public function qrcode($url="www.baidu.com",$level=3,$size=4)
  {
       Vendor('phpqrcode.phpqrcode');
       $errorCorrectionLevel =intval($level) ;//容错级别 
       $matrixPointSize = intval($size);//生成图片大小 
       //生成二维码图片 
       $object = new \QRcode();
       $object->png($url, false, $errorCorrectionLevel, $matrixPointSize, 2);  
  }

include 'phpqrcode.php';  
$value = 'http://www.cnblogs.com/txw1958/'; //二维码内容  
$errorCorrectionLevel = 'L';//容错级别  
$matrixPointSize = 6;//生成图片大小  
//生成二维码图片  
QRcode::png($value, 'qrcode.png', $errorCorrectionLevel, $matrixPointSize, 2);  
$logo = 'logo.png';//准备好的logo图片  
$QR = 'qrcode.png';//已经生成的原始二维码图  

if ($logo !== FALSE) {  
  $QR = imagecreatefromstring(file_get_contents($QR));  
  $logo = imagecreatefromstring(file_get_contents($logo));  
  $QR_width = imagesx($QR);//二维码图片宽度  
  $QR_height = imagesy($QR);//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 = $QR_width / 5;  
  $scale = $logo_width/$logo_qr_width;  
  $logo_qr_height = $logo_height/$scale;  
  $from_width = ($QR_width - $logo_qr_width) / 2;  
  //重新组合图片并调整大小  
  imagecopyresampled($QR, $logo, $from_width, $from_width, 0, 0, $logo_qr_width,  
  $logo_qr_height, $logo_width, $logo_height);  
}  
//输出图片  
imagepng($QR, 'helloweixin.png');  
echo '<img src="helloweixin.png">';