js script to make iOS app icons

make_icons.js

#!/usr/bin/env node

//
// Obviously, you should have node and npm installed.
//
// also do not forget to 
//     npm install q
//     npm install imagemagick
//
// before using this script
//

var fs = require('fs')
    , Q = require('q')
    , im = require('imagemagick');

// check command-line params, we should have at least one which is source file name

// idioms allowed for usage
var allowedIdioms = ['iphone', 'ipad', 'car'];
var requiredSizesAndScales = {'iphone': [{'size': 29, 'scale': 1} 
                                         , {'size': 29, 'scale': 2} 
                                         , {'size': 29, 'scale': 3}
                                         , {'size': 40, 'scale': 2}
                                         , {'size': 40, 'scale': 3}
                                         , {'size': 57, 'scale': 1}
                                         , {'size': 57, 'scale': 2}
                                         , {'size': 60, 'scale': 2}
                                         , {'size': 60, 'scale': 3}]
                                         
                              , 'ipad': [  {'size': 29, 'scale': 1}
                                         , {'size': 29, 'scale': 2} 
                                         , {'size': 40, 'scale': 1}
                                         , {'size': 40, 'scale': 2}
                                         , {'size': 50, 'scale': 1}
                                         , {'size': 50, 'scale': 2}
                                         , {'size': 72, 'scale': 1}
                                         , {'size': 72, 'scale': 2}
                                         , {'size': 76, 'scale': 1}
                                         , {'size': 76, 'scale': 2}]
                              , 'car':  [  {'size': 120, 'scale': 1}]};
                              

function printUsageAndExit() {
    console.log("Usage: " + process.argv[1] + " <source image> [idiom1] [idiom2] [idiom3]");
    console.log('Valid idiom values are "iphone", "ipad" and "car". If you specify no idioms all 3 will be used.');
    process.exit(1);
}

function flatten() {
    var merged = [];     
    Array.prototype.forEach.call(arguments, function (arg) {merged = merged.concat.apply(merged, arg)});

    return merged;    
}

function resizePromise(elt2) {
    return Q.promise(function(resolve, reject) {
        var res = {'idiom': elt2['idiom']
                  , 'size': elt2['size'] + 'x' + elt2['size']
                  , 'scale': elt2['scale'] + 'x'
                  , 'filename': 'Icon' + elt2['size'] + (elt2['scale'] === 1 ? '' : '@'+ elt2['scale'] + 'x') + '.png'};

        var sizeArg = elt2['size']*elt2['scale'] + 'x' + elt2['size']*elt2['scale'];
        if (processed.indexOf(res['filename']) == -1) {
            im.convert([sourceImageName, '-resize', sizeArg, __dirname + '/' + res['filename']], 
                       function (err, stdout) {
                           if (err) {
                               console.log('error processing ' + JSON.stringify(elt2));
                               console.log(stdout);
                               reject(stdout);
                           } else {
                               resolve(res);
                           }
                       });
        } else {
            resolve(res);
        }
    });
}

if (process.argv.length < 3 || process.argv.length > 6) {
    console.log("Usage: " + process.argv[1] + " <source image> [idiom1] [idiom2] [idiom3]");
    console.log('Valid idiom values are "iphone", "ipad" and "car". If you specify no idioms all 3 will be used.');
    process.exit(1);
}

var sourceImageName = process.argv[2];
var idioms = allowedIdioms;

if (process.argv.length > 3) {
    idioms = [];
    for (var i=3; i < process.argv.length; i++) {
        var idiom = process.argv[i].toLowerCase();        
        if (idioms.indexOf(idiom) == -1 && allowedIdioms.indexOf(idiom) != -1) {
            idioms.push(idiom);
        }
    }
}

if (idioms.length == 0) {
    printUsageAndExit();
}

console.log('will use following idioms: ' + idioms);

var result = {'images': []
            , 'info': {'version': 1, 'author': 'make_icons.js script'}};

var processed = [];
Q.all(flatten(idioms.map(function(elt){
    return requiredSizesAndScales[elt]
        .map(function(elt1){
            var res = elt1;
            res['idiom'] = elt;
        
            return res;})
        .map(resizePromise)})))
.then(function(e) {
    return Q.promise(function (resolve, reject) {
        result['images'] = e;
        fs.writeFile('Contents.json', JSON.stringify(result, undefined, 2), function (err) {
            if (err) {
                reject('error writing contents');
            } else {
                resolve();
            }
        });
    });
})
.done(function(e) {
    console.log("we're good!");
});