ZPL dpi converter for PHP

gistfile1.txt

<?php
/*
 * author:  Tres Finocchiaro transposed to PHP by Johan van de Merwe
 * date:    2020-08-10
 * license: Public Domain; Use as you wish.
 * source:  http://qz.io
 *
 * usage: 
 *
 *   $data = '^XA...your zpl data.. XZ';
 *   $zplconverter = new ZebraDPIConverter(203, 300);
 *   $zplconverter->setSource($data, 'string'); // when a string is used
 *   /* or */
 *   /* $zplconverter->setSource($path, 'path'); // when a path to your zpl template is used */
 *   $data = $zplconverter->scale();
 * 
 */
namespace ZebraConverter;

class ZebraDPIConverter
{
    private $baseDPI;
    private $targetDPI;

    private $sourceData;

    private $scaleFactor = 1;

    private static $cmds = ['FT', 'FO', 'A0', 'A@', 'LL', 'LH', 'GB', 'FB', 'BY', 'B3'];

    function __construct($baseDPI = 203, $targetDPI = 300, $source = null, $type = null)
    {
        $this->baseDPI = intval($baseDPI);
        $this->targetDPI = intval($targetDPI);

        $this->scaleFactor = $this->targetDPI / $this->baseDPI;

        if ($source !== null) {
            $this->setSource($source, $type);
        }

        return $this;
    }

    public function setSource($source, $type = 'string')
    {
        if (in_array(strtolower($type), ['string', 'text', 'data'])) {
            $this->sourceData = $source;
        } else if (in_array(strtolower($type), ['file', 'path'])) {
            $this->loadSourceFromPath($source);
        }

        return $this;
    }

    public function loadSourceFromPath($path)
    {
        if (file_exists($path)) {
            $this->sourceData = file_get_contents($path);
        } else {
            $this->sourceData = 'File not found in path : ' . $path;
        }

        return $this;
    }

    /*
     * Scales text from a raw ZPL label from 203 DPI to 300 DPI
     */
    function scale()
    {
        $sections = explode('^', $this->sourceData);

        foreach (self::$cmds as $cmd) {
            foreach ($sections as $idx => $section) {

                if (substr($section, 0, strlen($cmd)) === $cmd) {
                    $sections[$idx] = $this->scaleSection($cmd, $section);
                }
            }
        }

        return implode('^', $sections);
    }

    /*
     * Scales all integers found in a designated section
     */
    function scaleSection($cmd, $section)
    {
        $section = substr($section, strlen($cmd), strlen($section));

        $parts = explode(',', $section);

        foreach ($parts as $idx => $part) {
            if (is_numeric($part)) {
                $parts[$idx] = round($this->scaleFactor * intval($part));
            }
        }

        return $cmd . implode(',', $parts);
    }
}