gulp-image-optimization/index.js

Minify PNG, JPEG and GIF images. this is based on https://github.com/sindresorhus/gulp-imagemin with stream-limit implementation

'use strict';
var path = require('path');
var fs = require('graceful-fs');
var gutil = require('gulp-util');
var map = require('map-stream-limit');
var filesize = require('filesize');
var tempWrite = require('temp-write');
var imagemin = require('image-min');

module.exports = function(options) {
    return map(function(file, cb) {
        if (file.isNull()) {
            return cb(null, file);
        }

        if (file.isStream()) {
            return cb(new gutil.PluginError('gulp-image-optimization', 'Streaming not supported'));
        }

        if (['.jpg', '.jpeg', '.png', '.gif'].indexOf(path.extname(file.path)) === -1) {
            gutil.log('gulp-image-optimization: Skipping unsupported image ' + gutil.colors.blue(file.relative));
            return cb(null, file);
        }

        tempWrite(file.contents, path.extname(file.path), function(err, tempFile) {
            if (err) {
                return cb(new gutil.PluginError('gulp-image-optimization', err));
            }

            // workaround: https://github.com/kevva/image-min/issues/8
            fs.stat(tempFile, function(err, stats) {
                if (err) {
                    return cb(new gutil.PluginError('gulp-image-optimization', err));
                }

                var origSize = stats.size;

                imagemin(tempFile, tempFile, options, function() {
                    fs.readFile(tempFile, function(err, data) {
                        if (err) {
                            return cb(new gutil.PluginError('gulp-image-optimization', err));
                        }

                        var saved = origSize - data.length;
                        var savedMsg = saved > 0 ? 'saved ' + filesize(saved, {
                            round: 1
                        }) : 'already optimized';

                        gutil.log('gulp-image-optimization:', gutil.colors.green('✔ ') + file.relative + gutil.colors.gray(' (' + savedMsg + ')'));

                        file.contents = data;
                        cb(null, file);
                    });
                });
            });
        });
    }, 10);
};