PHP生成下载二维码图片

php框架是用的FLight，二维码类使用QrCode
download-qrcode.php文件

session_start();
// 参数处理
$user_id = $_SESSION['SESSION_KEY_AGENT'];
$type = isset($_GET['type']) ? $_GET['type'] : '';
// 初始化对象
$webroot = Flight::webroot();
$host = HOSTROOT;
$db = Flight::db();

$url = $host."/client/register?user_id=".$user_id;
$qr = new qrcode\QrCode($url);
$qr->level("L"); // L M Q H
// 显示图片
if($type == 'show'){
	header('Content-Type: image/png');
	$qr->size(400);
	echo $qr->generate();
}elseif($type == 'download'){
	// 下载图片
	Header("Content-type: application/octet-stream");
	Header("Accept-Ranges: bytes");
	Header("Content-Disposition: attachment; filename=qrcode.png");
	echo $qr->generate();
}

my-qrcode.php页面文件

		<img src="agent/download-qrcode?type=show"  alt="我的二维码" /><br>
		<a href="agent/download-qrcode?type=show" id="btn_search" class="layui-btn layui-btn-danger">查看a>
		<a href="agent/download-qrcode?type=download" id="btn_search" class="layui-btn layui-btn-danger">下载a>
		<div class="layui-tab-content">div>