });

};

var folderPath = path.join(__dirname);
var allfiles = getFiles(folderPath);
for (var i = 0; i < allfiles.length; i++) {
   resize(allfiles[i]);
};