function CssCollectionRenderer::render

Overrides AssetCollectionRendererInterface::render

File

core/lib/Drupal/Core/Asset/CssCollectionRenderer.php, line 55

Class

CssCollectionRenderer

Renders CSS assets.

Namespace

Code

public function render(array $css_assets) {
    $elements = [];
    // 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 = $this->assetQueryString
        ->get();
    // Defaults for LINK and STYLE elements.
    $link_element_defaults = [
        '#type' => 'html_tag',
        '#tag' => 'link',
        '#attributes' => [
            'rel' => 'stylesheet',
        ],
    ];
    foreach ($css_assets as $css_asset) {
        $element = $link_element_defaults;
        $element['#attributes']['media'] = $css_asset['media'];
        switch ($css_asset['type']) {
            // For file items, output a LINK tag for file CSS assets.
            case 'file':
                $element['#attributes']['href'] = $this->fileUrlGenerator
                    ->generateString($css_asset['data']);
                // Only add the cache-busting query string if this isn't an aggregate
                // file.
                if (!isset($css_asset['preprocessed'])) {
                    $query_string_separator = str_contains($css_asset['data'], '?') ? '&' : '?';
                    $element['#attributes']['href'] .= $query_string_separator . $query_string;
                }
                break;
            case 'external':
                $element['#attributes']['href'] = $css_asset['data'];
                break;
            default:
                throw new \Exception('Invalid CSS asset type.');
        }
        // Merge any additional attributes.
        if (!empty($css_asset['attributes'])) {
            $element['#attributes'] += $css_asset['attributes'];
        }
        $elements[] = $element;
    }
    return $elements;
}