php上传图片生成缩略图

function createThumbnail($imageDirectory, $imageName, $thumbDirectory, $thumbWidth, $quality){
$details = getimagesize("$imageDirectory/$imageName") or die('Please only upload images.');
$type = preg_replace('@^.+(?<=/)(.+)$@', '$1', $details['mime']);
eval('$srcImg = imagecreatefrom'.$type.'("$imageDirectory/$imageName");');
$thumbHeight = $details[1] * ($thumbWidth / $details[0]);
$thumbImg = imagecreatetruecolor($thumbWidth, $thumbHeight);
imagecopyresampled($thumbImg, $srcImg, 0, 0, 0, 0, $thumbWidth, $thumbHeight,
$details[0], $details[1]);
eval('image'.$type.'($thumbImg, "$thumbDirectory/$imageName"'.
(($type=='jpeg')?', $quality':'').');');
imagedestroy($srcImg);
imagedestroy($thumbImg);
}
foreach ($_FILES["pictures"]["error"] as $key => $error) {
if ($error == UPLOAD_ERR_OK) {
$tmp_name = $_FILES["pictures"]["tmp_name"][$key];
$name = $_FILES["pictures"]["name"][$key];
move_uploaded_file($tmp_name, "data/$name");
createThumbnail("/location/of/main/image", $name, "/location/to/store/thumb", 120, 80);
//120 = thumb width :: 80 = thumb quality (1-100)
}
}
?>