app.js

#!/usr/bin/env node
/*
 requirements:
 Node
 inkscape
Graphicsmagic
*/
'use strict'

const fs = require('fs')
const path = require('path')
const childProcess = require('child_process')
const gm = require('gm')
const PNG = require('png-js')

const files = fs.readdirSync(__dirname).filter(el => el.match(/\.svg$/))

console.log(childProcess.execSync(`rm -rf "${path.join(__dirname, 'out')}"`).toString('utf8'))

fs.mkdirSync(path.join(__dirname, 'out'))

function svgToPdf (descriptor) {
  const { svgLocation, tmpPdfLocation } = descriptor
  return new Promise((resolve, reject) => {
    childProcess.exec(`inkscape -A "${tmpPdfLocation}" "${svgLocation}"`, err => {
      if (err) {
        return reject(err)
      }
      console.log(`Converted ${svgLocation} to ${tmpPdfLocation}`)
      resolve(descriptor)
    })
  })
}

function getSizes (descriptor) {
  const { tmpPdfLocation, size } = descriptor
  return new Promise((resolve, reject) => {
      gm(tmpPdfLocation).size((err, sizings) => {
        if (err) {
          return reject(err)
        }
        const { width, height } = sizings

        const coefficientWidth = (size[0] / width)
        const coefficientHeight = (size[1] / height)

        const coefficient = coefficientHeight < coefficientWidth ? coefficientHeight : coefficientWidth
        const newWidth = Math.round(width * coefficient)
        const newHeight = Math.round(height * coefficient)
        descriptor.newWidth = newWidth
        descriptor.newHeight = newHeight
        descriptor.width = width
        descriptor.height = height

        console.log(`Got sizes for ${tmpPdfLocation}`)
        resolve(descriptor)
      })
  })
}

function getColors (descriptor) {
  const { tmpPdfLocation, newWidth, newHeight, pngLocation} = descriptor
  return new Promise((resolve, reject) => {
    gm(tmpPdfLocation)
      .resize(newWidth, newHeight)
      .write(pngLocation, err => {
        if (err) {
          return reject(err)
        }
        fs.readFile(pngLocation, (err, file) => {
          if (err) {
            return reject(err)
          }
          (new PNG(file)).decode(pixels => {
            const colors = {
              r: pixels[12].toString(16),
              g: pixels[13].toString(16),
              b: pixels[14].toString(16),
              a: (255 - pixels[15]).toString(16)
            }
            if (colors.r.length < 2) {
              colors.r = '0' + colors.r
            }
            if (colors.g.length < 2) {
              colors.g = '0' + colors.g
            }
            if (colors.b.length < 2) {
              colors.b = '0' + colors.b
            }
            if (colors.a.length < 2) {
              colors.a = '0' + colors.a
            }
            descriptor.colors = colors

            console.log(`Got colors for ${tmpPdfLocation}`)
            resolve(descriptor)
          })
        })
      })
  })
}

function generateTmpPng (descriptor) {
  const { size, colors, tmpPngLocation } = descriptor
  return new Promise((resolve, reject) => {
    gm(size[0], size[1], `#${colors.r}${colors.g}${colors.b}${colors.a}`)
      .write(tmpPngLocation, err => {
        if (err) {
          return reject(err)
        }

        console.log(`Generated ${tmpPngLocation}`)
        resolve(descriptor)
      })
  })
}

function compose (descriptor) {
  const { tmpPngLocation, pngLocation, size, newWidth, width, height, newHeight } = descriptor
  return new Promise((resolve, reject) => {
    gm(tmpPngLocation)
      .composite(pngLocation)
      .geometry(`+${Math.round( (size[0] - newWidth) * (width > height ? 1 : 0.5) )}+${Math.round((size[1] - newHeight) / 2)}`)
      .write(pngLocation, err => {
        if (err) {
          return reject(err)
        }

        console.log(`Composed ${pngLocation}`)
        resolve(descriptor)
      })
  })
}

function clean (descriptor) {
  const { tmpPngLocation, tmpPdfLocation } = descriptor
  return new Promise((resolve, reject) => {
    fs.unlink(tmpPngLocation, err => {
      if (err) {
        return reject(err)
      }


      fs.unlink(tmpPdfLocation, err => {
        if (err) {
          return reject(err)
        }
      })

      console.log(`Removed ${tmpPngLocation} and ${tmpPdfLocation}`)
      resolve(descriptor)
    })
  })
}

files.forEach(file => {
  [
    [996, 172],
    [3984, 688],
    [100, 100],
    [400, 400]
  ].forEach(size => {
    let svgLocation = path.join(__dirname, file)
    let pngLocation = path.join(__dirname, 'out', `${size[0]}x${size[1]}_${file.replace(/svg$/, 'png')}`)
    let tmpPngLocation = path.join(__dirname, 'out', `tmp_${size[0]}x${size[1]}_${file.replace(/svg$/, 'png')}`)
    let tmpPdfLocation = path.join(__dirname, 'out', `tmp_${size[0]}x${size[1]}_${file.replace(/svg$/, 'pdf')}`)

    let descriptor = {
      svgLocation,
      pngLocation,
      tmpPngLocation,
      tmpPdfLocation,
      size
    }
    svgToPdf(descriptor)
      .then(getSizes)
      .then(getColors)
      .then(generateTmpPng)
      .then(compose)
      .then(clean)
      .then(({ size, svgLocation }) => console.log(`Finished ${size[0]}x${size[1]} for ${svgLocation}`))
      .catch(console.error.bind(console, 'ERR'))
  })
})