How to get gravatar url alone

I would like to use gravatar image as background image for a button. When i use get_avatar function it returns with height width src parameters.

But i need only gravatar url.
I mean like http://gravatar.com/.../...

Can anyone tell me how?
Thanks

Solutions Collecting From Web of "How to get gravatar url alone"

Just generate the URL yourself. It’s just a hash of the user’s email address.

function get_gravatar_url( $email ) {
    $hash = md5( strtolower( trim ( $email ) ) );
    return 'http://gravatar.com/avatar/' . $hash;
}

This function requires that you pass the user’s email address in … but you could do anything you need to programatically grab the user’s address.

Look at how it is implemented here:

http://core.trac.wordpress.org/browser/tags/3.3.1/wp-includes/pluggable.php#L1578

Additionally check out the very simple Gravatar API:

http://en.gravatar.com/site/implement/images/

You can try to hook into the get_avatar filter and preg_match against the 'src' like so:

add_filter( 'get_avatar', function( $avatar ) {
    if ( preg_match( '# src=\'(.*)\' #U', $avatar, $matches ) )
        $some_globally_accessible_var = $matches[1];
    return $avatar;
} );

The some_globally_accessible_var would be an instance variable or some static variable, global.