Grunt PNGQuant Task

grunt-pngquant.js

/** //////////////////////////////////////////////////////////////////////////////////////////
* 
* PNG Quant Grunt Task
* 
* To install on OSX: brew install PngQuant
* To install on Windows or other OS: http://pngquant.org/
* 
* https://gist.github.com/josimard/ea29904cb58cc4b13ba6/
* 
* */

// Command line flags
var skipPngQuant = process.argv.indexOf("--nopng") > -1;

grunt.registerMultiTask('pngquant', 'PNGQUant custom task (using child processes)', function()
{
	var done = this.async();

	if(skipPngQuant)
	{
		console.log("Skipping PNG optimization...");
		done();
		return;
	}

	// Default options
	var options = this.options({
		
	});

	var pathWithPngs = [];

	function addPngPath(pngPath)
	{
		var path = pngPath.substring(0, pngPath.lastIndexOf("/"));
		if(pathWithPngs.indexOf(path)>-1) return;
		pathWithPngs.push(path);
	}

	// For each grunt file request
	this.files.forEach(function (f)
	{
		// For each file in globing pattern
		f.src.forEach(function (item)
		{
			//if(!grunt.file.isDir(item)) return;
			if(item.indexOf(".png")>-1) addPngPath(item);
		});
	});

	var async = grunt.util.async;
	async.forEach(pathWithPngs, function(path, next)
	{
		// http://nodejs.org/api/child_process.html#child_process_child_process_exec_command_options_callback
		var exec = require('child_process').exec;

		// http://nodejs.org/api/child_process.html
		exec("cd "+path+"; pngquant *.png --ext .png --force", function (error, stdout, stderr)
		{
			if (error !== null) {
				if((error+"").indexOf("command not found")>-1) {
					throw("\n\nPNGQuant NOT FOUND! \n * To install go to http://pngquant.org \n * Install on OSX with HomeBrew: brew install PngQuant\n\nTo skip PNG optimization: use 'grunt --nopng'\n");
					//done();
				}
				console.log('pngquant error: ' + error);
			} 
			console.log("Optimized PNGs in '"+path+"'");
			next();
		});

	}, function(error) {
		done(!error);
	});
});