edlp_d8/core/modules/color/color.install

<?php

/**
 * @file
 * Install, update and uninstall functions for the color module.
 */

/**
 * Implements hook_requirements().
 */
function color_requirements($phase) {
  $requirements = [];

  if ($phase == 'runtime') {
    // Check for the PHP GD library.
    if (function_exists('imagegd2')) {
      $info = gd_info();
      $requirements['color_gd'] = [
        'value' => $info['GD Version'],
      ];

      // Check for PNG support.
      if (!function_exists('imagecreatefrompng')) {
        $requirements['color_gd']['severity'] = REQUIREMENT_WARNING;
        $requirements['color_gd']['description'] = t('The GD library for PHP is enabled, but was compiled without PNG support. Check the <a href="http://php.net/manual/ref.image.php">PHP image documentation</a> for information on how to correct this.');
      }
    }
    else {
      $requirements['color_gd'] = [
        'value' => t('Not installed'),
        'severity' => REQUIREMENT_ERROR,
        'description' => t('The GD library for PHP is missing or outdated. Check the <a href="http://php.net/manual/book.image.php">PHP image documentation</a> for information on how to correct this.'),
      ];
    }
    $requirements['color_gd']['title'] = t('GD library PNG support');
  }

  return $requirements;
}