To Crop image using PHP GD function

cropImage(150,100, 'example.png', 'png', 'image.png');
function cropImage($nw, $nh, $source, $stype, $dest) {
$size = getimagesize($source);
echo "
".$w = 500;
echo "
".$h = 400;
switch($stype) {
case 'gif':
$simg = imagecreatefromgif($source);
break;
case 'jpg':
$simg = imagecreatefromjpeg($source);
break;
case 'png':
$simg = imagecreatefrompng($source);
break;
}
$dimg = imagecreatetruecolor($nw, $nh);
echo "
".$wm = $w/$nw;
echo "
".$hm = $h/$nh;
echo "
".$h_height = $nh/2;
echo "
".$w_height = $nw/2;
if($w> $h) {
echo "
".$adjusted_width = $w / $hm;
echo "
".$half_width = ($adjusted_width / 2)+25;
echo "
".$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);
}