phpqrcode生成二维码，并在底部加上图片
Vendor('phpqrcode.phpqrcode');
$font = ROOT_PATH.'public/static/common/font/hgzb.ttf';
$qrcode = new \QRcode;
$qr = $qrcode->png($url, $filename, 'H', 12, 13);
// 先读取存好的二维码图片,再追加文字
$image = imagecreatefrompng($filename);
$color = imagecolorallocate($image,0,0,0);
$res = imagettftext($image, 15, 0, 150, 430, $color, $font, $code);
imagepng($image, $filename);
注意事项：字体必须是物理路径
