php怎么把二维码透明

//二维码内容
	$qrcodeContent = '此处存链接的话，参数不宜过长，否则导致生成二维码时间太长！！！';
	//容错级别
	$errorCorrectionLevel = 'L';
	//生成图片大小
	$matrixPointSize = 6;
	//生成二维码图片
	\QRcode::png($qrcodeContent, 'qrcode.png', $errorCorrectionLevel, $matrixPointSize, 2);
	$QR = 'qrcode.png';//已经生成的原始二维码图
	//将二维码背景变透明
	$resource = imagecreatefrompng($QR);
	@unlink($QR);
	$bgcolor = imagecolorallocate($resource, 255, 255, 255);
	imagefill($resource, 0, 0, $bgcolor);
	imagecolortransparent($resource, $bgcolor);
	imagepng($resource,'qrcode_copy.png');	/*先处理成透明图再进行缩放就不会出现白黑点情况了！！！（至少效果好多了，而先进行缩放再处理背景透明就会出现很多白黑点！）*/
	@imagedestroy($resource);
 //获取对应游戏海报二维码位置
 $qrcode_pos = $pos;//$pos = [x,y]
 //获取对应游戏海报二维码规格
 $qrcode_spec = $spec;//$spec = [w,h]
 $resource = smart_resize_image('qrcode_copy.png', $qrcode_spec[0], $qrcode_spec[1], true);
 imagepng($resource,'qrcode_'.$gameType.'.png');//存储改变大小后的透明二维码
 $qrcode = 'qrcode_'.$gameType.'.png';
 //将透明背景的二维码贴到海报图指定位置
 $poster_with_qrcode_or_invitedcode_url = waterImage($posterUrl, $qrcode, $qrcode_pos[0], $qrcode_pos[1]);
 @imagedestroy($resource);
 @unlink('qrcode_copy.png');
 @unlink($qrcode);

/**
 * 调整图片大小并返回图片资源
 * @param $file
 * @param int $width
 * @param int $height
 * @param bool $proportional
 * @return bool|resource
 * @author zsb
 */
 function smart_resize_image($file, $width = 0, $height = 0, $proportional = false)
 {
 if ( $height <= 0 && $width <= 0 ) {
 return false;
 }
 $info = getimagesize($file);
 $image = '';
 $final_width = 0;
 $final_height = 0;
 list($width_old, $height_old) = $info;
 if ($proportional) {
 if ($width == 0) {
 $factor = $height/$height_old;
 }elseif ($height == 0) {
 $factor = $width/$width_old;
 }else {
 $factor = min ( $width / $width_old, $height / $height_old);
 }
 $final_width = round ($width_old * $factor);
 $final_height = round ($height_old * $factor);
 }else {
 $final_width = ( $width <= 0 ) ? $width_old : $width;
 $final_height = ( $height <= 0 ) ? $height_old : $height;
 }
 switch ($info[2]) {
 case IMAGETYPE_GIF:
 $image = imagecreatefromgif($file);
 break;
 case IMAGETYPE_JPEG:
 $image = imagecreatefromjpeg($file);
 break;
 case IMAGETYPE_PNG:
 $image = imagecreatefrompng($file);
 break;
 default:
 return false;
 }
 $image_resized = imagecreatetruecolor( $final_width, $final_height );
 if ( ($info[2] == IMAGETYPE_GIF) || ($info[2] == IMAGETYPE_PNG) ) {
 $trnprt_indx = imagecolortransparent($image);
 // If we have a specific transparent color
 if ($trnprt_indx >= 0) {
 // Get the original image's transparent color's RGB values
 $trnprt_color = imagecolorsforindex($image, $trnprt_indx);
 // Allocate the same color in the new image resource
 $trnprt_indx = imagecolorallocate($image_resized, $trnprt_color['red'], $trnprt_color['green'], $trnprt_color['blue']);
 // Completely fill the background of the new image with allocated color.
 imagefill($image_resized, 0, 0, $trnprt_indx);
 // Set the background color for new image to transparent
 imagecolortransparent($image_resized, $trnprt_indx);
 }
 // Always make a transparent background color for PNGs that don't have one allocated already
 elseif ($info[2] == IMAGETYPE_PNG) {
 // Turn off transparency blending (temporarily)
 imagealphablending($image_resized, false);
 // Create a new transparent color for image
 $color = imagecolorallocatealpha($image_resized, 0, 0, 0, 127);
 // Completely fill the background of the new image with allocated color.
 imagefill($image_resized, 0, 0, $color);
 // Restore transparency blending
 imagesavealpha($image_resized, true);
 }
 }
 
 imagecopyresampled($image_resized, $image, 0, 0, 0, 0, $final_width, $final_height, $width_old, $height_old);
 
 return $image_resized;
 }
 
 /**
 * 获取图片信息
 * @param $filename 传过来的参数是文件名字符串
 * @return mixed 返回值是一个数组，包含图片宽度、高度、创建和