wp-includes/class-wp-image-editor.php:443Builds an output filename based on current file, and adding proper suffix
$suffixstringoptionalnull$dest_pathstringoptionalnull$extensionstringoptionalnullstring public function generate_filename( $suffix = null, $dest_path = null, $extension = null ) { // If not empty the $suffix will be appended to the destination filename, just before the extension. if ( $suffix ) { $suffix = '-' . $suffix; } elseif ( '' !== $suffix ) { $suffix = '-' . $this->get_suffix(); } $dir = pathinfo( $this->file, PATHINFO_DIRNAME ); $ext = pathinfo( $this->file, PATHINFO_EXTENSION ); $name = wp_basename( $this->file, ".$ext" ); $new_ext = strtolower( $extension ? $extension : $ext ); if ( ! is_null( $dest_path ) ) { if ( ! wp_is_stream( $dest_path ) ) { $_dest_path = realpath( $dest_path ); if ( $_dest_path ) { $dir = $_dest_path; } } else { $dir = $dest_path; } } return trailingslashit( $dir ) . "{$name}{$suffix}.{$new_ext}"; }Introduced in 3.5.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
src/wp-includes/class-wp-image-editor.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.