(Experimental) Scales a Raw ZPL file from 203 DPI (dots per inch) to 300 DPI

scale-zpl.js

/*
 * author:  Tres Finocchiaro, updated by Alethea Rose
 * date:    2017-07-10
 * license: Public Domain; Use as you wish.
 * source:  http://qz.io
 */

const cmds = {
  FO: 2,
  PW: null,
  FT: 2,
  A0: null,
  'A@': null,
  LL: null,
  LH: null,
  GB: null,
  FB: null,
  BY: 1,
  B3: null,
  BC: null,
  B7: 2
}

/*
 * Scales text from a raw ZPL label from 203 DPI to 300 DPI
 */
function scaleZPL (rawCommands, scaleFactor) {
  const sections = rawCommands.split('^')
  if (!scaleFactor) {
    scaleFactor = 300 / 203
  }

  for (let cmd in cmds) {
    for (let j in sections) {
      if (sections[j].indexOf(cmd) === 0) {
        sections[j] = scaleSection(cmd, sections[j], scaleFactor)
      }
    }
  }

  return sections.join('^')
}

/*
 * Scales all integers found in a designated section
 */
function scaleSection (cmd, section, scaleFactor) {
  section = section.slice(cmd.length, section.length)
  const parts = section.split(',')

  for (let p in parts) {
    if (isInt(parts[p]) && (cmds[cmd] === null || p < cmds[cmd])) {
      parts[p] = Math.round(scaleFactor * parts[p])
    }
  }

  return cmd + parts.join()
}

/*
 * Checks if a string is an integer
 */
function isInt (value) {
  const integer = parseInt(value, 10)

  return !isNaN(value) && !isNaN(integer) && integer.toString() === value
}