src/Bot.php
public function onPicture(\Closure $handler)
    {
        $this->managers[] = new Manager(function (Event $event) {
            return (
                $event instanceof \Viber\Api\Event\Message
                && $event->getMessage() instanceof \Viber\Api\Message\Picture
            );
        }, $handler);

        return $this;
    }
public function onPicture(\Closure $handler)
    {
        $this->managers[] = new Manager(function (Event $event) {
            return (
                $event instanceof \Viber\Api\Event\Message
                && $event->getMessage() instanceof \Viber\Api\Message\Picture
            );
        }, $handler);

        return $this;
    }
public function onPicture ( \ Closure $ handler ) { $ this -> managers [ ] = new Manager ( function ( Event $ event ) { return ( $ event instanceof \ Viber \ Api \ Event \ Message && $ event -> getMessage ( ) instanceof \ Viber \ Api \ Message \ Picture ) ; } , $ handler ) ; return $ this ; }
Register picture message handler

@param Closure $handler event handler
@return \Viber\Bot
Register picture message handler