function drupal_get_css

Returns a themed representation of all stylesheets that should be attached to the page.

It loads the CSS in order, with 'module' first, then 'theme' afterwards. This ensures proper cascading of styles so themes can easily override module styles through CSS selectors.

Themes may replace module-defined CSS files by adding a stylesheet with the same filename. For example, themes/garland/system-menus.css would replace modules/system/system-menus.css. This allows themes to override complete CSS files, rather than specific selectors, when necessary.

If the original CSS file is being overridden by a theme, the theme is responsible for supplying an accompanying RTL CSS file to replace the module's.

Parameters

$css: (optional) An array of CSS files. If no array is provided, the default stylesheets array is used instead.

Return value

A string of XHTML CSS tags.

See also

drupal_add_css()

File

includes/common.inc, line 1894

Common functions that many Drupal modules will need to reference.

Code

function drupal_get_css($css = NULL) {
  $output = '';
  if (!isset($css)) {
    $css = drupal_add_css();
  }
  $no_module_preprocess = '';
  $no_theme_preprocess = '';

  $preprocess_css = (variable_get('preprocess_css', FALSE) && (!defined('MAINTENANCE_MODE') || MAINTENANCE_MODE != 'update'));
  $directory = file_directory_path();
  $is_writable = is_dir($directory) && is_writable($directory) && (variable_get('file_downloads', FILE_DOWNLOADS_PUBLIC) == FILE_DOWNLOADS_PUBLIC);

  // A dummy query-string is added to filenames, to gain control over
  // browser-caching. The string changes on every update or full cache
  // flush, forcing browsers to load a new copy of the files, as the
  // URL changed.
  $query_string = '?' . substr(variable_get('css_js_query_string', '0'), 0, 1);

  foreach ($css as $media => $types) {
    // If CSS preprocessing is off, we still need to output the styles.
    // Additionally, go through any remaining styles if CSS preprocessing is on and output the non-cached ones.
    foreach ($types as $type => $files) {
      if ($type == 'module') {
        // Setup theme overrides for module styles.
        $theme_styles = array();
        foreach (array_keys($css[$media]['theme']) as $theme_style) {
          $theme_styles[] = basename($theme_style);
        }
      }
      foreach ($types[$type] as $file => $preprocess) {
        // If the theme supplies its own style using the name of the module style, skip its inclusion.
        // This includes any RTL styles associated with its main LTR counterpart.
        if ($type == 'module' && in_array(str_replace('-rtl.css', '.css', basename($file)), $theme_styles)) {
          // Unset the file to prevent its inclusion when CSS aggregation is enabled.
          unset($types[$type][$file]);
          continue;
        }
        // Only include the stylesheet if it exists.
        if (file_exists($file)) {
          if (!$preprocess || !($is_writable && $preprocess_css)) {
            // If a CSS file is not to be preprocessed and it's a module CSS file, it needs to *always* appear at the *top*,
            // regardless of whether preprocessing is on or off.
            if (!$preprocess && $type == 'module') {
              $no_module_preprocess .= '<link type="text/css" rel="stylesheet" media="' . $media . '" href="' . base_path() . $file . $query_string . '" />' . "\n";
            }
            // If a CSS file is not to be preprocessed and it's a theme CSS file, it needs to *always* appear at the *bottom*,
            // regardless of whether preprocessing is on or off.
            else if (!$preprocess && $type == 'theme') {
              $no_theme_preprocess .= '<link type="text/css" rel="stylesheet" media="' . $media . '" href="' . base_path() . $file . $query_string . '" />' . "\n";
            }
            else {
              $output .= '<link type="text/css" rel="stylesheet" media="' . $media . '" href="' . base_path() . $file . $query_string . '" />' . "\n";
            }
          }
        }
      }
    }

    if ($is_writable && $preprocess_css) {
      // Prefix filename to prevent blocking by firewalls which reject files
      // starting with "ad*".
      $filename = 'css_' . md5(serialize($types) . $query_string) . '.css';
      $preprocess_file = drupal_build_css_cache($types, $filename);
      $output .= '<link type="text/css" rel="stylesheet" media="' . $media . '" href="' . base_path() . $preprocess_file . '" />' . "\n";
    }
  }

  return $no_module_preprocess . $output . $no_theme_preprocess;
}