get resized image from existing file

    $filehandler = new ElggFile();
    $filehandler->owner_guid = $currentuser->getGUID();
    $filehandler->setFilename("profile/" . $currentuser->guid . "master.jpg");
    $filename = $filehandler->getFilenameOnFilestore();
    $master = get_resized_image_from_existing_file($filename,256,256, true);

    if ($master !== false){
        $filehandler = new ElggFile();
        $filehandler->owner_guid = $currentuser->getGUID();
        $filehandler->setFilename("profile/" .  $currentuser->guid . "master.jpg");
        $filehandler->open("write");
        $filehandler->write($master);
        $filehandler->close();

        $user->icontime = time();

        system_message(elgg_echo("profile:icon:uploaded"));
    } else {
        register_error(elgg_echo("profile:icon:notfound"));
    }