自己写的php生成缩略图

今天无聊，学了一下php生成 缩略图···然后发现书上说得太复杂了，于是自己搞了一个，不会被拉伸的东东····代码极其简介 ···所以不注释····

<?php
        $sourceimage = '3.jpg';
        $maxthumbWidth = 200;
        $maxthumbHeight = 800;
        
        $original = imagecreatefromjpeg($sourceimage);
        $dims = getimagesize($sourceimage);
        
        $a = $maxthumbWidth/$dims[0];
        $b = $maxthumbHeight/$dims[1];
        if($a<$b)
        {
                $thumbWidth = $maxthumbWidth;
                $thumbHeight = $dims[1]*$a;
        }
        else 
        {
                $thumbWidth = $dims[0]*$b;
                $thumbHeight = $maxthumbHeight;
        }
        
        $thumb = imagecreatetruecolor($thumbWidth,$thumbHeight);
        
        imagecopyresampled($thumb,$original,0,0,0,0,$thumbWidth,$thumbHeight,$dims[0],$dims[1]);
        
        header("Content-type:image/jpeg");
        imagejpeg($thumb);

?>