From daf8284ccd1ea3e890a784a123ab098038a30544 Mon Sep 17 00:00:00 2001
From: Raphael Zschorsch <rafu1987@gmail.com>
Date: Wed, 27 Jun 2018 10:35:20 +0200
Subject: [PATCH] [FEATURE] Add preloadCss option to use with loadCSS
 (https://github.com/filamentgroup/loadCSS)

---
 Classes/Service/AssetService.php | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/Classes/Service/AssetService.php b/Classes/Service/AssetService.php
index 620d07dd4..f8cc138e4 100644
--- a/Classes/Service/AssetService.php
+++ b/Classes/Service/AssetService.php
@@ -427,8 +427,16 @@ protected function generateTagForAssetType($type, $content, $file = null, $integ
                 } else {
                     $tagBuilder->forceClosingTag(false);
                     $tagBuilder->setTagName('link');
-                    $tagBuilder->addAttribute('rel', 'stylesheet');
                     $tagBuilder->addAttribute('href', $file);
+
+                    // Preload?
+                    if ($GLOBALS['TSFE']->tmpl->setup['plugin.']['tx_vhs.']['assets.']['preloadCss'] == 1) {
+                        $tagBuilder->addAttribute('rel', 'preload');
+                        $tagBuilder->addAttribute('as', 'style');
+                        $tagBuilder->addAttribute('onload', "this.onload=null;this.rel='stylesheet'");
+                    } else {
+                        $tagBuilder->addAttribute('rel', 'stylesheet');
+                    }
                 }
                 if (null !== $integrity && !empty($integrity)) {
                     if (false === empty($GLOBALS['TSFE']->tmpl->setup['plugin.']['tx_vhs.']['settings.']['prependPath'])) {