Add code to admin bar only

Question

I am trying to add a QR code to the bar and I can do this but it's my first time to make a WordPress plug-in and I'm having trouble. It ends up showing to everyone even if they are not an admin or even not logged in.

Any ideas or guidance would be very grateful.

function selfURL() {
    $s = empty($_SERVER["HTTPS"]) ? ''
        : ($_SERVER["HTTPS"] == "on") ? "s"
        : "";
    $protocol = strleft(strtolower($_SERVER["SERVER_PROTOCOL"]), "/").$s;
    $port = ($_SERVER["SERVER_PORT"] == "80") ? ""
        : (":".$_SERVER["SERVER_PORT"]);
    return $protocol."://".$_SERVER['SERVER_NAME'].$port.$_SERVER['REQUEST_URI'];
}
function strleft($s1, $s2) {
    return substr($s1, 0, strpos($s1, $s2));
}

$urlToEncode=(selfURL());

generateQRwithGoogle($urlToEncode);
function generateQRwithGoogle($url,$widthHeight ='30',$EC_level='L',$margin='0') {
    $url = urlencode($url); 
    echo '<img src="http://chart.apis.google.com/chart?chs='.$widthHeight.
'x'.$widthHeight.'&cht=qr&chld='.$EC_level.'|'.$margin.
'&chl='.$url.'" alt="QR code" widthHeight="'.$widthHeight.
'" widthHeight="'.$widthHeight.' "/>';
}

Answer 1

You can limit to logged in users by wrapping the code with is_logged_in().

You can limit to levels via current_user_can('manage_options').

Answer 2

You only need one if statement:

if(is_admin()){
//your code here...
};

You can check out more about it here: http://codex.wordpress.org/Conditional_Tags