Ticket #39883: 39883.diff

src/wp-includes/media.php

@@ -183 +183 @@
  *                     the image is an intermediate size. False on failure.
  */
 function image_downsize( $id, $size = 'medium' ) {
-        $is_image = wp_attachment_is_image( $id );
+        $is_image = false;
+
+        /*
+         * Check attachment to see if we support returning image attributes for
+         * this type. This is to avoid the 'image_downsize' filter and making
+         * unneeded DB queries when the type is unsupported.
+         */
+        $supported = false;
+        $supported_types = array( 'image', 'pdf' );
+
+        foreach ( $supported_types as $type ) {
+                $supported = wp_attachment_is( 'type', $id );
+                if ( $supported ) {
+                        $is_image = ( 'image' === $type );
+                        break;
+                }
+        }
+
+        if ( ! $supported ) {
+                return false;
+        }
 
         /**
          * Filters whether to preempt the output of image_downsize().