PHP縮放圖片

function resize_image($filename, $tmpname, $xmax, $ymax)

{

    $ext = explode(".", $filename);

    $ext = $ext[count($ext)-1];


if($ext == "jpg" || $ext == "jpeg")  
    $im = imagecreatefromjpeg($tmpname);  
elseif($ext == "png")  
    $im = imagecreatefrompng($tmpname);  
elseif($ext == "gif")  
    $im = imagecreatefromgif($tmpname);  

$x = imagesx($im);  
$y = imagesy($im);  

if($x <= $xmax && $y <= $ymax)  
    return $im;  

if($x >= $y) {  
    $newx = $xmax;  
    $newy = $newx * $y / $x;  
}  
else {  
    $newy = $ymax;  
    $newx = $x / $y * $newy;  
}  

$im2 = imagecreatetruecolor($newx, $newy);  
imagecopyresized($im2, $im, 0, 0, 0, 0, floor($newx), floor($newy), $x, $y);  
return $im2;   

}</pre>