Reads folders of sequences of PNGs. Exports oodles of optimized GIFs at different sizes and crops to post at different internets places.

gif_process.js

//REQUIREMENTS: The following programs must be installed and accessible in your PATH
//	node > 6
//	imagemagick's command line tool "convert"
//	gifsicle
//USAGE: Change params at the top to your liking. `node gif_process.js` starts it up.
//	EXECUTES ALL TASKS IN PARALEL.
//	If you run it like this, it will CONSUME YOUR WHOLE COMPUTER (100% cpu, 100% memory) for a few minutes while it works.
//DISCLOSURE: I was running terribly low on sleep when I wrote this. It's a tool. It gets a job done like ten times ever. Don't judge me on this. The code I write for my day job is like way better and I care a lot more about it because I have to maintain it all the time.
//LICENSE: MIT

let imPath = 'script_output-imagemagick/';
let gsPath = 'script_output-gifsicle/';
let seriesName = 'rainbow_torus_spiral';
let inputPngFolderList = [
	'01-png_rgba',
	'02-png_rgba',
	'02-png_rgba-1',
	'02-png_rgba-2',
	'02-png_rgba-3',
	'02-png_rgba-4',
	'04-png_rgba',
];
let outputParams = [ //<-- only do like 1 set at a time for sanity
	{width: 960},
	{width: 800, height: 600},
	{width: 800, height: 600, resize: 540, colors: 240},
	{width: 480},
	{width: 400},
];
let backgroundColor = '#262626';

/*------------------------------------------------*/

const fs = require('fs');
const child_process = require('child_process');

let makePath = function(path){
	if(!fs.existsSync(path)){
		fs.mkdirSync(path);
	}
};
makePath(imPath);
makePath(gsPath);

let timeTask = function(taskName, callback){
	var start = Date.now();
	return function(err, stdout, stderr) {
		var time = (Date.now() - start);
		console.log([taskName, stdout, time, 'ms'].join(' ').replace(/\n/g, ' '));
		if (err) {
			console.error(err);
			return;
		} else if(callback) {
			callback();
		}
	};
};

let hellYeahGifProcess = function(x, y, scale, c){
	let width = x;
	let height = y || x;
	let resize = scale || y || x;
	let colors = c || 256;

	let leftRight = (width - resize) / 2;
	let topBottom = (height - resize) / 2;

	let scaledCount = 0;

	let dimensions = `${width}x${height}`;
	if(scale){
		dimensions += `x${scale}`;
	}
	if(c){
		dimensions += `-colors_${c}`;
	}
	let imSizePath = imPath + dimensions + '/';
	let gsSizePath = gsPath + dimensions + '/';
	makePath(imSizePath);
	makePath(gsSizePath);

	let imList = [];
	let gsList = [];
	let gifSicleImagesWhenDone = function(){
		imList.forEach(function(outputFileNameIM, index){
			let outputFileNameGS = gsList[index];
			child_process.exec(
				[
					'gifsicle',
					'-O3',
					`-o ${outputFileNameGS}`,
					outputFileNameIM
				].join(' '),
				timeTask(outputFileNameGS)
			);
		});
	};

	let onComplete = function(){
		scaledCount++;
		if(scaledCount === inputPngFolderList.length){
			gifSicleImagesWhenDone();
		}
	};

	inputPngFolderList.forEach(function(inputFileName){
		let name = `${seriesName}-${inputFileName}-${dimensions}`;
		name += '-imagemagick';
		let outputFileNameIM = imSizePath + name + '.gif';
		let outputFileNameGS = gsSizePath + name + '-gifsicle.gif';
		imList.push(outputFileNameIM);
		gsList.push(outputFileNameGS);
		child_process.exec(
			[
				'convert',
				'-dispose 2',
				'-delay 1/24',
				inputFileName + '/*.png',
				'-coalesce',
				'-crop 1080x1080+420+0',
				'-resize ' + resize,
				`-background "${backgroundColor}"`,
				'-alpha remove',
				`-bordercolor "${backgroundColor}"`,
				`-border ${leftRight}x${topBottom}`,
				`-colors ${colors}`,
				'+repage',
				outputFileNameIM
			].join(' '),
			timeTask(outputFileNameIM, onComplete)
		);
	});
};

outputParams.forEach(function(params){
	hellYeahGifProcess(params.width, params.height, params.resize, params.colors);
});