SvgSpriteExtractor.php

<?php

declare (strict_types=1);
namespace Drupal\Core\Theme\Plugin\IconExtractor;

use Drupal\Core\StringTranslation\TranslatableMarkup;
use Drupal\Core\Theme\Icon\Attribute\IconExtractor;
use Drupal\Core\Theme\Icon\IconDefinition;
use Drupal\Core\Theme\Icon\IconExtractorWithFinder;
use Drupal\Core\Theme\Icon\IconPackExtractorForm;

/**
 * Plugin implementation of the icon_extractor.
 *
 * This extractor needs the file content only to extract ids, no SVG is parse or
 * printed.
 *
 * @internal
 *   This API is experimental.
 */
class SvgSpriteExtractor extends IconExtractorWithFinder {
    
    /**
     * {@inheritdoc}
     */
    public function discoverIcons() : array {
        $files = $this->getFilesFromSources();
        if (empty($files)) {
            return [];
        }
        $icons = [];
        foreach ($files as $file) {
            $icon_ids = $this->extractIdsFromXml($file['absolute_path'] ?? '');
            foreach ($icon_ids as $icon_id) {
                $id = IconDefinition::createIconId($this->configuration['id'], (string) $icon_id);
                $icons[$id] = [
                    'absolute_path' => $file['absolute_path'],
                    'source' => $file['source'],
                    'group' => $file['group'] ?? NULL,
                ];
            }
        }
        return $icons;
    }
    
    /**
     * Extract icon ID from XML.
     *
     * @param string $source
     *   Local path or url to the svg file.
     *
     * @return array
     *   A list of icons with keys:
     *   - icon_ids: array of icon Id found
     *   - attributes: Attribute object from the svg
     */
    private function extractIdsFromXml(string $source) : array {
        if (!($content = $this->iconFinder
            ->getFileContents($source))) {
            return [];
        }
        libxml_use_internal_errors(TRUE);
        if (!($svg = simplexml_load_string((string) $content))) {
            // @todo do we need to log a warning with the xml error?
            return [];
        }
        return $this->extractIdsFromSymbols($svg->symbol) ?: $this->extractIdsFromSymbols($svg->defs->symbol ?? NULL);
    }
    
    /**
     * Extract icon ID from SVG symbols.
     *
     * @param \SimpleXMLElement|null $wrapper
     *   A SVG element.
     *
     * @return array
     *   A list of icons ID.
     */
    private function extractIdsFromSymbols(?\SimpleXMLElement $wrapper) : array {
        if ($wrapper === NULL) {
            return [];
        }
        $ids = [];
        foreach ($wrapper as $symbol) {
            if (isset($symbol['id']) && 0 === preg_match('/[^\\w-]/', (string) $symbol['id'])) {
                $ids[] = (string) $symbol['id'];
            }
        }
        return $ids;
    }

}