Streamed image resize using lwip (@wtr7)

resize.js

// modules
var lwip = require('lwip'),
    path = require('path'),
      fs = require('fs'),
 rstream = require('stream').Readable;

// config
var placesPath = '/Users/apx/Downloads/places';

// helper
var isHiddenPath = function (fn) {
	return /(^|.\/)\.+[^\/\.]/g.test(fn);
};

var resizePhotos = function () {
	var stream = new rstream,
	     files = [];

	// actual resize procedure
	var _resize = function () {
		var i = 0, n = files.length;

		var _next = function () {
			++i === n && stream.emit('end');
		}

		files.forEach(function (fn) {
			process.nextTick(function () {
				var image_base = fn[0];

				fs.readFile(image_base, function (err, buf) {
					// bubble up error if one is existent
					if (err) return stream.emit('error', 'Couldn\'t open image for resize: ' + image_base, err), _next();

					// instanciate lwip per image
					lwip.open(buf, fn[0].split('.').pop() === 'png' ? 'png' : 'jpg', function(err, image) {
						// bubble up error if one is existent
						if (err) return stream.emit('error', '[lwip] Unspecific error: ' + image_base, err), _next();

						image
						// make this call chainable,
						// so that it looks nicely
						.batch()
						// resize 400x400 where local center is global center
						.crop(400, 400)
						// export as buffer
						.toBuffer('jpg', function(err, buffer) {
							// bubble up error if one is existent
							if (err) return stream.emit('error', 'Couldn\'t export buffer: ' + image_base, err), _next();

							// remove extension, add jpg
							var out_path = fn[1].split(".").slice(0, -1) + '.jpg';

							// queue write
							fs.writeFile(out_path, buffer, function (err) {
								// emit resize event
								stream.emit('resize', fn[0], out_path);

								_next();
							})
						})
					});
				});
			})
		})
	};

	// aggregate files
	process.nextTick(function () {
		fs.readdir(placesPath, function(err, folders) {
			// remove all hidden paths
			folders = folders.filter(function (fn) {
				return !isHiddenPath(fn);
			});

			var i = 0, n = folders.length;

			var _next = function () {
				++i === n && _resize();
			}

			// iterate over folders
			folders.forEach(function(folder) {
				folder = path.join(placesPath, folder);

				fs.readdir(folder, function(err, images) {
					// bubble up error if one is existent
					if (err) return stream.emit('error', 'Couldn\'t read folder: ' + folder), _next();

					// remove all hidden files
					images = images
						.filter(function (fn) {
							// ignore hidden files and thumb_* files
							return !isHiddenPath(fn) && fn.indexOf('thumb_');
						})
						.map(function (fn) {
							return [
								folder + '/' + fn,
								folder + '/thumb_' + fn
							]
						});

					// append results to files array
					files.push.apply(files, images);

					_next();
				});
			});
		});
	});

	return stream;
}

/*
exports.setThumbs = function(req, res) {
	resizePhotos()
	// errors
	.on('error', function (msg) {

	})
	// resizes
	.on('resize', function (fn) {
		res.write('Resized "' + fn + "\n");
	})
	.on('end', function () {
		res.end("Ok, resized all of them!");
	});
}
*/

resizePhotos()
// errors
.on('error', function (msg, err) {
	console.log(msg, err);
})
// resizes
.on('resize', function (fn, thumb) {
	console.log('Resized "' + fn + '" -> "' + thumb + '"');
})
.on('end', function () {
	console.log("Ok, resized all of them!");
});