gm image manipulation

process.js

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

function getSize(image) {
  return new Promise((resolve, reject) => {
    image.size((err, size) => {
      if (err) {
        reject(err);
        return;
      }
      resolve(size);
    })
  });
}

function write(name, image) {
  return new Promise((resolve, reject) => {
    image.write(name, (err) => {
      if (err) {
        reject(err);
        return;
      }
      resolve();
    })
  })
}

const padding = 20;
const fontSize = 24;
const rectHeight = padding * 2 + fontSize - 10;

const image = gm('image.jpg');

getSize(image)
  .then(({width, height}) => {

    image
      .stroke('#ec2c22')
      .fill('#ec2c2233')
      .drawRectangle(0, height - rectHeight, width, height);

    image
      .stroke('#ffffff')
      .fill('#ffffff')
      .font('Change-Calibre-Regular.ttf', fontSize)
      .drawText(padding, height - padding, 'Sign this petition');

    console.log(width, height);

    return write('image_small.jpg', image)
  })
  .then(() => console.log('done'))
  .catch(console.log);