* @return string
*/
private static function fixBackgroundPosition( $css ) {
- $css = preg_replace_callback( self::$patterns['bg_horizontal_percentage'],
+ $replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage'],
array( 'self', 'calculateNewBackgroundPosition' ), $css );
- $css = preg_replace_callback( self::$patterns['bg_horizontal_percentage_x'],
+ if ( $replaced !== null ) {
+ // Check for null; sometimes preg_replace_callback() returns null here for some weird reason
+ $css = $replaced;
+ }
+ $replaced = preg_replace_callback( self::$patterns['bg_horizontal_percentage_x'],
array( 'self', 'calculateNewBackgroundPosition' ), $css );
+ if ( $replaced !== null ) {
+ $css = $replaced;
+ }
return $css;
}