PHP image proportional scaling to generate thumbnail function sharing_PHP tutorial

/*
*@im //需要缩放的图片资源
*@filetype //制作的缩略图文件类型
*@dstimW //缩放的图片的宽度
*@dstimH //缩放的图片的高度
*@thumbname //缩略图文件名字
function makethumb($im,$dstimW,$dstimH,$thumbname ,$filetype){
//获取im的宽度和高度
$pic_W=imagesx($im);
$pic_H=imagesy($im);
$arr = array();
swith($filetype){
case 'jpg':
$arr[$filetype]="imagejpeg";
break;
case 'png';
$arr[$filetype]="imagepng";
break;
case 'jif';
$arr[$filetype]="imagegif";
}
if(($dstimgW && $dstimgW<$pic_W) || ($dstimgH && $dstimgH<$pic_H) ){
if($dstimgW && $dstimgW<$pic_W){
$dsimgWratio = $dstimgW / $pic_w;
$resizereagW =true;

                                                                                                                                  $resizerreagH =true;                                The smallest aspect ratio between the thumbnail width and height and the original image is the smallest one if($resizereagW && $resizerreagH){
           $radio = $dsimgWratio;
else
                             $radio = $                                                                                                                                  $radio = $dsimgWratio;
                                                                                            resizerreagH){
                                                                                                                                                                                            $imgnewH = $pic_H * $radio;
if(function_exists("imgcopyresampled" )){
//Create the target resource canvas
$dst = imagecreatetruecolor ($imgnewW, $imgnewH);
imagecopyresampled ($dst,$im, 0,0,0,0,$imgnewW,$ imgnewH, $pic_W, $pic_H); imgnewW,$imgnewH,$imgnewH,$pic_W,$pic_H);
      }

        $arr[$filetype]($dst,$thumbname.".$filetype");
                                                                                                                                          The width and height of the original image
//Then the width and height of the thumbnail are the width and height of the original image
filetype");
imagedestroy();
}
}
?>