An Extbase ViewHelper which inlines svgs into the template

SvgImportViewHelper

<?php
class SvgImportViewHelper extends \TYPO3\CMS\Fluid\Core\ViewHelper\AbstractViewHelper
{
	private static $id = 0;

	/**
	 * Renders the content.
	 *
	 * @param string $src
	 * @return string
	 * @api
	 */
	public function render($src) {
		$content = file_get_contents(PATH_site . '/' . $src);
		$content = preg_replace('/\\<\\?.*?\\?\\>\\s*/', '', $content); // remove xml annotation
		$content = preg_replace('/\\<!DOCTYPE.*?\\>\\s*/', '', $content); // remove doctype annotation
		$content = preg_replace('/\\<\\!--.*?--\\>\\s*/', '', $content); // remove comments
		$content = preg_replace('/\\w+:\\S+=".*?"\\s*/', '', $content); // remove namespace attributes
		$content = preg_replace('/\\<metadata[^\\>]*\\>.*?\\<\\/metadata\\>/s', '', $content); // remove metadata
		$content = preg_replace('/\\<(\w+:\w+)[^\\>]*\\>.*?\\<\\/\\1\\>\\s*/s', '', $content); // remove namespace extensions
		$content = preg_replace('/\\<(\w+:\w+)[^\\>]*\\/\\>\\s*/s', '', $content); // remove namespace extensions single tag
		
		// convert style="" attributes
		$content = preg_replace_callback('/style="(.*?)"/', function ($matches) {
			$styles = preg_split('/\s*;\s*/', trim($matches[1]));
			$attributes = array();
			foreach ($styles as $style) {
				list($name, $value) = preg_split('/\s*:\s*/', trim($style));
				$attributes[] = "$name=\"$value\"";
			}
			return implode(' ', $attributes);
		}, $content);
		
		// prefix ids
		$prefix = 'svg_' . (self::$id++) . '_';
		$ids = array();
		$content = preg_replace_callback('/id="(.*?)"/', function ($matches) use($prefix, &$ids) {
			$ids[$matches[1]] = $prefix . $matches[1];
			return $matches[0]; // don't change for now
		}, $content);
		$content = str_replace(array_keys($ids), array_values($ids), $content);

		return $content;
	}
}