New Trait for fetchPriority attribute in images

system/blueprints/config/system.yaml

@@ -1311,6 +1311,17 @@ form:
                 auto: Auto
                 sync: Sync
                 async: Async
+
+            images.defaults.fetchpriority:
+              type: select
+              size: small
+              label: PLUGIN_ADMIN.IMAGES_FETCHPRIORITY
+              help: PLUGIN_ADMIN.IMAGES_FETCHPRIORITY_HELP
+              highlight: auto
+              options:
+                auto: Auto
+                high: High
+                low: Low
 
             images.seofriendly:
               type: toggle

system/config/system.yaml

@@ -169,6 +169,7 @@ images:
   defaults:
     loading: auto                                # Let browser pick [auto|lazy|eager]
     decoding: auto                               # Let browser pick [auto|sync|async]
+    fetchpriority: auto                          # Let browser pick [auto|high|low]
   watermark:
     image: 'system://images/watermark.png'       # Path to a watermark image
     position_y: 'center'                         # top|center|bottom

system/src/Grav/Common/Media/Traits/ImageFetchPriorityTrait.php

@@ -0,0 +1,40 @@
+<?php
+
+/**
+ * @package    Grav\Common\Media
+ * @author     Pedro Moreno https://github.com/pmoreno-rodriguez
+ * @license    MIT License; see LICENSE file for details.
+ */
+
+namespace Grav\Common\Media\Traits;
+
+use Grav\Common\Grav;
+
+/**
+ * Trait ImageFetchPriorityTrait
+ * @package Grav\Common\Media\Traits
+ */
+
+trait ImageFetchPriorityTrait
+{
+    /**
+     * Allows to set the fetchpriority attribute from Markdown or Twig
+     *
+     * @param string|null $value
+     * @return $this
+     */
+    public function fetchpriority($value = null)
+    {
+        if (null === $value) {
+            $value = Grav::instance()['config']->get('system.images.defaults.fetchpriority', 'auto');
+        }
+
+        // Validate the provided value (similar to loading and decoding attributes)
+        if ($value !== null && $value !== 'auto') {
+            $this->attributes['fetchpriority'] = $value;
+        }
+
+        return $this;
+    }
+
+}

system/src/Grav/Common/Page/Medium/ImageMedium.php

@@ -16,6 +16,7 @@
 use Grav\Common\Media\Interfaces\MediaLinkInterface;
 use Grav\Common\Media\Traits\ImageLoadingTrait;
 use Grav\Common\Media\Traits\ImageDecodingTrait;
+use Grav\Common\Media\Traits\ImageFetchPriorityTrait;
 use Grav\Common\Media\Traits\ImageMediaTrait;
 use Grav\Common\Utils;
 use Gregwar\Image\Image;
@@ -32,6 +33,7 @@ class ImageMedium extends Medium implements ImageMediaInterface, ImageManipulate
     use ImageMediaTrait;
     use ImageLoadingTrait;
     use ImageDecodingTrait;
+    use ImageFetchPriorityTrait;
 
     /**
      * @var mixed|string