Ticket #28512: 28512-2.diff

src/wp-admin/includes/post.php

@@ -1376 +1376 @@
         if ( $thumbnail_id && get_post( $thumbnail_id ) ) {
                 $old_content_width = $content_width;
                 $content_width = 266;
-                if ( !isset( $_wp_additional_image_sizes['post-thumbnail'] ) )
-                        $thumbnail_html = wp_get_attachment_image( $thumbnail_id, array( $content_width, $content_width ) );
-                else
-                        $thumbnail_html = wp_get_attachment_image( $thumbnail_id, 'post-thumbnail' );
+
+                $size = isset( $_wp_additional_image_sizes['post-thumbnail'] ) ? 'post-thumbnail' : array( $content_width, $content_width );
+
+                /**
+                 * Filter the admin post thumbnail size for the Featured Image meta box.
+                 *
+                 * @since 4.3.0
+                 *
+                 * @param string|array $size         Post thumbnail size. If the 'post-thumbnail' image size
+                 *                                   is set, `$size` equals an array with `$content_width`
+                 *                                   as the height and width values. Otherwise, 'post-thumbnail'.
+                 * @param int          $thumbnail_id Thumbnail ID.
+                 * @param WP_Post      $post         The post object associated with the thumbnail.
+                 */
+                $size = apply_filters( 'admin_post_thumbnail_size', $size, $thumbnail_id, $post );
+
+                $thumbnail_html = wp_get_attachment_image( $thumbnail_id, $size );
+
                 if ( !empty( $thumbnail_html ) ) {
                         $ajax_nonce = wp_create_nonce( 'set_post_thumbnail-' . $post->ID );
                         $content = sprintf( $set_thumbnail_link,