PHP image scaling function: scale the image proportionally according to the width

/*
A simple function that limits the image width and scales the image proportionally. The program does not overwrite the original image.
Image proportional scaling function parameter description:
$imgsrc The original image address can be a remote image or a path on the server.
$newimgname is the name of the reduced image.
$kuan limits the width of the image. If it exceeds this width, the image will be reduced.
Example:
$imgsrc = "http://www.xingzuo51.com/upload/20141116/20141116010041-0.jpg";//Can be a remote image.
$newimgname = "upload/20141116/000.jpg"; //Do not add "/" in front of the local path
$kuan = 600;
img_suofang($imgsrc,$newimgname,$kuan); //Call the image reduction function
 */
function img_suofang($imgsrc,$newimgname,$kuan){
 $info = getimagesize($imgsrc); //Get image information
 list($w,$h) = $info;
 $bl = ($ h/$w);
 // print_r($info);
 // die();
 // $type = $info[2];
 // die($type);
 if($w>$ kuan){
 $k = $kuan;
 $g = ($k*$bl);
 switch($info[2]){
 case 1:
 $im = imagecreatefromgif($imgsrc);
 $n = imagecreatetruecolor($k,$g);
 imagecopyresampled($n,$im,0,0,0,0,$k,$g,$w,$h);
 $type = ".gif";
 imagegif ($n,$newimgname."$type");
 break;
 case 2:
 $im = imagecreatefromjpeg($imgsrc);
 $n = imagecreatetruecolor($k,$g);
 imagecopyresampled($n,$ im,0,0,0,0,$k,$g,$w,$h);
 $type = ".jpg";
 imagejpeg($n,$newimgname.$type);
 break;
 case 3:
 $im = imagecreatefrompng($imgsrc);
 $n = imagecreatetruecolor($k,$g);
 imagecopyresampled($n,$im,0,0,0,0,$k,$g,$w ,$h);
 $type = ".png";
 imagepng($n,$newimgname.$type);
 break;
 default:
 die("No jpg Image");
 break;
}< /p>
if ($im && $n) {
 echo "Thumbnail generated successfully.";
}else{
 echo "Failed to generate thumbnail. ";
}
 imagedestroy( $im );
 imagedestroy( $n );
}else{
 echo "The image does not exceed the specified width and does not need to be scaled. ";
 }
}