function advagg_add_preload_header in Advanced CSS/JS Aggregation 7.2

Add in the preload header for CSS and JS external files.

Parameters

string $url: The url of the external host.

Return value

bool TRUE if it was added to the head.

2 calls to advagg_add_preload_header()

advagg_add_resource_hints_array in ./advagg.module

Find dns_prefetch and call advagg_add_dns_prefetch().

_advagg_process_html in ./advagg.module

Replacement for template_process_html().

File

./advagg.module, line 6466

Advanced CSS/JS aggregation module.

Code

function advagg_add_preload_header($url = '', $as = '') {

  // Get defaults and setup static's.
  $list =& drupal_static(__FUNCTION__ . ':list', array());
  $output =& drupal_static(__FUNCTION__ . ':output');
  $header_strlen =& drupal_static(__FUNCTION__ . ':strlen', 0);
  static $resource_hints_preload_order;
  if (!isset($resource_hints_preload_order)) {
    $resource_hints_preload_order = advagg_get_resource_hints_preload_settings();
  }
  if (!isset($output)) {
    $keys = array_keys($resource_hints_preload_order);
    $output = array_fill_keys($keys, array());
  }

  // Output headers.
  if (empty($url)) {

    // Call hook_advagg_preload_header_alter()
    drupal_alter('advagg_preload_header', $output);

    // Build header string.
    $header_value = '';
    foreach ($output as $value) {
      if (!empty($value)) {

        // Remove empty values.
        $value = array_filter($value);
        foreach ($value as $string) {
          $header_strlen += strlen($string) + 2;

          // Don't add if over the limit.
          if ($header_strlen >= variable_get('advagg_resource_hints_preload_max_size', ADVAGG_RESOURCE_HINTS_PRELOAD_MAX_SIZE)) {
            continue;
          }

          // Add to $header_value string.
          if (empty($header_value)) {
            $header_value = $string;
          }
          else {
            $header_value .= ',' . $string;
          }
        }
      }
    }
    if (!empty($header_value)) {
      drupal_add_http_header('Link', $header_value, TRUE);
    }
    return FALSE;
  }

  // Check for duplicates.
  if (isset($list[$url])) {
    return FALSE;
  }

  // Fill in missing info.
  $payload = "<{$url}>; rel=preload";
  list($as, $type, $crossorigin, $parse) = advagg_get_preload_info_from_url($url, $as);
  if (!empty($as) && $as === 'php') {
    $list[$url] = FALSE;
    return FALSE;
  }
  $additional_info = array();
  if (!empty($crossorigin)) {
    $additional_info[] = "crossorigin";
  }
  if (!empty($type)) {
    if ($type !== 'text/css' || $type !== 'text/javascript' || $as !== 'image') {

      // Type is not needed for css/js files and images.
      $additional_info[] = "type=\"{$type}\"";
    }
  }
  $additional_info = implode('; ', $additional_info);

  // Get settings.
  if (!empty($as) && !empty($resource_hints_preload_order[$as])) {
    $settings = $resource_hints_preload_order[$as];
  }
  elseif (!empty($resource_hints_preload_order['all_others'])) {
    $settings = $resource_hints_preload_order['all_others'];
  }

  // Apply settings.
  if (!$settings['enabled']) {
    $list[$url] = FALSE;
    return FALSE;
  }
  if (!$settings['local'] && empty($parse['host'])) {
    $list[$url] = FALSE;
    return FALSE;
  }
  if (!$settings['external'] && !empty($parse['host'])) {
    $list[$url] = FALSE;
    return FALSE;
  }

  // Add additional info and queue.
  if (!empty($as)) {
    $payload .= "; as={$as}";
  }
  if (!empty($additional_info)) {
    $payload .= "; {$additional_info}";
  }
  if (!$settings['push']) {
    $payload .= "; nopush";
  }
  $list[$url] = TRUE;
  $output[$as][] = $payload;
}