done

libraries/src/Image/Image.php

@@ -125,8 +125,10 @@ public function __construct($source = null)
             static::$formats[IMAGETYPE_WEBP] = $info['WebP Support'];
         }
 
-        // If the source input is a resource, set it as the image handle.
-        if (\is_resource($source) && get_resource_type($source) == 'gd') {
+        /**
+         * If the source input is a resource, set it as the image handle.
+         */
+        if ($source && (\is_object($source) && get_class($source) == 'GdImage')) {
             $this->handle = $source;
         } elseif (!empty($source) && \is_string($source)) {
             // If the source input is not empty, assume it is a path and populate the image handle.
@@ -536,14 +538,8 @@ public function getPath()
      */
     public function isLoaded()
     {
-        /**
-         * Make sure the resource handle is valid.
-         * @todo: Remove check for resource when we only support PHP 8
-         */
-        if (
-            !((\is_object($this->handle) && get_class($this->handle) == 'GdImage')
-                || (\is_resource($this->handle) && get_resource_type($this->handle) == 'gd'))
-        ) {
+        // Make sure the resource handle is valid.
+        if (!(\is_object($this->handle) && get_class($this->handle) == 'GdImage')) {
             return false;
         }
 

libraries/src/Image/ImageFilter.php

@@ -42,6 +42,11 @@ public function __construct($handle)
             throw new \RuntimeException('The imagefilter function for PHP is not available.');
         }
 
+        // Make sure the file handle is valid.
+        if (!(\is_object($handle) && get_class($handle) == 'GdImage')) {
+            throw new \InvalidArgumentException('The image handle is invalid for the image filter.');
+        }
+
         $this->handle = $handle;
     }