Asynchronous ImageMagick processing using Node.js.

Async image processing with node.js

let commands = {};
commands['make title text with drop shadow'] = `
	convert \
	-background none \
	-font "Roboto Condensed/RobotoCondensed-Regular.ttf" \
	-pointsize 500 \
	-gravity Center \
	-interline-spacing -30 \
	-bordercolor none \
	-strokewidth 16 \
	\\( \
		-stroke black \
		label:"This is my super duper cool title that is long" \
		-border 200x200 \
		-blur 0x32 \
	\\) \
	\\( \
		-stroke none \
		-fill white \
		label:"This is my super duper cool title that is long" \
		-border 200x200 \
	\\) \
	-flatten \
	+repage \
	title.png
`;

// Add more commands here.

// Promisifying `child_process`:
function promiseFromChildProcess(child) {
	return new Promise((resolve, reject) => {
		child.addListener('error', (code, signal) => {
			console.log('ChildProcess error', code, signal);
			reject();
		});
		child.addListener('exit', (code, signal) => {
			if (code === 0) {
				resolve();
			} else {
				reject();
			}
		});
	});
};

function childProcess(command) {
	let child = exec(command);
	child.stdout.on('data', function(data) {
		console.log('stdout:', data);
	});
	child.stderr.on('data', function(data) {
		console.log('stderr:', data);
	});
	child.on('close', function(code) {
		//console.log('closing code:', code);
	});
	return this.promiseFromChildProcess(child);
};

Promise.resolve(true) // Dummy promise to make following chain more readable.
.then(() => {
	console.log('Command 1 started …');
	return childProcess(commands['make title text with drop shadow']);
}).then(() => {
	console.log('Command 2 started …');
	//return childProcess(…); // Rinse, wash and repeat.
	return true;
}).then(() => {
	console.log('Done!');
}).catch(() => {
	console.log('SOME TESTS OR SOMETHING IN THE SAUCE STACK HAS FAILED!');
	process.exit(1);
});