ขอถามเกี่ยวกับการ crop ภาพครับ ผมพยายามหาในบอร์ดแล้วแต่ไม่เจอ

function cropImage($nw, $nh, $source, $stype, $dest) {

$size = getimagesize($source);
$w = $size[0];
$h = $size[1];

switch($stype) {
case 'gif':
$simg = imagecreatefromgif($source);
break;
case 'jpg':
$simg = imagecreatefromjpeg($source);
break;
case 'png':
$simg = imagecreatefrompng($source);
break;
}

$dimg = imagecreatetruecolor($nw, $nh);

$wm = $w/$nw;
$hm = $h/$nh;

$h_height = $nh/2;
$w_height = $nw/2;

if($w> $h) {

$adjusted_width = $w / $hm;
$half_width = $adjusted_width / 2;
$int_width = $half_width - $w_height;

imagecopyresampled($dimg,$simg,-$int_width,0,0,0,$adjusted_width,$nh,$w,$h);

} elseif(($w <$h) || ($w == $h)) {

$adjusted_height = $h / $wm;
$half_height = $adjusted_height / 2;
$int_height = $half_height - $h_height;

imagecopyresampled($dimg,$simg,0,-$int_height,0,0,$nw,$adjusted_height,$w,$h);

} else {
imagecopyresampled($dimg,$simg,0,0,0,0,$nw,$nh,$w,$h);
}

imagejpeg($dimg,$dest,100);
}