Original:

public static function getAvatarUrl(array $user, $size, $forceType = '')
	{
		if (!empty($user['user_id']) && $forceType != 'default')
		{
			if ($user['gravatar'] && $forceType != 'custom')
			{
				return self::_getGravatarUrl($user, $size);
			}
			else if (!empty($user['avatar_date']))
			{
				return self::_getCustomAvatarUrl($user, $size);
			}
		}

		return self::_getDefaultAvatarUrl($user, $size);
	}

My function:

public static function getAvatarUrl(array $user, $size, $forceType = '')
    {
        return "http://pixelface.net/helm/{$user['username']}/".XenForo_Model_Avatar::getSizeFromCode($size);
    }