index.php
<?php
header('Content-type:text/html;charset=UTF-8');
// 指定允许其他域名访问
header('Access-Control-Allow-Origin:*');
// 响应类型f
header('Access-Control-Allow-Methods:POST');
// 响应头设置
header('Access-Control-Allow-Headers:x-requested-with,content-type');
include 'phpqrcode.php';
//$uid = "100001";
$uid = $_POST["uid"];
$qrcodeurl = 'qrcode'.$uid.'.png';
$code = $uid.".png";
//二维码内容
$url = "http://域名/tp3.2/home/Wx2/code?uid=".$uid;//二维码内容
//容错级别
$errorCorrectionLevel = 'L';
//生成图片大小
$matrixPointSize = 4;
QRcode::png($url, $qrcodeurl, $errorCorrectionLevel, $matrixPointSize, 2);
//code【二维码+头像存放地址】、header【头像存放地址】、qrcode【二维码存放地址】
//准备好的logo图片,本人放在了根目录下
//头像地址[读数据库里面的头像具体到服务器的头像地址save_url]
//$logo = 'http://域名/tp3.2/Public/upload/header/header2.png';
require_once('file1.php');
$logo = func1($uid);
//已经生成的原始二维码图,也在根目录下
$qrcode = $qrcodeurl;
//logo图片存在
if ($logo !== FALSE) {
    $qrcode = imagecreatefromstring(file_get_contents($qrcode));
    $logo = imagecreatefromstring(file_get_contents($logo));
    if (imageistruecolor($logo))
    {
        imagetruecolortopalette($logo, false, 65535);//添加这行代码来解决颜色失真问题
    }
    $qrcode_width = imagesx($qrcode);   //二维码图片宽度
    $qrcode_height = imagesy($qrcode);  //二维码图片高度
    $logo_width = imagesx($logo);       //logo图片宽度
    $logo_height = imagesy($logo);      //logo图片高度
    $logo_qr_width = $qrcode_width / 5;
    $scale = $logo_width / $logo_qr_width;
    $logo_qr_height = $logo_height / $scale;
    $from_width = ($qrcode_width - $logo_qr_width) / 2;
    //重新组合图片并调整大小
    imagecopyresampled($qrcode, $logo, $from_width, $from_width, 0, 0, $logo_qr_width,
        $logo_qr_height, $logo_width, $logo_height);
}
//输出图片
imagepng($qrcode, $code);//保存合成图片，命名logqr.png放在该地址中
imagedestroy($qrcode);
imagedestroy($logo);
if(file_exists($qrcodeurl)){ //存在二维码图片
    unlink($qrcodeurl);
    //echo '输出code3下面的图片为66存在二维码图片就删除222:'.'<img src="'.$code.'" >';
    $showcode = "http://域名/code4/".$code;
    $json = json_encode($showcode,JSON_UNESCAPED_UNICODE);
    $json = str_replace("\\/","/",$json);//以免url地址被反编译
    echo $json;
}
else { //不存在二维码图片
    //echo '输出code3下面的图片为66不存在二维码图片就不管222:'.'<img src="'.$code.'" >';
    $showcode = "http://域名/code4/".$code;
    $json = json_encode($showcode,JSON_UNESCAPED_UNICODE);
    $json = str_replace("\\/","/",$json);//以免url地址被反编译
    echo $json;
}
//echo '输出的图片为66:'.'<img src="'.$code.'" >';
?>

file.php

<?php

function func1($uid)
{
    $servername = 'IP';
    $username = '用户名';
    $password = '密码';
    $dbname = '数据库名称';
    $port = '端口';
    // 创建连接
    $conn = new mysqli($servername, $username, $password, $dbname,$port);
    // Check connection
    if ($conn->connect_error) {
        die("连接失败: " . $conn->connect_error);
    }
    //$uid = "100001";
    $sql = "SELECT header.save_url FROM header where uid='$uid'";
    $result = $conn->query($sql);
    $arr = mysqli_fetch_row($result);
    $save_url = $arr[0];
    $conn->close();
    return $save_url;
}